Instr 12409 Calibrate Valves

8/13/2019 Instr 12409 Calibrate Valves

1/15

-----------------Calibrate Valves

Module 12409


2/15

Instrument Trainee Task Module 12409

CALIBRATE VALVES-

Objectives

Upon completion of this module, the trainee will be able to:

1. Discuss and describe primary valve operating mechanisms to becalibrated.

2. Identiy and select the appropriate calibration test e!uipment.". #et up and perorm instrument and test e!uipment or calibration

o valves.4. Discuss and prepare re!uired documentation o test perormance.

$rere!uisites

#uccessul completion o the ollo%ing &as' Modules is re!uired beorebeginning study o this tas' module( )**+, &as' Modules 12401 through1240-.

,e!uired #tudent Materials

1. #tudent Module2. ,e!uired saety e!uipment

Instrument &rainee &as' Module 12409 2


3/15

*ourse Map Inormation

&his course map sho%s all o the Wheels of Learningtas' modules in theourth level o the Instrument curricula. &he suggested training orderbegins at the bottom and proceeds up. #'ill levels increase as a traineeadvances on the course map. &he training order may be adjusted by thelocal &raining $rogram #ponsor.

+/+ 4 *OM$+&+

*alibrate /alves Module 12409 3


4/15

&+ O3 *O)&+)

Section Topic .Page

1.0.0 Introduction.. 42.0.0 &ypes o /alve Operating Mechanisms ..

5".0.0 *alibration and &est +!uipment .

9".1.0 $neumatic &est +!uipment 9".1.1 +lectrical &est +!uipment.. 10".1.2 6igh $ressure &est +!uipment

10

4.0.0 *alibration7&est $rocedures .11

4.1.0 *alibration7djustment o $neumatic /alve $ositioner ..11

4.1.1 *alibration7djustment o +lectro8$neumatic /alve $ositioner ..12

5.0.0 &est $erormance Documentation. 12

&rade &erms Introduced In &his Module

Actuator: part o a regulating valve that converts thermal electrical orluid energy into mechanical energy to open or close the valve.

Calibration:&he act or process o ma'ing adjustments or mar'ings on ascale so that the readings o an instrument conorm to an accepted andcertiied standard.

Control Valve: /alve that has an actuator that responds to signals sentby pneumatic electrical or other means or the purpose o controlling orvarying the luid lo% in a pipe line.

D:)ormal diameter 8 standard abbreviation or pipe si:e used in I#O

standards.

!ain: ,atio o output to input o any section o a control system.

Span:&he dierence bet%een the highest and lo%est scale values o aninstrument.

1.0.0 I)&,OD;*&IO)8

&he number o valves used or the control o luids today is enormous %ithvalves ranging rom very simple shuto devices to e


5/15

region to pressures o 100000 psi or more and temperatures rom thecryogenic region to those o molten metals. /alves may have very strictlea'age re!uirements in space vehicle applications %here even the tiniestlea' may be disastrous or they may have very generous lea'agere!uirements in many industrial uses %here loss is o minor importance orrecovery is very easy. /alves may be actuated by a variety o means suchas manual electric pneumatic or hydraulic. &hey may respond in aprescribed manner to signals rom pressure and temperature transducersand other types o sensors.

&he calibration o these valves and associated actuating mechanisms isessential to the proper operation o the system in %hich they are installed.

&he ollo%ing sections %ill describe various instruments test e!uipmentand calibration procedures or valves used in luid transport systems.

2.0.0 &=$+# O3 //+ O$+,&I)> M+*6)I#M#8

&here are several dierent types o devices %hich may be used to actuateor control a variety o valves. &hese devices use dierent orms o energyto perorm their unctions and re!uire speciic procedures or calibrationand adjustment.

$neumatic instruments generally use air a highly compressible gaseousluid as the medium o energy transmission. ?hen used as an actuatingmechanism or a valve pneumatic devices provide the positive controland sensitivity re!uired by many process systems. &ypically pneumaticvalve positioners are used %ith diaphragm8actuated control valveassemblies (Figure 1).



6/15

3igure 1. Operational #chematic

#olenoid8operated valve actuators are among the physically smallest oall actuators and the smallest o all actuated valves @Figure 2A. =et theyare !uite signiicant since many o these valves are incorporated onlarger control vlves as accessories as %ell as being used independently.

3igure 2 #olenoid /alve or In8ine Mounting

solenoid is an electromagnetic device in %hich a coil o %ire surroundsa steel rod and induces a magnetic ield that moves the rod into and outo the coil. ?hen the current is varied the rod can be made to move inand out o the coil %ith varying orce. ?hen a spring is added thevariable current can move the rod in and out by a speciic distance untilthe spring orce and the magnetic orce e!uali:e. &he rod can be used toproduce %or' such as moving a valve disc up and do%n. &heconventions used %ith solenoid valves are that normally8closed valvesare closed %hen the solenoid is not po%ered @de8energi:edA and open%hen the solenoid is energi:ed. )ormally8open valves are energi:ed toclose the valve and de8energi:e to open. &he spring moves the valve discto its normal position and the solenoid %or's against it.

