In Part 1, we discussed the orifice plate and the necessary precautions one should take in handling such a delicate device. In part 2, we’d like to address the upstream/downstream piping – aka “The Run”.
Even though this installment is quick and dirty, we think you’ll find it delightful… on with the show!
The most important (as well as most difficult to measure) aspects of flow measurement are flow conditions within the pipe upstream of the meter.
Flow conditions mainly refer to the gas velocity profile, irregularities in the profile, varying turbulence levels within the velocity or turbulence intensity profile, swirl and any other fluid flow characteristics which will cause the meter to register flow different than that expected.
It will change the value from the original calibration state referred to as reference conditions that are free of installation effects.
So how do we keep from giving away our gas?
Tip 1: Anything in the meter run piping will reduce the effective internal diameter of the meter run and will result in “giving away” gas to the purchaser. For example, (liquid) carryovers from the separator that fill the meter run with liquid will cause a drop in gas sales.
Tip 2: Although straightening vanes and honeycombs are designed to help the accuracy of readings, more times than not they become plugged by paraffin or covered in debris from the gas line. Straightening vanes should be avoided unless they are completely necessary!
Tip 3: If any of you are using a bellows meter, and that meter must be jarred for the differential pen to read zero, this signifies that you have “static pin friction”. What happens when our pins are “static”? The seller ends up giving away 3.5% of his gas to the purchaser (this is based on a chart reading mid-scale). If the differential were only 10, this error would be much greater than 3.5%.
On a similar note, we had a new client call us and ask our opinion on sales volume ‘check meters’. Now, this operator in particular is one savvy dude, and he’s doing a lot of overhauls on his company to be able to run as lean as possible…
Basically, he wanted to know what the GreaseBook community thought about paying $30/mo per check meter…
What’s your experience? Is it worth the money? Leave your 2 cents in the comment section below!