Morrison Bros. 244 Series 5 in. Male Threaded Emergency Vent - 8 oz/sq inch

Morrison Bros.
5 in.
8 oz/sq inch
184,651 SCFH
15.00 LBS
Adding to cart… The item has been added

Emergency vents are installed on aboveground storage tanks as a code requirement. Emergency vents provide high capacity pressure relief if the tank is exposed to fire. When the internal tank pressure reaches the opening pressure of the vent, the weighted cover moves up on the center pin allowing air to escape. When the internal tank pressure falls, the cover automatically lowers back onto the body and is automatically reset.

UL Listed emergency vent (pressure relief only) used on aboveground storage tanks, as a code requirement, to help prevent the tank from becoming over-pressurized and possibly rupturing if ever exposed to fire. The vent must be used in conjunction with a "normal vent."

CFH = Cubic Feet Per Hour @ 2.5 PSI


  • Automatically resets after opening
  • Durable powder coated cast iron covers
  • Male NPT mounting connection
  • CARB EVR models
  • Certified CFH flow capacities
  • Theft deterrent screens available

Construction Details

  • 244OMA Model
    • Body: Aluminum
    • Cover: Aluminum
    • O-Ring: Viton
    • Screen: 4 mesh stainless steel (optional)
    • Center Pin: Zinc plated steel
  • 244OM Model
    • Body: Aluminum
    • Cover: Powder coated cast iron
    • O-Ring: Viton
    • Screen: 3 mesh stainless steel on 3", 4", & 6" models (optional)


When properly sized for the tank, this vent will conform to the following requirements:

  • NFPA 30
  • 30A
  • UL 142
  • ULC S601
  • API 2000
  • IFC
  • PEI RP200
  • California Air Resources Board Phase I AST EVR

Venting Guide

Venting Guide (PDF Download)