Apparatus and method for proving at low temperatures

A flow meter prover for low temperature fluids comprising:

• a flow tube having a flow passage therein and a magnetic pickup coil mounted thereon;
• and
• a piston disposed in the flow passage and including a carbon-free magnetic member;
• wherein the piston is moveable to move the magnetic member past the magnetic pickup coil and communicate with the magnetic pickup coil via magnetic reluctance;
• wherein an inner surface of the flow passage includes a microfinish configured to maintain a lubricating microfilm of the low temperature fluids;
• wherein the carbon-free magnetic member comprises at least one of high mu (μ) metal, HYMU metal, and HYMU 80 metal.

A system for proving low temperature fluids comprising:

• a pipeline carrying the low temperature fluids;
• a prover coupled into the pipeline and receiving the low temperature fluids, wherein the prover comprises:
• a flow tube including a piston moveably disposed therein;
• and
• at least one of a magnetic pickup coil and a pair of transceivers coupled to the flow tube;
• wherein the piston is configured to communicate with the at least one of the magnetic pickup coil and the pair of transceivers;
• wherein an inner surface of the flow tube includes a microfinish configured to maintain a lubricating microfilm of the low temperature fluids;
• wherein the piston is configured to rotate while being moved axially.