Pressure and Vacuum Relief Thief Hatch


Pressure & Vacuum Relief Thief Hatch provides ready access to the tank interior for inspection, gauging or sampling operations. The unit also provides pressure and vacuum relief of the tank’s vapor space through integral, spring-loaded pressure and vacuum relief mechanisms. Valves open and close to permit only that intake or outlet relief necessary to keep interior pressure within permissible working limits.


  • Certified test report verifying specified settings and leakage performance
  • Precision lapped valve seat for low leakage performance of no more than 1 SCFH at 90% of the set pressure
  • Lightweight, non-sparking aluminum cast cover for easy installation, operation and maintenance
  • High quality 316 S.S. hardware for increased durability
  • Anodized vacuum pallet for improved corrosion resistance
  • Oversized step pad allowing for hands-free operation
  • Wide variety of spring and gasket materials to accommodate many applications
  • Sizes: 8” API flat face flange
  • Settings Pressure:  2, 4, 6, 8, 12, 16, 24, 32 oz./sq. in.
  • Settings Vacuum:  0.4, 0.9, 3.5 oz./sq. in.
  • Materials: Cover and base flange – non-sparking cast aluminum; Hardware – 316 S. S.
  • Springs:  Plated Steel; Inconel
  • Soft Goods: Pressure Gasket – HBNR; Viton® | Vacuum Gasket – Fluorosilicone; Viton®; FEP
  • Lockout Safety Pin

Viton® is a Registered Trademark of E. I. DuPont de Nemours & Co., Inc.