Instrumentation Engineering Interview Question:

What happen if i install my pressure transmitter below the elevation of pipe in natural gas service?

Submitted by: Administrator

Pressure will be added up a bit more, see its detail:
1. Suppose,you want to install a pressure transmitter 10
meter below of pipe line.
2. Density of methane (Examlpe) 0.656 kg/m3 at 25C.
3. your pressure transmitter will show (10 x 1000 x0.656 =
6560mm) 6569 mm of water pressure more.
4. Suppose gas pressure is 20Kg/cm2, then due to this
elevation, transmitter will show 20.66Kg/cm2
Submitted by: Administrator

Pressure transmitter in a gas service shall be installed above pipe line. If it is installed below pipeline, the moisture in the gas service gets trapped in the impulse line and acts like a cushion in your chairs which will provide you erroneous readings lesser than the actual pressure in the pipe line. if pressure transmitter is installed below pipeline, moisture to be collected in a separate condensate point and needs to be drained at a frequent interval .
Submitted by: Ashwani Kumar