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Dwyer Model 660

Model 660 Air Velocity Monitor

Continuously Measures Fume Hood Airflow

Dwyer Model 660
Model 660

The Dwyer Model 660 Air Velocity Monitors are a practical, affordable way to continuously monitor for safe air flows through laboratory fume hoods. They are typically installed in the fume hood side fascia and connected to the interior sidewall via 1-1/8″ flexible tubing. As the exhaust fan draws air through the device, a sensitive constant temperature thermistor measures flow and lights a green (normal), yellow (high) or red (low) LED. An audible alarm also warns of low flow and requires manual resetting. Mounting holes fit standard single gang electrical box.

Typical Application: 

  • Warns user if insufficient fume hood face velocity is encountered.


Dwyer Model 660 Specifications

  • Service:Air and non-combustible, non-corrosive gases.
  • High Setpoint Range:0-275 FPM (0-1.397 m/s).
  • Low Setpoint Range:0-150 FPM (0-.792 m/s).
  • Repeatability:±7% of full span, 0-50 and 150-275 FPM; ±5% of full span, 50-150 FPM.
  • Compensated Temperature Range:50 to 90°F (10 to 32.2°C).
  • Operating Temperature Range:32 to 120°F (0 to 48.9°C).
  • Power Supply:24 VAC, 3 watts maximum.
  • Response Time:6-10 seconds.
  • Warm-Up Time:3-5 minutes (no flow).
  • Audible Alarm:75 dB between 3-10 feet.Weight:3 oz (85 g).
  • Mounting Hardware:(2) #6 x 1″ sheet metal screws, (2) 6-32 x 7/8″ machine screws.


  • Model 660 Air velocity monitor, includes 3′ flexible tubing, pre-fittings and 90º elbow, 120 VAC to 24 VAC power transformer.