" Explosion proof" does not necessarily mean there are no sparks inside the
housing. Its pretty difficult to make a high voltage/current switch or
relay that does not spark but these are available in explosion proof
versions. "Explosion proof" also does not mean these devices are
hermetically sealed.
For these devices, and some motors, "explosion proof" means operation of
the device will not ignite a flammable atmosphere surrounding the device.
Since the device is not gas tight there is a flammable atmosphere inside.
When the spark occurs a very small explosion/flame is generated but there
are no openings in the device that are large enough to permit this flame to
escape and ignite the surrounding atmosphere.
If you have a bilge blower motor that uses brushes I don't think it would be
an explosion proof unit as these are very expensive. To be economical for
the average boater, not the Coast Guard, I would think a bilge blower motor
would have to use a different electrical design to be explosion proof.
If you have a motor with brushes you need to mount it well above the bilge.
If you leave your boat unattended for a month and it fills up with gasoline,
and you don't check the bilge before switching on the blower, you may still
have a bang up problem.

"WKensit" wrote in message
landnet.com...


Rich Hampel wrote:
They use AIR (NOT electric) motors in explosion application.

You must mean "TENV" .... totaly enclosed/non-vented: For 'hazardous'
atmospheres but certainly NOT for explosive atmospheres. Usually ONLY
pneumatic motors and controls are used in 'explosive' applications.


How do they make industrial electric motors explosion proof?
Impossible you say?


Obviously you have never seen TEXP motors. Check, for example, the
Westinghouse site. Handy if you want to mount a 150HP blower in your
canoe.

In article uixfd.4961$9b.2815@edtnps84,
"Gordon Wedman" wrote:

Its pretty difficult to make a high voltage/current switch or
relay that does not spark but these are available in explosion proof
versions.

No, not hard at all. the Big Boys use Mercury Switches when they need
to have sparkless DC Switches. The spark is in a sealed Mercury Switch
tube, with just the wires coming out.

Me who uses Mercury Switches in Intrinsically Safe appliances....