Analog gas meter HK-G4-G6-G10

mechanicalIoT

Overview
The YUNYI Roots flow meter is a volumetric rotary vane (Roots) gas meter that measures gas volume by precise displacement. Two precision-machined 8-shaped rotors rotate in opposite directions inside the measuring chamber, generating four fixed-volume pockets per revolution for direct, pulse-capable volume measurement. Designed for custody transfer and trade settlement, it delivers long-term stability and repeatability suitable for city gas and natural gas networks.

Product Advantages

• Trade-grade accuracy: accuracy class up to ±1.0% over a wide operating range.
• Very low start-up flow and wide turndown: sensitive to small flows with turndown ratios typically up to 1:100 or higher.
• Superior repeatability and stability: repeatability better than ±0.2%; extended calibration intervals.
• Direct volumetric readout with robust pulse outputs: measurement less dependent on gas composition (use T&P correction for standard volume); pulse outputs resistant to EMI.
• Integrated temperature and pressure compensation: built-in T&P sensors and corrector options provide standard volume outputs (20°C, 101.325 kPa).
• Durable construction and simple maintenance: housings in high-strength aluminum alloy or cast iron, precision bearings, washable filters and replaceable lubrication.

Core Application Areas

• Urban gas custody transfer and trade settlement for gate stations, transmission and distribution networks.
• Natural gas production and refueling stations (CNG/LNG), wellhead metering and power plant furnace gas measurement.
• Industrial gas billing and energy management for compressed air, nitrogen and other process gases.
• Pressure regulation and metering stations in regional pipeline networks.
• Reference standard in testing and on-line calibration of other gas meters.

How it achieves high accuracy and repeatability

• Fixed-volume displacement: synchronized rotors trap defined gas volumes each revolution for inherently accurate measurement.
• Minimal internal leakage: very tight clearances reduce slippage, preserving accuracy at low flows.
• Magnetic coupling and pulse output: rotor movement couples to an index generating precise, repeatable pulses proportional to actual volume.

Comparison
Aspect | Gas Roots Meter | Gas Turbine Meter | Ultrasonic Meter
Accuracy | Excellent at low to mid flows | Good at high flows, reduced low-flow performance | Very good, may vary with gas composition
Turndown Ratio | Very wide (up to 1:100 or more) | Moderate | Wide
Moving Parts | Yes (rotors) | Yes (high-speed rotor) | No
Upstream Pipe Requirements | Minimal (often ≤5D) | Long straight runs (10–20D) | Model-dependent installation
Custody Transfer Use | Extensive history | Common | Increasing use

Smart / Corrected Volume
Units can include an integral corrector or external flow computer using T&P inputs and industry-standard equations (AGA, etc.) to output corrected standard volumes for billing and custody transfer.

Selection & Installation Best Practices

• Selection: define min/normal/max flows and select meter size to keep normal flow in optimal range; confirm gas composition, pressure and temperature; choose appropriate pressure rating and materials (ductile iron or aluminum standard, stainless steel for corrosive gases); verify required outputs (pulse, 4–20 mA, RS485/Modbus).
• Installation: fit a high-efficiency upstream filter/coalescer; typical orientation horizontal (follow manufacturer); short straight runs required (commonly 3–5D upstream, 0–3D downstream); perform flow calibration traceable to national standards and load factors into corrector.
• Maintenance: periodic filter replacement and condition checks; long service life with predictable bearing and lubrication maintenance; recommended recalibration interval typically 5–10 years or per regulation.

Technical Specifications

• Accuracy Class: ±1.0%
• Turndown Ratio Qmax:Qmin: 1:100 or higher
• Nominal Diameters: DN25, DN40, DN50, DN80, DN100, DN150, DN200
• Maximum Working Pressure: PN16 (1.6 MPa), PN25 (2.5 MPa) or higher (e.g., 4.0 MPa)
• Repeatability: ≤ ±0.2%
• Output Signals: mechanical counter, voltage pulse, 4–20 mA, RS485 (Modbus)
• Smart Features: built-in T&P compensation, data logging, IC card, optional GPRS
• Materials: housing — aluminum alloy or cast iron; rotors — high-strength alloy; bearings — precision long-life
• Installation: horizontal standard, vertical optional
• Protection Rating: IP65