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The Shand & Jurs Model 94520 Emergency Vent provides emergency
venting and manhole requirements, where intermediate pressure relief beyond that
provided by tank breather 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 Model 94520 is available in 10", 16" and 20" sizes and is designed
to utilize a patented, magnetic latch system, which provides greater flow
capacities than conventional weight loaded vents. It also provides for 100%
opening at set pressure with no over pressure required. The magnetic latching
principle eliminates hundred of pounds of loading weights required by
conventionally loaded vents. The vent is tightly latched utilizing permanent
magnets, which are mounted to the vent cover and act on a magnetic stainless
steel plate on the vent base. 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
90° via spring loaded cables. These cables are attached to the cover and the
vent body. This will assure the cover to self close once fully opened.
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