McDonnell & Miller 250-1-30 Valve

For high-performance hydronic heating systems, the McDonnell & Miller 250-1-30 (Part Number 181925) is a heavy-duty 1" NPT pressure relief valve engineered to protect ASME Section IV pressure vessels. This bronze body relief valve is factory-set at 30 PSI and provides a substantial 1,170,000 BTU capacity to prevent over-pressure conditions in large-scale boiler applications. Designed for maximum durability, it features an EPDM rubber diaphragm and seat disc to ensure a tight seal and consistent operation across a wide operating temperature range up to 250°F. The low differential pressure design—maintaining only a 3 PSI gap between opening and closing—minimizes hammering and system stress caused by flash steam. Whether you are performing a boiler pressure relief valve replacement or a new installation, this ASME rated safety valve delivers the reliability required for critical heating infrastructure.

Key Benefits for Contractors:

• High BTU Rating: Offers a 1,170,000 BTU/hr capacity, making it suitable for high-demand industrial and commercial hydronic systems.
• Rugged Construction: Features a corrosion-resistant bronze body and seat for long-term service life in harsh mechanical rooms.
• Stable Operation: The EPDM diaphragm ensures positive shut-off and resists heat degradation better than standard elastomers.
• Code Compliance: Fully meets ASME Pressure Vessel and Boiler Code, Section IV requirements for safety and performance standards.
• Reduced System Fatigue: Precision engineering minimizes steam hammering, protecting downstream piping and components from thermal and mechanical shock.

Common Questions:

What is the maximum operating temperature for the McDonnell & Miller 181925?
This valve is rated for a maximum temperature of 250°F (121°C), making it ideal for standard and high-temperature hydronic heating applications.

Can this valve be used for steam service?
The Series 250 is specifically designed for water heating boilers and storage tanks. Always verify your specific boiler's BTU output and pressure requirements against the 1,170,000 BTU and 30 PSI ratings before installation.

What is the difference between this and the 3/4" model?
While the internal mechanics are similar, this 1" NPT model provides a higher flow capacity (BTU rating) compared to the smaller units, ensuring proper pressure relief for larger vessels.

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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.