McDonnell & Miller 171802 150S-MD Low Water Cut-Off & Boiler Pump Controller (1 Inch NPT, Max Differential, 150 PSI)
McDonnell & Miller 171802 150S-MD Low Water Cut-Off & Boiler Pump Controller (1 Inch NPT, Max Differential, 150 PSI)
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| Performance Parameter | Engineering Baseline Value |
|---|---|
| Manufacturer Part Number (MPN) | 171802 |
| Model Designation | 150S-MD (Max Differential Series) |
| Equalizing Pipe Connections | 1" NPT (Female Threaded) |
| Maximum Operating Steam Pressure | 150 PSI (10.5 kg/cm²) |
| Switch Configuration | 1 SPST (Pump Control) / 1 SPDT (LWCO & Alarm) |
| Electrical Rating (Pump Circuit) | 7.4A @ 120VAC / 3.7A @ 240VAC (345 VA Pilot Duty) |
| Enclosure Protection Rating | NEMA 1 General Purpose Heavy Metal Housing |
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Apply for Trade Account & Terms →McDonnell & Miller 171802 (Model 150S-MD) Combination Low Water Cut-Off & Pump Controller
Engineered for primary or secondary low water fuel cut-off and automatic feed pump control on commercial and industrial steam boilers, the McDonnell & Miller 171802 (Model 150S-MD) is a heavy-duty mechanical level controller designed for demanding high-temperature steam applications. Rated for operating steam pressures up to 150 PSI (10.5 kg/cm²), this unit features a durable cast iron float chamber and heavy-duty Monel bellows construction for superior corrosion resistance and long operating life.
The 150S-MD model is factory-configured with a Maximum Differential (MD) operating profile, widening the switching distance between pump-off and burner-off settings to 1-3/8". This specialized differential setting compensates for setpoint shifts in low-pressure steam boilers (operating below 50 PSI), effectively eliminating rapid cycling and nuisance burner shutdowns caused by severe surging or rapidly fluctuating boiler water levels.
Key Performance & Construction Features:
- Maximum Differential (MD) Tuning: Widened switching differential prevents rapid burner cycling and false trips in systems operating under 50 PSI.
- Monel Bellows Seal Isolation: Corrosion-resistant Monel bellows seal isolates mechanical switch linkages from harsh steam and boiler water environments.
- Dual Heavy-Duty Snap Switches: Factory-equipped with one SPST snap switch for direct boiler feed pump activation and one SPDT switch for low water fuel cut-off and alarm signaling.
- 1" NPT Equalizing Tappings: Heavy-duty cast body with 1" female threaded steam and water equalizing ports for solid pipe mounting directly to the boiler shell or external water column.
⚠️ Application Profile: Recommended for commercial and industrial steam boilers of any steaming capacity requiring primary or secondary low water fuel cut-off, automated boiler feed pump control, or high/low level alarm activation up to 150 PSI.
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