McDonnell & Miller 93 Pump Control

The McDonnell & Miller 93 Pump Control (Part Number 162300) is a heavy-duty combination low water cut-off and pump controller designed specifically for commercial and industrial steam boiler applications. Engineered for systems with a maximum pressure of 150 PSI, this unit utilizes magnetic repulsion to actuate its switches, effectively eliminating the mechanical fatigue and leakage risks associated with traditional bellows. The Series 93 features two snap-acting SPDT switches (No. 5 switches) that provide reliable automatic reset functionality for burner safety and precise water level control. With its 1" NPT connections and integral tappings for gauge glass and tri-cock sets, it serves as a robust float-operated solution for maintaining steady waterline elevations regardless of steaming capacity. This unit is built for technical durability in high-demand environments, ensuring seamless integration into existing boiler feed pump circuits and safety limit strings.

• Magnetic Repulsion System: Inherently reliable design that removes the need for flexible bellows, preventing a common point of failure in high-pressure environments.
• Dual SPDT Switching: Features a dedicated No. 5 switch configuration for independent pump control and low water fuel cut-off.
• High Pressure Rating: Robust cast iron construction certified for steam boiler operations up to 150 PSI.
• Integral Water Column: Equipped with built-in 1" tappings for simplified installation of diagnostic gauge glasses and secondary safety tri-cocks.
• Multi-Voltage Compatibility: Precision switches are rated for both 120V and 240V industrial electrical services.

Common Questions

How do I wire the McDonnell & Miller 93 for both a pump and a burner?
The unit uses two SPDT switches. Typically, one set of terminals is wired in series with the burner's safety circuit to interrupt power during a low water event, while the second switch is utilized to energize the boiler feed pump or a motorized feed valve as water levels fluctuate.

Does this unit require a manual reset after a low water condition?
No, the standard 162300 model is an automatic reset control. It will restore the burner circuit once the water level returns to a safe operating elevation. If your local code requires manual intervention, a manual reset head assembly must be specified.

Can the Series 93 be used as a high water cut-off?
Yes, the internal SPDT switches can be field-configured to actuate an alarm or shut down a feeder in high water scenarios, though its primary industry application is low water protection and pump management.

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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.