『CNG Flow Meter: High-Pressure Compressed Natural Gas Mass Custody Transfer』Related information(v cone flow meter|rotary gas meter|gallon meter|gear meter|metal tube rotameter|glass tube rotameter|nutating disk meter|transit time ultrasonic flow meter|wedge flow meter|pd meters|hydraulic flow meter|ultrasonic water flow meter|water flow meter|air flow meter|magnetic water flow meter|oxygen flow meter|gas flow meter|argon flow meter|air velocity meter|gasoline flow meter|fuel flow meter|ultrasonic water meter|digital water meter|nitrogen flow meter|solid flow meter|Oxygen tank flow meter|digital water flow meter|diesel fuel flow meter|steam flow meter|02 flow meter|compressed air flow meter|oil flow meter|liquid flow meter)
CNG Flow Meter: High-Pressure Compressed Natural Gas Mass Custody Transfer
Quick Answer: A CNG flow meter for high-pressure compressed natural gas mass custody transfer should be a Coriolis mass meter. It measures mass flow directly, so pressure and temperature compensation is not needed. Silver Instruments offers CNG Coriolis meters rated up to 350 bar in DN15 to DN50 line sizes.
Why CNG Custody Transfer Demands a Mass Meter
Compressed natural gas changes density with pressure and temperature. A volume meter shows a different gas amount under the same mass flow when pressure moves from 200 bar to 250 bar. Custody transfer between a CNG trailer and a filling station cannot accept that error.
A Coriolis meter measures mass directly. You get kg/h or kg per delivery, not normal cubic meters that depend on compensation. Because the meter has no moving parts in the flow path, filter dust and small pressure spikes do not change the reading for long. Most engineers skip turbine or differential pressure meters for high-accuracy CNG transfer.
In practice, the key value is long-term stability. Silver Instruments uses 316L stainless steel sensor tubes and a rigid twin-tube design. Accuracy of 0.15 percent of rate is standard on the CNG line. Repeatability is better than 0.05 percent, which matters when a customer audits daily delivery records.
Pressure Ratings That Matter for a CNG Flow Meter
High-pressure CNG systems often run between 200 bar and 250 bar at a dispenser or cascade storage. Pipeline CNG can be lower, around 16 bar to 100 bar. Your CNG flow meter must handle at least the maximum allowable working pressure of the skid. Do not select a 100 bar meter for a 250 bar trailer loading station.
Silver Instruments CNG Coriolis meters come with a standard 350 bar pressure rating. This covers most CNG daughter stations, trailer fill posts, and virtual pipeline skids. Process temperature range is -20 °C to +80 °C. For cold climates, a low-temperature option down to -40 °C is available. Wetted parts are 316L stainless steel with no internal seals that could leak at high pressure.
Process connections vary by country. Many customers in Southeast Asia and Australia use 1/2 inch NPT or 3/4 inch NPT compression fittings. Others use ANSI 1500 or 2500 flanges on DN15 and DN25 lines. We have seen a gas distributor in Vietnam order a DN25 meter with 3/4 inch NPT threads, and the same model in Oman is built with ANSI 2500 flanges.
Silver Instruments Coriolis Meter Models for CNG
Three models cover most high-pressure CNG custody transfer jobs.
The CMF-DN15 handles low flow dispensers and pilot metering from 0.5 kg/min to 30 kg/min. The CMF-DN25 is the workhorse for CNG refueling stations and trailer loading. Its flow range is 1.5 kg/min to 90 kg/min, which matches a typical 250 bar dispenser filling a vehicle tank at 30 to 60 kg/min. The CMF-DN50 covers bulk transfer and virtual pipeline unloading from 5 kg/min to 300 kg/min.
All three models output mass flow, volume flow, temperature, and density. An internal PT100 measures process temperature for live density correction. If the gas composition changes, the meter still reports mass correctly. The electronics support 4-20 mA HART, pulse output, and Modbus RTU. A local display shows totalized mass in kg or tonnes.
Field Notes from CNG Distribution Sites
Last year a customer in Thailand asked us to replace a turbine meter on a CNG trailer fill post. The turbine bearing wore out after 13 months because of fine dust from pipeline
In Indonesia, a CNG daughter station uses two CMF-DN50 meters to unload bulk CNG from trailer cascades. The site logs mass flow every 30 seconds through Modbus RTU. Because the meter reports density live, the station manager detects water or heavier hydrocarbon carryover before it reaches the dispenser.
Most engineers skip the low-price volume meters for custody transfer. The issue is not the initial price but the uncertainty after six months. A Coriolis meter costs more upfront and less in calibration and billing disputes.
Outputs and Approvals for Custody Transfer
A custody transfer system needs a pulse output for a flow computer or PLC. The pulse represents a fixed mass increment, such as 1 kg or 0.1 kg. A 4-20 mA HART signal can carry mass flow rate to a remote indicator or RTU. Modbus RTU is common for data logging at CNG stations in the Middle East and Latin America.
Silver Instruments offers ATEX Zone 1 and Zone 2 certified transmitters for CNG areas. The sensor is intrinsically safe and can be installed in a hazardous area with a suitable barrier. Some countries require local pattern approval or OIML R139 type certification for custody transfer. We can provide test certificates and calibration reports for your local weights and measures office.
Because CNG is dry and clean when filtered properly, the meter does not need frequent cleaning. A gas filter upstream of 5 micron is enough to protect the sensor tubes. No internal moving parts means pressure drop is low, typically less than 0.3 bar at peak flow on a DN25 meter.
FAQ
Q: Why not use a turbine meter for CNG custody transfer?
A: Turbine meters measure volume. CNG volume changes a lot with pressure and temperature. Mass balance is easier with a Coriolis meter, and there are no bearings to wear from dust or rapid pressure pulses.
Q: What pressure rating do I need for high-pressure CNG metering?
A: At least 350 bar for most CNG trailer and dispenser systems. Pipeline CNG can use lower pressure classes, but 350 bar covers the majority of custody transfer skids without risk.
Q: Can the same meter measure mass flow and density?
A: Yes. Silver Instruments CNG Coriolis meters output mass flow, density, temperature, and calculated volume flow. Density data helps detect gas quality changes before they damage downstream equipment.
Q: Which line sizes are available for CNG dispensers?
A: DN15, DN25, and DN50 are the standard sizes. DN25 matches most CNG dispenser flow rates from 1.5 kg/min to 90 kg/min. DN50 is for bulk unloading and virtual pipeline transfer.
Q: How do I get a price quote for a CNG flow meter?
A: Send us your pressure in bar, temperature in Celsius, pipe size in DN, and flow range in kg/h. Include gas composition and hazardous area classification. We will reply with a model, accuracy statement, and price.
Request a CNG Flow Meter Quote
Send us your pressure in bar, temperature in Celsius, pipe size in DN, and flow range in kg/h. We will recommend a CMF-DN15, CMF-DN25, or CMF-DN50 Coriolis meter for your CNG custody transfer duty.
Silver Automation Instruments is a flow meter manufacturer with direct factory pricing for CNG skid builders. Tel: +86-135-1213-1526. Whatsapp: 86-135-12131526. WeChat: +86 13512131526.
Hot Product
Related AD
