Publication
- Code: R 144
- Edition: 2006 (E)
- Published by: Organisation Internationale de Métrologie Légale (OIML)
- Custodian: OIML Technical Committee TC 8 (Measurement of quantities of fluids)
Scope
This Recommendation specifies metrological and technical requirements for diaphragm gas meters, positive-displacement instruments that measure fuel gas volume by alternately filling and emptying chambers formed by flexible diaphragms.
It covers:
- Residential and commercial meters from G1.6 to G100 (rated flow capacity in m³/h).
- Accuracy classes 1.0, 1.5, and 2.5.
- Meters operating on fuel gases at pressures up to 0.5 bar (low pressure) or 200 mbar (typical service).
Accuracy classes
| Class | MPE in upper zone (Qt to Qmax) | MPE in lower zone (Qmin to Qt) | Typical use |
|---|---|---|---|
| 1.0 | ±1.0% | ±3.0% | Custody transfer (high precision) |
| 1.5 | ±1.5% | ±3.0% | Custody transfer (standard) |
| 2.5 | ±2.5% | ±5.0% | Industrial sub-metering |
The transition flow Qt is declared per meter size and class. The
two-zone MPE structure is encoded as a Table primitive in the SMART model.
SMART model coverage
- 28 requirements covering metrological, technical, and construction provisions.
- 11 conformance tests including the cyclic volume test and endurance test.
- 8 test report forms with MPE zone-lookup computations.
- The full terminology (~45 terms).
How to use it
| Goal | Path |
|---|---|
| Browse the structured requirements | the SMART Recommendations browser ↗ |
| Read the Recommendation overview | /recommendations/r144/ |
Cross-references
- R 6, General provisions for gas volume meters (companion framework).
- R 32, Rotary piston gas meters (related technology).
- D 30, Application of ISO/IEC 17025 to testing laboratories.