The Shand & Jurs Model 94510 Magnavent is a pressure operated emergency vent designed specifically to meet the NFPA ruling on venting requirements for small storage tanks. An economically designed and priced unit, the principle of operation is based on a unique magnetic latch.
The pressure setting is accomplished by an Alnico permanent magnet attached to the base acting on a magnetic stainless steel plate on the hinged cover. As the pressure increases, the force required to overcome the magnetic attraction between the base and cover increases until the set pressure is reached. The setting is determined by the size and strength of the magnet.
Because the force required to overcome the magnet is much greater than the force (or pressure) required to support the lightweight cover, the vent instantaneously goes to full open at the release pressure - there is no 'simmering' or leakage as the tank pressure approaches set pressure.
The time - and service - proved Alnico magnet, which is cadmium plated has been extensively tested with no deterioration in magnetic strength due to shock, time or temperature.
Another innovation incorporated in the Magnavent is the Teflon Expanding Seal. The seal never contacts two hard surfaces at one point. The tank pressure forces the seal away from the cover and at the same time forces it against the seat surface of the base with the result that the higher the tank pressure, the tighter the seal becomes.
Tests have shown that there is less than 0.5 cubic foot per hour leakage at high pressure right up to the release pressure. The Teflon Expanding Seal is an added benefit to those users who are concerned about conserving product. The performance of the Expanda-Seal™ technology makes the 94510 an economical alternative to expensive pilot operated valves or rupture disks where blowdown is not a major concern.