Flow Measurement System

Flow Measurement System Features:

  • Flow Rate can be measured in CFM, CFH, MCFH or MCFD
  • The current flow rate (CFR) is displayed on the LCD screen
  • User defined log interval from 1 second to 10 minutes
  • The logs can be saved to a USB key and opened in Excel
  • The logs include the flow rate, minimum flow rate, maximum flow rate, and average (median) flow rate
  • These logs meet the EPA Quad O reporting requirements
  • Supports telemetry over cellular, satellite, or radio with RS-232 or RS-485
  • Modbus Slave Protocol allows it to communicate with other devices, software and SCADA systems

Thermal Mass Meter Benefits

  • Direct Mass Flow – No need for separate temperature or pressure transmitters
  • High Accuracy and extraordinary repeatability
  • Turndown of 100 to 1 and resolution as much as 1000 to 1
  • Low-End Sensitivity – Measures as low as 5 SFPM (e.g., 1 SCFM in a 6" pipe)
  • Negligible Pressure Drop – Will not impede the flow or waste energy
  • No Moving Parts – Eliminates costly bearing replacements, and prevents undetected accuracy shifts
  • Dirt Insensitive – Provides sustained performance
  • Ease of installation and convenient mounting hardware

The Flow Measurement System measures the flow rate of gas using thermal-dispersion flow measurement technology.

How the Thermal Mass Meter works

The instrument consists of two high precision platinum sensors contained in a stainless steel covering. The temperature sensor is the reference and also provides a measurement of the gas temperature. The flow sensor is heated to maintain a slight temperature difference (overheat) above the temperature sensor. As the gas flow past the heated flow sensor heat transfer occurs. The instrument measures the amount of power required to obtain the desired overheat which is proportional to the mass flow rate.

Thermal Mass Flow Measurement is an inferred flow measurement. This meter type measures heat transfer and then relates the heat transfer to the mass flow rate from the NIST traceable calibration. To calibrate, the flow meter is put into a calibration bench, a known amount of gas flows past the sensor, and the signal is measured. This is performed multiple times over the operating range of the instrument. A curve showing signal vs. flow rate is created for each instrument. A typical curve is shown below.

The thermal mass meter can be easily installed in line with the process gas stream and connected to the HY-BON/EDI Controller.