Z-134

CLEAN COMPRESSED AIRTHE NORGREN GUIDE TO EFFECTIVE AIR PREPARATION

Z-135

The air leaving a compressor is hot, dirty,wet and generally at a higher pressure thanthe downstream equipment requires.A typical 50 dm3/sec (100 scfm) compressorwill push 4500 liters of water and 8 liters ofdegraded compressor oil into the system in ayear along with considerable amounts of dirtparticles. Before this air can be used it needsto be treated to remove the contaminants,have its pressure reduced to the right level,and in many cases have oil added to lubricatedownstream equipment.

Figure 1.Compressed air installation, showingexamples of air prepration applications.See details on pages Z-137 and Z-138.

Z-136

APPLICATIONSZ-137

REMOVING CONTAMINANTSZ-139

PRESSURE CONTROLZ-144

LUBRICATIONZ-147

PROTECTING SYSTEMS, PERSONNEL AND THE ENVIRONMENT

Z-149

NORGREN AIR PREPARATIONPRODUCT OVERVIEW

Z-152

GLOSSARYZ-155

REFERENCE TABLESZ-156

Z-137

Compressed air is often wrongly assumedto be a cheap or even ‘free’ source ofpower. In fact it can be 10 times asexpensive as electricity by the time allgeneration, transmission, treatment andsystem costs are taken into account. Goodair preparation must therefore consider theenergy consumption of the system and airtreatment equipment.

The process of air preparation has been atthe core of Norgren’s business for over 70 years. The aim of this booklet is tooffer guidance on the correct, economicand safe treatment of compressed air inindustrial applications. Here we can onlyprovide a brief summary of the extensiveexperience Norgren has as a world leaderin FRL technology.

For more detailed advice contact your localNorgren Technical Sales Center, Tel: 0345 662266.

APPLICATIONSThe following section shows severaltypical systems of a generic type and theequipment normally used for theapplication. Remember every systemshould be treated on its merits and brokendown into several elements to ensureoptimum installation, running andmaintenance costs are achieved.

The applications below are typicallybranches taken off a large worksdistribution mains and isolating valves areusually placed in front of all branches topermit isolation from the mains to allowfor maintenance to take place withoutrecourse to complete plant shut-down.

For expert advice on the right equipmentfor your application contact your localNorgren Technical Sales Center, Tel: 0345 662266.

General Pneumatic Circuits:eg: directional control valves andcylinders, in multi-valve circuits, machinecleaning, air motors and high speed tools.

A Micro-Fog lubricator is required for theseveral varying flow paths to ensure fulllubrication (Figure 2).

Multiple Simple Applications:eg: OEM machines.

It is often a case that with fairly simplemachines, lubricated air is require forvalving and pneumatic circuitry and oil-free air for air bearings. To keep costs lowtwo separate lines are unnecessary and atypical arrangement from one air supplyonly can be arranged as shown.

Other elements such as pressure switchesand check valves may be made availablewithin modular systems (Figure 3).

Figure 2.

Shut-off valve, filter/reg, micro-foglubricator, soft start/dump, relief valve.

Figure 3.

Shut-off valve, filter/regulator, oil removal filter, porting block, micro-fog lubricator.

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Breathing Air:eg: face masks and hoods, air agitation.

The typical application assumes that airintakes are of a reasonable quality with noC0 or C02 contamination. It may in someinstances be a consideration to removewater vapour (Figure 4).

Oil-Free Applications:eg: paint spraying, foodstuffs, filmprocessing, powders.

These applications need to be free from anywater deposits in the downstream system.For many installations this will require airdrying. The drying medium (for desiccantor deliquescent dryers) will need protectingfrom oil to allow it to work efficiently andthe downstream system will also needprotection from accidental migration of thematerial into it. A typical arrangementwould be as figure 5 and in some instancesit might be worth considering an oil vapourremoval filter too.

Heavy Duty Lubrication:eg: large slow moving cylinders.

In such applications large amounts oflubricant are required for effectivelubrication. Again a soft start/dump valveis shown but is dependent upon theapplication (Figure 6).

Critical Pressure Control(Instrumentation):eg: precision regulation, fluidic systems,air gauging, process control.

A typical arrangement is shown, where oilaerosols which can prevent fast responseof downstream devices, need to beremoved. Dependant upon air qualitydrying may not be required (Figure 7).

Direct InjectionLubrication:eg: conveyor chains.

The application does not allow for‘fog’ type lubrication because of thesurrounding environment and absence of a lubrication chamber (Figure 8).

Continuous Processes:

Another facet of Norgren’s Olympian Plusis the ability to make duplex systems. Thisis invaluable for systems which cannot beshut-down, such as continuous processplant. Two identical air sets are joinedtogether and one may be isolated (andserviced) whilst the other set is inoperation (Figure 9).

Figure 4.

Shut-off valve, general purposefilter, ultraire filter, regulator.

Figure 5.

Shut-off valve, general purposefilter, oil removal filter, drier, oilremoval filter, regulator, relief valve.

Figure 6.

Shut-off valve, filter/reg, oil-foglubricator, soft start/dump valve,relief valve.

Figure 7.

Shut-off valve, general purposefilter, oil removal filter, drier, oilremoval filter, precision regulator.

Figure 8.

Shut-off valve, filter/reg + directinjection lubricator.

Figure 9.

Duplex system: shut-off valve,filter/reg, lubricator, porting block,oil removal filter and shut-offvalve x 2 with manifold block connectors.

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take-off points from the distribution mainsshould be taken from the top of the mainto prevent water from entering the take-offlines. See figure 1 (page Z-135) for atypical good distribution mainarrangement.

As stated earlier most efficient waterremoval will take place at high pressure, soanything which will produce a pressuredrop within the distribution system shouldbe avoided. This will also be a loss ofenergy to the system and increase the thecost of compressed air generation. Areasto avoid here are complex flow paths withundue bends and inadequately sizedpiping. See page Z-156 Reference Data forfriction losses in pipe and forrecommended pipe flows.

The action of water removal can beachieved by drip leg drains, automaticdrain valves and as discussed later, filters.These devices should be located inpositions where liquid water is present inamounts large enough to be removed.(See figure 11). Because of the possibilityof cooling occurring during the passage ofthe air through distribution mains andbranch lines it is preferable to installsmaller individual filters as near to theactual point of air usage as possible, ratherthan rely on one large filter adjacent to theair receiver. A point to remember is thatsince most water will be present at higherpressures, always locate filters upstreamof any pressure reducing valves.

Filters which have the ability to removewater are designed for efficient waterremoval and low pressure drop inaccordance with the recommended pipeflows (see page Z-156) and Norgren filterswill have high efficiencies up to 200% ofthis recommended figure.

WATER VAPOUR

A properly designed air line filter of thecorrect size, in the correct location willeffectively and efficiently remove liquidwater, but will not reduce the water vapourcontent of the air. Further air cooling mayresult in more water condensing out. Ifcomplete freedom from watercontamination is essential then the watervapour content of the air must be loweredsuch that the ‘Dew Point’ of the air is lowerthan any temperature that the air can beexposed to in the system.

