Neptune RV-PVC-75 Relief Valve-Standard Set Pressure 150 PSIG - Cannon Water Technology
UPVC safety valve Back pressure valve PVC plastic pressure relief valve Safety relief valve 32mm DN25 1 inch - AliExpress
Plast-O-Matic RVD Series PVC Relief Valve for Low Through High Pressure, For Corrosive and Ultra-Pure Liquids, 5-100 psi Pressure Range, 1/4" NPT Female: Industrial Relief Valves: Amazon.com: Industrial & Scientific