These in-line (spool-piece) style flow meters have no moving parts and are available for use in pipe diameters from ¼ inches to 2 inches (6 mm to 51 mm). Process connection options include male NPT, female NPT, and flanged. These thermal flow meters feature wide 100:1 turndown and depending on pipe size, will measure from 0.01 SCFM to 559 SCFM (0.01 NCMH to 950 NCMH).

The ST75 Series electronics are housed in rugged, IP67 rated enclosure with dual conduit ports in either NPT or M20 threading. The instrument comes standard with dual 4-20 mA outputs and a 500 Hz pulse output. The models ST75A and ST75AV include HART or Modbus, as well as NAMUR compliant 4-20 mA outputs and SIL compliance rating. The flow meter’s transmitter/electronics can be integrally mounted with the flow element (probe) or be remote mounted to best match your installation situation. The complete instrument carries global Ex agency approvals for Division l/Zone 1 installations.

The ST75 flow meter sensing element features precision, platinum RTD in small diameter, “equal-mass,” all-metal thermowells to provide superior accuracy, repeatability, and fast response. The “V” suffix models (ST75V and ST75AV) include Vortab® flow conditioners built-in to the spool-piece to provide accurate and repeatable flow measurement installations with limited straight-run and/or for operating in transitional flow ranges.


  • Burner and boiler fuel and air feed lines
  • Industrial furnaces, kilns, and oven fuel/air controls
  • Natural gas sub-metering
  • Chiller air flow measurements
  • Dosing and gas injection rate controls
  • Heat treating gas controls industrial furnaces, kilns, and oven fuel/air controls
  • Air compressor system control and point-of-use monitoring
  • Co-gen and turbine generator fuel flow measurements

Key Facts

  • Direct mass, standard volumetric or standard velocity flow measurement
  • Triple outputs: flow rate, temperature and total flow
  • HART or Modbus I/O (ST75A, ST75AV)
  • Non-clogging, no moving parts
  • 2 line digital display option
  • Small, compact design
  • Easy installation
  • Built-in Vortab® flow conditioning (ST75V, ST75 AV)
  • SIL compliant

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