NEW Model SP158B, fully engineered freeze protection valve is constructed of a one piece brass body, and supplied with a removable cartridge for easy cleaning and maintenance. Automatic thermal actuator bleed valve opens when internal water temperature falls below 35° F (1.7° C) and closes completely when the water climbs back to 42° F (5.6° C) or above. 1/2" NPTF inlet and outlet. FREEZE PROTECTION Protects an emergency shower and/or eyewash from water temperatures that can drop below 35° F (1.7° C) by bleeding off the excessively cold fluid during 'snap freezes'.