Johnson Controls P29NC-49 Pressure Control

The Johnson Controls P29NC-49 is a specialized low pressure cutout control designed for heavy-duty protection in industrial and commercial refrigeration systems. Built for the veteran technician, this unit features a manual reset mechanism to ensure that equipment remains locked out until a manual inspection is performed following a low-pressure event. The 120-second time delay is factory-calibrated to mitigate nuisance shutdowns caused by temporary pressure drops during startup or transient load changes, allowing the system to stabilize before the circuit trips. Rated for 120/240 Vac, the P29NC-49 operates within a pressure range of 20 inches Hg to 100 PSIG, making it compatible with a wide variety of non-corrosive refrigerants. The 36-inch capillary provides significant installation flexibility, allowing for secure mounting in any position while ensuring the pressure sensing bellows are correctly oriented. This pressure control with time delay includes a dust-protected, snap-action switch to maintain electrical integrity in demanding environments.

• Enhanced System Reliability: The 120-second thermal expansion time delay relay prevents unnecessary downtime by filtering out momentary pressure fluctuations.
• Field-Replaceable Components: The internal timing mechanism and terminal board can be interchanged in the field, reducing mean time to repair (MTTR).
• Rugged Construction: Features a high-overrun pressure element that withstands extreme testing pressures without losing calibration accuracy.
• Ambient Compensation: The P29NC-49 is engineered to maintain consistent timing performance across varying ambient temperatures at the control location.

How do I adjust the setpoint on the P29NC-49?
The cutout point is adjusted by turning the setpoint screw at the top of the case; clockwise increases the pressure setting, while counter-clockwise decreases it. Always verify the setting using a calibrated gauge during commissioning.

Can the time delay be modified in the field?
No, the 120-second delay is factory-set and sealed to ensure safety compliance. If a different timing interval is required for your specific application, a different P29 series model must be selected.

Is the P29NC-49 compatible with ammonia systems?
Standard P29 series controls are designed for fluorinated hydrocarbons. For ammonia service, you must specifically utilize a model with an "Ammonia" designation and the appropriate stainless steel or non-ferrous connectors.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.