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FastFlo 620S Air Flow Sensor

High-Performance Air Flow Sensors 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.

  • 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
  • Buy online for fast delivery of in stock products. 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.

Our 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.

Purchase Online Configure a unit, check stock selection, or request a quote. Purchase Online Request for Quote

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.

Unique Airflow Sensor Features
  • ±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 Related Documents & Downloads


  File Title Version Release Date
  FastFlo 620S Instruction Manual E 07/31/2015
  S-Series Pulse Output Information Sheet B 05/08/2013
  S-Series Smart Interface Software User Manual B 08/01/1999


  File Title Version Release Date
  FastFlo 620S Technical Datasheet I 6/15 07/31/2015
  600/700 Series Application Datasheet V5 10/17/2014


  File Title Version Release Date
  600/700 Series Product Software SIP134 04/16/2013

Digital Communications - Modbus RTU(3)

  File Title Version Release Date
  600/700 Series Modbus Instruction Manual V1.1 05/06/2013
  600/700 Series Modbus Quick Install Guide PN: 47-0493-B 07/19/2014
  KepserverEx 4.0 Software for Use With MODBUS 4.0 05/29/2014


  File Title Version Release Date
  600/700 Series CE Declaration of Conformity 1.0 12/23/2013
  China Patter Approval Certificate 01/28/2014
  ISO 9001:2008 1.0 01/22/2013
  CRN Approval 0F09333.26 Quebec 1.0 04/09/2009
  CRN Approval 0F09333.25 Ontario 1.0 12/29/2008
  CRN Approval 0F09333.24 Manitoba 1.0 11/20/2008
  CRN Approval 0F09333.23 Saskatchewan 1.0 09/09/2009
  ARRA Certificate of Conformity 8/5/14 08/06/2014
  CRN Approval 1.0 11/20/2008
  CRN Approval 0F09333.21 British Columbia 1.0 12/29/2008
  CRN Approval 0F09333.2 Alberta 1.0 12/21/2010


  File Title Version Release Date
  Service Brochure 2.0 04/06/2015
  Warranty Statement 2.0 04/01/2015
  Sierra Clean Energy Guide V1 01/28/2011
  Full Line Product Offering V2 06/03/2015
  Terms and Conditions 1.0 11/01/2010
July, 2008 - Processing: Flowmeter Solutions
Air Compressor Supply Inc.:
Putting a Price Tag on Compressed Air Waste 

The Sierra Chronicles show how Sierra has provided mass flow solutions to our customers' flow challenges for the last 4 decades.  Our commitment  to increasing customer productivity and efficiency has always been and will always be, the common thread.
Modbus RTU

Modbus RTU

Sierra supports Modbus RTU digital communication protocol for flexible integration of our mass flow meters and controllers into any automation or control system. Modbus Protocol is a messaging structure developed by Modicon in 1979. It is used to establish master-slave/client-server communication between intelligent devices.
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* For a limited time, InnovaSonic 203 ultrasonic liquid flow meters are 40% off when purchased online, in-stock only. Offer ends on 9/18 5 p.m. PST.