Johnson Controls AK-51642 Pneumatic Relay

The Johnson Controls AK-51642 is a pneumatic relay designed to select the lower of two temperature-derived pressure signals in a pneumatic control system. It is commonly used in building automation and HVAC applications where control logic requires modulation based on the lowest of two monitored temperatures, such as in dual-duct or multi-zone systems.

IN STOCK

Technical Specifications

  • Model: AK-51642
  • Type: Pneumatic low selector relay
  • Function: Selects the lower of two input air pressure signals
  • Input Signal Ports: Two (for dual pneumatic temperature inputs)
  • Output Signal Port: One (matches lower of the two inputs)
  • Main Air Supply Pressure: Typically 20 psi (regulated, dry air)
  • Mounting: Panel or wall mount
  • Connections: Barbed or compression fittings for standard pneumatic tubing

Key Features

  • Selects and transmits the lower of two pneumatic input signals
  • Enables logic-based control in multi-temperature or multi-zone systems
  • Compact design for easy integration into control panels or terminal boxes
  • Passive, air-powered operation—no external power required
  • Reliable mechanical operation with no electrical components

Compatible Components & Accessories

  • Pneumatic thermostats and transmitters
  • Johnson Controls pneumatic control panels
  • Actuators and receiver-controllers
  • Air line tubing, tees, and fittings

Industry Applications

  • Dual-duct HVAC systems
  • Multi-zone temperature averaging or comparison control
  • Energy management systems
  • Pneumatic logic circuits in commercial and institutional buildings

Installation & Maintenance Notes

  • Mount securely on a stable panel or surface near the control zone
  • Connect input tubing to two separate pneumatic temperature sources
  • Output line should be routed to the next control stage (e.g., actuator or controller)
  • Use dry, filtered air at regulated pressure to ensure consistent operation
  • Periodically inspect for tubing leaks, clogging, or pressure drift

 

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