Rice Lake EL232 XPCD Explosion Proof Remote Serial Display - Manual (Page 7)

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The design intent of an explosion proof enclosure is not to contain an explosion, but to control it. The flame
path is carefully controlled at the flanges. This insures that if an explosion occurs, any gases that escape will
be cooled to a temperature below the ignition point of any atmosphere specified within that enclosure’s
rating.
Explosion
HAZARDOUS
AREA
High temperature
gases
Cooling from
expansion of gas
(Boyle’s Gas Law)
The distance from the boundary of
the inside of the enclosure to the
gasket is known as the Flame Path.
This distance must be at least 1" for
Group C throughG.
INSIDE OF
ENCLOSURE
Lower
temperature
gases
Enlarged view
below
Propagation of gas due to
pressure from an internal
explosion
Gasket
For clarity, the slope of the flange
faces has been greatly enhanced
(Typically, the slope is .0015"/inch)