Monitoring generator output, allocating process consumption and capturing short injection pulses require different capabilities. Specify minimum, normal and maximum flow, gas composition, purity, moisture conditions and operating pressure. For Nm³/h or Sm³/h output, document reference temperature, absolute pressure and the dry or wet gas basis. A flow meter does not measure gas purity.
Thermal mass flow meters depend on the gas's thermal properties; air calibration is not automatically equivalent to nitrogen or oxygen calibration. Use the manufacturer's approved gas selection or conversion. Coriolis, differential-pressure and variable-area instruments have different installation, density and pressure-loss considerations. No single technology is best for every line; assess the instrument for the specified gas and operating range.
Determine whether accuracy is a percentage of reading or full scale. For a 100-unit range specified solely as ±1% of full scale, the error is ±1 unit; at a reading of 10 units this equals ±10%. This is an explanatory example, not an instrument guarantee. Check required straight pipe lengths, orientation, vibration, pulsation and response time against the manufacturer's instructions.
For oxygen service, verify wetted materials, cleanliness and seals as well as pressure and temperature ratings. Include allowable pressure loss, output signal, totalizer units and calibration documentation in the specification. At commissioning, compare the display with PLC scaling and plan verification using a suitable reference instrument. Keep a record of the selected gas and configuration changes.
Prepare gas composition, flow range, pressure and measurement purpose for a flow measurement review with Mentis Engineering.
