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The Shand & Jurs Model 94221 Emergency Vent and Manhole
Cover provides emergency relief of excessive internal pressure and vacuum beyond
that provided by tank breather requirements.
This weight loaded vent utilizes
Expanda-Seal™ diaphragms which provide tight seals between pallets and
seats. Special diaphragm materials are available for vents subjected to severe
low temperatures or used on tanks storing heated stock. Corrosion resistant
pressure/vacuum seat is standard.
Model 94221 is available in 20" and 24" size
to fit a standard API or ANSI flange. Special Flanges are available including
DIN.
The pallet starts to lift when set pressure is approached. Flow efficiency
rises rapidly to approximately 60% of a perfect orifice at 40% excess of the set
pressure.
At a higher overpressure, the pallet completely clears the manhole and
the efficiency approximates 75%. For a standard setting the capacity at
1.4 oz./sq. in.(40% overpressure) is approximately 500,000 SCFH for the 20”
size.
Pallet construction permits settings from 1.0 oz./sq. in. for aluminum
pallet & 1.3 oz./sq. in. for S.S. pallet standard to 8 oz./sq. in. maximum
pressure. Vacuum settings are from 1.1 oz./sq. in. standard to 4.0 oz./sq. in.
maximum. If specifying other than standard vacuum setting, it must be recognized
that increased vacuum setting automatically increases the set point of pressure relief.
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