Circle Seal Controls 559B-8M-.5 Control Valve

Circle Seal Controls Model 559B-8M-.5 is a 1" brass pop-off relief valve (500-Series) designed for compact, automatic overpressure protection in small-diameter systems. It features a male pipe-thread inlet, Buna N seals, and an adjustable cracking pressure from 0.5 to 150 psig (the.5 variant specifies a minimum setting of 0.5 psi) with a cracking‑pressure tolerance of ±5%, and it operates from -65 to 275 °F. The valve is rated for 400 psig proof pressure and 500 psig burst pressure, with overall dimensions of about 3.16" long and 1.89" in diameter and a weight near 1 lb. Typical applications include storage tanks, refrigeration and HVAC equipment, process control instrumentation, and vacuum pump safety, with optional body materials such as brass, 303/316 stainless steel, or aluminum and features like tamper‑proof adjustment and factory preset options to ensure precise, repeatable set pressures.