Omega FST-200 and FST-300 Series Owner's manual

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INTRODUCTION/TABLEOFCONTENTS StepOne

Offered in liquid and gas sensor types, the general purpose flow switch provides reliable low or no‐flow

detectionofrelativelyclean,non‐coatingmediawithone1Arelayoutput.Liquidexamplesincluedwaterand

aceticacid.AvailableinPolypropylene‐PPSorPVDF,theshortflowsensorisusedinpipeorductingfrom½”

to1‐1/2”,andthelongflowsensorisusedin2”andup.Theflowswitchsetpointmaybeadjustedfrom0.,04

to3 fps in liquids or 1 to 90fpsingasesasalow‐flow alarm.The flowsensorisbestappliedinapplications

withrelativelyconstanttemperatures.

NewFeatures

 RuggedPolypropylene‐PPSorPVDFsensorforcorrosiveliquidsandgasses.

 AdjustablesetpointwithLEDforfloworno‐flowstatusindication.

 60VArelayselectableNOorNCviapowersupplywiringpolarity

 SolidStatesensorisnotdamagedbyover‐rangingflowvelocities.

TableofContents

Specifications:........................................................................................................................................................4

 MakeaFail‐SafeSystem:...........................................................................................................................4

Dimensions: .........................................................................................................................................................5

 Configurations:...........................................................................................................................................5

SafetyPrecautions:................................................................................................................................................6

Introduction: .........................................................................................................................................................7

 Technology:................................................................................................................................................7

 InitializingSequenceforFST‐200Series:...................................................................................................7

 SetPoints:..................................................................................................................................................7

Installation: .........................................................................................................................................................8

Wiring: .........................................................................................................................................................9

 SupplyVoltage:..........................................................................................................................................9

 SignalOutput:............................................................................................................................................9

 WiringtoanOmegaEngineeringController:.............................................................................................9

 WiringtheRelayOutput:..........................................................................................................................10

 WiringasaP‐ChannelorN‐ChannelOutput:..........................................................................................11

Calibration: .......................................................................................................................................................12

 SetPoint:..................................................................................................................................................12

Maintenance:.......................................................................................................................................................13

 CleaningProcedure:..................................................................................................................................13

 TestingtheSensor(FST‐200SeriesOnly):...............................................................................................13

 TestingtheSensor(FST‐300SeriesOnly):...............................................................................................14

 4

SPECIFICATIONS StepTwo

Setpointrange: FST‐200:.04to3fps(.012to.91mps)

 FST‐300:1to.90fps(.3to27mps)

Factorysetpoint: FST‐200:.2fps(.06mps)

 FST‐300:10fps(3mps)

Repeatability: ±.5%ofsetpoint@fixedtemp.

Responsetime: 1‐10seconds

Setpointadjust.: Potentiometer

LEDindication: FlowStatus

Viscosityrange: 1‐200centipoise(FST‐200seriesonly)

SupplyVoltage: 14‐36VDC

Consumption: 70mAmaximum

Contacttype: (1)SPSTrelay

Contactrating: 60VA,1Amax

Contactoutput: SelectableNO/NC

Processtemp.: F:32°to140°

 C:0°to60°

Electronicstemp. F:‐40°to140°

 C:‐40°to60°

Pressure: 150psi(10bar)@25°C.,derated@1.667

psi(.113bar)per°C.Above25°C.

Sensorrating: NEMA4X(IP65)

SensorMaterial: FST‐211/‐221/‐321/‐323: PP‐PPS

 FST‐212/‐222/‐322/‐324: PVDF

Cablejacketmat.: FST‐211/‐221/‐321/‐323: PP

 FST‐212/‐222/‐322/‐324: PFA

Cabletype: 4‐conductor,#22AWG(shielded)

Cablelength: 10’(3m)

Processmount: 3/4"NPT(3/4”G/Rp)

Mount.Gasket: FKM(Gversiononly)

Classification: Generalpurpose

CEcompliance: EN61326EMC

 EN61010‐1safety

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Make a Fail‐Safe System:Design a fail‐safe system that accommodates the possibility of switch and/or

power failure.OMEGA ENGINEERING recommends the use of redundant backup systems and alarms in

additiontotheprimarysystem.Addingaredundantalarmswitchtothesystemisacosteffectivemeans

topreventcostlyrun‐dryissues.

