Photo of 94520 Emergency Pressure Vent and Manhole Cover
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Photo of 94520 Emergency Pressure Vent and Manhole Cover

94520 Emergency Pressure Vent & Manhole Cover

The Shand & Jurs 94520 Emergency Vent provides emergency venting and manhole requirements, where intermediate pressure relief beyond that provided by tank conservation vents is required. This vent is not intended to meet requirements of explosion relief, but is designed to relieve excessive internal pressure. It is a economical solution to costly and dangerous tank roof rupture problems.

The 94520 is available in 16” and 20” sizes and is designed to utilize a magnetic latch system, which provides greater flow capacities than conventional weight loaded vents. It also provides for 100% opening at set pressure with no overpressure required. The magnetic latching principle eliminates hundred of pounds of loading weights required by conventionally loaded vents. The “snap action” operation of the vent is achieved by opposing magnets in the cover and base. It is this force that ensures a tight seal when closed. As the pressure increases, the magnetic attraction between the base and cover remains constant, until the set pressure is reached. The setting is determined by the size and strength of the magnets.

Since the force required to overcome the magnets is much greater than the force (or pressure) required to support the lightweight cover, the vent immediately goes to full open at the set pressure. There is no “simmering” or leakage as the tank pressure approaches set pressure.

The vent cover is prevented from opening more than 80° by a hydraulic damper attached to the cover and vent body. This will assure the cover to self close once fully opened.

Shand & Jurs “Expanda-Seal” option is available on all pressure pallet assemblies. This feature significantly reduces leakage. The ballooning effect of the Teflon diaphragm effectively seals the valve.


  • Magnetic latching eliminates expensive loading weights
  • Instantaneous opening at set pressure, no overpressure required
  • Unique diaphragm construction assures tight seal between pallet and seat
  • Seat opening provides for clear passage when used as a manhole

Related Products

94200 Emergency Vent And Manhole Cover

94201 Emergency Vent And Manhole Cover (With Expanda-Seal™)