Gas Meters: Long-Term Diaphragm Stability in Natural Gas Environments.

Gas Meters: Long-Term Diaphragm Stability in Natural Gas Environments

Problem Statement

Diaphragms in natural gas meters fail due to methane permeation, plasticizer extraction, and compression set degradation. Standard NBR compounds lose elasticity below -40°C and swell in gas condensates.

Material Science Analysis

NBR fails due to nitrile group polarity absorbing condensates. FKM resists permeation with 66% fluorine content but lacks low-temperature flexibility. HNBR balances hydrogenation (reduced double bonds) for chemical resistance with acrylonitrile content for gas barrier properties.

Technical Specifications

• Material: HNBR (Hydrogenated Nitrile)
• Shore A Hardness: 70 ±5
• Tensile Strength: 22 MPa (ASTM D412)
• Elongation at Break: 300%
• Temperature Range: -50°C to +150°C
• Compression Set (22hrs @ 150°C): 18% (ASTM D395)

Parameter	HNBR	Standard NBR	FKM
Methane Permeation (cc·mm/m²·day)	120	450	85
Low-Temp Flexibility (°C)	-50	-25	-20
Swelling in Condensates (%ΔV)	8	35	5
Compression Set @ 10,000 cycles (%)	12	45	10

Standard Compliance

RubberQ's IATF 16949 processes enforce:

• Batch traceability for raw polymer lot numbers
• ISO 3601 Class A for dimensional tolerances
• ASTM D2000 BF, BG material callouts
• Post-vulcanization bake cycles to stabilize compression set

For custom material compound development or IATF 16949 documentation, consult RubberQ's engineering department.