P74AA-1C Johnson Controls Pressure Control

Overview

The Johnson Controls P74AA-1C is a Penn P74 Series electromechanical differential pressure control designed to sense the difference in pressure between two distinct points in a system. It serves as an operating control or indicator for system functions in commercial HVAC and refrigeration setups. The control features a single-pole single-throw (SPST) switch mechanism that closes on a decrease in the pressure difference, providing corrective action or signaling to connected equipment.

Features

• Field-proven Penn switch with a completely enclosed contact mechanism.
• Easily adjustable pressure differential setting without removing the cover.
• Enclosed contact structure with high contact force and no contact bounce.
• Heavy-duty, low-profile stainless steel bellows designed to withstand high overrun pressures.
• Single unit mounting and wiring to reduce installation time and materials.
• Includes a universal mounting bracket for versatile installation.

Specifications

• Switch Action: SPST, closes on decrease in pressure difference
• Range Pressure Differential: 8 to 70 psig (55 to 483 kPa), adjustable
• Switch Differential: 8 to 30 psi (55 to 207 kPa), adjustable
• Pressure Connection: 36-inch capillary tubing with a 1/4-inch flare nut (Style 13)
• Bellows Material: Stainless steel
• Maximum Low Pressure Bellows Overrun: 180 psig (1241 kPa)
• Ambient Temperature Range: 32°F to 104°F (0°C to 40°C)
• Electrical Contact Ratings: 22A @ 120 VAC (non-inductive), 20A FLA / 120A LRA @ 120 VAC, 17A FLA / 102A LRA @ 240 VAC
• Conduit Opening: 7/8-inch diameter hole for 1/2-inch conduit

Applications

• Differential pressure sensing on chillers or water-cooled condensers.
• Proof of flow monitoring in heating systems or cooling coils.
• Lube oil failure cutout for refrigeration compressors.
• Proving pump operation in closed water circulating or supply systems.