ET205 Densimeter Repair (1)

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One VolumeRevision 1.03

ET-205TN Densimeter Repair


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Introduction

Defini tion of Terms

Theory of Operation

Radiation Safety Review

Detector Assembly

BJ Digital Transmitter

Controllers/Data Acquisition Systems

Specifications andConversions

Nuclear Densimeter Calibration

Nuclear Density


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Nuclear Densimeter IntroductionET-205 Densimeter Repair

BJ Services IntroductionBJ Services is an oilfield service company specializing in pressure-pumping and coiled tubingoperations. A large part of the pressure pumping services include the cementing and stimulation of wells. These services require a means to measure the density of the various slurries pumped into the well

during a given job.Nuclear Densimeter Introduction

To this end, BJ utilizes the TN Technologies Nuclear Densimeter, which measures the density of a slurrythrough radiation detection. This method of measurement works well with both proppant-laden and cement-laden slurries. This device, however, is extremely sensitive, and the Electronic Technician, or ET, is usually assigned the duty of ensuring the Nuclear Densimeter works properly.


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Scope Of This Manual

Nuclear Densimeter Introduction Terminology Theory Of Operation Radiation Safety Course Review Detector Assembly

Transmitters Specifications Conversion Calibration Maintenance Troubleshooting

Scope Of This ManualIn order to properly maintain the Nuclear Densimeter, the ET must first understand both Operational and Standardization procedures. The scope of this course, then, can be divided into three main objectives:

Operation

Standardization Duties Of The Electronic Technician

OperationBefore an Electronic Technician can perform his required duties for the Nuclear Densimeter, he mustfirst understand its operation (bullet points 1-6), down to the electronic level.

StandardizationWith BJs acquisition of various oilfield service companies through the years, the issue of

standardization (bullet points 7-8) has increased in importance. The Instrumentation Engineeringdepartment has made the effort to incorporate the plug n play concept, where if a district borrows a

Nuclear Gauge, or any other piece of instrumentation from another district, no modification is necessary.The device is simply hooked up and used for the job. While these various companies use the same

Nuclear Technology, there are electronic differences that can make the plug n play concept difficultto implement It is the responsibility of the ET to ensure that all Nuclear Densimeters are wired the same


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Transmitter

TN Nuclear Densimeter

0-10VDC Signal

15VDC Power

Nuclear Densimeter/Transmitter

TN Nuclear Densimeter/Transmitter RelationshipTo receive its needed dual-polarity power, the TN Nuclear Densimeter is typically connected to atransmitter. There are additional functions of the transmitter, which are discussed in Section 3, Nuclear

Densimeter Theory of Operation . The slide above shows a Gauge connected to a BJ Digital Transmitter,

operating as a Stand Alone Transmitter . In addition to this type of transmitter, there are other devicesthat possess the capacity to power a Gauge. These include: Data Acquisition Systems Control Systems


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3305 Mini Monitor 3600 Well Treatment A nalyzer

Data Acquisition Systems

Data Acquisition SystemThe primary function of a Data Acquisition System is to monitor and record the processes during a job.In addition to this function, they possess the capacity to power a Nuclear Densimeter. The dataacquisition, or monitoring systems used by BJ include:

3305 Mini Monitor 3600 Well Treatment Analyzer Isoplex36 Well Treatment Analyzer Isoplex DAU

Operations ManualsEach data acquisition system listed has an operations manual available which discusses the connection of a Nuclear Densimeter, therefore they are not covered in this manual. The 3305 Mini Monitor is

mentioned in the Calibration section to demonstrate the calibration procedure for a Nuclear Densimeter.


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Pendant Contro l System

611C Control System

Control Systems

Control SystemsThe primary function of a control system is to regulate the processes of a job. Similar to the dataacquisition systems, most control systems have the ability to power a Nuclear Densimeter. Theseinclude:

Pendant Control System (shown above) 611C Control System (shown above) Universal Control Module II (UCM II) Mixing Control Module Series (MCM Series) Automatic Cement Controller II (ACC II)

The Nuclear Densimeter provides the Operator with a density reading at the controller and, on blendersused in stimulation applications, this density reading from the Gauge can be compared with the densityreading calculated from sand-screw rpm's for control purposes.


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125C Blender

8 Nucl ear Densim eter, Mounted on 125C Blender

Stimulation Applications

Stimulation ApplicationsWhen used in stimulation applications, a Nuclear Densimeter is usually mounted at the followinglocations:

Blender discharge line (Low Pressure)

The Treating Line (High Pressure)Nuclear Densimeter Mounted On The Blender

A Gauge is mounted on the discharge side of a blender, so that the Operator knows the density of theslurry as it leaves the blender tub. At this point in the process, the slurry is pumped at low-pressure,ranging between 40-100 PSI. The advantage of the low pressure Densimeter is its rapid response tochanges in concentration. Once the slurry leaves the blender, it enters the frac pump(s). The photosabove show a low pressure Nuclear Densimeter mounted on a 125C blender discharge line.


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Nuclear Densimeter, Mounted i n the Treating Line

Stimulation Applications

Nuclear Densimeter Mounted In The Treating LineOnce the slurry exits the frac pumps, it travels to the well head under high pressure via the treating line.A Gauge is mounted on a short line (Pup Joint) and installed in the treating line in order to monitor thedensity of the slurry just before it enters into the well head. Pressure in the treating line may approach

15,000 PSI, and in some cases, 20,000 PSI. The photo above shows a Nuclear Densimeter mounted inthe treating line. Because the low pressure slurry from the blender may contain some air, thus limitingthe accuracy of the low pressure Nuclear Densimeter, the high pressure Densimeter is generally moreaccurate. Additionally, having two Nuclear Densimeters on the job provides backup insurance and ameans for comparison. For these reasons, a high pressure Nuclear Densimeter is normally used on every

job.

Additional Application

In addition to stimulation applications, the Nuclear Densimeter can be used in cementing applications.


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RAM Cement Uni t

Nuclear Densimeter, Mounted on RAM Cement Unit

Cement Applications

Cementing ApplicationsWhen used in cementing applications, a Nuclear Densimeter is mounted on cement units (on-shorecement applications), or cement skids (off-shore cement applications). For these applications, the

Nuclear Densimeter is usually powered by one of the following:

AutomaticCement

Controller II (Control System) 3305 Mini Monitor (Data Acquisition System) 3600 Well Treatment Analyzer (Data Acquisition System)

The Automatic Cement Controller IIWhen powered by the Automatic Cement Controller II , or A C C II, the Nuclear Densimeter can be used to provide feedback to the A C C II, in order to regulate the cement-mixing process. Additionally, it is

possible to serially link the A C C II and the 3305 Mini Monitor so that the density reading can betransmitted to the 3305 for monitoring and recording purposes.

The 3305 Mini MonitorIn some instances, a DB-IV electronic densimeter is used to regulate the cement-mixing process. In thiscase, the Nuclear Densimeter is powered by a 3305 Mini Monitor and used for monitoring and recording

purposes.


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Review QuestionsIntroduction, Densimeter Repair

1. The Nuclear Densimeter can be mounted on a wide range of pipe sizes. For BJ

Services, this range is from 2 to 10 in. If the Gauge is removed from one pipe and mounted on another, it must be ____________________.

2. Specifications list the Operating Temperature as __________ to __________F(__________ to __________C).

3. Depending on the Density of the Fluid circulating through the pipe, the Gauge outputsa ____________________ Non-Linear Signal.

4. The Nuclear Densimeter requires ____________________ to operate.

5. When used in Stimulation Applications, a Nuclear Densimeter is usually mounted atthe following locations: _________________________ (Low Pressure) _________________________ (High Pressure)

6. The advantage of the Low Pressure Densimeter is its ____________________ tochanges in Concentration.


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Review QuestionsIntroduction, Densimeter Repair

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Definition Of TermsDensimeter Repair

Definition Of TermsThe first step an Electronic Technician, or ET, must take toward learning Nuclear Densimeter operationis to understand the associated terminology used by Operations personnel. This is important because,usually, the ET isnt on location where job problems may occur. When the equipment arrives to the

yard, the ET must repair the problem, and the Operator is usually the only person who can tell the ETexactly what happened. The Electronic Technician, however, must be capable of interpreting thenecessary information from the Operator. To achieve this goal, this section discusses terminologyassociated with the Nuclear Densimeter that is used at the operations level.


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DensityThe density of a material is defined as the ratio of a materials weight to the volume that it occupies. For example, if a 1-gallon ( volume ) bucket is completely filled with water, it weighs 8.34 pounds ( weight ).Therefore:

Units Of MeasurementFor BJ Services US Operations, the units of measurement for density are usually expressed in pounds

per gallon , or PPG. For International Operations, the units of measurement for density are expressed inkilograms per cubic meter (kg/m 3), or kilograms per cube.

