Flow measurement tubing installation

[3ooody]

Hello,
I have a flow transmitter installed on a crude oil pipline, the pipeline is very low to the ground and the gap between the pipeline and the ground is almost 12 inches, so for that issue the flow transmitter is installed even below 12 inches (to illuminate gas lock)and it is very hard to calibrate or service this transmitter, I was thinking of lifting it up to body level to install it on a pole with a sunshade but I was awared by the technician that this may cause error in reading, I came across hook up arrangements and flow measurement tubing installation also bubble pots (check attachement), but still not sure will the flow reading be effected if I raise the transmitter up to body level?

need your kind help people

 

[danw2]

The oil in the two impulse tubes to the high and low sides of the DP transmitter creates a static head pressure proportional to the height of the column of oil and the oil's specific gravity, yet neither pressure should contribute to a DP or flow value. These impulse tubing pressures and any mounting attitude pressure are typically zeroed out when the transmitter is commissioned.

If you change the mouting, the transmitter would have to be "re-zeroed to account for new mounting attitude and any change in the impulse tubing head pressure.

 

[lacajun]

What danw2 wrote is correct. Also, if the taps on the bottom are used, you shouldn't have problems with bubbles in the impulse tubing. Do you have entrained gas throughout the pipeline?

 

[danw2]

Best Practice Guide: Impulse Lines for Differential Pressure Flowmeters

http://www.idc-online.com/technical...entation/Differential pressure meters_nel.pdf

 

[3ooody]

nice, would you think installing a bubble pot (just for extra precautionS) be in handy after the new mounting is raised?

 

[lacajun]

It could be, if you have room in your budget and it won't cause more maintenance for someone. You'll have to make that call, as the engineer.

I've never installed a bubble pot in all the points I've done in manufacturing. Internal standards called for liquid taps to be 45° off the bottom to avoid particulates or outright sludge. The orifice plates required vent holes at the top to allow gas to flow through.

I'm sure all of the flows were not "well behaved" thus had no entrained gas. But, the readings were never called into question. I had to conclude everything worked as designed.

I've done some pipeline measurements but again bubbles were not a big issue. I don't know how well behaved oil pipeline flows are. Perhaps some of your upstream guys can tell you.