Jon

Fine until there is a power cut: the ventilation stops, the conveyor
stops, there are flammable goods on the conveyor, the heaters remain hot
enough and BOOOOM! Had this happen at a customers 30 years ago with an
IR fusing oven. Fortunately, the flux had little that was really
volatile, so the explosion was very minor, although half-a-dozen large
multilayer boards rendered their soul. I was forced to provide a NiCd
UPS system for the conveyor and ventilator.

Brian

[log in to unmask] wrote:
> In a message dated 12/8/2003 9:12:50 AM US Eastern Standard Time,
> [log in to unmask] writes:
> Thank you for the observation, but I have a question.  I agree that an oven
> with an enclosed workspace needs to be the Class A explosion proof variety,
> but does this same restriction apply to an IR tunnel where you have air
> access on either end of the machine, i.e. not an enclosed work space?
> Actually there are two OSHA accepted ways to deal with an oven under these
> conditions.  One is to make everything explosion proof.  The other, which I have
> used for 10+ years at several installations, is to guarantee enough airflow
> through the heated tunnel and out the exhaust to prevent a build up of vapors
> sufficient to cause an explosion.  Usually a measured linear airflow of 100
> ft/min or higher in every opening (in this case both ends of the oven) will meet
> the OSHA requirement and provide a safe operating environment.
>
> Jon Moore
>
> By His grace,
> Jon
>
> Stop telling God how big your storm is. Instead tell your storm how big your
> GOD is.
>
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