PPG8.34Gallon

Lbs 8.34

Gallon

Pounds 8.34

(Volume)Gallon1

(Weight)Pounds8.34 Water Of Density ====

Density = =Weight

Volume

Weight Volume

Density


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Bulk Density14.3 PPG

Absolute Density22.1 PPG

Example: 20/40 Sand

Types Of Density

Types Of DensityDensity can be divided into 2 distinct categories:

Bulk Density Absolute Density

Bulk DensitySome materials, such as sand, are granular, or powdered in nature. These materials have air pockets

between the grains, or particles. The total volume that the material and the air pockets occupy is referred to as bulk volume . Bulk density can then be defined as the ratio of a materials weight to its bulk volume.

Absolute DensityOther materials, such as liquids, are continuous in nature. That is to say, there is no air pockets, or voids,

in the material. The volume of space that a material occupies, without any air pockets, is referred to asthe absolute volume . Absolute density can then be defined as the ratio of a materials weight to itsabsolute volume.

Bulk Density Versus Absolute DensityIn its natural state, 20/40 sand is a granular material. If a 1-gallon bucket is completely filled with sand,


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1 Gallon8.34 Pounds 8.34 PPG

.045 Gallon1.00 Pound 22.1 PPG

1.045 Gallons9.34 Pounds9.34 Pounds

Slurry

+ Absolute Volume, not Bulk

1.045 Gallons

Slurry Density = Slurry = 8.93 PPG

Absolute Density, not Bulk

Base Fluid

MaterialType Weight(Pounds) Volume(Gals) Density(PPG)

20/40 Sand

Absolute Density

Properties Of MixturesWhen a proppant, such as 20/40 sand, is mixed with a base fluid, such as water, the entire mixture may

be thought of as continuous. That is to say, the space between the grains of sand is no longer filled withair, but is filled with fluid. In the case of proppant laden slurries, it is important to use the absolutevolume, rather than the bulk volume of the sand when computing the total volume and density of theentire mixture.


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Proppant ConcentrationProppant concentration is a measurement of the amount of a material that is contained in a unit volumeof a mixture or solution. For BJ Services applications, the amount of sand added to 1-gallon of basefluid is referred to as the proppant concentration. The units for proppant concentration are pounds of sand added, or PSA.

Density/Proppant Concentration RelationshipAs the above diagram shows, density is not the same as proppant concentration. Density is expressed inunits of pounds per gallon (PPG), while proppant concentration is expressed in units of pounds of sand added to 1 gallon of base fluid (PSA). These two items, however, are directly related. The followingequation mathematically relates density to proppant concentration:

Keep in mind that the proppant concentration is in units of PSA, and all density measurements are in

( )

=

DensityProppantDensitySlurry

1

DensityFluidBase-DensitySlurry ionConcentratProppant

1 Gallon

Base Fluid

8.34 PPG

.045 Gallon 22.1 PPG

1.045 Gallon

20/40 Sand

Slurry

+ Absolute Volume, not Bulk Absolute Density, not Bulk

Proppant Concentration = 1 PSA

Slurry Density = 8.93 PPG

MaterialType Weight(Pounds) Volume(Gals) Density(PPG)

9.34 Pounds

1.045 Gallons

8.34 Pounds

1.00 Pound

9.34 Pounds

Proppant Concentration


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Specif ic Gravity = =Materials Density

Water Density

Material Water

=

Water = = 1.0 (No Units)= Water

Water

8.34 PPG

8.34 PPG

Specific Gravity

Specific GravityThe specific gravity of a material is the ratio of the materials density to the density of water, which is8.34 PPG. Since the units, PPG, are both in the numerator and in the denominator, they cancel, whichmeans that specific gravity does not have any units associated with it .

Specific Gravity Of Water, WaterTo obtain the specific gravity of water, Water , take the density of water, 8.34 PPG, and ratio it with itself,to obtain a result of 1.0, as mentioned before there are no units.


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Density Units For Various Applications

Stimulation Applications Density Pounds Per Gallon, or PPG

Proppant Concentration Pounds Sand Added to 1 Gallon of clean fluid, or PSA Pounds Proppant Added to 1 Gallon of clean fluid, or PPA

Cement Applications Density

Pounds Per Gallon, or PPG

Sand Control Applications Proppant Concentration

Pounds Sand Added to 1 Gallon of clean fluid, or PPG

Density Units For Various ApplicationsThe items above list the units that are used to express density and proppant concentration for the variousapplications within BJ Services. For both stimulation and cementing applications, the units used for density and proppant concentration are consistent with the units described in this section. In Sand Control applications, however, proppant concentration is expressed in units of PPG.


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Review QuestionsTerminology, Densimeter Repair

1. The first step an Electronic Technician, or ET, must take toward learning Nuclear

Densimeter Operation is to understand the associated ____________________ used by Operations Personnel.

2. The Density of a material is defined as the Ratio of a materials____________________ to the ____________________ that it occupies.

3. For BJ Services U.S. Operations, the Units Of Measurement for Density are usuallyexpressed in ____________________ . For International Operations, the Units Of

Measurement for Density are expressed in ____________________ .

4. The ____________________ can then be defined as the Ratio of a materials Weight to its Bulk Volume .

5. The ____________________ can then be defined as the Ratio of a materials Weight to its Absolute Volume .

6. In the case of Proppant Laden Slurries, it is important to use the ____________________, rather than the ____________________ of the sand whencomputing the Total Volume and Density of the entire mixture.

7. In BJ Services, the amount of sand added to 1 unit volume of Base Fluid is referred toas the ______________________________.

8. The units for Proppant Concentration are _________________________

9. The ____________________ of a material is the ratio of the materials density to thedensity of water, which is 8.34 Pounds per Gallon.


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Nuclear Densimeter Theory Of OperationET-205 Densimeter Repair

Theory Of Operation Now that terminology has been covered, the ET is ready to learn how a Nuclear Densimeter Gaugeworks. This section provides the ET a general overview of the operation of a Nuclear Gauge.


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RadiationEnergy

process fluid

pipe

radiationsource holder

Detector Assembly

Transmitter

Main Components

Main ComponentsThe drawing above shows the main components of the Nuclear Densimeter, which includes the:

Radiation Source Holder Process Fluid Pipe Detector Assembly Transmitter

This section discusses the components in the order listed, since the radiation energy originates at theradiation source holder and interacts with the remaining components in this sequence.


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RadiationEnergy

Lead FilledHousing

Cesium 137finished source

0-10VDC

Radiation Source Holder

Radiation Source HolderThe radiation source holder consists of a protective lead-filled housing and a small Cesium-137 finished source pellet. The housing has a small window which serves to focus the radiation beam from thefinished source.

Radiation StrengthsRadiation strengths are available in: 50 mCi (millicuries) or 1.8 GBq (gigabequerels) 100 mCi (3.7 GBq) 200 mCi (7.5 GBq)

Radiation WindowRadiation energy is emitted from the finished source uniformly in all directions. Because the source is

mounted inside the lead-filled housing, the radiation energy is unable to penetrate the lead walls, and cantravel only through a cavity or window. The radiation energy collimates into a relatively narrow 12 -13 beam that travels through the process fluid and pipe, which is then received by the Detector Assembly.


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Lead FilledHousing Cesium 137finished

source

Cavity

shutter

Radiation Source Holder

Radiation Source HolderThe photo above shows a cutout view of a radiation source holder, with a simulated radiation sourceinstalled . Notice the lead-filled housing walls. The Cesium 137 finished source is mounted in thecavity, as shown. The radiation energy can escape only through the cavity. A stainless steel disc, welded in place, protects the cavity from external contamination.

Shutter Notice also that this particular radiation source holder has a slide gate, or shutter associated with it.When closed, the shutter places lead plates over the cavity, which blocks all radiation. This type of source allows the radiation source holder to be removed by qualified personnel. Shutters are used withradiation source holders that are mounted on process fluid pipes ranging from 5-8, typically low

pressure applications. Some 4 applications may also use a shuttered source, but this is not common.

NOTE BJ Services personnel DO NOT have the authorization to open the radiation source holder, or toremove a non-shuttered source from the pipe. Only TN Technologies personnel may do so.


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RadiationEnergy

ProcessFluid

0-10VDC

Process Fluid Pipe

process fluid

pipe

Process Fluid PipeWhile the radiation energy travels across the process fluid pipe, its magnitude is attenuated, or weakened, by the process fluid traveling through the pipe. As the density of the process fluid increases ,the magnitude of the radiation energy reaching the Detector Assembly decreases .

Empty Process Fluid PipeIf the process fluid pipe is empty, the radiation energy effectively passes through unmolested (neglectingthe radiation attenuated by the process fluid pipe); and reaches the Detector Assembly at what isconsidered to be full magnitude.

