Hinged Emergency Pressure Relief Manhole Cover Vent


Protectoseal Series 51700 Hinged Emergency Pressure Relief Vent provides emergency pressure relief when installed on the manhole opening of the storage tank. In emergency situations (fire involvement of the tank) the unit is designed to open on its hinge and provide pressure relief beyond the capacity of the normal breather vents. The hinged design allows the use of a lever principal counterweight so that the pressure settings higher than those available on other dead weight loaded vents of similar size may be achieved. The design also allows convenient access through the manhole opening for tank inspection and maintenance. 


  • Certified test report verifying specified settings and leakage performance
  •  “Air-cushion” pallet design for low leakage performance of no more than 1 SCFH at 90% of the set pressure
  • Hinged Pallet Assembly can open approximately 75 degrees to provide full flow area as well as automatic resealing when tank pressure is decreased.
  • Serialized unit and associated weights for easy identification and traceability
  • Flow at fully open pressure marked on unit [OSHA 1910.106(b)(3)(v)]
  • Sizes: 16” (DN 400) through 24” (DN 600)
  • Flange Connections: Mates with applicable ANSI, API flange or DIN 16 PN connections
  • Materials: Aluminum, Steel and Stainless Steel
  • Testing & Certifications: Conforms with the latest ATEX Directive 
  • Standard Setting Range*:  Pressure: 0.57 – 34.6 oz/in2 | 2.45 – 149.10 mbar

*Settings vary by size

  • Flange Connections: Other drilling patterns available upon request
  • Diaphragm Materials: FEP, Viton®, Buna N, EPDM, and Neoprene; other materials available upon request
  • Settings: Non-standard setting available
  • Special Coatings: PROSHIELD™, FEP and Kynar®
  • Material certifications for flange and seat

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

Kynar® is a Registered Trademark of Arkema, Inc.