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DIMENSIONS StepThree

LongSensor(FST‐221/‐222/‐323/‐324)

ShortSensor(FST‐211/‐212/‐321/‐322)

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Configurations(LiquidFlowSwitches):

Part

Number

Length

Material

(body)

Material

(cable)

Thread

(insidexoutside)

FST‐211‐SPST Short(3”) PP‐PPS Polypropylene ¾”NPTx¾”NPT

FST‐212‐SPST Short(3”) PVDF PFA ¾”NPTx¾”NPT

FST‐221‐SPST Long(4.5”) PP‐PPS Polypropylene ¾”NPTx¾”NPT

FST‐222‐SPST Long(4.5”) PVDF PFA ¾”NPTx¾”NPT

Configurations(GasFlowSwitches):

Part

Number

Length

Material

(body)

Material

(cable)

Thread

(insidexoutside)

FST‐321‐SPST Short(3”) PP‐PPS Polypropylene ¾”NPTx¾”NPT

FST‐322‐SPST Short(3”) PVDF PFA ¾”NPTx¾”NPT

FST‐323‐SPST Long(4.5”) PP‐PPS Polypropylene ¾”NPTx¾”NPT

FST‐324‐SPST Long(4.5”) PVDF PFA ¾”NPTx¾”NPT

Note:Theaboveproductsshipwithastandard10’cablelength.Adding“‐25”totheendofthepartnumber

indicatesthattheproducthasa25’cablelength(ex.FST‐211‐SPST‐25).Adding“‐50”totheendofthepart

numberindicatesthattheproducthasa50’cablelength(ex.FST‐321‐SP

ST‐50).

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SAFETYPRECAUTIONS StepFour

Aboutthis Manual:PLEASEREADTHE ENTIRE MANUALPRIOR TOINSTALLING OR USINGTHIS PRODUCT.

ThismanualincludesinformationonallmodelsofOmegaEngineeringThermalDispersionFlowSwitches:FST‐

200andFST‐300series.Pleaserefertothepartnumberlocatedontheswitchlabeltoverifytheexactmodel

whichyouhavepurchased.

User’s Responsibility for safety:Omega Engineering manufactures a wide range of flow switches and

technologies, while each of these sensors is designed to operate in a wide variety of applications; it is the

user’sresponsibilitytoselectasensormodelthatisappropriatefortheapplication,install itproperly,perform

tests of the installed system, and maintain all components. The failure to do so could result in property

damageorseriousinjury.

Proper Installation and Handling:Because this is an eclectically operated device, only properly trained

staffshouldinstalland/orrepairthisproduct.Use apropersealantwithallinstallations.  Note: Alwaysinstall

the 3/4” FKM gasket with all versions of Flow switches withmetric threads. The G threaded version will not

seal unless the gasket is properly installed. Never over tighten the sensor within the fitting, beyond a

maximumof80inch‐poundstorque.Alwayscheckforleakspriortosystemstart‐up.

Material Compatibility:The FST‐200 and FST‐300 series sensors are available in two different wetted

materials. Models FST‐211/‐221/‐321/‐323 are made of Polypropylene (PP) with PPS tips. Models FST‐212/‐

222/‐322/‐324 are made of Polyvinylidene Fluoride (PVDF). Make sure that the model you have selected is

compatible with the application liquid. To determine the chemical compatibility between the sensor and its

applicationliquids,refertoanindustryreferencesuchastheCompassCorrosion.

WiringandElectrical:Thesupplyvoltageusedtopowerthesensorshouldneverexceedamaximumof36

voltsDC.Electricalwiringofthesensorshouldbeperformedinaccordancewithallapplicablenational,state,

andlocalcodes.

Flammable,ExplosiveandHazardousApplications:DONOTUSETHEFST‐200orFST‐300SERIESGENERAL

PURPOSEFLOWSWITCHESINHAZAROUSLOCATIONS.