&he solenoid valve used independently and used as part o a largercontrol valve are similar in operation although not al%ays similar in

appearance. 3or stand8alone solenoid valves the uses are generallysimilar to those o small hand8operated needle valves. &hey ind theirapplication in small board8mounted piping arrangements or controllingvery small lo%s in small lines generally in 18in. pipe si:e @D) 25A andsmaller do%n to 1748in. si:e @D) BA. asically a solenoid valve is li'eeither a globe or a diaphragm8type but is considered here separatelybecause it can also be classiied as an electrical device and the solenoidis really an integral part o the valve.

In the simplest type o actuators the actuating orce is provided by ahuman being. &his generally means that the mechanical parts are simplerthan those in other po%ered actuators since a human being can adjust

the magnitude and direction o applied orces and can supply additionalpo%er @a bigger person or a longer %renchA as it is needed. It is ho%ever



7/15

oten 8possible or the orce re!uired to e


8/15

hydraulic pump or a source o air pressure in %hich case the combinationis reerred to as a hydraulic7 pneumatic actuator @Figure 3A.

3igure ". #el8*ontained >as86ydraulic ctuator or +mergency #hutdo%n /alve

esides the greater po%er there can be several other reasons or thechoice o a hydraulic actuator. I space is at a premium the hydraulicactuator can deliver the same po%er in a much smaller pac'age. It is easyto provide a system that %ill unction during a plant ailure %here it is alittle more diicult to ensure that an air system %ill continue to unction.

&he operation o a hydraulic system tends to be smoother than apneumatic system and the positioning accuracy can be greater.

#ometimes the hydraulic luid is supplied rom a central source li'einstrument air but this is rare in process plant design. ircrat controls are

done this %ay but standard actuated valves generally are not unless anentire installation is designed %ith hydraulic actuators and unless the total



9/15

area is very small. &he conventional arrangement is to provide a hydraulicreservoir adjacent to the valve %ith pressure supplied by an electric8po%ered hydraulic pump an air motor driven by the -0 psi @5.5 barA airsupply or by a high8pressure gas reservoir oten nitrogen. &hese gasreservoirs 'no%n as CaccumulatorsC consist o a high8pressure bottle %ithnitrogen supplied to the top rom bottled nitrogen or another highpressuresource. &he hydraulic luid is also in the accumulator. &he solenoid valvesand manual override valves gauges electrical connections and tubingare generally installed in a s'id near the valve. &he same accumulators%ith dierent actuation controls can sometimes supply several valves inthe near vicinity.

&he hydraulic actuator is pretty similar in appearance to the air actuator.&he actuating pressures are much higher than or pneumatic actuators.&ypical hydraulic systems %ill use actuating pressures on the order o2000 psi @140 barA %ith pressure supplied by bottled nitrogen at 2200 to2B00 psig @150 to 1-0 barA and overpressure relie valves located near

the po%er source set at about 2900 psig @200 barA. &he cylinders arenormally steel %ith sturdy tie rods but the cylinder area %ill be smallerthan an e!uivalent pneumatic cylinder. &he pilot or solenoid valve isgenerally a solid machined8steel design to %ithstand the pressure ratherthan the typical cast8brass valve suitable or air. +ven the tubing isdierent( air systems use brass or stainless steel %ith compressionittings but hydraulic tubing is heavier %all oten carbon steel %ithheavy8duty hydraulic ittings. Incompressible hydraulic luids do not posethe same 'inetic energy release dangers i a rupture should occur.

".0.0 #++*&IO) O3 *I,&IO) )D &+#& +;I$M+)&8

"TE: +nsure that the calibration e!uipment meets the toleranceand accuracy re!uirements or the speciication.

$roper operation o any luid transport or process system re!uires periodicadjustments to various lo% control devices in the system. #peciicallyactuators and positioners that operate system valves must be calibratedto manuacturersE speciications to ensure their correct response tovarious inputs.

#pecial test e!uipment provides a means by %hich these speciicationsmay be tested veriied and7or adjusted.

9&he selection o the proper test e!uipment is determined by availableprocedural documents and data sheets.

".1.0 $neumatic &est +!uipment

calibration procedure or a pneumatic instrument %ill typically re!uirethe use o t%o basic types o test e!uipment( pneumatic simulator andpneumatic po%er supply.

&he pneumatic simulator provides a variable air signal to the instrument to

be calibrated thus simulating the operational input. y varying the signalto the instrument the output o the instrument can be changed and



10/15

adjusted to the speciied setpoint. &he simulator is a sel8contained unit%hich provides accurate indication o instrument parameters.

&he source o air or calibration o a pneumatic instrument is thepneumatic po%er supply. &he po%er supply provides a regulated gas lo%at a prescribed pressure to operate the components.

".1.1 +lectrical &est +!uipment

+lectrical simulators are used to calibrate solenoid8operated motor8operated and electronically8controlled valves. &his test device providesvoltage and current outputs over the range necessary to operate thevalves being tested.

