The A.J. Antunes JD-2-PURPLE Differential Air Pressure and Vacuum Switch provides reliable airflow, pressure, and vacuum monitoring for HVAC equipment, air handlers, fan systems, and combustion safeguard controls.

Calibrated with a purple spring, this automatic reset switch monitors pressure differentials from 0.1 to 10 inches W.C. to help confirm proper system airflow and support safe equipment sequencing.

The Single-Pole, Double-Throw electrical contact is rated at 10 amps and 125 VAC, while dual 1/8-inch NPT connection ports allow positive and negative pressure tracking.

Built with a compact die-cast aluminum housing, the JD-2-PURPLE is designed for dependable performance in air proving, filter pressure drop detection, blower verification, and burner interlock applications.

A visible dual-scale indicator supports set point tracking in inches and millimeters of water column, with field adjustment available through the protected top stem.

This switch is intended for vertical mounting with the adjusting stem facing upward and is a reliable replacement option for systems requiring accurate differential pressure control.
 

Frequently Asked Questions

• What is this pressure switch used for?

This pressure switch is commonly used in HVAC systems, air handlers, fan verification, and combustion safeguard applications. It monitors pressure or airflow conditions to help confirm proper system operation.

• How does the switch help HVAC and air handler systems?

It measures pressure drop across air filters. A rising pressure drop can indicate a clogged or restricted filter, helping support better airflow and energy efficiency.

• Can this switch detect fan or blower operation?

Yes. The switch can verify airflow across blowers or fans, helping confirm that air movement is present and reducing the risk of damage caused by stalled or failed airflow.

• How is it used in combustion safety systems?

The switch can interlock with commercial burner logic to prevent ignition when adequate combustion air is not available.

• Does the switch display the set point?

Yes. It includes a visible dual-scale on-off indicator that displays set points in both inches and millimeters of water column.

• How is the set point adjusted in the field?

The protective hexagon cap at the top of the indicator stem can be removed, allowing the threshold to be adjusted manually with a screwdriver.

• What is the correct mounting position?

The switch must be installed vertically with the central adjusting stem facing upward.

• Why is vertical installation important?

Vertical mounting helps maintain proper switch operation and ensures the adjustment stem is positioned as required by the product instructions.

• Can this switch help prevent equipment damage?

Yes. By confirming airflow or pressure conditions before equipment continues operating, it can help reduce risks related to blocked filters, stalled fans, or insufficient combustion air.

• What measurement scale does the switch use?

The indicator shows set points in inches of water column and millimeters of water column.