Series BDPA Adjustable Differential Pressure Alarm

Brand: Dwyer Instruments, LLC

The Series BDPA Adjustable Differential Pressure Alarm with built-in audible and visual set point indication is designed for overpressure, vacuum, and differential pressure applications.

The scaled adjustment knob allows changes to the switching pressure to be made without a pressure gauge. The BDPA is available with settings from 0.08" w.c. (20 Pa) to 20" w.c. (5,000 Pa). The silicone diaphragm and PA 6.6 body make the Series BDPA perfect for use with air and other noncombustible gases.

The Series BDPA Adjustable Differential Pressure Alarms offer a versatile range of configurations allowing utilization of their many features. The BDPA can be powered by battery or 24 VDC/VAC line power. If connecting line power, the battery can act as back-up power in case of power outage. 

When set point threshold is reached, a local loud audible buzzer and bright LED will indicate periodically notifying of set point activation. An SPDT contact may also be wired to send a signal remotely to a DDC or building management system.

A snooze button located through an opening in the cover can be pressed by the user to manually disengage the audible and visual indication until a maintenance operation is performed. 

If the instrument is mounted where it is difficult to access, a remote contact may be connected allowing the user to deactivate the buzzer and LED at the remote contact location.

The Series BDPA Differential Pressure Alarm's great functional versatility makes it perfect for filter, fan, and ventilation applications or any retrofit job where installing electrical wiring proves cost-prohibitive.

Note: For a 1/2" npt connection, use the 1/2" conduit fitting adapter (A-483).
  • Adjustment knob changes switching pressure easily with a pressure gage reducing components for application
  • Low cost device makes it an excellent solution in BAS and HVAC applications requiring duct control and monitoring
  • Relay contact allows simple integration with DDC or building systems



  • Alarm Acknowledge Button Press
  • Alarm Level 90 Decibels at 4”

Approvals & Certifications

  • CE
  • RoHS

Battery Life

  • Approximately 1.5-Years with 3.6 V / 1.2 Ah

Cover - for Local Enclosure

  • Polystyrene

Deadband, Approximate - Bottom of Range

  • inch WC: 0.04 to 1.0

Deadband, Approximate - Top of Range

  • Inches WC: 0.05 to 1.4

Diaphragm Material

  • Silicone

Electrical Connectors

  • 1/2” NPT
  • M20 x 1.5 with Cable Strain Relief
  • Screw Terminal

Electrical Rating

  • 1 A at 30 Vdc/Vac

Enclosure, Body Material

  • PA 6.6 & POM

Environmental Protection

  • IP21


  • Audible Alarm
  • Red Status Light


  • Diaphragm in Vertical Position

Operating Temperature

  • 0° to 50° C (32° to 122° F)

Power Requirement

  • 16-30 Vdc
  • 18-30 Vac
  • 3.6 V LS14250 Lithium Metal Battery


  • ± 15 % of Full Scale

Set Point - Decreasing

  • Inches WC: 0.08 to 20.0

Set Point - Increasing

  • Inches WC: 0.08 to 20.0

Switch Type

  • SPDT

System Pressure

  • 40” WC

Tube Connection

  • 5/16˝ (7.94 mm) Outside Diameter Tubing, 1/4˝(6.0 mm) Inside Diameter Tubing

  • Air Filter and Ventilator Monitoring
  • Industrial Cooling Circuits
  • Fire-protection Damper Control
  • Ventilation Duct Monitoring
  • Fan Heater Overheating Protection
  • Heat Exchanger Frost Protection
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