Once all liquid water is removed fromcompressed air, then normally the air will becompletely saturated with water vapour. Theparticular temperature and pressure at whichthe compressed air exists at that moment isknown as the ‘Pressure Dew Point’.

Figure 11. Drip Leg Drain

Figure 10.Typical Compressor Installation

Removing ContaminantsThe air produced by a compressor is hot,wet and dirty. The first step in good airpreparation is to filter out thesecontaminants. This section considers theremoval of liquid water, water vapour,solid particles and finally oil.

LIQUID WATER

In compressed air systems water vapourexists as a contaminant originating at thecompressor outlet in vapour form, but asthe air cools, it will exist as both liquid andvapour.

The amount of water vapour that can existin any given volume of compressed air isdirectly proportional to the air temperatureand inversely proportional to the pressure.

Most liquid water will be present when thetemperature is lowest and the pressure ishighest and removal at this point willachieve the highest efficiency.

In order to achieve this an essentialelement of any system following thecompressor is an efficient after cooler ofsufficient capacity to reduce thetemperature of the outgoing air to within8°C of the temperature of the waterentering the after cooler.

The outgoing air should then be piped to areceiver of adequate capacity located in thecoolest location available, definitely notwithin the compressor house itself. Thiswill permit further cooling of the air tooccur and therefore more condensation.

Generally the capacity of the receiver isabout 30 times greater than the rated freeair delivery of the compressor whenoperating in the 7 bar g region, typical ofmost industrial air supplies. See figure 10for a typical compressor installation.

Further cooling may occur in thedistribution mains themselves. Theseshould be laid out with a pitch in thedirection of air flow so that gravity and airflow will carry water to drain legs locatedat appropriate sites. Down loops indistribution mains should be avoided, ifnot locate a drain leg at the down loop.With the exception of drain legs all air

Z-140

WATER VAPOUR, cont.

Dew Points are normally measured atatmospheric pressure and can be relatedto Pressure Dew Points throughappropriate charts.In order to remove water vapour from acompressed air system Air Dryers must beemployed. The efficiency of these devicesis much increased by ensuring that theyare not contaminated by liquid water or oil(or combinations - emulsions) and aresupplied with air at the lowest possibletemperature. So they are additions to thesystem and not alternatives to filters andafter coolers.

There are 3 principle types of Air Dryer;Refrigerant, Regenerative Adsorbent Desiccant and Deliquescent Absorbent Dryers

(The general comparative abilities andcomparative costs are tabled in theReference Data on page Z-156)

In order to keep the costs of air drying to aminimum consider the following:

a) Does the particular process requireair drying or will efficient aftercoolers, receivers and filters suffice?

b) Do not specify extremely low DewPoints if the process does notwarrant them.

c) Limit the volume of air being dried to that actually needed for theparticular process with an adequatemargin for future expansion. Thismay indicate only one area of aprocess plant need employ a dryer.

d) The major requirement for air dryers in general industrialapplications is where high ambienttemperatures exist.

SOLID PARTICLES

Like water, solid particles exist in anycompressed air system regardless of the typeof compressor. These can arise from fourprinciple sources:

a) Atmospheric dirt inhaled at thecompressor inlet port.

b) Corrosion products due to the action ofwater and weak acids, formed by theinteraction of water and gases such assulphur dioxide inhaled by thecompressor.

c) Carbon products formed by the actionof the heat of compression on thelubricating oil or the normal wear ofthe carbon piston rings used in sometypes of oil free compressors.

d) Particles originating from themechanical fixing of the metal pipework and components into the airdistribution system.

The size of dirt particles covers a very widerange from several hundred to below onemicron (see figure 12) and the level offiltration depends upon the degree ofcleanliness needed for the particular processinvolved. Generally it is inadvisable to providefiner filtration than is absolutely necessarybecause the finer the filtration, the greater thequantity of dirt trapped by the filter elementand the more rapidly it will become blocked.

Particles can be broken broadly into twogroups, coarse (40 microns and above) or fine. Most normal air line filters willsatisfactorily remove particles down to 40 microns.

Fine filtration in the region 10 - 25µm isnormally required for high speedpneumatic tools or process controlinstrumentation. Filtration of 10µm andbelow is essential for air bearings andminiature pneumatic motors. Norgrengeneral purpose filters are available withdifferent grades of element to offer thesevarious filtration levels. Some applicationsmay need filtration better than this andindeed for paint spraying, breathing air andfood related applications particle removalbelow 1µm is also essential. Standard airline filters cannot be used and high

Figure 13. General Purpose Filter

Figure 12. Particle Sizes

Particle Diameter, Microns0.01 0.1 1.0 10.0 100

Aerosols ll l l l l l l l l l l lSprayTobacco SmokeHuman HairVirusesBacteriaSiltFine SandCarbon BlackCoal DustPollens

Z-141

SOLID SOLID PARTICLES, cont.

efficiency filters (oil removal/coalescingfilters) must be employed. Standard airline filters should still be employed as pre-filters to these high efficiency filters.High efficiency filters will remove theseextremely fine particles and if exposed alsoto the coarser particles they will simplyclog and become congested with dirtextremely quickly.

All elements will become blocked in use.The level to which the blocking isacceptable is dependent upon theapplication and the energy consciousnessof the plant operation. Standard filters canbe cleaned and reused but in today’senvironment with labour costs high andspare parts inexpensive it is normallybetter to replace elements. This will alsoensure minimum pressure drop onreinstallation as cleaning at very best willonly remove 70% of accumulatedparticles. High efficiency filter elementscannot be cleaned and must be replacedbefore they become blocked with dirt.

Under normal usage conditions generalpurpose filter elements are usuallychanged before their pressure drop isgreater than 0.5 bar, or in routine annualmaintenance. The period can always beadjusted by monitoring for criticalapplications using a service indicator(figure 15).

High efficiency filters should have theirelements replaced when a pressure drop of0.7 bar is achieved. Again a low costservice indicator is often employed. Thisdevice has a scale of two colours, usuallygreen/red. The elements should bechanged when or before all red isachieved. Electrical service indicators arealso available from Norgren, to provideremote signalling. Maintenance schedulescan be produced to ensure this ‘lastchance’ situation is not achieved, indeedsome applications cannot tolerate eventhis much pressure drop, especially if thisis at the generation point of a largecompressed air distribution main as the cost of extra energy alone would bevery large.

OIL

The principle source of oil contaminationwithin a compressed air system is fromthe compressor. An oil lubricatedcompressor of 50dm3/s capacity mayintroduce as much as 0.16 liters of oil perweek into the system.

Oil is used for lubrication of thecompressor but when it emerges with thecompressed air prior to distribution the oilis now in a totally unusable state. Havingbeen subjected to high temperaturesduring air compression it becomesoxidized and acidic and can be consideredas an aggressive contaminant rather than alubricant and so must be removed.

Normal air line filters will remove sufficientliquid oil (along with water) to leave the airin a suitable condition to supply mostpneumatic tools and cylinders, but certainprocesses demand completely oil-free air.

One solution is to use oil-freecompressors. These will still produce aircontaminated with dirt and water and it isoften more economical to use lubricatedcompressors in conjunction with aftercoolers and standard air line filters, onlyfitting high efficiency oil removal filters atthe points in the system which demand oil-free air. This ensures that the amount ofair needing special treatment is kept to aminimum by allowing a smaller specializedfilter in the affected area and not a largespecialized filter for the whole plant.

