AGA Compliant Gas Flow Meter
AGA-Compliant Orifice Gas Flow Metering System (Honed Metering Pipes with Flow Straightener & Multivariable Transmitter)
AGA Compliant Gas Flow Meter
The AGA-Compliant Orifice Gas Flow Metering System is a fully engineered differential pressure (DP) flow measurement package designed for high-accuracy fiscal and custody transfer measurement of natural gas and other process gases, in strict accordance with AGA Report No. 3 and API MPMS Chapter 14.3 requirements. The system integrates a precision orifice plate assembly, honed metering pipes, an integral flow straightener, a Multivariable Transmitter, and complete instrument hook-up into a single coordinated measurement package, engineered to deliver traceable, repeatable mass flow measurement.
The upstream and downstream metering pipes are honed at the internal bore to a tightly controlled surface finish and roundness tolerance, ensuring a stable, fully developed, and repeatable flow profile at the orifice plane — a critical requirement for meeting AGA-3 uncertainty and accuracy standards. An integral flow straightener (tube bundle or perforated plate type) is incorporated upstream of the orifice to eliminate swirl and velocity profile distortion caused by upstream piping disturbances such as bends, valves, and tees, further reducing the required straight-run length while preserving measurement accuracy.
The Multivariable Transmitter, connected via engineered instrument hook-up (root valves, manifold, and tubing) up to the tapping points, simultaneously senses differential pressure, static line pressure, and process temperature, and applies internal compensation for gas compressibility (Z-factor), density, and thermodynamic properties to compute fully compensated mass flow, standard volumetric flow, and energy flow in real time — eliminating the need for a separate external flow computer in most applications.
Supplied as a complete, pre-engineered assembly from the metering pipe through to the transmitter, the system minimizes on-site fabrication and alignment errors, ensures full traceability of measurement uncertainty per AGA-3 methodology, and is well suited for gas custody transfer, allocation metering, and fiscal measurement applications.
Specifications
- Orifice plate, carrier and metering tube built to AGA Report No. 3 / API MPMS 14.3 dimensional tolerances with honed-bore metering pipes.
- Integral flow straightener with AGA-3 straight-run compliance for swirl-free, repeatable flow profile.
- Multivariable transmitter with AGA-8 compressibility compensation for mass, standard-volume and energy flow.
- Complete hook-up scope — root valves, impulse tubing, fittings and manifold — with traceable calibration documentation.
Technical specifications.
| Parameter | Specification |
|---|---|
| Metering principle | Differential pressure, orifice-based (AGA Report No. 3 / API MPMS 14.3) |
| Service | Natural gas / process gas, custody transfer grade |
| Line size | DN50 – DN600 (2"–24"), customizable |
| Output | Multivariable 4–20 mA with HART; compensated mass / standard volume / energy flow |
| Supply | Pre-engineered assembly with hook-up up to transmitter, AGA-3/AGA-8 documentation |
| Measuring principle | Differential Pressure (Orifice Plate per AGA Report No. 3) |
| Fluid type | Natural Gas / Process Gas (Custody Transfer Grade) |
| Line size range | DN50 to DN600 (2" to 24") — customizable |
| Metering pipe | Upstream & downstream spools, ID honed for controlled roundness & surface finish |
| Honing tolerance | As per AGA-3 / ISO 5167 bore tolerance requirements |
| Straight run length | As per AGA-3 Part 2 tables (reduced with flow straightener) |
| Flow straightener | Tube bundle / perforated plate type (integral, upstream mount) |
| Orifice plate material | SS316 / SS316L (standard); Monel / Hastelloy on request |
| Plate type | Concentric bore, precision machined & certified |
| Tapping type | Flange Tap / D & D/2 Tap (per AGA-3 requirement) |
| Process connection | Flanged (ANSI/DIN/JIS) |
| Design pressure | Up to ANSI Class 900 (application dependent) |
| Design temperature | -29°C to 250°C |
| Root (isolation) valves | Needle/Ball type, direct-mount at tapping points |
| Root valve material | SS316 (standard); other alloys on request |
| Impulse tubing | SS316 seamless tubing, 1/2" OD (standard) |
| Tube fittings/connectors | Twin/double ferrule compression type, SS316 |
| Manifold type | 2-Valve, 3-Valve, or 5-Valve (as per application) |
| Manifold material | SS316 (standard); other alloys on request |
| Sensed variables | Differential Pressure, Static (Line) Pressure, Process Temperature |
| Compensation | Integral Pressure, Temperature & Compressibility (Z-factor per AGA-8) |
| Computed outputs | Mass Flow, Standard/Normal Volumetric Flow, Energy Flow (optional) |
| Accuracy | ±1% of reading (fully compensated mass flow) |
| Repeatability | ±0.1% |
| Rangeability | Up to 10:1 |
| Output signal | 4–20 mA with HART; optional Foundation Fieldbus / Profibus PA / Modbus RTU |
| Local display | Integral LCD indicator (flow rate & totalized flow) |
| Power supply | 24 VDC (loop powered) |
| Enclosure protection | IP66 / IP67 |
| Area classification | Weatherproof / Flameproof (Ex d) / Intrinsically Safe (Ex ia) – as required |
| Applicable standards | AGA Report No. 3, AGA Report No. 8, API MPMS Ch. 14.3, ISO 5167-1/2 |
| Certification | CE, ATEX / PESO / OIML / Custody Transfer Approval (as applicable) |
Key features engineered in.
- Fully AGA Report No. 3 / API MPMS 14.3 compliant metering package
- Honed internal bore metering pipes for stable, repeatable flow profile
- Integral flow straightener reduces swirl and required straight-run length
- Multivariable Transmitter with onboard DP, pressure & temperature sensing
- Real-time compensated mass flow, standard volume & energy flow computation
- Engineered instrument hook-up (root valves, manifold, tubing) included up to transmitter
- Reduced installation error through pre-fabricated, matched-tolerance assembly
- Suitable for fiscal/custody transfer and high-accuracy allocation metering
- Full documentation and calculation traceability per AGA-3 methodology
Applications we serve.
- Natural gas custody transfer and fiscal metering
- Gas allocation metering between operators/facilities
- Gas transmission pipeline metering stations
- Gas processing plant inlet/outlet measurement
- LNG terminal and gas distribution custody points
Scope of supply.
- Orifice plate (certified per AGA-3)
- Upstream & downstream metering pipes (ID honed)
- Integral flow straightener
- Root (isolation) valves
- Impulse tubing, fittings & connectors
- Manifold (2V/3V/5V)
- Multivariable Transmitter
- Calibration & calculation documentation (AGA-3/AGA-8 traceable)
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