Light Fluid in the Process Fluid PipeA light fluid is a fluid with a relatively low density. Water, with a density of 8.34PPG, is a good example. If water passes through the process fluid pipe, the magnitude of the radiation energy reaching

the Detector Assembly is inversely proportional to the water density.Heavy Fluid in the Process Fluid Pipe

A heavy fluid is a fluid with a relatively high density. Cement and proppant laden slurries are good examples. If a slurry passes through the process fluid pipe, the magnitude of the radiation energyreaching the Detector Assembly is attenuated even further.


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RadiationEnergy

0-10VDC

Detector Assembly

Detector Assembly

Detector AssemblyThe Detector Assembly consists of the following major subassemblies:

Ion Chamber High Voltage Board Preamplifier Board

Because there are a number of things that can be done to repair and maintain these components, both the preamplifier board and high voltage board are discussed in detail in this manual. The ion chamber isdiscussed, but is a sealed component that cannot be repaired by an Electronic Technician. A generaloverview, however, will be given on all three components.

Role of the Detector AssemblyWhen properly powered, the ion chamber converts received radiation energy into a proportional currentsignal that is sent to the preamplifier board; where it is converted and amplified to a proportional voltagesignal of 0 to 10V DC. This non-linear 0 to 10V DC voltage signal is then sent to the Transmitter through a10-Pin connector.

Density of the Process FluidIf the process fluid pipe is empty (density = 0.00PPG), then most of the radiation energy reaches thed bl Thi b i h h l i l f h d bl i 10V


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+-

-

+ +

- ---

----

+

++ +

-

RadiationEnergy

+

-

+

-

Ano de

Cathode

Ion Chamber Filled with XenonGas

Positrons

ElectronsV

R

V

Ion Pair

CurrentSignal

Ion Chamber

Ion ChamberThe Ion Chamber is a cylinder that receives radiation energy and converts it into a proportional electricalsignal. The assembly consists of a stainless steel cylinder filled with xenon gas and an insulated center wire. A stable +1400V DC from the high voltage board is applied to the wall (canister) of the ionchamber . The TN Technologies Densimeter is configured so that the chamber wall acts as an anode and the wire acts as a cathode. The principle is similar to that of a Geiger Counter, however most Geiger Counters use polarity which is reversed from the above example.

Ion Chamber OperationIonization is the process of an atom becoming charged due to its losing or gaining an electron. When theradiation energy enters the ion chamber, it ionizes with the xenon gas, creating ion pairs. Each ion pair consists of:

A Negative Ion (also known as an Electron) A Positive Ion (also known as a Positron)

The positrons are drawn to the wall of ion chamber, while the faster moving electrons are drawn to thewire. A charge collects on the Anode, resulting in a voltage change in the circuit. The size of thisvoltage change depends on the number of electrons collected from the ionizing process. This causes aproportional current signal to flow to the preamplifier board, where it is then converted to a voltage


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high voltageboard

preamplifier board

IonizationChamber

Lead Shield

Detector Assembly

Detector AssemblyThe photo above shows the detector assembly. The high voltage board is mounted above the ionchamber. The lead shield, mounted on the top plate, blocks radiation from passing through thesignal/power connector. This shield might not be found on new units.


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RadiationEnergy

0-10VDC

15VDC

Transmitter

Transmitter

TransmitterA transmitter provides four important functions:

Linearizes the 0-10VDC density signal Displays the density Supplies the Nuclear Densimeter with 15V DC Transmits the density signal to a remote monitor via frequency signals, analog signals or digital

communication.A transmitter linearizes the voltage signal from the Detector Assembly and produces a numerical value,which is indicative of the density for the process fluid. Additionally, it provides a display of the densityfor the Operator.

Proppant ConcentrationIn stimulation operations, the transmitter also calculates the proppant concentration in the fluid.Proppant concentration is measured in units of PSA, or Pounds Sand Added .

T i


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3305 Mini Monitor 3600 Well Treatment Analyzer Pendant Contro l System

Anal og Tr ansmit ter TN Nuclear Transmitter Digital Transmitter

Transmitters

TransmittersThere are a number of devices that may be utilized, in whole or part, as a Transmitter.

TN Analog Transmitter TN Digital Transmitter BJ Digital Transmitter 3305 Mini Monitor 3600/Isoplex36 Well Treatment Analyzer Pendant Control System MCM 1000 Series (Not shown)

N l D i t R i


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RadiationEnergy

0-10VDC

Nuclear Densimeter Review

process fluidpipe

radiationsource holder

Detector Assembly

Transmitter

Nuclear Densimeter ReviewThe Nuclear Densimeter consists of four main components:

Radiation Source Holder Process Fluid Pipe Detector Assembly Transmitter

The radiation source holder emits radiation energy through the process fluid pipe. Depending on thedensity of the process fluid passing through the pipe, the proportional magnitude of the radiation energyis received by the Detector Assembly, where it is converted to a 0-10VDC non-linear signal. This signalis passed on to the transmitter, where the voltage signal is linearized, converted into a density reading,displayed for the Operator, and made available for a remote monitor.

Review Questionsh f


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Theory of Operation, Densimeter Repair

1. The Radiation Source Holder consists of a protective ______________________________ and a small ____________________ Finished Source pellet. The housing has a small ____________________ which serves tofocus the radiation beam from Finished Source.

2. BJ Services Personnel ____________________ have the authorization to open theRadiation Source Holder, or to remove a non-shuttered Source from the pipe.

3. Additionally, when the Shutter is in the ON position, stay at least

____________________ away and keep others away from the gauge.

4. As the Density of the Process Fluid ____________________ , the magnitude of theradiation energy reaching the Detector Assembly ____________________ .

5. It important to keep the _________________________of the Process Fluid Pipe asclean as possible. Even a small buildup of sand or cement within the pipe cansignificantly alter the readings of the Nuclear Densimeter.

6. When properly powered, the ____________________ converts received radiationenergy into a proportional Current Signal and sends it to the Preamplifier Board

7. If the Process Fluid Pipe is empty (Density = 0.00PPG), the ____________________ of the radiation energy reaches the Detector Assembly.

8. When the radiation energy enters the Ion Chamber, it ionizes with the Xenon Gas,creating ____________________.

9. The ____________________ linearizes the Voltage Signal from the Detector Assembly and produces a numerical value, which is indicative of the Density for theProcess Fluid. Additionally, it provides a display of the Density for the Operator.

Review QuestionsTh f O i D i R i


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Theory of Operation, Densimeter Repair



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Radiation Safety ReviewET-205 Densimeter Repair

Radiation Safety ReviewSo far in this presentation, the Nuclear Densimeter has been discussed on a general level. In the sectionsto follow, a more in depth discussion is given, which involves opening the Detector assembly, calibrationand troubleshooting. Whenever working around a device that is radioactive, safety must always be a top

priority for the ET and personnel in the area. Before going forward, a review of the Radiation SafetyCourse is given in this section.

Radiation Safety CourseThe purpose of the Radiation Safety Course, offered by TN Technologies, is to provide personnel with ageneral understanding of the possible hazards associated with Nuclear Densimeters. Additionally, thecourse explains how to work confidently and safely around this device.

A PrerequisiteThis section is intended only as a supplement to the Radiation Safety Course offered by TNTechnologies. Before an Electronic Technician can handle/repair a Nuclear Densimeter, he mustsuccessfully complete the Radiation Safety Course. This is necessary due to the potential hazards if theDensimeter is handled incorrectly.

Topics of Discussion

What Is Radiation?


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What Is Radiation?

Alpha Radiation Beta Radiation Gamma Radiation X-Ray Radiation Neutron Radiation

What Is Radiation?In order to work safely around Nuclear Gauges, one must first understand some basic facts aboutradiation. Radiation originates from atoms, which are the building blocks of all matter. Certain atomsare at excited states and release energy in the form of radiation. This energy is transferred as either

particles or electromagnetic waves.

Types Of Ionizing RadiationThere are 5 types of Ionizing Radiation:


Each has a unique penetrating ability that needs to be considered when protecting oneself fromRadiation.

What Is Radiation?


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What Is Radiation?


Alpha RadiationAlpha radiation occurs when the atom emits large atomic particles. These particles have very littleexternal penetrating power, and can be shielded with something as thin as a piece of paper. Whenexposed externally to Alpha radiation, it poses no external hazard because it can be shielded by the dead layer of skin covering the body. Alpha radiation, however, can be internally harmful if inhaled or

ingested.Beta Radiation

Beta radiation occurs when the atom emits small, fast moving particles known as electrons. These particles are more penetrating than Alpha particles, but are still considered to have relatively low penetrating ability. Beta radiation can be easily shielded by materials such as cardboard or plastic. Itcan, however, penetrate the dead layer of skin on the body.