Warning 

Theratingfortherelayis60VA,1Ampmax.

Omega Engineering’s Thermal Dispersion flow switches are not recommendable for use with

electricallychargedapplicationliquids.Formostreliableoperation,theliquidbeingmeasuredmay

needtobeelectricallygrounded.

Thesensingtipofthesensormustalwaysbesubmersedintheliquidandneverexposedtoair.

Theliquidtemperaturemustremainconstantandnotchangethroughouttheprocess.

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INTRODUCTION StepFive

Technology:TheThermalDispersionflowswitchesmeasureliquidorgastemperaturetodeterminechanges

in flow velocity.As fluid flows across the sensing tips, the temperature is reduced proportionately  as a

functionoftheflowrate.Whenatemperatureorvelocityshiftreachestheuserdefinedsetpoint,theswitch

changesstateindicatingtheappropriateflowcondition(flowofno‐flow).

OMEGAENGINEERING’s sophisticatedelectronics convert thetemperatureshift intoa signalwhich indicates

whetherafloworno‐flowconditionoccurs.Dependingonhowthesensoriswired,thissignalmaybewired

fornormallyopenornormallyclosedcircuits.

OMEGAENGINEERING’sThermalDispersionflowswitcheshavenomovingpartstoclogorfoul,makingthem

suitableforaverity ofapplications,includingnon‐coatingandnon‐scalingliquids.TheFST‐200seriesdirectly

measuremassflowandcanoperateoverboardrangeofliquidsfrom0.4to1.2specificgravityand1to300 

cp.

InitializingSequenceforFST‐200ser

ies:Whentheflowswitchispoweredupwhilesubmersed,theFST‐200

series will immediately indicate flow before switching to its correct state.A time delay may be used to

eliminatetheinitializationsequence.OmegaEngineering’sthermaldispersionrelaycontrollersfeaturea0to

60secondti

medelayforyourconvenience.

SetPoints:TheFST‐200seriesliquidflowswitchsetpointisfactorycalibratedto0.2fpsandtheFST‐300gas

flowswitcharesetto10fps.Toconvertfeet/sectoGPM,pleaserefertothechartbelow.

FST‐200Series

FlowRatevs.Velocity

(gpmvs.fps)



FST‐300Series

FlowRatevs.Velocity

(scfmvs.fps)





 8

Installation StepSix



The FST‐200 series flow switch must always be  in  contact  with

the liquid being measured. The FST‐300 series flow switch must

never be submersedin liquid.Both flow switches feature a 3/4”

NPTthreadswhich will allowittobe used with varioustypesof

fittings.Besuretochecktheinsertiondepthofth

eflowswitchin

thefittingafteritisinstalled.Seethediagramtotherightforthe

recommendedinsertiondepth.

 Thetwotipofthesensoraretobeperpendiculartothe

flow(asseentotheright).Nevermountthetipswith

oneinfromtoftheothe

r.



When using any type of fitting, the orientation as well as the

insertiondepth ofthe flowswitchin thepipeis critical. Seethe

diagramtotherightfortherecommendedorientation.





Warning 

Theflowswitchtipshaveathinplasticwallwhichmaybedamagedifdroppedorinstalledimproperly.

The FST‐200series flowswitch isdesigned foruse in liquid. For bestresults, avoid installing theFST‐200

serieswherebubblesarepresentorwherethetipsoftheswitchmaybeoutoftheliquid.

TheFST‐300seriesflow switchisdesigned for usin gas applications. Forbest results,  avoidinstalling the

FST‐300serieswhereitmaybesubmersedinliquid.

Always install the FKM gasket with all versions of the model FST‐212/‐222/‐322/‐324. The G threaded

versionwillnotsealunlessthegasketisproperlyinstalled.

The two temperature probes (tips) must always be perpendicular to the flow (see the flow at the same

time).



 9

WIRING StepSeven



Supply Voltage:The supply voltageto theThermal Dispersion flow switch should  never exceed a minimum

outputof14VDCormaximumoutputof36VDC.

