Level Measurement Formula

HELLO FRNDS


I AM INTERESTED IN MEASURING THE HEIGHT OF A LIQUID IN A TANK OPEN TO ATMOSPHERE ,BY FLANGED TYPE DIAPHRAGM TRANSMITTER ,THE FLIUD BEING DIESEL OIL.WATS THE EXACT FORMULA FOR
MEASURING THE PRESSURE, IS IT


H = P/SG

H = HEIGHT , P= PRESSURE SG = SPECIFIC GRAVITY

OR SHOULD I CONSIDER GRAVITY ALSO

P =H *RHO *g


h =height rho =density g =gravitonal force


regards


jose

You could do it either of those ways, although I'm not sure if the calculations you have are right. But the way I've done it in the past is by putting in a known amount the first time, note the pressure, and use that as a starting point.

It depends on the output scale of your pressure transmitter. If the output is inches of water, then h = P ÷ SG where h = height in inches, P = pressure in inches water, and SG = specific gravity.

If P = 27.7 " H2O and SG = 0.80 then the height is 34.6 inches of fuel oil.

On the other hand, if the output is in psi you need the density term. h = P ÷ rho

If P = 1.0 psi and rho = 0.0288 lb/cu in (49.92 lb/cu ft) then h = 34.6 inches of fuel oil.

A very handy trick I learned in ancient times (college) is to write out the formula and make sure the units cancel out properly. In the case of the second formula lb/sq in ÷ lb / cu in results in units of inches (1/1/in = in). Having the right units doesn't guarantee the formula is right, but having the wrong units guarantees the formula is wrong.