orifice flange tap routing

[pipe15]

another issue regarding orifice flange connections...

in liquid flow measurement, I try to tell the layout guy not to orient the taps vertically, but he says if properly vented it will work. I don't know about that, it seems you are asking to trap air. what do you think?

also, what if the tap does come off the side but then goes up and over something and then down to the instrument station. it seems that it does not matter if the station is at or below the process pipe elev, air could still get trapped in the vertical loop of tubing after it comes off the process pipe. any ideas here?

thanks again
mark

 

[jsummerfield]

What is the fluid and PRESSURE?

For liquid flow measurement the taps should not be above horizontal. 45 degree down is my preference. Vertically down can trap particulates. Vertical up is not good for liquid.

I prefer the transmitters to be located near the process connection. Vapor would be contained in the vertical loop described.

Conversely, the vapor transmitter should at least be off the side, 45 up is better and vertical top is just fine with the transmitter above the tubing. If the gas transmitter is below the taps, the process head affects the measurement. AHA!! What if the pressure is 1000 psig and the transmitter is one foot below the taps in gas service. This is the reason for my first question. The measurement is affected in this case, but not significantly. It is significant if the gas pressure is three psig.


John