Required Cable Length:Determine the length of the cable required between the Thermal Dispersion flow

switch and its point of termination. Allow enough slack to ensure the easy installation, removal and/or

maintenance of the sensor. The cable length may be extended up to a maximum of 1000 ft, using a well‐

insulated14to20gaugeshieldedfourconductorcable.

WireStripping:Usinga10gaugewirestripper,carefullyremovetheouterlayerofinsulationfromthelast1‐

1/4” ofthe sensor’scable. Unwrapand discardthe exposed foil  shieldfromaround thesignal wires,leaving

the drain wire attached if desired. With a 20 gauge wire stripper, remove the last 1/4” of the colored

insulationfromthesignalwires.

SignalOutput(RelaySwitching):

Allows the sensor to switch a small load on or off

directly, using an internal relay rated below 60 VA.

TheNO/NCstatusissetby thepolarityofthevoltage

feedingtheredandblackwires.Thegreenwireisthe

commonfortherelayandthewhitewireistheNOor 

NC,dependingonthepolarityofredandblack.

NormallyOpenWiring:



WiringtoanOmegaEngineeringController:

LVCN‐131/‐141SeriesController



FLCN‐100SeriesController





 10

WIRING StepSeven



WiringtheRelayOutput:TheFlowswitchrelayoutputcanbewiredasadrycontacttoaVDCorVACpower

source. The flow switch does require 14‐36 VDC power to operate the sensor and switch the relay. All

installationsbelowidentifyadryswitchstateasthenormalpositionoftherelay.

SwitchingaNormallyOpenDCLoad(OpenduringFlow,ClosedduringNo‐Flow):

The Red wire connects to Positive (+) of the power

supplyandtheBlackwireconnectstoNegative(‐).The

LOAD can be attached to either the Green or White

wires.Completeth

ecircuitbyconnectingtheGreento

(+) VDC power or White to (‐) VDC power (see

illustrationtotheright).



SwitchingaNormallyClosedDCLoad(ClosedduringFlow,OpenduringNo‐Flow):

The Black wire connects to positive (+) of the power

supplyandtheRedwireconnectstoNegative(‐).Th

e

Load can be attached to either the Green or White

wires. Complete the circuit by connecting the Green

to (+) VDC power or White to (‐) VDC power (see

illustrationtotheright).

SwitchingaNormallyOpenACLoad(OpenduringFlow,ClosedduringNo‐Flow):

TheRedwire connects toPositive(+)of theDC power

supplyandtheBlackwireconnectstoNegative(‐).The

LOADcanbeattachedtotheGreenwireandtheHotof

the VAC power. Connect the white to the Neutral of

the VAC power (see illustration to the right).Low

voltageVACislessthan36VAC.

SwitchingaNormallyClosedACLoad(ClosedduringFlow,OpenduringNo‐Flow):

The Black wire connects to Positive (+) of the DC

powersupply andthe Redwire connects toNegative

(‐).TheLOAD canbe att

achedtotheGreenwire and

theHot oftheVAC power.Connect the Whiteto the

Neutral of the VAC power (see illustration to the

right).LowvoltageVACislessthan36VAC.



ForallSensorWiringdiagramsabove:

SensorPower:RedandBlackWires(36VDCMax.)

Rela

yRating: GreenandWhiteWires(60VA,1AMax.)





 11

WIRING StepSeven

WiringasaP‐ChannelorN‐Channeloutput:TheFlowswitchcanbesubstitutedforeitheraP‐Channel(PNP,

Sourcing)outputorN‐Channel(NPN,sinking)output.

NormallyOpenDCLoadasaP‐ChannelOutput(OpenduringFlow,ClosedduringNo‐Flow):

To wire as a NO P‐Channel o

utput follow the

directions below. The Red Wire connects to Positive

(+) of the power supply and the Black wire connects

toNegative(‐).TheGreenwireisjumpingtotheRed

wire while the White wireis connectedto the LOAD.

JumpertheLOADbacktotheNegative(‐)tocomplete

thecircui

t.