Oil in a compressed air system can exist inthree forms, oil/water emulsions, aerosols(small particles suspended in the air) andoil vapours.

Emulsions can be removed by standard airline filters but the aerosols are our nextconcern.

Figure 14. ‘Puraire’ Coalescing Filter

Figure 15.Filter Service Indicator

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OIL AEROSOLS

These particulate oil droplets exist in theairstream and the most troublesome are inthe size range 0.01 to 1 micron (approx90%), the rest may be slightly larger (seefigure 12 particle size chart, page Z-140).

Most standard air line filters achieve waterremoval by centrifugal action but due totheir small particle size these aerosols areunaffected and require special coalescingfilters.

In addition to removing the oil dropletsthese filters will also remove minute waterdroplets, but they must be protectedagainst gross dirt or water contaminationby means of standard air line filtersmounted immediately upstream (figure16). It is normally advisable that thesefilters are capable of removing particlesdown to 5 microns or less otherwise thecoalescing filter may quickly becomechoked and blocked with dirt, requiring afilter element replacement.

Coalescing filters are normally rated by theamount of air which they can ‘process’ toachieve a given oil removal performance,normally a maximum remaining oil contentin the exit air of 0.01 mg/m3 (or 0.01ppm). To try to overflow these units willnot only result in a greater pressure dropacross the unit and therefore extra energycost but more importantly the remainingoil content will increase. This may beacceptable for some applications where oilremoval down to the order of 0.5 mg/m3 isquite adequate to give a degree ofprotection to a system particularly prone togross oil contamination.

Figure 19 (see page Z-143) shows Norgrencoalescing filters flow capacities to achievetheir given performance.

OIL VAPOUR

For most processes the removal of oilvapour is unnecessary since unlike watervapour, oil vapour exists only in minutequantities and is not objectionable exceptin circumstances where its odour isunacceptable eg. in food processing,pharmaceutical and beverage industriesand breathing air applications.

The most common method of removal isto pass the air through an adsorbing bed,usually of activated carbon, although othermaterials can be used.

Such vapour removal filters will normallyreduce the total remaining oil contentwhen used in conjunction with a pre-filter(general purpose filter) and a coalescingfilter to 0.003mg/m3.

A common misconception of these filtersis that they will remove carbon monoxideor carbon dioxide - they will not.

As with oil removal (coalescing) filters thevapour removal filters should only beemployed where their function is needed,the maximum flow rating is not exceededand they are preceded by a generalpurpose and a coalescing filter. This willminimise the size of the filters requiredand therefore the cost of the installation.

Norgren offers an integrated coalescingand vapour removal filter in the OlympianPlus range. This includes a colour changeservice indicator as standard.

The location of the compressor intake mayalso have an effect on the level of filtrationrequired, if for example the intake issituated by a source of hydrocarbonvapours etc. Clean air intake will reduce thecost of producing clean compressed air.

Figure 16.oil removal filter with generalpurpose pre-filter

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FILTER SELECTION

Once all of the contaminants have beenconsidered the degree of cleanliness of airfor each part of an industrial plant orprocess can be determined. By onlyemploying the correct filters in the rightlocation energy and maintenance costs can be kept to a minimum. The volume of air involved in each stage must alwaysbe considered as undersized, inappropriatefilters are a prime cause of high energy costs.

A very general guide to the typical levels of cleanliness required for commonprocesses is given in figure 21. Eachapplication should however be consideredon its own merits.

Recommendations on air drying areparticularly difficult since this is dependantupon the temperature of the compressedair main adjacent to the application/machine the level of pressure reductionand air flow rate.

For well laid out generation anddistribution systems drying is seldomrequired in countries of typically low tomoderate relative humidities and ambienttemperatures.

When choosing a filter to cleancompressed air ensure:

� The correct type of filter and elementrating is selected for particle removal.

� The liquid removal efficiency is high andthat re-entrainment is not possible.

� Ease of maintenance and liquidcondensate collection is possible.

� Easy visibility of condensate and/orelement ensures that function isachieved or shows if maintenance is required.

This may be a pressure drop device, liquidlevel indicator or transparent bowl.

In order to aid determining the type ofwater and particle removal, figure 20shows ISO 8573 Air Quality Classification.

Figure 18. General Purpose Filter Flows

Pipe Unit Flow (dm3/s)*Size

1/8" F07 15

1/4" F72G 30

1/2" F64G 70

F74G 83

1" F15 175

* Flow at 6.3 bar and 0.5 bar pressure drop.

Figure 19. High Efficiency Filter Flows

Pipe Unit Flow (dm3/s)* OilSize Removal

Class**

1/8" F39 2.8 2

1/4" F72C 4.5 2

3/8" F64C 16 2

F64B 7 1

F74C 16 2

1/2" F64H 28 2

F64L 11 1

F74H 28 2

1" F53 60 2

F52 60 1

11⁄2" F47 85 2

F47 120 3

2" F47 200 2

F47 286 3l l l l

0 10 100 1 000

* Flow with 6.3 bar inlet to achieve ‘class’requirements.** See figure 20.

Figure 21.

Recommended Filtration Levels.

Application Typical Quality Classes

Oil Dirt

Air agitation 1 3

Air bearings 2 2

Air gauging 2 2

Air motors 4 4

Brick and glass machines 5 4

Cleaning of machine parts 3 4

Construction 4 5

Conveying, granular products 2 4

Conveying, powder products 1 3

Fluidics, power circuits 2 5

Fluidics, sensors 2 3

Foundry machines 4 5

Food and beverages 1 1

Hand operated air tools 5 5

Machine tools 5 4

Mining 5 5

Micro-electronics manufacture 1 1

Packaging and textile machines 5 3

Photographic film processing 1 2

Pneumatic cylinders 3 5

Pneumatic tools 5 4

Pneumatic tools (high speed) 4 3

Process control instruments 2 3

Paint spraying 1 1

Sand Blasting 4 5

Welding macines 5 5

General Workshop air 5 4

Figure 20.

Air Quality Classifications ISO 8573Quality Class Dirt Water Pressure Dew-point Oil

Particle Size in Microns °C (ppm vol.) at 7 bar g (including vapour) mg/m3

1 0.1 -70 (0.3) 0.01

2 1 –40 (16) 0.1

3 5 –20 (128) 1

4 40 +3 (940) 5

5 — +7 (1 240) 25

6 — +10 (1 500) —

PRESSURE CONTROL In order to use compressed air mosteffectively and efficiently it is necessary toreduce the pressure to precisely the levelrequired for its application.

All pneumatic equipment has an optimumoperating pressure. Using it at a higherpressure causes excessive wear, with nosignificant increase in output, whilstwasting the compressed air itself and thecost expended in generating it. If thecompressed air is stored at this higherpressure and only used at exactly thelower level required for the application thestorage vessel or receiver need only betopped up from some intermediate figureto the full capacity, which is more efficient.In order to achieve this optimum usage thecompressor usually operates between twopressure levels, that is the receivernormally has a pressure switch set to givecompressor cut-off at the required storagepressure (usually the highest achievablefor filtration efficiency) and a lower levelusually about 10 - 20% lower. This figurecan be adjusted for the optimum when thereceiver size, system flow demand andcompressor output rating are considered.The outcome of this arrangement is thatthe compressor is not continually running,using up excess energy, producing moreheat which produces more water, whichmust be removed (extra cost) to supply asystem requirement at too high a pressurewhich causes excessive wear (extra cost)for no increase in output.

