Insertion Mass Flow Meter - FastFlo™ 620S

High-Performance Air Flow Sensor for Industrial Gas Mass Measurement

The FastFlo™ 620S – an insertion thermal air flow sensor that contains FastFlo® Sensor Technology and Smart Electronics – was designed to give you a highly reliable, responsive and affordable mass flow meter for light industrial applications where a NEMA 4X (IP65) enclosure is acceptable.

The 620S air flow sensor enclosure is available in probe-mount or remote-mount configurations and has a 316 stainless steel, 3/8-inch diameter insertion probe available in lengths from 3.7 inches up to 24 inches. Mass flow rate and totalized flow, as well as other configuration variables, can be displayed on the meter's optional 2 x 12 backlit LCD readout.

 FastFlo™ 620S Air Flow Sensor

FastFlo™ 620S Air Flow Sensor




Technical Details

  • +/- 1.0% of full scale accuracy
  • 200 msec time-response time
  • NEMA 4X (IP65) enclosure
  • Field validation & diagnostics
  • Field adjustment
  • 2 x 12 backlit LCD readout
  • 3/8-inch diameter insertion probe
  • Probe lengths up to 24”
  • 316 stainless steel construction
  • Digital communications solutions include: Modbus RTU.

Product Information

The FastFlo™ 620S – an insertion thermal air flow sensor that contains FastFlo® Sensor Technology and Smart Electronics – was designed to give you a highly reliable, responsive and affordable mass flow meter for light industrial applications where a NEMA 4X (IP65) enclosure is acceptable.

  • Accuracy is +/- 1.0% of full scale, 0.2% of full scale repeatability
  • NEMA 4X insertion mass air flow sensors measure air, nitrogen or any other inert gas with a fast, 200-millisecond response time
  • High-accuracy glass sensor technology
  • Available in 1, 2, 3, 4, inch schedule 40 pipe sizes

This airflow sensor – which includes a compact, versatile, microprocessor-based transmitter – integrates flow-range adjustments and meter validation and diagnostics, giving you the ability to “field-validate” your meter’s calibration.

Sierra’s digital communications solutions offer engineers and systems integrators, full industrial system integration and networking capability with Sierra's light industrial flow meters. Digital communications solutions include: Modbus RTU. This flexibility of communication features offers turnkey solutions for integration of Sierra's vortex flow meters into any industrial automation system or application.


Operating Principle

Sierra’s unique FastFlo 620S sensor probe is responsible for the unsurpassed accuracy and reliability of Sierra mass flow meters. The sensor consists of two sensing elements–a velocity sensor and a temperature sensor which automatically corrects for changes in gas temperature. When power is applied to the flow meter, the transducer electronics heats the velocity sensor to a constant temperature differential above the gas temperature and measures the cooling effect of the gas flow. The electrical power required to maintain a constant temperature differential is directly proportional to the gas mass flow rate. The meter electronics measure this power and convert it into a linear 0-5 VDC (0-10 VDC optional) and 4-20 mA output signal.

The FastFlo sensors are reference-grade platinum resistance temperature detectors (RTD) encapsulated in glass. The platinum RTD wire is wound on a rugged ceramic mandrel for strength and stability. The sensor is located at the tip of a 0.375 inch (3/8”) diameter, 304 stainless steel probe which is inserted in the gas stream. The 620S electronics are packaged in a weather-proof NEMA 4X (IP65) enclosure mounted either directly on the sensing probe or remotely up to 100 feet (60 meters) away.