NormallyClosedDCLoadasaP‐ChannelOutput(ClosedduringFlow,OpenduringNo‐Flow):

To wire as a NC P‐Channel output, follow the

directionsbelow. TheBlackwire connectsto Positive

(+)ofthepowersupplyandtheRedwireconnectsto

Negative (‐). The Green wire is jumping to the  Black

wire while the White wireis connectedto the LOAD.

JumpertheLOADbacktotheNegative(‐)tocomplete

thecircuit.



NormallyOpenDCLoadasaN‐ChannelOutput(OpenduringFlow,ClosedduringNo‐Flow):

To wire as a NO N‐Channel output, follow the

directions below. The Red wire connects to Positive

(+) of the power supply and the Black wire connects

toNegative(‐).ThewhitewireisjumpingtotheBlack

wirewhile theGreenwire is connectedto theLOAD.

JumpertheLOADbacktothePositive(+)tocomplete

thecircuit.



NormallyClosedDCLoadasaN‐ChannelOutput(ClosedduringFlow,OpenduringNo‐Flow):

To wire as a NC N‐Channel output, follow the

directionsbelow. TheBlackwire connectsto Positive

(+) of the directions below. The Black Wire connects

toNegative (‐).The white  wire is ju

mping to theRed

wire while the White wireis connectedto the LOAD.

JumpertheLOADbacktoPositive(+)tocompletethe

circuit.



ForallSensorWiringdiagramsabove:

SensorPower:RedandBlackWires(36VDCMa

x.)

RelayRating: GreenandWhiteWires(60VA,1AMax.)





 12

CALIBRATION StepEight

Set Point:If the preset factory calibrationis notadequate for your application,follow the calibration steps

listedbelow.

Note: The switch’s internal LED will be on when the switch detects no‐flow and will off when the switch

detects flow, regardless of the polarity of the Red and Black wires.Reversing the Red and Black wires will

reversethepolarityoftherelayswitch,butnottheinternalLED.

1. Install the fitting and flow switch as described in the Installation section of this manual. Turn the  flow

switch and controller power on and adjust the flow rate to the application setting. If the medium to be

sensed is likely to be subject to any temperature variation, the flow switchshould be set as the highest

normaltemperaturelikelytobeencountered.

2. Locate the potentiometer knob at the top of the  flow switch. The red LED is visible through the

potentiometer.Theadj

ustmentisasingleturn270°potentiometer.Theinitialresponsetimeoftheflow

switchafteradjustmentis1to10seconds.Adjustthepotentiometerinslowincrementsandwaitforthe

response.

a. LEDisON‐IftheLEDison,slowlyadjustthepotentiometercounter‐clockwise,withasmallflathead

screwdriveruntiltheLEDturnoff.

b. LED is OFF‐

If the LED is off, slowly adjust the potentiometer clockwise. with a small flat head

screwdriveruntilthelightturnson.

3. AdjustthepotentiometerbackandforthwheretheLEDisswitching,eventuallysettlingforwheretheLED

isOFF(thisisthelowflowstatefortheswitch).

a. Iftheflowisincreased,theLEDwillremainOFFindicatingaflowcondition

b. Iftheflowisdecrease,theLEDwillturnONindicatingano‐flowcondition.

4. Verifythatthenewcalibrationiscorrectbyloweringthesystemflowratebelowthesetpointandcheckto

seethattheredLEDturnson.ThenincreasetheflowrateabovethesetpointandverifythattheredLED

turnsoffaccordingly.

FST‐200SeriesFlowSwitch

(LiquidOnly)

Potentiometer

Location

FST‐300FlowSwitch

(GasOnly)





 13

MAINTENANCE StepNine

General:TheFlowswitchrequiresnoperiodicmaintenanceexcept tocleanoffanydepositsorscalingfrom

the sensor tip as necessary. It is the responsibility of the user to determine the appropriate maintenance

schedule,basedonthespecificcharacteristicsoftheapplicationliquids.

CleaningProcedure:

1. Power: Make sure that all power to the sensor, controller and/or power supply is completely

disconnected.

2. Sensor Removal: Make sure that the flow is off and the pressure is down prior to removing the Flow

switch.Carefully, remove the sensor from the installation. Replace the sensor with a 3/4” NPT plug to

insure that the liquid doe

s not leak out during this procedure. Do not re‐install the Flow switch if the

threadsaredamaged.