A pressure reducing valve can thereforegenerate cost savings greater than itspurchase price in a short time period. Alsoit is mandatory in such applications asblow guns and cooling nozzles where theuse of compressed air at high pressure ispotentially hazardous.

Pressure reducing valves or regulatorshave two principle characteristics whichmust be considered in establishing whichto select, their ability to keep the outletpressure constant irrespective of the inletpressure (called the regulationcharacteristic) and irrespective of theoutlet flow (flow characteristic). Standard

designs are manufactured which achievecertain levels of the ideal performance oneach characteristic. A simple applicationwith loose demands of the two principlerequirements could employ a standard andtherefore low cost reducing valve. Thecorrect selection and deployment in therelevant part of the air system will achievethe lowest cost most energy efficientsystem.

The penalty for poor regulationcharacteristics is that the outlet pressurewill vary but in the bulk of compressed airapplications, inlet pressures are fairlyconstant so this poses few problems.

The penalty for poor flow characteristics ispressure drop which directly reflects inenergy costs. Every regulator suffers fromsome amount of pressure drop so forgood system design this is the moreimportant property to examine.

An important cost saving can be achievedby employing a reducing valve inconjunction with double acting cylinderswhere a reduced pressure can often beused advantageously on the non-workingreturn stroke and cost savings as high as30% can be achieved. This can be veryimportant on multi-cylinder installations.

A point common to all pressure regulatorsis that in order to work constantly andrepeatability within their design limits theywill require a supply pressure at least 1 barhigher than the required outlet pressure.They will work with a lower differential butperformance can be impaired.

TYPES OF REGULATORS

Although Norgren produces a vast array ofregulators they can be broadly broken into 4 types:

General PurposePilot OperatedPrecisionSpecial Purpose

Most general purpose regulators are of thediaphragm type (figure 22). In general theseare more sensitive than piston typeregulators which tend to have better flowcapacity for a given size. In the majority ofcompressed air systems response, ratherthan compactness for a given pipe size is themajor requirement, hence diaphragm typeregulators are most common.

Regulators can be relieving or non-relieving.The relieving feature allows for the system(outlet) pressure to adjust from a higher levelto a lower one without actuating downstreamequipment (this is done by having a vent holethrough the diaphragm to atmosphere).Generally this relief hole is very small inrelation to the regulator main ports so nomore than a bleed flow can be achieved andthis should not be considered a full relief oreven safety relief device.

Non-relieving versions do not have aconnection from the downstream system toatmosphere and so can only be adjustedfrom a higher desired or achieved outletpressure to a lower one by cyclingdownstream equipment or using a 3/2 shut-off valve to expel excess air from thedownstream system.

Figure 22. General Purpose Regulator

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TYPES OF REGULATORS, cont.

Pilot operated regulators are those whichdo not have a direct mechanical means ofadjusting the outlet pressure. Thiseliminates leverage problems in achievinghigh (16 bar plus) pressures in large pipesize units. The outlet pressure iscontrolled by means of an air pressuresignal (Figure 23) which is normallyproduced by a precision regulator. Thisallows for example a pilot operatedregulator to be remotely situated in thelarge distribution mains normally in abuilding’s roof, but be adjusted to give thedesired output pressure from shop floorlevel. For the majority of pilot operatedapplications it is best to take the systemor outlet pressure reading from the pilotoperated (often called a slave or main)regulator itself or the distribution systemas the pilot regulator’s outlet pressure isgenerally not the same.Pilot operated regulators also give betterperformance by eliminating the controlspring and usually have a large diaphragmarea compared to valve area which alsoimproves the accuracy of pressure controlin response to small pressure changes.

Another level of control accuracy can beachieved by employing a feedback pilotregulator. This device senses the outletpressure in the system and a pipedconnection feeds this signal back to thepilot regulator which compares it to thedesired outlet signal and ‘compensates’ byincreasing the outlet pressure if thefeedback signal is too low, or decreases ifthe signal is too high. This type of controlis usually employed where a large steadyair flow to a continuous process isrequired.

Precision regulators (or controllers) arenormally used for instrumentationapplications where exact repeatability andfreedom from outlet pressure setting driftover short or long term operation isnecessary. These regulators normally havea small outlet flow range, but exhibitsuperior flow and regulationcharacteristics. Their ability to achieve theideal of these characteristics over flow andpressure ranges is reflected in their sizeand price.

Generally most precision regulatorsemploy a special arrangement to allow aconstant bleed of air to escape toatmosphere. Although this is a cost to

system as a whole, being a loss of air, it isthe price which must be paid in order toachieve the very fast response to theapplications demands needed to keep thesystem pressure as constant as possible.The best types of precision regulators alsoemploy an integral pilot operation,producing effectively two diaphragms andvalves, one small and sensitive the other aslave to ensure that the overallperformance meets the requirements ofthe particular application.

Another feature of precision regulators istheir relief capacity and some have theability to relieve up to 80/90% of theirrecommended regulated flow for specialistapplication such as tensioning belts, paperrolling and balancing. (Figure 24).

Special purpose regulators can cover awhole range of specific demands includingmeeting exact environmental requirementswith special materials, having high reliefflows, plunger operation in place ofhandwheels etc. They can be derivatives ofany of the other types of regulators withapplication specific additions.

REGULATOR SELECTION

Ensure the regulator chosen exactly fits theperformance requirements of theapplication. A regulator which controls thepressure to a distribution main is usuallyof the general purpose type or for largevolume/flow applications pilot operated.

Figure 24.Norgren Micro-Trol Precision Regulator

SUPPLYAIR

SUPPLYAIR

OUTLETAIR

PILOT OPERATEDREGULATOR

PILOT OUTPUTLINE

CONVENTIONALPILOTREGULATOR

Figure 23.

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REGULATOR SELECTION, cont.

Decide if the performance requirementsneed a standard or precision regulator.Then decide if the flow capacity of theregulator is suitable for the pipe sizeneeds (see figure 38) and check with theregulators flow characteristics. Figure 25shows flow ratings of Norgren GeneralPurpose Regulators . If there is novariation in the inlet pressure to anapplication then the regulationcharacteristic of the regulator isunimportant but the flow characteristic willbe. If the inlet pressure is exposed tovariations then the regulationcharacteristics of the chosen regulatormust also be considered.A variety of spring ranges are offered withmost regulators. Ideally the regulatorsshould be operated inside the middle thirdof their range, since at the lower end oftheir range the spring loses somesensitivity and at the higher end may sufferin linearity. Also low rate springs can helpreduce pressure droop, so springs can beselected to best fit the systemsrequirements.