*7D* po%er supplies are used to convert * to D* and vice versa. &heyalso step up or step do%n voltage rom a source to supply po%er to a test

set or a calibration procedure.

/olt8ohmmeters 'no%n as CmultimetersC are indicating devices %hich%hen connected to electrical leads in the valves or operating mechanismsdisplay voltages and resistance values. &hese values may correspond tovalve position @percent open or closedA and valve condition @energi:ed orde8energi:edA.

".1.2 6igh $ressure &est +!uipment

#ome valve actuators positioners or operators re!uire a high pressureluid supply or proper calibration and adjustment. s mentioned earlierpneumatic po%er supplies are used as a source o pressure or somecalibration procedures but they may not provide suicient pressure orhigh8pressure applications.

In these cases a high8pressure air or nitrogen cylinder %ill be used as thesource o pressure. &he test rig %ill consist o a regulator test pressuregauge cylinder pressure gauge relie valve and a manual isolation valve(Figure 4). &his rig %ill be connected to the supply line o the valveactuating mechanism and the pressure is adjusted as necessary using theregulator. &he gauges provide indication o pressure and the relie valveprevents overpressuri:ation o the test component.



11/15

3igure 4. $ressure regulator system. )ote that both a regulator and pressure relievalve are used.

4.0.0 *I,&IO)7&+#& $,O*+D;,+#8

In this section t%o common test methods %ill be outlined. &he methodschosen in the ield %ill depend on cost available e!uipment the intendeduse and type o device. *onsideration must also be given to the nature othe testing re!uired such as military !ualiication testing ne% researchand development production acceptance or sample testing.

4.1.0 *alibration7djustment o $neumatic /alve $ositioner

&he ollo%ing is a general procedure or calibrating a pneumatic valvepositioner. ,eer to Figure 5connection points or test e!uipment.

Step # oc' out and isolate component rom the system.Step $ *onnect e


12/15

3igure 5 $ositioner Operational #chematic

4.1.1 *alibration7djustment o +lectro8$neumatic /alve $ositioner

&he ollo%ing is a general procedure or calibrating an electro8pneumaticvalve positioner. ,eer to Figure 6 or test e!uipment connection points.

Step # oc' out and isolate component rom the pneumatic andelectrical system.

Step $ *onnect e


13/15

3igure B. electro8$neumatic #chematic

5.0.0 &+#& $+,3O,M)*+ DO*;M+)&&IO)8

One o the most important tools or any test or calibration evolution is the%ritten procedure rom %hich instructions or perormance %ill beobtained. &his document i properly %ritten %ill be the recipe or timelyand accurate calibration o the various components in the system.

&he ollo%ing is a brie list o inormation that should be part o thisprocedure(

*omponent operational schematic sho%ing test connections.

&est e!uipment list.

$ersonnel and e!uipment saety precautions. *omponent speciications i.e. ma


14/15

#ummary

*alibration7adjustment o various valves in a process system is essential tothe eicient and sae operation o the system. +ach o the components

discussed in this module re!uire dierent types o test e!uipment andprocedures or proper adjustment. thorough understanding o ho% eachtest is perormed and the test e!uipment to be used %ill prove invaluableto an instrument cratsperson in the ield.

,eerences

3isher *ontrols $roduct ulletins

Valve Selection and Secification !uide" /an )ostrand ,einhold 1991)e% =or'.

L#ons$ Valve %esigner$s &and'oo" /an )ostrand ,einhold 19-2 )e%=or'.

#+38*6+*F ,+/I+? 7 $,*&I*+ ;+#&IO)#

1. rue or False*&ypically pneumatic valve positioners are used %ithdiaphragm8actuated control valve assemblies.

2. normally8open solenoid valve is(a. *losed %hen po%er is applied to the solenoid.b. Open %hen po%er is applied to the solenoid.c. Manual overridden normally.d. In the same position %henever de8energi:ed.

". ?hy are hydraulic actuators preerred to pneumatic typesGa. Much less e


15/15

4. In a high8pressure test rig %hich indications are available at theregulatorGa. #ystem pressure and test pressure.b. #ystem pressure and cylinder pressure.c. *ylinder pressure and test pressure.d. tmospheric pressure and cylinder pressure.

$+,3O,M)*+ 7 O,&O,= +H+,*I#+#

1. >iven a pneumatic valve positioner and valve assembly(Step #: ?rite a test procedure to calibrate the assembly.Step $: #elect the proper test e!uipment.Step %: #et up test e!uipment and perorm calibration.Step &: Document test results.

2. >iven an electro8pneumatic valve positioner and diaphragm8

actuated valve assembly(Step #: ?rite a test procedure to calibrate the assembly.Step $: #elect the proper test e!uipment.Step %: #et up test e!uipment and perorm calibration.Step &: Document test results.

)#?+,# &O #+38*6+*F ,+/I+? 7 $,*&I*+ ;+#&IO)#

1. &rue2. a". c4. c

* lib t / l M d l 12409 15

Date post:	04-Jun-2018
Category:	Documents
Upload:	meliana-butar-butar
View:	222 times
Download:	0 times

Instr 12409 Calibrate Valves

Documents