Gamma RadiationGamma radiation occurs when electromagnetic waves are emitted from an atom as a result of radioactivedecay. This form of radiation has a high penetrating ability, and is considered an external threat.Gamma radiation can be shielded by a dense material such as concrete or lead.

X-Ray Radiation


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Using Radiation Safely


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AL

AR

A

sowseasonablychievable

g y

Safety FactorsThe different types of ionizing radiation are harmful, but there is a very little risk associated with thelow levels of radiation of a Nuclear Densimeter . Nevertheless, in practice a person should keep hisexposure As Low As Reasonably Achievable , or ALARA . This can be done by following 3 simpleconcepts:

Time Distance Shielding

TimeThe more Time one remains in a radiation field, the larger the radiation dose. At times, especially duringemergencies, work must be performed in a strong radiation field. In this case, the work procedure should

be carefully planned outside the work area so that a minimum amount of Time is used to complete the

job. If the Time required for one man to complete the job would result in an exposure beyond prescribed limits, then a team of workers should be employed. This would mean a small exposure for several

people instead of a large exposure for one person.

DistanceRadiation is emitted from a point source uniformly in all directions The further one is from the

BJ Services Radiation Protection Manual


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Emergency Instructions Radiation Program Management Organization Radioactive Materials Records Management Radioactive Materials - Employee Notices and

Instructions

Use of Densimeters Having Nuclear Gauges Transportation Procedures Handling Procedures Radiation Protection Program Review Nuclear Gauge Procedures

BJ Services Radiation Protection ManualThe Nuclear Regulatory Commission, and equivalent Agreement States have strict safety standards for

Nuclear Densimeters. These strict regulations for radioactive material provide a high degree of worker and environmental safety when dealing with radiation. Each state, or country, operates under a specificradioactive materials license or a manufacturers general license. Individuals operating Nuclear

Densimeters should be aware of the license conditions and follow them accordingly. There are,however, BJ specific regulations that must be followed regardless of state, or country, which are listed inthe BJ Services Radiation Protection Manual . The topics in this manual include:

Emergency Instructions Radiation Program Management Organization Radioactive Materials Records Management Radioactive Materials - Employee Notices and Instructions Use of Densimeters having Nuclear Gauges Transportation Procedures Handling Procedures Radiation Protection Program Review Nuclear Gauge Procedures

Labels


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CAUTION RADIOACTIVE MATERIAL

ISOTOPE

AMOUNT

DATE MEAS .

MODEL

SERIAL NO .

Texas Nuclear ProductsTN Technologies

DO NOT REMOVE TAGMADE IN USA

5190

BXXX

Cs-137

EMPTY

09/97

BJ DEMO TAG NO.

Radiation Source Holder PlaqueThe Radiation Source Holder Plaque , which provides information about the finished source, is mounted on the end of the Radiation Source Holder . When installing or removing a Nuclear Gauge, be carefulnot to drag the Radiation Source Holder on the ground, as this could destroy the information on the

plaque, resulting in a loss of critical information.

Missing Or Illegible PlaqueMissing or illegible plaques must be replaced immediately. These plaques must be ordered through themanufacturer. A missing or illegible plaque renders the device out of service until a replacement plaqueis mounted.

Labels


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R A D I O A C T I V E I I

C O N T E N T S : C

E S I U M 1 3 7

A C T I V I T Y :

7 T

R A N S P O R T I N D E X

RAY II Label

R A D I O A C T I V E I I

C O N T E N T S : C E S I U M 1 3 7

A C T I V I T Y :

7

T R A N S P O R T I N D E X

RAY II Label

USA DOT 7ATYPE A

RADIOACTIVEMATERIAL

SPECIAL FORM, N.O.S.,UN 2974 (CS-137; SEALED)

Notify if found:BJ SERVICES CO., USA

HOUSTON, TEXASEmergency RSO contact:

(281) 351-8131 24 hour

Marking Label

LabelsTo comply with the licensing agreement, every Nuclear Density Gauge must have two RadioactiveYellow II Labels (RAY II Labels) and one Marking Label .

Radioactive Yellow II Labels (RAY II Labels)The 2 Radiation Yellow II, RAY II, Labels must be placed on the Radiation Source Holder on oppositesides. A RAY II Label displays the following information:

Contents (Always Cesium 137 for BJ Services) Activity (In Gigabecquerels, GBq) Transport Index

This activity can be obtained from the AMOUNT reading on the Radiation Source Holder Plaque. TheAMOUNT value is expressed in units of millicuries, so a unit conversion is necessary. (100mCi =3.7GBq and 200mCi = 7.4 GBq).

Transport IndexWhen transporting the Nuclear Densimeter, the TRANSPORT INDEX must be filled in. This value isdetermined by taking the highest radiation survey meter reading at any point 1 meter (39 inches) fromany surface of the Radiation Source Holder. The value must be less than 1.0 (no units necessary) to useh RAY II L b l Th T I d i i h h (E l 0 3 0 25)

Review QuestionsRadiation Safety Review, Densimeter Repair


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1. Radiation originates from ____________________, which are the building blocks of all matter.

2. When exposed externally to _________________________, it poses no externalhazard because it can be shielded by the dead layer of skin covering the body.

3. _________________________ can be easily shielded by materials such as cardboard or plastic.

4. ____________________ Radiation has a high penetrating ability, and is considered an external threat. Gamma Radiation can be shielded by a dense material such asconcrete or lead.

5. The more time spent around a radioactive source, and the closer the distance to thesource, a greater ____________________ results.

6. A person must physically come in contact with, and take a portion of the radioactive

material to become ____________________

7. A ____________________is defined as a physical entity placed between theRadiation Source and the object to be protected in order to reduce the Radiation Levelat the objects location.

8. The ______________________________, which provides information about theFinished Source, is mounted on top of the Radiation Source Holder.

9. The 2 Radiation Yellow II, RAY II, Labels must be placed on the _________________________ on opposite sides.

10. When transporting the Nuclear Densimeter, the ______________________________ must be filled in. This value is determined by taking the highest radiation surveymeter reading at any point 1 meter (39 inches) from any surface of the RadiationSource Holder.

Review QuestionsRadiation Safety Review, Densimeter Repair


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Detector AssemblyET-205 Densimeter Repair


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ET 205 Densimeter Repair

RadiationEnergy

Detector Assembly

Nuclear DensimeterThe Fast Start Up (FSU) detector is an improved version of the early SGO detector. This section of the

presentation will deal with the theory of operation and maintenance of the FSU. The following will bediscussed in this section:

General theory of operation review

FSU and SGO Gauge comparisons High Voltage and Preamplifier Board circuit detail Calibration and adjustments Maintenance and Troubleshooting Procedures

NoteOnly personnel who have successfully completed an approved Nuclear Safety Course are permitted toservice nuclear densimeter systems.

Detector Assembly


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IonizationChamber

High VoltageBoard Preamplifier

Board

Densimeter Detector AssemblyThe above photo shows a Detector Assembly, also known as an FSU Gauge. The primary subassembliesthat make up the FSU Gauge are:

Ionization Chamber, or Ion Chamber High Voltage Board

Preamplifier Board Types of Detector Assemblies

BJ has used two types of TN Technologies Gauges: TN SGO Gauge (Obsolete) TN FSU Gauge

NOTESeveral activities using a Detector Assembly and simulated nuclear sources will be performed in theclass. Because there may be residual high voltage present after power is removed, be careful not touchthe Ion Chamber when removing it from the housing. To discharge the residual voltage, first connect a

jumper to one of the grounded aluminum plates separating the boards. Next, touch the other end of the jumper to the body of the Ion Chamber.

Nuclear Densimeter Block Diagram


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+ 1400 V

Gain(For Analog Transmitter Only)

IonChamber

Preamplifier Board

High VoltageBoard

GND-15V

+15V

GND-15V

+15V

0-10V

Power FromTransmitter

DensitySignal ToTransmitter

RadiationEnergy

Nuclear Densimeter Block DiagramThe diagram above shows how the components of the Detector Assembly connect.

Ion ChamberThe Ion Chamber consists of a stainless steel canister filled with Xenon gas at eight atmospheres. Aninsulated wire is inserted into the chamber, and high voltage potential is applied across the anode and cathode. Radiation energy received from the radiation source causes a release of free electrons from thegas. These electrons are attracted to the anode, which creates a small current flow into the preamplifier.

Preamplifier BoardThe preamplifier board converts and amplifies this current flow into a voltage signal that is inversely

proportional to the density of the material in the path of the radiation energy.

High Voltage Board

The high voltage board supplies a highly regulated +1400V DC, which allows sufficient voltage differencefor the attraction of the free electrons.

