| 摘要 |
Apparatus and methods for proving a flow meter at low temperatures. A flow meter measuring low temperature fluids (e.g., less than about−50° F., or less than about−220° F.) must still be proved. Low temperature fluids can be destructive to piston or compact provers, or may require indirect proving methods. The apparatus disclosed is a low temperature prover directly coupled into the pipeline carrying the low temperature fluids. In some embodiments, a magnetic pickup coil and a magnetic member communicate between the displacer and the flow tube. The magnetic target member may be carbon-free. In some embodiments, a pair of ultrasonic transceivers coupled to the flow tube communicate a signal across the flow tube and a displacer is moveable to interrupt the signal. In some embodiments, the flow tube includes an inner surface having a microfinish for lubrication. The displacer may be a piston rotatable while being moved axially.
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