Pressure Indicator instalation 2

[leomiranda]

According standards, to install a pressure transmitter, if liquid, the process connection shall be from middle to bottom, if gas, from middle to top.
But when the instrument used is one PI (Pressure Indicator) I always see on top (90 degree) for liquid or gas. For PI, don’t I need to follow this rule?

Best regards

 

[danw2]

For gauge pressure measurments the recommendations do get ignored, don't they?

Here's Wika's recommendations for gauge pressure measurment installation, but I note that they omit the common 45° offset that is the most common to avoid sludge collection in liquid lines.

There is a freeze factor for liquid water caught in a below-center impulse line, but is 4" (100mm) of water column that big an error on a pipe carrying 100 psi (7 bar) pressure?

For differential pressure (DP) flow measurement, it's a different situation altogether because serious errors can occur in impulse tubing given the low DPs associated with flow measurement.

For DP impulse tubing the above center line for gas, below center line for liquid and below bottom with condensate filled impulse lines for steam need to be adhered to.

 

[powerjunx]

good comment danw2


"..the more, the merrier" Genghis Khan

 

[dcasto]

for high pressures, it all comes out in the wash. A 1000 psig stream with any fluid it doesn't really matter.