Power SourceThe Nuclear Densimeter is powered from an external 15V DC, which is supplied by a transmitter or other suitable power supply

Ion Chamber


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+-

-

+ +

- ---

----

+

+

+ +

-

Ion Chamber

RadiationEnergy

+

-

+

-

Ano de

Cathode

+ 1400 V

CurrentFlow

Ion ChamberGamma particles from the nuclear source striking xenon gas ions cause ionization to occur,which results in a current flow. This extremely small current flow is converted by the

preamplifier board into a representative 0 to 10V DC density signal.

Ion Chamber


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Adhes ive FromHeater Wrapping

Modified GaugeThe adhesive residue in the above photo identifies this Ion Chamber as part of a former SGO assembly.Due to the inherent sensitivity of the obsolete SGO Gauge to changes in temperature, a heater was taped to the Ion Chamber in order to maintain a constant temperature inside the housing. Additionally, heater resistors on the top plate kept the electronics warm. Because of this temperature sensitivity, the SGO

Gauge required long a warm up time before the density readings would stabilize, usually about an hour or more in cold climates. Upgrading an SGO unit consists of replacing the two boards and removing theheater.

The FSU GaugeThe improved FSU Gauge contains temperature stabilization circuitry that enables it to remainremarkably stable over a wide range of temperatures. Additionally, the warm up time from initial

power up is dramatically reduced to 15 minutes or less.

High Voltage To Ion ChamberThere is a +1400V DC potential applied to the Ion Chamber. Although the actual measured voltage has a100V tolerance, it must be well-regulated, because any fluctuation, no matter how slight, will cause acorresponding change in the output signal voltage .

FSU High Voltage Board


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Drain Wire

InsulatedCollar

High Voltage BoardThe high voltage board provides the potential necessary for ionization to occur. This voltage must bewell regulated, as any fluctuation will result in a corresponding signal output change. The board uses15V DC, supplied by an external power source, for conversion to +1400V DC at approximately 20 A.The output voltage may be within 100V of the specified voltage, but should have no measurable

fluctuation. In the photo shown, notice the Drain Wire , separated from the Ion Chamber by an Insulated Collar . This combination is used to drain any static voltage, and to act as an electrostatic shield for thesignal current, thereby reducing noise pickup. The signal output current from the Ion Chamber is verysmall, in the order of nano amps (nA), so even minimal electrical interference can cause large errors inthe output signal.

High Voltage ProbeA high voltage probe should ALWAYS be used to measure the potential on the Ion Chamber. Most

modern digital volt meters will read only to 1000V, but this is not the only reason to use a high voltage probe. Because the high voltage board can supply only 20 A, if a conventional digital multimeter alonewere used for measurement the meters internal resistance (typically 10 M ) would drain much of theavailable current from the power supply, resulting in a erroneous reading. An example of a suitable

probe for high voltage use is the Fluke model 80K-40 High Voltage Probe, which is useful for readings

High Voltage Board/Ion Chamber Connection


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HVConnection

Screws

High Voltage Board/Ion Chamber ConnectionThe three screws that secure the high voltage board to the Ion Chamber also provide the electrical pathfor the 1400V DC to the Ion Chamber canister. It is important that these screws be properly tightened and free from corrosion. Removable thread lock, such as Locktite Green or Red , is recommended.Additionally, make sure that the star lock washers are in place.


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High Voltage Block Diagram


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-12VRegulator

Rectifier &Voltage Doubler

U3AU3B

15V +1400V(To Ion Chamber) Oscillator

Voltage Regulation & Filtering

High Voltage Operational Block DiagramThe high voltage circuit consists of a DC/DC converter that uses active voltage feedback for bothregulation and dynamic filtering of the output voltage. Major circuits on this board include:

Free-running LC sine wave oscillator Voltage regulator IC

Step-up power transformer Voltage Doubler circuit Active feedback voltage regulation

These circuits will be discussed shortly.

High Voltage OperationHigh voltage for the ion chamber is generated by a free running oscillator circuit, using a step uptransformer, along with active feedback to maintain constant voltage under varying loads.

Fusible Resistors


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High Voltage Board Power InputThe high voltage board power input is protected using 10 , 1/4 watt resistors on the input power. If found to be open, the cause of the short should be repaired and flame proof resistors installed.


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Voltage Doubler


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Fig 1

700V

- +

700V

- +

Fig 2

X

+ 700V = 1400V

CR2

CR1

C7

CR2

CR1

Voltage Doubler CircuitEarly SGO Detector Gauges used +700V DC to power the Ion Chamber. This high voltage was increased to +1400V DC on the FSU Detector Gauge in order to achieve improved sensitivity and stability. In order to achieve this higher potential with minimal component changes, a voltage doubler circuit, consisting of only two extra components (a diode and capacitor), has been added.

Theory Of OperationThe output from the secondary winding of the step-up transformer is an AC sine wave providing500VRMS. During the negative-going portion of this sine wave (Fig 1), CR1 conducts and charges C7 to +700V. When the sine wave begins going positive (Fig 2), its voltage is added to the +700V alreadyon C7 and then coupled through peak detector diode, CR2 , to give an output of +1400V. This isanalogous to the way batteries in series add their voltage.

NOTES

1. Due to the high frequency of the oscillator circuit, when replacing the diodes in the power supply useonly fast-switching replacements, not general purpose rectifiers.2. Loose lamination plates in the transformer may result in a high-pitched audible squeal. Although thehigh voltage circuit may work, extra energy is used to make the laminations resonate. The transformer h ld b l d

FSU Preamplifier Board


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Preamplifier BoardThe preamplifier board converts the current flow from the Ion Chamber into a proportional non linear voltage signal that represents actual density. It performs this task using a unique negative-going rampingaction, the slope of which varies in accordance with the incoming current. This ramp is then converted into a DC voltage, inversely proportional to density.

FSU Preamplifier Board FeaturesFeatures of the FSU preamplifier board include:

Quick warm up using temperature compensation circuitry. On-board regulation of input power supply voltage. Output span adjustable via active gain set jumpers. Gain fine adjust using trim pot.


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Power Input

Fusible


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Fusibleresistors

Power InputFusible 10 , 1/4 watt resistors are used on the preamplifier board for short-circuit protection. Becausean open resistor may be difficult to spot visually, supply voltage measurements should be taken not at theconnector, but at the test points on the board. Flame-proof resistors should be used for replacement after the cause of the short is repaired.


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T 2

Summing Point

Converting Ramp to Current


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T 2

U 2

R

14

13

TP 6C 12

.33 F

AR1

U 2Mult

T 2

10 M

C 5

V sig

Gain

TP 1

-15 V

AR4

+15V

-15V

Zero

C 13

330 pFR

15W 1

(X2 Mult)150 k

300 k

Zero VoltPotential

Q4R7

0 V

-+

Op Amp, AR1 , Converts Ramp To DC CurrentThe negative-going ramping voltage is changed to a proportional current at the summing junction of C12and R7 . Voltage output from AR1 holds the summing point voltage at ground potential so that TP6 rampvoltage also occurs across C12 .

IC, U2 , Sets The Overall GainThe Electronic Gain Set IC, LF13006, is similar to a resistor network, however the resistance iscontrolled using logic voltages.


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Ramp Integration

Ramp


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SummingPoint

OvervoltageProtection

RampConverted to

Current

Ramp InputFrom Preamp

NULL Adjustment

Potentiometer

Ramp Converted To DC VoltageThe sawtooth ramp must be converted into a proportional DC voltage for use by a suitable transmitter.This function is performed primarily via operational amplifier, AR1 , which converts the ramp into acurrent at the summing point, C12 & R7 , by feeding back its output voltage through R7 . This actionholds the summing point voltage at ground potential to ensure TP6 voltage change (ramp) rate alsooccurs across C12 . At the same time, capacitor, C5 , is seeing the same potential, but at this point has noground return path. A return path will be provided for the low side of this capacitor during the resetfunction in order to prevent the reset pulse from being seen on the output of AR1. Its operation will bediscussed later in the presentation.

AR1 ProtectionTwo back-to-back 15V zener diodes protect AR1 from external voltage spikes and prevent voltages inexcess of 15V from being seen on the signal output line, thereby protecting the external monitoringdevices.

Reset Circuit (Part of Preamplifier Board)T 2

C 12

AR1 AR4R6


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U 2

.33 uF

U 2Mult

T 2

C 5

K1

-15 V

C 13

330 pF

K 1

T 1

AR6

+10 V

-10 V

T 1

T 2

T 2

T 2

Reset Circuit

Q4R7

Ramp Reset CircuitSo far, only the ramp has been discussed. Because the signal cannot continue its negative rampindefinitely, a reset must take place when the ramp reaches a preset voltage limit . The ramping actioncan then then start again.

Sequence Of Events

In order to reset the ramp without causing an anomaly in the output signal, several events must occur simultaneously:

The signal path from AR4 to the output, AR1 , must be disabled to avoid a spike from being seenon the output signal. This is accomplished using an FET as an electronic switch, or gate, to openthe ramp signal path to the output IC during reset mode.