If a precision regulator is required decideon the level of sensitivity, flow andregulation characteristics and if requiredrelief capacity and temperature sensitivity.Select only a regulator suitable for itsapplication. Correct selection could see ageneral purpose regulator with ordinaryperformance characteristics fulfilling whatmay be considered a precision regulatorsfunction without system degradation at alower installed cost and more costefficiently.

Figure 25.

General Purpose Regulator Flows

Pipe Unit Flow (dm3/s)*Size1/8" R07 6.51/4" R72G 331/2" R64G 120

R74G 1051" R15 180

* Flow with 10 bar inlet, 6.3 bar outlet and1 bar pressure drop.

FILTER/REGULATORS

Filter/regulators both clean the air to theapplication and control the pressure in onecompact unit. For general purposeapplications filter/regulators are usuallylower cost than two separate units.

Some specialist filter/regulators areavailable for instrument applications withfine particle removal or even oil removalproperties with precision regulatorcharacteristics, as are others with specialmaterial compatibility.

Figure 26.Norgren Filter/Regulator FlowCapabilities.

Pipe Unit Flow (dm3/s)*Size

1⁄8" B07 6.21⁄4" B72G 381⁄2" B64G 1101⁄2" B74G 1001" B15 230

* Flow with 10 bar inlet, 6.3 bar outlet and1 bar pressure drop.

Figure 27.General Purpose Filter/Regulator

Figure 28.Aluminum Instrument Filter/Regulator

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LUBRICATION The next important step in processingcompressed air is that of introducing intothe air a suitable amount of lubricant,usually oil to enable the operatingequipment to perform to its requirementsefficiently without excessive resistance orwear. Excessive resistance to motion willresult in extra power consumption andexcessive wear will result in shortenedequipment life. Both result in extra cost.

There are two basic type of lubricator ingeneral use, aerosol and injection pump.

The most widely used is the aerosol, whichwas the first type of dependable automaticair line lubrication device, invented byNorgren in 1927.

Aerosol lubricators are available in twomain types, oil-fog and micro-fog. In anoil-fog lubricator the fog producedgenerally has relatively large oil particlesand so will only remain airborne forrelatively short distances. As a general ruleof thumb the maximum distance an oil-foglubricator should be placed from thepneumatic device which it is to service is 9 meters. Large particles are morestrongly affected by gravity and so oil-foglubricators should not be used inattempting to lubricate a device at a higherlevel than the lubricator.

The micro-fog lubricator uses a special fog generator to atomise only a fraction of the oil.

Because the airborne fog is now made up of only light particles, less than about 2 microns in size, gravity does not havethe same effect upon it and so this fog cantravel not only “up-hill” but also for longdistances and through more complex feedlines without wetting out in the pipe.micro-fog can also ensure proportionatedistribution through multiple lubricationoutlets, ideal for multiple valve controlcircuits.

A comparison of these two types oflubricators can lead to a simple division ofthem as being high delivery (oil-fog) orlow delivery types (micro-fog). All of thedroplets of oil shown in the oil-fog sight

dome will be delivered into the system andfor the micro-fog only about 5 to 10% ofthe droplets witnessed will be delivered.The micro-fog can therefore be used inapplications where only very smallamounts of lubricant are required, possiblyover large areas. By adjustment of the driprate higher oil delivery can be achieved tomatch that of an oil-fog lubricator atnormal usage rates.

The micro-fog principle has made possiblethe application of aerosol lubrication togeneral machine lubrication such asbearings, gears, chains etc.

Both oil-fog and micro-fog lubricatorsinclude a non-return valve in the syphontube to ensure immediate lubrication assoon as the air is turned on. However forsome rapidly cycling duties or systemswith small stroke cylinders it is sometimesnot possible to lubricate correctly withconventional lubricators. For suchapplications system modifications such asquick exhaust valves must be employed ora bi-directional lubricator suitably locatedcan overcome such problems.

The second type of lubricator, the injectionoil-pump is a positive displacement device.Because of its nature it cannotcontinuously deliver lubricant but hasparticular applications in multi-spindle nutrunners where conventional lubricators willsplit air flows according to passagewaygeometry. The injection pump will deliverthe same amount of lubricant to theapplication point every time it is cycled.This type of lubricator is often used onconveyor chains where their applicationwill overcome problems of incorrectlylocated or adjusted conventionallubricators.

Several such injectors can be manifoldedtogether to lubricate at several differentpoints, but at the same frequency.

Whichever type of lubricator is employed itis important to remember that alllubricators are total loss systems in thatthe dispensed lubricant will reach its‘bearing’ surface and be broken down intosmaller particles and ‘lost’ as the system iscycled.

The amount of oil which should bedelivered to a pneumatic system to providesufficient lubrication is difficult todetermine as all systems will be different.Pneumatic devices in a system mayrequire different amounts of lubricant andso equipment manufacturersrecommendations should always befollowed, where they exist.

For a general guide for most pneumaticsystems an oil output density of 60mg/m3is a good basic starting point. From regularinspection and servicing the optimumsetting may be found by increasing ordecreasing the amount delivered.

FILLING LUBRICATOR BOWLS

With all lubricators eventually the bowl orreservoir will need filling. Most oil-foglubricators have a check valve fitted to allowthem to be refilled whilst in use. Most micro-fog lubricators can be fitted with a quick fillnipple and so be topped up with lubricant,supplied at a pressure of approximately 1 bar above that within the bowl.

Figure 29. Oil-Fog Lubricator

Z-148

FILLING LUBRICATOR BOWLS, cont.

Remote fill devices also exist which cando this automatically. Such devices can beused to supply several bowls or reservoirsfrom one central position.Another way to reduce the scheduled taskof refilling lubricators or to ensure criticaloperations never ‘run dry’ is to employ aliquid level switch. Such devices arenormally float operated switches whichcan give an electrical signal on low or highliquid level. Such signals can then be builtinto a control system to fill or stop fillingor give warning alarms.

Although a high level signal may at firstseem strange remember that overfillingwill not only prevent the lubricator fromperforming its function of producing anair/oil mix of fog, but will distribute bulklubricant into the pneumatic system,flooding it.

LUBRICATOR SELECTION

Determine which parts of the systemrequire lubrication (some distribution lines

will be to oil free areas such as paintspraying or breathing air applications).

Determine what type of lubrication isrequired for each part of the system. Slowmoving heavy cylinders need high deliveryso chose an oil-fog type lubricator. Longruns of pipe in multi-valve circuits requirea micro-fog (or several oil-fog) lubricatorsto lubricate effectively. High speed toolsare better served by a micro-fog, as aretips of cutting tools.

All lubricators are a source of pressuredrop and therefore energy loss, soalthough micro-fogs may be positionedalmost anywhere in a system select andplace them as conveniently close to theapplication as possible. Always selectlubricators and locate them where differentlevels of lubrication are required, neverattempt to fit one lubricator to supply awhole distribution system as differingparts will then be over lubricated, whilstothers are under lubricated.

Ensure that only special purpose micro-fog lubricators are used for bearinglubrication as other types are not suitable.

Check that the lubricator chosen hassufficient flow capacity without excessivepressure drop for the pipe line size beingused (see figure 37 and individuallubricator performance graphs, on page Z-156).

