Manual

RevB MN301035 9of16
GETTINGSTARTED(continued) StepSix
Howtoselectthecorrectpressuretransmitter?
Theobjectiveistoselectasensorwithanoperationalrangethatwillcovertheentireapplicationspan.Ifthe
liquid height of the tank is above the sensor’s Maximum Liquid Height, then the sensor will not be able  to
read a full tank level.Compare the tank’s Pressure @  Full against the sensor’s pressure range to select a
sensor.
Tocalculatethetank’sPressure@Full,usethefollowingformula:
Pressure@Full=[Height@FullTank(feet)xSG]/2.31(feet/psi)
Pressure@Full=[Height@FullTank(meters)xSG]/0.704(m/psi)
Toselectthecorrectpressuretransmitter,followthestepsbelow:
 MeasuretheHeight@FullTank(infeetormeters).
 DeterminetheSGfortheliquid(ifthecustomerdoesnotknow,checktheMSDSsheet).
 UsetheformulaabovetocalculatethePressure@Full.
a. Example:A40’tankwithaliquidmediaSGof0.9hasaPressure@Fullof15.58psi.
b. [(40’x0.9)/2.31’/psi]=15.58psi
 SelectapressuretransmitterwithapressuregreaterthanorequaltothePressure@Full.
a. Intheexampleabovefora40’talltankwithaSG=0.9,youneedapressurerangegreaterthan
orequalto15.58psi.
b. Using a sensor with a pressure range of 20 psi provides a Maximum Liquid Height of 51.33’,
whichwillreadtheentirerangeofthe40’talltank.
c. Using a sensor with a pressure range of 15 psi provides a Maximum Liquid Height of 38.50’,
whichisshortby1.5’.
i. Thismeansthatthesensorwilloutput20mAat38.5’ofliquidandthetop1.5’ofliquid
willnotbemeasured.
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