A reed relay is activated to discharge ramping capacitor, C13 , which causes the reset to occur. Another FET gate and a capacitor ( C5 ) are used as a version of a sample and hold circuit to keep

the output at its last voltage level during the reset action.This entire reset activity starts at virtually the same time (the actual reset time for C13 is slowed somewhat due to inherent mechanical delay of the reed switch), and takes approximately 80 millisecondsto complete . In order to understand the dynamics of the circuit, the reset action will be looked at first,then the FET gates controlling the output will be discussed.

Ramp Reset

RampInput


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0 V

+7.5 V

-10 V

Integration Mode

Reset Mode

0 V

-15 VT1+10V

-10V

To U3C

Voltage LimitsWhen the ramp voltage from the preamplifier reaches a predetermined positive or negative voltage level,an action will occur to reset the ramp. Voltage divider resistors, R27 , R32 , and R33 are connected to15V DC to form the positive and negative 10V reference for voltage comparator IC, AR6A and AR6B .This dual-package op amp senses the ramp voltage limits and triggers a positive output whenever theinput ramp from the preamplifier is equal to the reference voltage. In order to achieve a positive outputfrom either ramp extreme, AR6A is configured as a non-inverting output and AR6B is an inverter. The+10V DC reference voltage limit is connected to pin 6 of AR6A, and the-10V limit is tied to AR6B , pin 3.

NoteUnder normal operation, the ramp resets to +7.5V DC, which is set by voltage divider circuit consisting of

R30 & R31 (not shown in this drawing). The +10V DC limit is not normally activated, and will only beseen in the event of an abnormal condition, such as a saturated preamplifier input signal.

NAND GatesWhen AR6 output goes high, NAND gates will be activated. (NAND gates are inverting AND gates,therefore both inputs must be high for the output to go low.) An RC network makes these gates act

M bl M l i ib O Sh i h ill b i l l h b h

Output Signal During ResetT 2

AR1

U 2Mult

T 2

C 5

V sig

TP 1


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T 2 Gain

K1

AR6+10 V

-10 V

T 1

T 2

T 2

0 V

-15 V

From U3B

0 V

-15 V

PulseStretched

Output Must Be Stable During ResetIf no provision were made to hold the output signal from AR1 at a constant value during the reset portionof the ramp, the output voltage would drop to near zero during the reset period, resulting in a largedensity spikeseen at the transmitter and recorder. In order to avoid this situation, two additional

pulses , T2 and /T2 , are used to isolate the output during reset in an analog version of a sample-and-hold circuit.

Output Signal During Reset FunctionWhen a reset action starts, the pulse from T1 is stretched to approximately 80 milliseconds by an RCcircuit on the input of NAND Gate, U3 , starting at the same time as T1s pulse. (Stretching the hold

pulse allows time for the reed reset switch to complete its mechanical cycle.) Pulse T2 goes from -15Vto 0V and can be observed at TP3 . This same pulse is inverted by U3D , and seen at TP2 as a negativegoing pulse (/T2 ), from 0V to -15V. MOSFET, Q1 , is used as an ultra low-resistance switch (gate),which is turned off by the action of T2, thereby isolating the ramp signal. At the same time, another MOSFET, Q2, is turned on by /T2 to provide a return (through a 10 M resistor) for the voltage chargeacross C5 , effectively holding the output at its present value until the reset action is completed.

Integration FET Q6The pulse at /T2 also turns off FET Q6 The purpose of this semiconductor is to provide a ground return

TP 6C 12

T 2

Review of Reset and Output Circuit


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AR1

T 2

10 Meg

C 5

Gain

K1

-15 V

AR4

C 13

330 pF

300 K

K 1

AR6

+10 V

-10 V

T 1

T 2

T 2 0 V

-15 V

@ 60 msec

T 2

Reset Circuit

Reset Start

0V

+7.5 V

-10 V

Reset

Slope DeterminesOutput Signal

TP 6 Signal V R

Q4

0 V

-15 V

@ 30 msec

T1

0 V

-15 VT2

T2

Key Sequence SummaryTo summarize the sequence of events occurring during the reset mode:

T1 pulses high, turning on transistor, Q5 , which activates reset relay. T2 goes turns off Q1, to isolate the ramp signal. /T2 turns off Q6 and turns on Q2 to provide return path for C5 , effectively holding the output at

the latest voltage. C13 discharges through reset reed switch. T1 then goes low, turning off Q5 and opening reed switch. 30 ms later, T2 goes low and /T2 goes high. The ramp starts and C13 begins to charge on its negative-going journey.

AR1, Output IC C12, SummingCapacitor

Key Reset and Output Components


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Q1, Off DuringReset

Q2, On Durin gReset

Capacitor

R7, Summin gResistor

Key Reset And Output ComponentsMOSFET gates, Q1 and Q2 , are mounted on high resistance Teflon standoffs in order to prevent highresistance leakage which could cause erratic output signals. It is recommended that only exactreplacement semiconductors be used to replace these components.

Electronic Voltage Divider IC, LF13006

W1C8

C13 TP6


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DECODER

LATCH LATCH LATCH

W3 W2

15V 15V

W6

9 8

1514 13

2

12

Digital 2 Digital 1

Resistor Array

W4

Signal In Output

AR1

LF13006 Digital Gain Set ICThe IC, U2 is a precision laser-trimmed digital gain set IC. As part of the RC gain set in thisPreamplifier circuit, it is simply an electronic version of a multiple-resistance voltage divider , the valueof which is set by external jumper combinations that control internal latches. This circuit is used to setthe overall gain of the preamplifier for adjustment of open pipe signal voltage to 10V.

Setting The Gain of AR1The gain of op amp, AR1, is varied by changing the voltage level of two inputs to U2 : Digital 1 on pin 8and Digital 2 on pin 9, which changes feedback resistance in the circuit. By placing a jumper in theappropriate position, Digital inputs 1 and 2 can be latched on (15V) or off (ground). When the latchis off, the digital resistor used for feedback is at its highest value, resulting in the lowest gain settingfor the system. Conversely, when the latch is on, the resistance is minimal and the circuit gainincreased. Digital 1 (least significant digit) function is identical to Digital 2 (middle significant digit).

Ramp Gain SetShorting pin 15 of U2 to ground puts a second precision voltage divider resistor into the ramp feedback loop, thereby increasing gain by a factor of 2. In place of a jumper, a 50 k trim pot ( R35 ) can beinstalled at W1 to enable a fine adjustment of the integration gain circuit. The gain of the circuit isinversely proportional to the resistance of the trim pot This trim pot comes factory installed on later

REV C, D &E Gain Jumper Settings


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GAIN W2 / W3 W4 / W6X - 1 W3 W4X - 2 W3 W6X - 4 W2 W4X - 8 W2 W6

Jumper Gain SettingsThe above chart gives approximate gain values for various jumper combinations, however actual gainfigures may vary due to component tolerances. On Revision C boards, jumper wires must be soldered toindividual components in order to set W4/W6, while Revision D & E boards have plated-through holesfor easier jumper installation. Because of this, Revision C boards should be replaced with newer versions when servicing is needed.

Resistance Gain

R35 Gain Settings


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0 (short) 2.02.2 k 1.874.7 k 1.7610 k 1.615 k

1.5

22 k 1.533 k 1.3147 k 1.24Open 1.0

Variable Gain SetOn earlier revision boards, installing a 50 k trim pot ( R35 ) in place of jumper W1 will provide a meansfor setting the integration rate. The above chart lists the approximate gain at various resistance settings.For best performance, R35 should initially be set for the lowest gain. Jumpers W2 through W6 can beconfigured to set open pipe voltage close to, but not exceeding 9.9V, and R35 is then used for adjustmentto 9.9V. Revision D and newer boards will have this trim pot factory-installed.

Rev F Gain Set


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W3

W1 & W2R35

New Style Preamplifier BoardPictured is a portion of the new version Preamplifier Board, which uses discrete resistors in place of Electronic Gain Set IC, U2 . The board has different locations for jumpers W1, W2, and W3.Additionally, notice that R35 is no longer in W1 position. Be careful when installing jumpers, as there isa pad (marked in red in this photo) adjacent to W3 that can be mistaken for part of the gain set circuit.


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Rev F Gain Set Components


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Gain Set IC Replaced by ResistorsOn Revision F and higher preamplifier boards, the obsolete Digital Gain Set IC , U2 , has

been replaced with discrete resistors, R5, R37 and R36 , which are low drift, 1% metal filmcomponents. Soldered-in jumpers continue to be used for gain setting, however theconfiguration of these jumpers and their effective gain values have changed. There are nowthree jumpers, which enable a wider range of gain settings. Additionally, jumper W1 isnow part of the fixed gain set circuit. Trim pot, R35, (not pictured) is still used, but nolonger in W1 position.