Figure 31. Lubricator Flow Rates

Pipe Unit Flow (dm3/s)*Size

1⁄8" L07 51⁄4" L72 241⁄2" L64/L74 721" L15 175

* Flow at 6.3 bar and 0.5 bar pressure drop.

Since lubricators require a minimumpressure drop to operate which is normallyrelated to a flow, ensure that this minimumflow condition is met or there will be no oiloutput. It is important to note that leaksfrom compressed air systems are a sourceof energy loss and also such leaks areeffectively a constant flow through thesystem. If a lubricator with a very low start

point is used then even a small leakage, ifin excess of the start point will cause it todrip and supply oil to the system. This isoften the cause of oil flooding duringperiods of shut-down, especially overweekends.

Where continual usage exists select alubricator with sufficient reservoircapacity. For units in 1/2" pipe size andabove, several reservoir capacities areusually available. Where this is notpossible because of space or usage rateutilise remote fill devices or liquid levelswitches to auxiliary systems.

Where very high flows are encountereduse a fixed venturi type lubricator. Unlikestandard types this does not automaticallyadjust to give a constant air/oil density, sothe flow requirement needs to beessentially constant. This type of devicewill then not produce excessive pressuredrops associated with high flows and sobe more energy efficient.

For exceptionally high flow rates smallamounts of lubricant (especially for anti-freeze usage) can be injected by smalllubricators into large distribution mains of 1 to 2" and above, where a full borelubricator would be expensive in both costand pressure drop.

Figure 30. Micro-Fog Lubricator

Z-149

PROTECTING SYSTEMS, PERSONNEL AND THE ENVIRONMENTSafety in the workplace is essential and isemphasised via the Machinery Directive,the Pressure Systems legislation and theProvision and Use of Work EquipmentRegulations (PUWER).

The following section can help machinedesigners and others using pneumatics byillustrating those air line products which,when correctly applied, can be used toensure safe pneumatic systems.

In it we have cross referenced relevantdocuments. Norgren strongly recommendthat all who are involved with machine andsystem design should become familiarwith these and other relevant safetydocuments.

OVERPRESSURE PROTECTIONThe components in pneumatic systemswill often have a pressure rating lower thanthat generated at the compressor andpressure regulators are used to reduce thispressure to safe efficient levels. In theevent of a fault the components can beexposed to excess pressures leading tomis-function or in extremes failure of thepressure containing envelope.

To protect against this excessive overpressure situation several solutions can beemployed the most common being a reliefvalve. Selecting a relief valve is not asimple process, and detailed considerationof the system or element of the system isrequired.

In general all pneumatic components andequipment will have a Safe WorkingPressure (SWP) and over pressure limit of10%. The designer of the pneumaticsystem can use regulators to run thesystem at pressures below the SWP anduse the 10% safety factor to be the limit ofover pressure that the system canexperience with the relief valve inoperation.

A relief valve is defined as a device with itsoutlet so connected to a pressure systemto enable the system pressure to be held at

a constant level. This constant level wouldthen be at or below the stated SWP + 10%over pressure allowance.

Relief valves need to be set to only operatewhen the regulated pressure is exceededand so need to be set higher than theregulator. There will be a tolerance on therelief valve setting and on the regulatorsoutlet setting, depending on its flow andregulation characteristics. A commonproblem is a relief setting too close to thesystem operating pressure. Theconsequence of this is to have the reliefvalve operating and venting air duringnormal system operation, which is anexpensive waste of air. (See figure 22, on page Z-144).

Once the relief valve setting pressure andacceptable level of over pressure arechecked the flow capacity of the reliefdevice and that of the system can beconsidered. The relief device must be ableto match or exceed the amount of flowthrough the part of the system beingprotected without the system pressurerising above the acceptable over pressurelevel.

Several methods can be used to achieve this:

The relief device has a flow capacity inexcess of the compressors free airdelivery capacity - in systems where noreceiver exists - i.e. flow out of systemis greater than flow in.

The relief device has a capacity in excessof the flow through the smallest flowpassageway upstream of the equipmentbeing protected. Tables of orifice flowexist to determine the flow at differentpressures through differing sizes of orifice.The smallest bore is acting as a restrictionto the flow into the downstream systemand unless the upstream pressure can beincreased the flow will be choked throughthis area and therefore limited. This isimportant since a mains distributionsystem can be of very large volume withpipes of large bore and compressors ofhigh capacity, but the device beingprotected could be fed by 1/8" nominalbore tubing. So a small low cost device

only is required and not one large enoughto cope with the full system capacity.

In areas where no such flow restrictionexists, one should be created in order toreduce the cost of the relief valve to beemployed, ensuring of course that therestriction does not cause excessivepressure drop in the course of normaloperation.

Legislation Reference: BS EN 983 5.1.2

TYPES OF RELIEF VALVES

Several types of relief valves exist toachieve different levels of performancewith respect to the flow capacity and overpressure limitations. The most common isthe ‘pop’ type, followed by the diaphragmtype. For better performance use pilotoperated valves with the integral pilotoperated type being the most compact andcost effective (figure 32, on page Z-150).

An “in-line” type of relief device has reliefport at 90° to the direction of flow and innormal operation flow passes through thebody of the device, without interfering withnormal upstream operation. A commonuse of this type of device is with machinebuilders, where all the controlequipment/protection devices are in onediscrete position, aiding both installationand scheduled servicing.

The in-line device differs from the pop ordiaphragm type of relief valves which areconnected into the system on a tee-piece.Flow through these devices only occurswhen in operation and air vents toatmosphere.

In both cases the exhaust flow can bepiped away to an area where the noise andflow will not cause disruption or harm tothe environment or the operators. Exhaustsilencers may be required to reduce noiselevels in high flow exhaust applicationswhere piping away to less sensitive areasis not possible.

Z-150

SOFT START/DUMP VALVES

The next form of protection is thatassociated with the moving parts of thesystem, where the parts themselves canneed protection against excessive weardue to loading on start up or there isdanger to personnel from suddenmovement of the parts.

Here the use of “soft start” (“slow start”)valves is desirable. The normal operationis to allow air to pass to a pneumaticsystem or device in a gradual manner,where the rate of pressure build-up can becontrolled by adjustment of the valve. Thevalve design is generally an internal poppetvalve which is spring operated and whenthe gradual pressure build-up produces aforce in excess of that holding the poppetclosed, the poppet moves to the openposition allowing flow to proceed throughthe normal flow passageways. The level atwhich the poppet operates is called thesnap point and for most devices this snappoint will be in the range of 40 to 70% offull line pressure.

Because pressure build up in any systemis dependant upon the system volume it isimportant to locate these devices close tothe piece of equipment they are to protect.Fitting of a larger valve to a completedistribution system will generally mean thesystem will take many minutes to fullypressurise.

It is extremely common to couple the slowstart valve with a dump or exhaustfunction valve within one body, forcompactness.

The function of the ‘dump’ valve is toquickly exhaust the pressure from thedownstream system. The valve can havesolenoid or air pilot operators and often amanual override or emergency dumpfunction.

Legislation Reference: BS EN 983 5.1.4

Figure 34. Coalescing SilencerFigure 33. Soft Start/Dump Valve

Figure 32. Internal Pilot Relief Valve EXHAUST AIR

Exhaust air needs to be treated correctly toreduce the effects of noise, oil mist and tominimise danger to personnel.

