CMP Hydroseal™ 25830-150-000 Black 1-1/2" Socket x 2" Spigot Serviceable Check Valve, CPVC. Traditional check valves are very effective, but can be difficult to service. The Hydroseal™ Thread-On Check Valve has a serviceable clear lid with a lock nut. The clear lid makes it easy to identify problems, and the lid removes easily for servicing and cleaning. The CPVC construction of this valve meets NSF Certification standards. It is high-heat resistant and can be used in temperatures exceeding 104 degrees. It is an extremely durable material that is also highly resistant to corrosive water environments.