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Gain Adjustment Via C13


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Capacitor, C13If the correct open pipe voltage cannot be obtained via jumper configurations, the value of feedback capacitor, C13 , can be changed to raise or lower the Preamplifier gain. Raising the capacitance willdecrease the gain , and vice versa.

Care When Replacing C13

It is important that latex surgical gloves be worn when handling the capacitor , as any contaminationdeposited on the capacitor body will affect the performance of the gauge. It has been determined by TNTechnologies that even thoroughly washed hands will still leave trace oil and dirt deposits on thecapacitor. These contaminants can cause long term drifting and instability of the output voltage.Additionally, the capacitor must be secured to the shield plate using non-corrosive RTV siliconcompound. Do not use acid-curing compound , as contamination can result, and do not let any compound make contact with the capacitor leads. If contamination is suspected, the capacitor and surrounding areacan be cleaned with isopropyl alcohol. Other cleaning agents may dissolve the polystyrene body.

Dont Forget!

Lower the value of C13 inPreamplifier Board to raise


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gain.Raise the value to lower the gain.

Use non-corrosive silicon sealto secure C13 to shield, and donot let compound touch theleads .

Nominal value of C13 is330pF.

Dirt and oil from your handscan contaminate C13

Cleanliness Is CriticalEven resistances in excess of 1x10 13 will have a major impact upon the output signal. ThePreamplifier Board must be kept clean and free from corrosion and moisture! This is especially true of

polystyrene gain set capacitor, C13 .

Expiration Date

Because polystyrene capacitors can absorb moisture, do not use any capacitors that have been sitting onthe shelf for a long time (over a year in humid climates). It is a good idea to store the capacitors in asealed container, and to keep a dated inventory list.

Nuclear Source Simulator


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Nuclear Source SimulatorAn alternative to using a nuclear source for servicing and testing the FSU Gauge is a

Nuclear Source Simulator , such as the one pictured, which can be constructed by anElectronic Technician, and will provide a very low adjustable current signal to thePreamplifier input, thus simulating actual operation.

Construction and Operation of Nuclear Source Simulator


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NOTE: Keep leads short.

CircuitThe Nuclear Source Simulator consists of:

2K ten-turn potentiometer 15G Resistor 8 RG174 coaxial cable

Additional components include a suitable plastic case, LED and clip leads. When buildingthe simulator, it is important to keep the leads as short as possible, especially the coaxialcable.

OperationThe simulator works best with the complete assembly attached, but can be used with justthe preamplifier board, connected to 15V. To use the simulator, disconnect the 15Vconnector on the preamplifier board that powers the HV board and connect the simulator

power connector in its place. Connect the coaxial lead from the simulator to the junction of R12 & R13. Adjust the potentiometer fully CCW, apply power and slowly adjust the potentiometer for desired output voltage at TP1 on the preamplifier board.

Note:This simulator is a troubleshooting aid only; it is not suitable for use as a calibration device.

Review QuestionsDetector Assembly, Densimeter Repair

1. The three main component parts of the Detector Assembly are:

1


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1. ________________________________________

2. ________________________________________

3. _________________________________________

2. Briefly explain why the Fluke 80K-40 High Voltage Probe is designed to work only

with meters that have 10M

input impedance.

3. Components Q1 , T1, C5 , C6 , R4 , and R5 , on the High Voltage Board, form a ____________oscillator. This oscillator uses _______________ feedback tomaintain a constant voltage.

4. Other than radiation strength, the four variables which affect the overall gain of the preamplifier are:

1. __________________________ 2. __________________________ 3. __________________________ 4. __________________________

5. The original NE-2 lamp was replaced with a solid-state FET lamp on newer version boards to reduce the possibility of _________ due to variances in glass manufacture.

6. When powered up, The preamplifier will always be in one of two modes:

1. __________________________

2. ___________________________ 7. IC, U2, used as part of the RC gain set in the Preamplifier circuit, is simply a

Review QuestionsDetector Assembly, Densimeter Repair

8. Increasing the capacitance of C13 will:( ) raise( ) lower the output voltage from the Preamplifier Increasing the value of the resistance in


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the output voltage from the Preamplifier. Increasing the value of the resistance inthe feedback will:( ) raise( ) lower the output voltage from the Preamplifier.

9. When the voltage ramp applied to pins 5 and 2 of AR6 reaches the value set by

________________, one output will go ____________ and trigger the NAND gate U3Aand U3B .

10. Temperature stability is primarily provided by component _____________________.

Activity One - Test PointsDetector Assembly, Densimeter Repair

IntroductionThere are several Test Points on the FSU Preamplifier Board to aid the in troubleshooting

and calibration Some Test Points are labeled as such (TP followed by a number) whileh l b l d h i f i h GND


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and calibration. Some Test Points are labeled as such (TP followed by a number), whileothers are labeled as to their function, such as GND.

Prerequisites None

ObjectiveThe objective of this activity is to present a guide for locating and identifying Test Pointsfound on the FSU Preamplifier Board

Parts and/or Tools RequiredFSU Densimeter AssemblyDensimeter Test Stand 15V Power Supply (May be provided by Analog or Digital Transmitter)Power /Signal Wiring HarnessDigital Volt Meter High Voltage ProbeInsulated Alignment Tool

Procedure1. Mount FSU Nuclear Densimeter Assembly into Test Stand. Remove any test sticks

from tube.

2. Verify power supply is turned off. Connect Power/Signal Wiring Harness from J1 onPreamplifier Board to 15V Power Supply.

3. Locate, on the FSU Preamplifier Board, The Test Point marked GND. Connectcommon lead of DVM to this Test Point.

4. Turn on power.5. Locate the following Test Points and measure the voltage at each:

+15 ________ -15 _________ TP1 (Signal Output) _________ TP6 (Ramp Signal) __________

6. Connect High Voltage Probe to DVM and measure voltage on the Ion Chamber,

Activity One - Test PointsDetector Assembly, Densimeter Repair

Study Questions

1. What other voltage(s) can be found on the Preamplifier Board?


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1. What other voltage(s) can be found on the Preamplifier Board?

2. Why is it preferable to check 15V at the Test Points, rather than on the MolexConnector?

3. Why must the High Voltage be stable and well regulated?

Activity - Observing Ramping ActionDetector Assembly, Densimeter Repair

IntroductionThe ramping action (slope) created in the first stage of the preamplifier affects the output

voltage of the Nuclear Densimeter. There are three main factors that determine the slopeof the ramp:


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g pof the ramp:1. Radiation at Ion Chamber 2. High Voltage level3. Value of R-C Feedback Circuit

Prerequisites Test Points Activity High Voltage Measurement Activity

ObjectiveThe objective of this Activity is to demonstrate the ramping action of the Preamplifier,and how it affects output signal voltage.

Parts and/or Tools RequiredFSU Densimeter AssemblyDensimeter Test Stand or insulated matAnalog or Digital Transmitter, or power supply capable of providing 15VDC at 1 ampPower /Signal Wiring Harness

Nuclear Source Simulator OscilloscopeClip lead, to discharge high voltage

Procedure1. Place FSU Nuclear Densimeter Assembly into Test Stand 2. Connect Power/Signal Wiring Harness from J1 on Preamplifier Board to 15V power

supply. Connect the Nuclear Signal Simulator 3. Set up oscilloscope to measure voltage and display waveform (5V/Div, DC Scale,

100mS) and connect to Preamplifier Board: Probe to TP6 Ground clip to GND test point

4. Apply power to Densimeter 5. Adjust the Source Simulator to maximum current (fully clockwise.)6. Observe the ramping action on TP6.


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Activity - Zeroing PreamplifierDetector Assembly, Densimeter Repair

IntroductionThe Nuclear Densimeter will require periodic checks and adjustments to ensure that, with

no received radiation, the output signal at TP1 stays near zero volts. Otherwise, accuracyof the unit may be compromised. TN Technologies recommends a slight offset voltage in


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of the unit may be compromised. TN Technologies recommends a slight offset voltage inorder to minimize disturbance in output signal caused by the ramp reset.

Prerequisites Test Points Activity High Voltage Measurement Activity Ramp Observations Activity

ObjectiveThe objective of this Activity is to instruct the technician in the proper procedure tofollow when zeroing the Nuclear Densimeter.

