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SMC Flow Meters and Dwyer Flow Meter Equipment for High-Precision Pneumatic Air and Gas Lines

Quick Answer

For compressed air, nitrogen, argon, and other pneumatic gas lines, high-precision measurement depends on the sensor type, line size, and flow span. SMC flow meters and Dwyer flow meter equipment are common options for low to medium flow ranges. Silver Instruments offers thermal mass and vortex flow meters that match these applications with 4-20 mA HART output, local display, and accuracy within 1 percent of reading.

Why Air and Gas Lines Need a Different Meter

Gas measurement is not the same as liquid measurement. Pressure changes, temperature swings, and pipe vibration affect the reading. A meter for a 6 bar compressed air header needs a different range than a meter for a 2 bar pilot air line. We always ask for pressure in bar, temperature in degrees Celsius, pipe size in DN, and flow range in Nm3/h before recommending a model.

In practice, many users oversize the meter. A paint manufacturer in Southeast Asia replaced a float type meter with a thermal mass flow meter on a DN25 air line. The old meter could not read below 8 Nm3/h. The new meter measures from 0.5 Nm3/h to 80 Nm3/h with stable output. That span matters for plant audits and energy management.

SMC Flow Meters for Pneumatic Air and Gas

SMC offers compact digital flow switches such as the PF2A series. These are common in pneumatic panels and production machines. The PF2A has a local display and switch or analog output. Typical accuracy is around 3 percent of full scale. That works for many machine level checks. For energy metering or interlock control, full scale accuracy is often not enough.

Silver Instruments thermal mass flow meters give accuracy within 1 percent of reading on gas lines from DN15 to DN50. The analog output is 4-20 mA HART. The sensor has no moving parts. This design reduces drift on wet or oily compressed air. We have seen this on customer sites many times. A customer in Vietnam used a Silver Instruments TMF-G DN25 meter on an instrument air header running at 7 bar. The meter has worked with no zero drift for 18 months.

Dwyer Flow Meter Equipment for Gas and Air

Dwyer flow meter equipment covers variable area, differential pressure, and thermal dispersion types. Series RM and Series SF are common for air and gas. Variable area meters from Dwyer are low cost and easy to install. They do not require power. But they are sensitive to pressure changes and are often specified as full scale accuracy from 2 to 5 percent. Digital totalizing is not built in.

For high-precision pneumatic air and gas lines, a direct mass flow output is easier to integrate with PLC and SCADA systems. Vortex flow meters from Silver Instruments are another option for larger pipe sizes from DN40 to DN200. They handle air, steam, and inert gas with a single meter. The electronics include pressure and temperature compensation. That gives a direct mass flow total in kg or Nm3.

Recommended Silver Instruments Models

Select the model by line size, flow range, and output. Two series cover most pneumatic air and gas applications.

Silver Instruments TMF-G series thermal mass flow meter. Pipe sizes DN15 to DN50. Flow range 0.5 to 200 Nm3/h air. Accuracy 1 percent of reading. Output 4-20 mA HART. Inline or insertion connection. Temperature range -20 to 60 degrees Celsius. Pressure up to 16 bar. Best for compressed air, nitrogen, and argon.

Silver Instruments VX-G series vortex flow meter. Pipe sizes DN40 to DN200. Flow range 10 to 3000 Nm3/h air. Accuracy 1 percent of reading for gas. Output 4-20 mA HART with pulse. Best for larger air headers, blower air, and mixed gas lines.

Both series accept pipe size, pressure, temperature, and flow range data from the customer. That is how we avoid oversizing. Send us your pressure in bar, temperature i