Orifice in a vertical pipe run

[InCgeek]

Are there any special considerations for an orifice installed in a vertical run besides insuring the sensing lines are sloped down to the transmitter?

 

[rmw]

If you are measuring the flow of a fluid, or if it is a gas or vapor that will condense in the sensing lines, then the difference in height between the transmitter taps above and below the orifice has to be taken into account in the delta p that the transmitter is reading. That difference has to be zeroed out.

rmw

 

[quark]

rmw has raised a good point and you should take care of this for better accuracy(ofcourse, your meter manufacturer does suggest you). Secondly is it a downflow or upflow application? IF downflow, justt take care of wetted perimeter. Don't pressume that pipe will be totally filled up.

Regards,


Eng-Tips.com : Solving your problems before you get them.

 

[Thomasjl]

Hi InCgeek,

On top of the previous comments bear in mind that the direction of the flow is important. This is depending on the medium going through the pipe.
A gasline the flow should be downwards.
A liquid line the flow should be upwards.

Dood luck,
Thomasjl

 

[InCgeek]

Thank you for the input. The flow direction is up toward a flow control valve which is connected to the condenser. Upstream pressure is 1215 psia and downstream is approaching 0 psia. Last year the trim was replaced in the FV and not sure it was sized correctly. There are times when operating the system that even though the FV is opened the transmitter shows 0 flow. Please note the FV is operated from a blind controller and is not equipped with position indication. When the zero flow condition occurs operations sends a tech out to blow down the orifice sensing lines because it is perceived that air is in the lines even though there is no indication of erratic flow. Enough rambling any other thoughts would be greatly appreciated. SFE

 

[rmw]

Just to clarify, is this line a steam line, or liquid. At that pressure, in my experience, it could be either. Or, should I say, is there steam or water passing the flow measuring orifice, and if it is a fluid, is it saturated?

rmw

 

[InCgeek]

This is a liquid line at 120 deg F and are assuming that since the orifice is upstream from the FV (drag valve) it is also seeing liquid.

SFE

 

[25362]

To InCGeek, not knowing the nature of the fluid in question, your assumption would, apparently, have to be taken with a pinch of salt. Don't you think ?