# US 8,739,597 B2 · Apparatus and method for proving at low temperatures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,597 B2 - Document ID: US8739597B2 - Status: Granted - Kind: B2 - Application number: 12/990,129 - Filed: 2009-04-29 - Published: 2011-02-17 - Granted: 2014-06-03 - Earliest claimed: 2008-04-30 - Assignees: Daniel Measurement and Control, Inc. - Applicants: Donald Day - Inventors: Donald Day - Web page: https://patentgrep.com/patent/US8739597B2 ## CPC - G01F 25/17: using calibrated reservoirs - G01F 25/11: {using a seal ball or piston in a test loop} - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME ## Abstract 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. ## Claims ### Claim 1 A flow meter prover for low temperature fluids comprising: an inlet configured to be directly coupled to a pipeline carrying the low temperature fluids; an outlet configured to be directly coupled to the pipeline carrying the low temperature fluids; a flow tube coupled between the inlet and the outlet; a displacer moveable in a flow passage of the flow tube; wherein the flow tube and the displacer are configured to receive the low temperature fluids; and at least one of a magnetic pickup coil and a pair of transceivers coupled to the flow tube; wherein the displacer is configured to communicate with the at least one of the magnetic pickup coil and the pair of transceivers; wherein the displacer includes a vane disposed at an angle relative to the flow direction of the low temperature fluids. ### Claim 2 (depends on 1) The prover of claim 1 further comprising: a magnetic member coupled to the displacer communicating with the magnetic pickup coil via magnetic reluctance. ### Claim 3 (depends on 2) The prover of claim 2 wherein the displacer is a piston and the magnetic member is a target ring wrapped around the piston. ### Claim 4 (depends on 1) The prover of claim 1 further comprising: a carbon-free target member coupled to the displacer communicating with the magnetic pickup coil. ### Claim 5 (depends on 4) The prover of claim 4 wherein the carbon-free target member comprises at least one of high mu (μ) metal, HYMU metal, and HYMU 80 metal. ### Claim 6 (depends on 4) The prover of claim 4 wherein the carbon-free target member comprises a nickel alloy, an iron alloy, a molybdenum alloy, or any combination of nickel, iron or molybdenum. ### Claim 7 (depends on 1) The prover of claim 1 wherein: the pair of transceivers communicate a signal across the flow passage in the flow tube; and the displacer is moveable in the flow passage to interrupt the signal. ### Claim 8 (depends on 1) The prover of claim 1 wherein the flow passage includes an inner surface having a microfinish. ### Claim 9 (depends on 8) The prover of claim 8 wherein the microfinish maintains a microscopic film of the low temperature fluids between the flow passage inner surface and the displacer for lubrication. ### Claim 10 (depends on 8) The prover of claim 8 wherein the microfinish is in the range of 32 microinch to 16 microinch. ### Claim 11 (depends on 1) The prover of claim 1 wherein the displacer is a piston including a set of inner vanes extending along a longitudinal axis of the piston and set at an angle relative to the axis. ### Claim 12 (depends on 1) The prover of claim 1 wherein the vane rotates the displacer in response to the flow of the low temperature fluids. ### Claim 13 (depends on 1) The prover of claim 1 wherein the low temperature fluids include a temperature of less than about −50° F. ### Claim 14 (depends on 1) The prover of claim 1 wherein the pair of transceivers comprises a pair of ultrasonic transceivers. ### Claim 15 (depends on 1) The prover of claim 1 wherein the low temperature fluids include at least one of liquid natural gas (LNG), liquid nitrogen, liquid butane, liquid propane, and liquefied petroleum gas (LPG). ### Claim 16 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. ### Claim 17 (depends on 16) The prover of claim 16 wherein the piston includes a set of piston rotating vanes. ### Claim 18 (depends on 16) The prover of claim 16 further comprising: a pair of ultrasonic transceivers disposed on the flow tube and communicating across the flow passage; and wherein the piston movement interrupts the ultrasonic transceiver communication. ### Claim 19 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. ### Claim 20 (depends on 19) The system of claim 19 wherein the pair of transceivers comprises a pair of ultrasonic transceivers. ### Claim 21 (depends on 19) The system of claim 19 wherein the low temperature fluids include a temperature of less than about −220° F. ### Claim 22 (depends on 19) The system of claim 19 wherein the piston includes a carbon-free magnetic target member.