McDonnell & Miller 302600 Head Gasket

The McDonnell & Miller 302600 Head Gasket, also identified by model number CO-12, is a critical 4-hole sealing component designed for low water cut-off (LWCO) maintenance and float head repairs. Engineered specifically for high-pressure steam and hydronic applications, this gasket provides a high-integrity seal between the float chamber and the float head assembly. It is the primary replacement seal for a wide range of industry-standard controls, including the McDonnell & Miller Series 42, Series 61, Series 63, Series 64, Series 65, and the 42S Series pump controllers. When performing a head mechanism replacement or annual inspection, ensure the sealing surface is scraped clean of all old material and debris to prevent bypass leaks. This OEM replacement part is essential for maintaining the safety parameters of the boiler’s low water protection system and ensuring accurate float response. Using a genuine 302600 gasket during routine blow-down service or repair cycles prevents nuisance shutdowns and maintains the pressure-tight environment required for optimal system performance.

• McDonnell & Miller 302600
• CO-12 Head Gasket
• Low Water Cut-Off Gasket
• Float Head Replacement Seal
• Series 64 Gasket Replacement

• Multi-Series Compatibility: Designed to fit the Series 42, 61, 63, 64, 65, and 42S, streamlining inventory for commercial service technicians.
• Precision 4-Hole Alignment: Ensures exact bolt-hole registration with the float head assembly for a rapid, leak-free installation.
• High-Temperature Durability: Fabricated from materials capable of withstanding the thermal demands of both steam and hot water boiler environments.
• Critical Safety Seal: Maintains the pressure boundary between the float chamber and the head mechanism to ensure reliable LWCO operation.

• Can I use the CO-12 gasket for Series 764 units? Yes, the 302600 (CO-12) is the standard replacement gasket for the 764 series low water cut-offs.
• What is the recommended torque for the head bolts when installing this gasket? For most compatible M&M series, technicians should tighten the four head bolts to approximately 14-20 ft-lbs using an alternating star pattern.
• Does the gasket require any additional sealant or RTV? No, the gasket is designed for dry installation on clean, smooth metal surfaces; applying additional sealants may interfere with the compression seal.

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.