Orifice meter up/down stream straight pipe
Orifice meter up/down stream straight pipe
(OP)
good day,
An orifice upstream straight pipe length requires 5D, I put a PI in upstream 4D. Is it ok?
thanks.
An orifice upstream straight pipe length requires 5D, I put a PI in upstream 4D. Is it ok?
thanks.





RE: Orifice meter up/down stream straight pipe
At point 0, you have a pressure tap mounted in the side of the pipe.
At point 4D, you have a flow orifice.
A standard static pressure tap has no flow into or out of it, and its (very small) hole doesn't stick into the fluid flow path. So how could the pressure tap significantly affect the orifice flow, which will be at the centerline of the pipe?
Now, you do need to make sure there is a straight section of pipe downstream of the orifice plate before the next bend, and the pressure tap should be in a bend itself.
RE: Orifice meter up/down stream straight pipe
Get the API MPMS chapter 14 for designing orifice meters.
RE: Orifice meter up/down stream straight pipe
my question is: the distance between PI and orifice, is shorter than the length required by the orifice meter up/down straight pipe.
I agree with racookpe1978. Is there any other opinion?
Thanks!
RE: Orifice meter up/down stream straight pipe
It all comes down to what you are using the meter tube for. If it is used for plant control then the PI is fine. If you are using it for custody transfer then you have to conform to the minimums in AGA 3 (which is the same as API MPMS Chapter 14)--they are not negotiable at all. If the book calls for 5D in a 6-inch Sched 40 pipe, then you cannot have any part of a purtabation in the flow within 30.34 inches of the upstream face of the plate. Some people would claim that the distances are based on the OD of the pipe, but I don't find support for that in the code.
David
RE: Orifice meter up/down stream straight pipe
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Orifice meter up/down stream straight pipe
RE: Orifice meter up/down stream straight pipe
My PI is for plant control, I put it within distance required by orifice meter up/down straight pipe. otherwise, it is too high to access.
RE: Orifice meter up/down stream straight pipe
David
RE: Orifice meter up/down stream straight pipe
Then WHAT is your question?
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Orifice meter up/down stream straight pipe
my question is: is there problem putting a PI in the orifice meter upstream straight pipe?
RE: Orifice meter up/down stream straight pipe
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Orifice meter up/down stream straight pipe
That goes for PI's also.
RE: Orifice meter up/down stream straight pipe
RE: Orifice meter up/down stream straight pipe
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Orifice meter up/down stream straight pipe
Upstream tap is less affected by the meter, while the downstream tap should be located beyond the vena contracta and preferrably 20 D or so, however, in common plant installations this rule is not always possible to implement, so you take what you can get.
Most meter manufacturers have recommeded upstream runs as do the meter standards.
RE: Orifice meter up/down stream straight pipe
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Orifice meter up/down stream straight pipe
Meter stations often with provision for testing, inspection, flow conditioning, etc. are another mater because of the need for contactural accuracy.
good day
RE: Orifice meter up/down stream straight pipe
The downstream tap should be located beyond the vena contracta but not 20 D downstream. Nothing more than six diameters downstream should cause concern.
RE: Orifice meter up/down stream straight pipe
As others have said, the closer any disturbance is to the orifice, the greater the inaccuracy of the reading. Given the lack of information, you will need to make the decision on the size of the disturbance and whether it will have a 'real' effect.