​First Let’s Understand the concept
 
the calculation is very similar to Normal level calculation
 
Here’s our simple pressure measurement formula 

​The Pic above shows a Container of Height 100 Inches
And this tank contains Liquid of Specific gravity 0.5
 
So what is the pressure at the bottom?
 
Height x Specific gravity= InH2O ……..(Reference 1)
 
100 (inches) X 0.5 = 50 inH2O 

Now let’s keep the “Height Same” and Change specific Gravity to 0.9
 
Height x Specific gravity= InH2O
 
100 (inches) X 0.9 = 90 inH2O
 
So if Height is kept CONSTANT then change in pressure is just due to CHANGE IN DENSITY (Specific gravity)
 
When Transmitter fells a pressure of 50inH2O we get to know the S.G of liquid inside is 0.5
 
And, When Transmitter fells a pressure of 90inH2O we get to know the S.G of liquid inside is 0.9
 
If this Concept is clear the calculation is “Piece of Cake” !!!
 
Our Calibration range is 50inH2O to 90inH2O
 
Here are the steps in simplified manner
 
For 4mA Cases (LRV-Lower Range value case)
1) Calculate the Pressure at LP side (tapping) of Transmitter
2) Calculate the Pressure at HP side (tapping) of Transmitter
3)Differential pressure = Pressure at (HP Side – LP Side)
 
Repeat the same for 20mA case (URV-Lower Range value case)
 
Refer Simple Level calculation article for reference as to how to execute the above steps

SIMPLE LEVEL MEASUREMENT CALCULATION

Thanks for reading !!