McDonnell & Miller 250-3/4-50 Valve

The McDonnell & Miller 250-3/4-50 (Part Number 181525) is a high-capacity pressure relief valve engineered specifically for technical boiler applications and hydronic heating systems. Field-proven to handle a 1,160,000 BTU capacity, this 3/4" NPT valve is set at a precise 50 PSI to prevent over-pressure conditions in demanding mechanical environments. Built with a heavy-duty bronze body and seat, it utilizes an EPDM rubber diaphragm and seat disc to maintain a tight seal up to a maximum temperature of 250°F. For the veteran installer, the Series 250 is a standard for reliability, featuring a low differential pressure of only 3 PSI between opening and closing, effectively minimizing hammering caused by flash steam. This unit meets the rigorous safety requirements of the ASME Pressure Vessel and Boiler Code, Section IV, ensuring code compliance for commercial and residential hot water boilers.

• ASME Section IV Certified: Verified performance for heating boilers and storage tanks requiring a 50 PSI pressure relief valve.
• High Thermal Capacity: Rated for systems up to 1,160,000 BTU, providing a necessary safety margin for large-scale hydronic loops.
• Durable Bronze Construction: Resists corrosion and scaling, featuring an EPDM diaphragm for extended service life in high-temperature HVACR applications.
• Anti-Hammer Design: Engineered to reduce system shock and noise by managing steam flashing and differential pressure.
• Standard NPT Connection: Rugged 3/4" NPT threading allows for straightforward integration into existing pipe headers.

What is the maximum operating temperature for the 181525?
This relief valve is rated for a maximum fluid temperature of 250°F (121°C), making it suitable for most high-temperature hydronic heating configurations.

Can this valve be used for steam service?
Per McDonnell & Miller specifications, the Series 250 is designed for hot water heating boilers and storage tanks; always verify your specific system medium against the ASME Section IV code requirement.

How do I verify if the valve is functioning?
Technicians should manually lift the test lever periodically to ensure the bronze seat hasn't bonded and that the valve relieves pressure and reseats properly at the 50 PSI threshold.

This item is not eligible for free shipping.

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.