Replies

1. 
   Rich14 | Dec 29, 2006 10:20pm | #1

   Quick,

   The hysteresis motor, being an induction motor is a type of motor referred to as "explosion proof." The motor itself, having no electrical sparking potential is "safe," but if it has any mechanical switches included for a starting capacitor circuit, these can be an explosion source and should be in enclosed "pots" that are sealed with gaskets.

   Of course, any of the switches which turn on power to the motor must be out of the area where the spraying is to occur.

   Rich

    

1. 
   JohnWW | Dec 30, 2006 01:54am | #2

   True explosion proof motors are designed to harmlessly contain the explosion of any vapors that get inside of the motor housing, anything less isn't considered explosion proof and a true explosion proof motor will be clearly labeled as such.

   I don't know what a hysteresis motor is, the term isn't commonly used, but if it has a starter circuit with a centrifugal switch, or a thermal switch to prevent overheating, both will generate a spark.

   John White, Shop Manager, Fine Woodworking Magazine

1. 
   RickChristopherson | Dec 30, 2006 02:35am | #3

   A hysterisis motor doesn't have a starting circuit so it is fine. More importantly, if the vapor concentration passing the motor ever reached the lower explosive limit (LEL), then you would likely be passed out in the corner, or dead. The areas where you would need to be concerned would be dead-air, not flowing air.

2. 
   mudman | Dec 30, 2006 04:57am | #4

   Good point John.

   True explosion proof systems are very complex. They allow gasses to ignite then expel in some controlled fasion.Pardon my spelling,

   Mike

   Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.

2. 
   PaulC | Dec 30, 2006 05:00pm | #5

   yeah, as a rule if it doesn't say "explosion proof", it isn't. explosion proof is essentially explosion containing. intrinsically safe equipment is designed not to produce a spark or heat source with enough energy to act as a source of ignition. oh, and you would reach the LEL of most VOCs well before oxygen deficiency would be a problem. acute toxicity varies.

   Amateurs talk strategy, Generals talk logistics.

1. 
   QCInspector | Dec 30, 2006 11:08pm | #6

   I haven't a clue as to whether a hystersis motor is explosion proof or not. What will happen over time is that the open motor will eventually fill with the over spay being drawn through and that may cause overheating. If nothing else the motor's life will be shortened and need to be replaced in the future, and the hunt for a suitable motor will be resumed. The other question that should be considered is, what would the insurance company do if it was found that a motor, not rated for this application, was being used and a fire resulted?

3. 
   milanuk | Dec 30, 2006 11:39pm | #7

   I've only seen hysteris motors in use in one place I worked... and it was one of those 'if I told you I would have to kill you' scenarios. But yes, from what I recall of them they should be as explosion proof (in terms of not causing/propagating a spark or ignition source) as anything you can find. As others have touched on already, whether the overall construction of the motor, it's housing, etc. meets the legal definition of 'explosion proof' is a separate issue.