Dwyer Series FLST

The Series FLST utilizes an airflow averaging element in a head-type device, generating a differential (velocity) pressure signal similar to the orifice, venturi, and other had producing primary elements. Strategically located sensing ports continually sample the total and static pressures when inserted normal to flow.


Total pressure sensed by the upstream ports are continually averaged within the airflow element in an isolated chamber. The static sensing ports are averaged in a second isolation chamber. Multiple elements are joined together for connection to a differential measurement device (gage, transmitter, etc.) for flow measurement and indication purposes.

  • Sensing fan, blower, and air handler output.
  • Determine duct flow rates in various zones in builiding.

Features & Benefits

  • Low signal-to-noise ratio.
  • Multiple total and static pressure sensing ports along the length of the element.
  • Factory mounted and pre-piped in a flanged duct section (casing).
  • ±2% accuracy throughout velocity ranges of 100 fpm and over.
  • Standard construction includes galvanized casing and 6063-T5 anodized aluminum flow sensors.
  • Standard airflow stations can be operated (in air) continuously in temperatures up to 350°F or intermittently in temperatures up to 400°F.
  • All airflow stations can be operated in humidity ranges of 0 to 100%.
  • Standard airflow stations have good salt air resistance and are suitable for most HVAC applications.


Accuracy: Within 2% of actual flow when installed in accordance with published recommendations.

K-Factor: 0.97.

Velocity Range: 100 to 10,000 fpm (0.51-51 m/s).

Wetted Materials: Elements: 6063-T5 anodized aluminum; Casings: 16 ga G90 galvanized steel.

Coatings: Imron 333 polyurethane enamel.

Temperature Limits: Galvanized Casings and Aluminum Elements: 350°F (177°C) continuous operation (in air) 400°F (204°C) intermittent operation (in air).

Humidity: All Airflow Stations 0 to 100% non-condensing.

Process Connections: 1/4″ compression fittings.