Where a dump valve is employed, largevolumes of air can be released at highspeed which will produce high noiselevels. Simple silencers made of porousmaterials are often able to deal with this.In more demanding high velocity cyclingapplications a heavy duty silencer may beneeded.

Silencers are normally rated for their noisereduction and associated back pressure sothe choice should be dependent upon theduty required of the device to ensure themost cost efficient silencer is utilised.

The next major pollutant is oil. Allpneumatic lubrication systems are totalloss systems, the lubricant goes into thesystem, gets degraded in its function andis carried along with impurities and dirt tothe atmospheric exhaust.

In well maintained and correctly lubricatedsystems of a general engineering naturethe amount of exhausting oil is very smalland will disperse without generallyaffecting the working environmentadversely. However incorrectly lubricatedsystems or those which require high levelsof lubrication for heavy duty applicationscan expel high levels of oil into theatmosphere on their exhaust cycle. Insuch instances use of a coalescing exhaustsilencer should be considered. The action

Z-151

EXHAUST AIR, cont.

of this device is exactly as those for oilremoval filters which cause the small oildroplets to merge together into largedroplets which fall into a container forremoval (see figure 34, on page Z-150). In the course of this process the porousmaterial employed also reduces the noiselevel of the exhaust air.

Since these devices are on the exhaustside of the pneumatic system they areexposed to sudden shock loading, whichmeans their oil removal capabilities are notas good as those employed in coalescingfilters. A good exhaust coalescing silencerwill however give figures of typically 2ppmunder average usage conditions.

PROTECTION DEVICE SELECTION

(i) Decide which parts of the systemcannot withstand the maximum pressurewhich can be developed in the distributionsystem (or compressor).

Determine which type of relief valve isrequired to control this air pressure mosteffectively with consideration of failureflow through that part of the system.Consider using a restrictor (orifice)without producing excessive pressurelosses in the normal operation of that partof the system.

For very large flows consider a pilotoperated regulator as a dump valve.

For machines consider an in-line device tobuild-up one complete integral modularpreparation assembly for ease of piping,location and servicing.

(ii) Decide upon which parts of the systemcan suffer from problems on initial startup, or resetting where excessive initialspeeds can lead to wear problems orentrapment, or where an emergencystop/dump function is required.

Employ one soft start/dump valve for eachsection of the system operated in this way.The larger the system the longer the dumpor emergency stop function will take tofully empty the system.

Locate soft start/dump valves in the FRLassembly at the downstream end toprevent high back flows through thelubricator.

(iii) Where large volumes of air are to beexhausted consider fitting a silencer if theair cannot be piped away to a convenientposition.

Where rapid cycling of exhaust is presentfit a heavy duty silencer.

Where the exhaust air can be heavily ladenwith lubricant, usually from equipmentrequiring high levels of lubrication fit acoalescing exhaust silencer.

OTHER PRODUCTS FOR SAFESYSTEMS

Other air line products that can help createsafe pneumatic systems -

Preset pressure regulators - whereunauthorized adjustment of the setpressure can be injurious to personnel.

Guidance Document: HS (G) 39

Lockable shut-off valves - ensure that a‘safe to work’ procedure can be adoptedwithout jeopardy from the unauthorized re-application of pressure.

Legislation: BS EN 983 5.1.6

Guidance Document HS (G) 39

Tamper resistant kits - can be fitted topressure regulators, filter/regulators, reliefvalves and lubricators to ensure that flow,pressure and other settings are securedagainst unauthorized adjustment.

Legislation Reference: BS EN 983 5.1.9

Z-152

NORGREN AIRPREPARATION PRODUCT OVERVIEW

UNRIVALLED PRODUCT RANGENorgren, the world leader in airpreparation offers an unrivalled range ofproducts to enable you to produce cleancompressed air and use it economicallyand safely.

Whatever your need from the simplestfactory installation to a complex medicalapplication, Norgren has the right airpreparation equipment for you.

Figure 36.Olympian Plus System

Figure 35.Excelon System

Z-153

NORGREN AIRPREPARATION PRODUCT OVERVIEWThese pages show the main productfamilies, together with just a few of themore specialized standard products. Inaddition we produce hundreds of productsto customers specifications, utilizing thevast experience Norgren has accumulatedover the past 70 years.

All the main ranges include:

General Purpose Filters

High Efficiency Filters

Vapour Removal Filters

General Purpose Regulators

Filter/Regulators

Oil-Fog and Micro-Fog Lubricators

Soft Start/Dump Valves

Shut-Off Valves

Relief valves

These are supported by a wide choice ofmounting methods and accessories:

Porting Blocks

Pressure Switches

Level Controls

Service Indicators

Manifold Blocks

OLYMPIAN PLUS

Olympian Plus is the new generation FRLsystem, which sets new standards for easeof use and flexibility. The unique plug infeature allows quick installation or removalof units with a simple quarter turn of theclamp ring. The easily connected yokesystems allows speedy assembly ofcombination units.

Packed with features to make fieldmaintenance easy and convenientOlympian Plus is ideal for industrialinstallations. Equally the wide range ofsystem accessories mean it offers the OEMuser a highly flexible solution.

Olympian Plus is available in basic 1/2",with optional 1/4, 3/8 and 3/4 porting.

OLYMPIAN 15 SERIES

The 15 Series is the basic 1" version of theOlympian system. Available in 3/4 through1 1/2 inch ports it offers a flexible solutionfor larger machines and high volumeindustrial use.

EXCELON

Excelon is a completely new airpreparation system from Norgren.Although direct ported, thanks to apatented Quikclamp connection system,Excelon can be used where both standalone units or modular assemblies arerequired.

It offers exceptional performance in acompact well styled unit. It is ideal forOEM’s offering a flexible modular systemwith useful accessories such as pressureswitches and manifold blocks. The quickrelease bayonet bowl, high visibility liquidlevel indicator and easy to operatepatented Quikdrain are just a few of thefeatures designed with ease ofmaintenance in mind.

There are two sizes in the Excelon range.

Excelon 72 is basic 1/4 (with optionaloverporting to 3/8). However there isnothing basic about its performance,which is actually better than manycompetitors 3/8 products.

Excelon 74 is a 1/2 inch range (optional3/8 and 3/4).

Z-154

PORTED UNITS

The ported products have no modularconnection system, and are generally usedas stand alone units. They cover a widerange of basic port sizes from 1/8" (07Series) through 2" (18 Series).

07 SERIES

The miniature range offers goodperformance units for smaller flowrequirements. Here regulators are the mostcommon product and in addition to thecatalogued units Norgren offers a vastarray of options. Units are available in arange of body materials, with internalcomponents chosen to deliver the specificperformance characteristics requested bythe customer.

11 SERIES

A basic 3/8" size the 11 Series is alsooffered with 1/4" and in some cases 1/2"ports. These are well proven reliable unitsoften used as an alternative to a true 1/2"product, where the flow requirements arenot high.

18 SERIES

The 18 Series is a basic 2 inch rangedesigned for factory air mains or high flowOEM applications such as shot blasting ortextile machines.

