McDonnell & Miller 193-B-7B Controller

The McDonnell & Miller 193-B-7B (Part Number 164700) is a heavy-duty combination low water cut-off and pump controller specifically engineered for commercial and industrial steam boiler applications. Designed to handle a maximum pressure of 150 PSI, this unit features a No. 7B proportional control switch that provides a 135-ohm potentiometer signal. This allows for precise, continuous modulation of the feed water flow rather than simple on/off cycling, ensuring a consistent water level and improved thermal efficiency. The 193-B configuration includes alternate tappings for flexible piping and an integrated water column that accommodates gauge glass and tri-cock installations. By utilizing magnetic repulsion instead of a bellows mechanism, this controller eliminates a common point of mechanical failure, providing reliable pump control and burner protection in demanding high-pressure environments.

• Enhanced Stability: The 7B switch provides a proportional signal for constant boiler water level management, reducing system stress.
• Durable Construction: Features magnetic repulsion to operate switches, removing the need for leak-prone bellows.
• Installation Flexibility: Includes alternate tappings and a 1-1/4" FIP connection to suit various boiler trim configurations.
• Multi-Functional Design: Serves as both a steam boiler LWCO and a primary pump interface with integrated water column features.
• Industrial Standard: Rated for a max pressure of 150 PSI, making it a staple for high-output steam systems.

What is the difference between the 7B and standard switches?
The No. 7B switch is a proportional control switch using a 135-ohm potentiometer, which allows the system to modulate feed water valves or variable speed pumps for precise leveling, unlike standard single-pole switches.

Can this unit be used as a primary low water cut-off?
Yes, the McDonnell & Miller 164700 is designed to act as a combination low water cut-off and pump controller, providing critical safety shutdown for the burner during low water conditions.

What are the tapping specifications for this model?
This model features 1" NPT equalizing tappings and 3/4" NPT alternate tappings for gauge glass and tri-cock sets, facilitating comprehensive boiler monitoring.

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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.