Parts and/or Tools RequiredFSU Densimeter AssemblyDensimeter Test Stand or insulated matAnalog or Digital Transmitter, or power supply capable of providing 15VDC at 1 ampPower /Signal Wiring HarnessAlignment toolDigital Volt Meter Clip leads

Procedure1. Place FSU Nuclear Densimeter Assembly into Test Stand.2. Connect Power/Signal Wiring Harness from J1 on Preamplifier Board to 15V Power

Supply.3. Place DVM to measure voltage at TP6

Positive lead to TP6 Negative lead to Gnd test point

4. Install jumper wire from resistor, R13 to TP6, to remove the effects of residual input

signal.5. Apply power to Densimeter.6. Adjust Trim Pot R28 for 0 V at TP6.7. Leaving jumper wire in place, move meter lead to TP1.

Activity - Zeroing PreamplifierDetector Assembly, Densimeter Repair

Study Questions


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y Q 1. Can the zeroing procedure be performed without the Ion Chamber or High VoltageBoard attached? ________. Explain:

2. Why is the voltage at TP6 re-checked after adjusting TP1?

3. What will be the slope of the ramp at TP6 with a properly zeroed system.

Activity - Setting Preamplifier GainDetector Assembly, Densimeter Repair

IntroductionThe Detector should be set for an open pipe signal output between 9.5 9.9VDC. This

is referred to as setting the gain, and a trim pot adjustment and several soldered-in jumpers are provided on the preamplifier board for setting this voltage. This activity will


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j p p p p g g y be similar to actual field practices, however a nuclear source simulator will be used and the training preamplifier unit will have plug-in jumpers instead of soldered in jumpersfor setting the gain.

Prerequisites Test Points Activity High Voltage Measurement Activity Ramp Observations Activity Zeroing Preamplifier Activity

ObjectiveThe objective of this activity is to familiarize the ET with gain-set adjustments and

jumpers on the FSU preamplifier board.


Nuclear Source Simulator Digital Volt Meter Alignment toolClip lead, to discharge high voltage


Procedure1. Place FSU Nuclear Densimeter assembly into test stand

2. Connect power/signal wiring harness from J1 on preamplifier board to 15V.Connect the source simulator to the connector next to J1 Adjust the simulator knob


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Connect the source simulator to the connector next to J1. Adjust the simulator knobfully counterclockwise.

3. Connect DVM to measure DC voltage between TP1 and GND.4. Adjust trim pot, R35, to mid scale (it is a 20-turn pot).

Refer to the above gain-set chart for the next steps .

5. Configure the preamplifier for a gain of X1.6. Apply power to Densimeter.7. Turn the simulator knob clockwise just enough to give approximately 1 VDC at TP1.

Record X1 voltage: _________.8. Do not change the setting of the simulator for steps 9 - 11.9. Configure jumpers for a gain of X2.

Record X2 Voltage: _________.10. Configure jumpers for a gain of X4.

Record X4 Voltage: ________.11. Configure jumpers for a gain of X8.Record X8 Voltage: ________.

12. Return to X1 setting and adjust the simulator to give approximately 8V at TP1.13. Adjust trim pot, R35, at W1 to give approximately 9.9V open pipe voltage at TP1.14. Remove power.15. This Activity is complete.

Study Questions1. In the above Activity, it is seen that the gain of the preamplifier can be adjusted by acombination of jumper settings. What parameter is being changed with these jumpers?

GAIN W2 / W3 W4 / W6

X - 1 W3 W4X - 2 W3 W6X - 4 W2 W4X - 8 W2 W6


2. What are your observations concerning the actual gain values set by the various jumper configurations?


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3. What other component value can be changed to vary the gain of the Preamplifier?

Activity - Observing and Comparing Reset PulsesDetector Assembly, Densimeter Repair

IntroductionBecause the ramp cannot continue indefinitely, a voltage pulse is used to reset the ramp

when it reaches a predetermined level. Additional pulses prevent the reset action from being seen on the output signal.


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Prerequisites Test Points Activity High Voltage Measurement Activity Ramp Observations Activity Zeroing Preamplifier Activity Gain Setting Activity

ObjectiveThe objective of this activity is to observe and compare the operation of the three reset

pulses. By observing the time relationship between these pulses, an understanding of their purpose should become apparent.


Nuclear Source Simulator OscilloscopeClip lead, to discharge high voltage

Procedure1. Place FSU Nuclear Densimeter Assembly into Test Stand 2. Connect Power/Signal Wiring Harness from J1 on Preamplifier Board to 15V.

Connect the Nuclear Signal Simulator.3. Connect Oscilloscope to Reset Test Points:

Channel A to TP6 Channel B to TP4 Ground lead to GND

4. Set up Scopemeter for waveform measurements as followsS i i i 5V/Di


7. Observe and compare the two waveforms. Voltage range of TP6 (Ramp) from _________ to __________ V Voltage range of TP4 (Reset Pulse) from ________ to _______V

8. Sketch the two wave forms atTP6 and TP4. Overlay the two signals to show their time (period) relationship.


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9. Leaving Channel B probe on TP4, move Channel A probe to TP3 and compare thesetwo pulses. For ease of observation, move the base line (zero point) of one channel,thereby separating the two waveforms. Performing a waveform capture usingsingle sweep function will help in this effort. Sketch these two waveforms, again

showing the period relationship:

10. Move TP4 probe to TP2. Compare and sketch these two waveforms.


Study Questions1. Identify the function of each reset pulse:

T1 (TP4) __________________________________________________________

T2 (TP3) __________________________________________________________


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/T2 (TP2) _________________________________________________________

2. What would be the observed result if pulse T1 was not present?

3. What would be the observed result of a failure of pulse T2 or /T2?


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BJ Digital Transmitter ET-205 Densimeter Repair


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The BJ Digital TransmitterOriginally designed to interface with the 611C Computer Controlled Blender and provide Proppantinformation, the BJ Digital Transmitter is an alternative to the TN Analog and Digital Transmitters.

Modified UCM-IIThe BJ Digital Transmitter is a slightly-modified version of the popular Universal Control Module II, or UCM-II. The differences are discussed later in the presentation.

BJ Digital Transmitter Features


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Features Of BJ Digital TransmitterThe features of the BJ Digital Transmitter include:

Stand Alone or System (611C Blender) Applications Easy To Program via Function Keypad Entry Firmware Easily Upgraded Operational Voltage Range 10.5 to 15 VDC

Frequency, LAN and Local Bus Outputs Built in 15 V Supply for Nuclear Densimeter Supported by the Instrumentation Department

Stand Alone Or System (611C Blender)The BJ Digital Transmitter is water and dust resistant. Although the BJ Digital Transmitter is water resistant, it should not be exposed to high pressure water. Additionally, the photo above shows anexample of a custom enclosure that can be used for Stand Alone application.

Easy To Program Via Function Keypad EntryMenu driven commands make the Transmitter user friendly.

Wide Operational Voltage Range (10.5 to 15 VDC)

0-10VDC Signal

15VDC Power

12VDC Power

Inputs/Outputs


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LANOutput LocalBus(611C)

FrequencyOutput

InputsThe BJ Digital Transmitter requires 10.5 - 15VDC power to operate. It receives a 0-10V signal from the

Nuclear Densimeter.

OutputsThe BJ Digital Transmitter has three data outputs available:

1 - Frequency Output 1 - LAN Output 1 - Local Bus

Frequency OutputThe frequency output is self powered, which means it does not require external excitation voltage for itshigh level (approx 10VP-P) output signal. It is scaled so that 1000 Hz = 10 Pounds Proppant Added (PPA), which equates to a PPU = 6000.

LAN CommunicationThe BJ Digital Transmitter can communicate over the BJ Local Area Network via RS-422communication. By assigning unique ID numbers, up to three BJ Digital Transmitters can send data to a3600, Isoplex36 or Isoplex monitor. To view this data at the 3600 and Isoplex36 Monitoring Systems,

611C Control Console


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BJ DensityTransmitter

611C InstallationThe above photos show a BJ Digital Transmitter in a typical 611C installation. Notice the location of thetransmitter. It is usually mounted in the lower, right hand, slot.

Power/SignalConnector

ContrastControl

Rear View


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Contrast ControlThe contrast control is a 10-turn potentiometer, located on the rear of the BJ Digital Transmitter. This

potentiometer adjusts the contrast of the display, which changes with the angle of view. If power for theBJ Digital Transmitter is turned on, but nothing appears on the screen, check to insure that the contrastcontrol is properly adjusted.

Power/Signal ConnectorPower and signals are routed through this single multi-pin connector.

MainScreen

Keypads


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NumericalKeypads

BJ Digital Transmitter Keypads Now that a general overview of the BJ Transmitter has been given, it is appropriate to take a closer look at its software. Upon power up, a Firmware Revision screen briefly appears, then the Main Screendisplays operator-selected density information. The transmitter is programmed through menu drivenfunctions, which involve use of the keypads. The available keys are:

Numeric Keypads

Reference Key ( REF ) Apparent Specific Gravity Key ( ASG ) Fluid Weight Key ( WT ) Corrected Specific Gravity

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ET205 Densimeter Repair (1)

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