PRECISION REGULATORS

Norgren has several different precisionregulators, each offering the designer aparticular combination of performancecharacteristics from which to select thebest unit for the application. Many specialsare produced in addition to the cataloguedoptions.

11-818

Compact, high precision regulators for airgauging, laboratory use and precise pilotcontrol.

11 400

For high accuracy pilot control of largeregulators and relief valves.

R24 Micro Trol

Exceptionally high flow with excellent reliefperformance.

R38

Instrument regulator produced inaluminum or stainless steel.

R27

High precision regulators featuring a widechoice of operators.

SPECIALIZED PRODUCTS

STAINLESS STEEL

Norgren produces units which meet NACErequirements for use offshore and in harshprocess environments. The 38 Seriesregulator and filter regulator are 1/4 NPTunits offering high flow with goodprecision. The 22 Series filter, regulatorand lubricator are basic 1/2" and for lowerflow applications there is the 1/4" 05Series.

WATER REGULATORS

Regulators with plastic or brass bodiessuitable for general or potable water duty.

RELIEF VALVES

In addition to the relief valves which arepart of the main FRL families Norgren hasseveral specialized units including PopType and the air piloted 40AC.

ELECTRONIC REGULATORS

Norgren can offer fully programmableelectronic regulators for use with anystandard industrial PLC. The R26 Pneu-Stat electronic regulator gives stableoutput over long periods and is ideal forclosed loop pressure control inapplications such as welding machineswhich require many different pressuresettings.

Z-155

Flow Characteristics:A characteristic of a pressure regulatorwhich shows the variation of outletpressure with varying outlet flow ratesat a constant supply pressure.

Free Air:Air flow measure in dm3/s at STP (1 013 mbar and 21°C) (ISO R554). All air flows are converted to this tomake system sizing easier.

Initial Droop:The amount of pressure drop incurredby a pressure regulator in going from aflow (static) condition to a small flow(dynamic) condition.

Micro-Fog:A suspension of light oil fractions in air,typically less than 2µm in size which cantravel long distances, through complexpassageways.

Micron (micrometer):A measurement of size on millionth of ameter (symbol µm).

Oil-Fog:A suspension of oil fractions in air,heavier and larger than Micro-Fog,suitable for heavy duty lubrication.

Pilot Operated Regulator:A regulator which has its outlet pressurecontrolled by the outlet pressure ofanother (piloting) pressure regulator,and not by an integral adjustable springload as with standard pressureregulators.

Porting Block:A modular device for allowing several airtake-off from a main air flow control set.

Pressure Drop (Droop):The amount of pressure loss incurred bythe flow of air through a device.

Pressure Reducing Valve/Pressure Regulator:

A device which is used to lower airpressure in a pneumatic system to adesired working level.

Regulation Characteristic:A characteristic of a pressure regulatorwhich shows the variation of outletpressure with varying inlet pressure at a constant flow rate.

Relative Humidity:The ratio of the actual amount of watervapour present in a given volume of air,to the amount of water vapournecessary to saturate the same volumeof air at the same temperature.

Soft Start Valve:A device which on initial pressurizationof a system allows the pressure to buildup slowly to a pre-determinedintermediate level before allowing astep-up to full line pressure to beachieved.

GLOSSARY

After Cooler:A heat exchanger mounted on acompressor outlet to extract the heat of compression.

Ambient:The conditions, usually temperature, inthe vacinity of the equipment undernormal working conditions.

Back Pressure Regulator:A device connected to a system in sucha way that the system pressure is heldeffectively constant by control of theoutlet flow to atmosphere.

Check Valve:A device which allows flow in onedirection only.

Coalescing:The action causing small particles tounite to form larger particles.

Deliquescent Dryer:A dryer using material which absorbswater vapour to such an extent that thematerial ultimately dissolves into thewater it absorbs.

Desiccant:An adsorbing material used in somedryers. Many such dryers areregenerative in that they use some oftheir energy to dry the material making it suitable for reuse.

Drip Leg Drain:A device at the bottom of a down legfrom a distribution main or a system lowspot to remove condensed water fromthe system. Such devices are normallyfitted with automatic drain valves.

Dump Valve:A valve which is connected toatmosphere in such a way as to rapidlyexhaust the system pressure.

Emulsion:A mixture of oil and water.

Failure Flow:The maximum flow through a device at agiven pressure with the valve open tomaximum extent.

Z-156

REFERENCE TABLESFigure 37.

FRICTION LOSS IN PIPE FITTINGS IN TERMS OF EQUIVALENT METERS OF STRAIGHT PIPE.

8 mm 10 mm 15 mm 20 mm 25 mm 32 mm 40 mm 50 mmTee (straight through) 0.15 0.15 0.21 0.34 0.46 0.55 0.67

0.92Tee (side outlet) 0.76 0.76 1.01 1.28 1.62 2.14 2.47 3.1890° elbow 0.43 0.43 0.52 0.64 0.79 1.07 1.25 1.5945° Elbow 0.15 0.15 0.24 0.30 0.38 0.49 0.58 0.73Ball valve* 0.01 0.03 0.09 0.12 0.15 0.22 — —

* Self exhausting – full open.

Reproduced with permission of Norgren, Inc.

Figure 38.

MAXIMUM RECOMMENDED FLOW * THROUGH ISO 65 MEDIUM SERIES STEEL PIPE.

Applied Nominal Standard Pipe Size (Nominal Bore) – mmGauge 6 8 10 15 20 25 32 40 50 65 80Pressure Approximate Pipe Connection – inchbar 1/8 1/4 3/8 1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3

0.4 0.3 0.6 1.4 2.6 4 7 15 25 45 69 120

1.0 0.5 1.2 2.8 4.9 7 14 28 45 80 130 230

1.6 0.8 1.7 3.8 7.1 11 20 40 60 120 185 330

2.5 1.1 2.5 5.5 10.2 15 28 57 85 170 265 470

4.0 1.7 3.7 8.3 15.4 23 44 89 135 260 410 725

6.3 2.5 5.7 12.6 23.4 35 65 133 200 390 620 14085

8.0 3.1 7.1 15.8 29.3 44 83 168 255 490 780 14375

10.0 3.9 8.8 19.5 36.2 54 102 208 315 605 965 14695

* Air flow rates in dm3/s free air at standard atmospheric pressure of 1 013 mbar.

General notes:

The flow values are based on a pressure drop (∆P) as follows:

10% of applied pressure per 30 meters of pipe 6 – 15 mm nominal bore inclusive

5% of applied pressure per 30 meters of pipe 20 – 80 mm nominal bore inclusive

Figure 39.

DRYER COMPARISONDryer Type Pressure Atmospheric Drying Media Power Initial Cost Pre Filters After Filters Maintenance

Dew Point Dew Point Replacement Consumption Cost

Refrigerated 2°C 23°C Nil For Medium General purpose None Regular maintenancerefrigeration motor and coalescing of refrigeration motor

Regenerative –40°C –57°C Infrequent For drying desiccant High General purpose Coalescing SmallDesiccant and coalescing

Deliquescent 10°C –15°C Regularly, Nil Low General purpose Coalescing Rechargingminimum and container6 monthly coalescing