Series 335 ASME rated Boiler Pressure Relief Valves were developed to fill the hydronic industry's need for a smaller valve for OEM use on popular size boilers up to 510,000 BTU at 30psi. The compact design, all bronze construction, and modern appearance make them an ideal choice for a wide variety of smaller size OEM boilers. ASME Section IV at 30 PSI set point. Silicone disc is highly heat-resistant. Bronze body with bronze seat and stainless steel spring.