3. Cleaningthe sensor: Use a soft bristle brush and mild detergent, carefully wash the Thermal Dispersion

flowswitch.Donotuseharshabrasivessuchassteelwoolorsandpaper,whichmig

htdamagethesurface

sensor.Donotuseincompatiblesolventswhichmaydamagethesurfacesensor.Donotuseincompatible

solventswhichmaydamagethesensor’sPP/RytonorPVDFplasticbody.

4. Sensor Installation: Follow the appropriate steps of installation as outlined in the installation section of

thismanual.

TestingtheSensor(FST‐200SeriesOnly):

1. Immersingtheswitch:Placetheswitchinacupofwater.Makesurethetipsaresubmersedinthewater.

2. Power: Turn on power to the switch with Red to (+) and Black to (‐).You can reverse the polarity if

desired.

3. No‐Flow/Flow Test: With the switch setting still in the cup, wait until the Red LED turns ON (no‐flow

condition).

a. SwirltheswitchinthecupandwaituntiltheRedLEDturnOFF(flowcondition).

b. Stopswirlingthesensorand letitrestinthecupwaitingfortheRed LEDtoturnONagain(no‐flow

condition).

c. Repeattheabovetwosteps.

4. RelayTest: Connect amultimeter(settoreadOhms)totheWhite andGreenWires.Performtheabove

No‐Flow/Flowtestwiththemultimeterconnecttoobservetheactuationoftherelay.

a. With Red to (+) and Black to (‐), the multimeter will reada small resistanceduring no‐flow (closed

relay)andOLduringaflowcondition(openrelay).

b. Reverse Polarity [Red to (‐) and Black to (+)] to see the multimeter read OL during a no‐flow state

(openrelay)andasmallresistanceduringaflowcondition(closedrelay).

TheNo‐Flow/Flowtestdeterminesiftheswitchiscapableofsensingthechangesbetweenno‐flowandflow.

TheRelaytestdeterminestheabilityoftherelaytoswitchbetweenano‐flowandflowcondition.Thisisthe

basictesttodeterminefunctionalityofthesensor.



 14

MAINTENANCE StepNine

TestingtheSensor(FST‐300SeriesOnly):

1. Creatinga No‐Flow TestPoint: The purpose ofthis step is tocreate ano‐flow statefor thesensor to be

tested against.Sincethis isa low flow switch, even abuildings HVAC system can create a flow that the

sensorcanread.

a. Placetheswitchonatableandplaceanemptycupoverthesensingtips.

b. Thecupwillactlikeashieldtoprotectthesensorfromairflow.

2. Power: Turn on power to the switch with Red to (+) and Black to (‐).You can reverse the polarity if

desired.

3. No‐Flow/FlowTest:Withtheswitch setting still under thecup,waituntiltheRedLED turnsON(no‐flow

condition).

a. Remove the cup and move the sensor in air and observe when the Red LED turn OFF (flow

condition).

b. Place thesensor onthe tableand placethe cup over thesensor andletit rest waitingfor the

RedLEDtoturnONagain(no‐flowcondition).

c. Repeattheabovetwosteps.

4. RelayTest: Connect amultimeter(settoreadOhms)totheWhite andGreenWires.Performtheabove

No‐Flow/Flowtestwiththemultimeterconnecttoobservetheactuationoftherelay.

a. With Red to (+) and Black to (‐), the multimeter will read a small resistance during no‐flow

(closedrelay)andOLduringaflowcondition(openrelay).

b. Reverse Polarity [Red to (‐) and Black to (+)] to see the multimeter read OL during a no‐flow

state(openrelay)andasmallresistanceduringaflowcondition(closedrelay).

TheNo‐Flow/Flowtestdeterminesiftheswitchiscapableofsensingthechangesbetweenno‐flowandflow.

TheRelaytestdeterminestheabilityoftherelaytoswitchbetweenano‐flowandflowcondition.Thisisthe

basictesttodeterminefunctionalityofthesensor.





 15



 16



Omega FST-200 and FST-300 Series Owner's manual

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