Starting at $179.00

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  • Pressure, flow, and velocity measurements
  • Measures positive, negative, and differential pressure
  • Pressure ranges up to 150 psi or 40" w.c.
  • Accuracy:
    • ±0.5% FS, 60 to 78°F (15.6 to 25.6°C)
    • ±1.5% FS all other ranges
  • Operates up to 100 hours on a single 9 volt battery
  • Stores up to 40 readings
  • 0.42" 4 digit LCD display

The Dwyer 477AV Digital Manometer features pressure, flow, and velocity measurements along with a number of other convenient features. The 477AV uses a highly accurate differential pressure sensor to offer ±0.5% full scale accuracy. It displays negative, positive, and differential pressure. For pressure, flow, and velocity there are selectable English and metric units, as seen in the specifications. The built-in air velocity and flow calculations provide accuracy and conserve time associated with cumbersome manual calculations. Additionally, up to 40 readings can be saved—perfect for HVAC technicians making Pitot tube traverses of airflow readings across a duct. The accuracy that the 477AV series provides is critical to maintenance personnel and technicians who require a highly accurate standard to check their instrumentation or equipment, to ensure proper performance.

The digital display offers a backlight feature for easier viewing in darker areas. Meanwhile, battery conservation is monitored and displayed in the event of low battery voltage. The digital manometer will automatically shut off after 20 minutes to prevent battery drain. This shut-off time can be reduced or disabled if desired. Series 477AV can be field-calibrated by setting zero and span values. Furthermore, the damping feature compensates for the fluctuating readings by averaging input values to display a more stable readout. Included is an audible and visual alarm to warn over flow, over pressure or over velocity.

Applications for the 477AV Manometer include:

  • Field calibration
  • Monitoring trouble shooting HVAC systems
  • Clean room checks
  • Air velocity monitoring with pilot tube
  • Natural gas appliance line pressure
  • Air flow
  • Duct static pressure
Dwyer 166T Telescoping Pitot Tube
Unique air flow sensor can quickly and easily be adjusted for any duct insertion length from 11.5 to 36 inches
Dwyer A-303 Static Pressure Tip
Portable static pressure tip, for 3/16" ID rubber or plastic tubing with 4" insertion
Dwyer A-375 Compression Fitting
Compression fitting, 1/8" tube to 1/8" NPT male
Dwyer A-402A Carrying Pouch
Nylon carrying pouch, 7-1/2" x 3" x 2-1/4"


This product can be used in the following applications:

Application Notes

Here's how some of our customers used this product.

Testing Duct Smoke Detectors

The Background: Our customer is a company that installs building sprinkler systems and other fire protection devices. They seek a means of testing pressure that can be used to test and verify the duct smoke detectors used in many of their installations.

The Problem: Many commercial smoke detectors sample the air by using a small amount of vacuum to draw air over the sensor. Testing these detectors to ensure air is being properly sampled is crucial to fire detection efforts. As there are often many of these detectors and they have just a very small flow over the sensor, a portable unit with low range is crucial.

The Solution: We recommended the Dwyer 477AV Digital Manometer which features pressure, flow, and velocity measurements that are accurate to ±0.5%. The 477AV provides a high level of reliability at a great price.