CEAC-2020-10-October

News
(Continued from page 31)
There are additional risks associated with sandwich-style
composite vents.
Over time, pounds of debris can accumulate inside the layers,
doubling and even tripling the weight. In cold weather conditions,
icing can occur as well.
“We’ve seen instances where a small 3-foot by 3-foot vent
that weighs 20 pounds brand new, after years of accumulating
material between its layers, now weighs 40 pounds.”
In addition to being unsanitary, particularly for food processors,
the increase in mass due to the accumulation of material
means that the vent will not open as fast as planned.
The result can be higher-than-expected pressure in the dust
collector or other protected equipment in the event of explosion
vent activation. “Without the expected relief [from
venting] a dust explosion can over-pressurize the equipment,
causing significant damage,” says Brazier. “Worst case, the
explosion could escape through a weak point — and not the
explosion vent — causing an uncontrolled release of flame,
dust and pressure where it wasn’t planned.”
Single Section Vents
As the demand for explosion protection technology grew,
BS&B later developed the single section vent. In this design, a
single sheet of metal is intermittently cut about its perimeter
and then gaskets are applied to cover the cut pattern.
The vent panel with a compound dome provides greater intrinsic vacuum
resistance, stability and resilience, and increased service life compart to
conventional flat panels.
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Eliminating the fragile plastic film seal and one sheet of
metal greatly reduces the mass of an explosion vent, making
it more efficient at responding to the rapid rate of pressure
rise arising from a dust or gas explosion.
The superior design allows the vent to handle high vacuum
operating conditions and cyclical operating pressure conditions.
It also eliminates product build-up, enabling the vents
to be used in clean service applications.
Single Section Compound Domes
In 2010, BS&B improved on the single section vent design
by altering the shape of the dome to a unique compound
geometry. This advance was born out of a desire to increase
the vacuum resistance of the vents, without increasing the
weight.
The compound dome has curves at the corners of rectangular
and square vents that deliver even greater rigidity for high
vacuum or vibration applications.
The primary purpose of the domed construction, on the
other hand, is to provide greater intrinsic vacuum resistance.
This is important, as storage, pneumatic conveying and dust
collection systems often operate under light vacuum conditions.
Industrial dust collectors can also utilize short pulses of
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| Chief Engineer