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I want to apply a xylene-based urethane coating with a flash point of 81 degrees (F) to an epoxy floor in a windowless 8' x 8' room equipped with near-new 100-CFM exhaust fan. I hope to be able to encapsulate the room and vent the rather noxious vapors with just this exhaust fan.

If the ambient temperature of the room will be about 65 Degrees (F) - below the coating's flash point - as the motor runs, am I still at risk of the motor igniting the vapors, or do I need to rent an explosion-proof blower to vent the room?

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You should be aware that the just because the temp. of the liquid is below the listed flash point, does not mean that the liquid is not giving off flammable vapors. It means only that it is not giving off enough vapors to reach the low end of its flammable range (LFL- lower flammable limit) concentration in air under specific test conditions. If the conditions you describe were to change, you could have a problem because xylene ignites at a relatively low concentration in air (1% - 6%).

That being said, I think it would be difficult to achieve the LFL concentration (1% for xylene) in a room that small, at that temperature, with a 100cfm fan. The fuel-air mixture would just be too lean.

Don't forget to wear a good respirator rated for organic vapors.

  • Well, It's Oregon in the fall, so I'll have no problem keeping the room temp and the product temp low enough (but not below minimum working temp). I can get my hands on a 8" 1500-CFM explosion-proof axial blower - probably way overkill – PJN Nov 7 '17 at 18:55
  • For the record, I already had success doing this in a 12' x 6' laundry room with an 80-CFM exhaust fan - But there was an exterior door that gave ventilation for the first hour, I saw ample negative pressure with that fan once I buttoned up the room. The interior room gives me more concern. I can rent a 8" 1500-CFM explosion-proof axial fan to be safe - overkill for a 512-cu. ft. room And yes, I have a full-face respirator with P100 cartridges. Thanks for the reply! – PJN Nov 7 '17 at 19:07
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    P-100 is for particulates, you need organic vapor cartridges! Check the application instructions and the Safety Data Sheet (SDS)! Just don't want you to get sick yo. – Jimmy Fix-it Nov 8 '17 at 2:45
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    Oops, I thought I had the combo OV/P100 cartridges, but digging into my safety gear box, I see I just have the 3M 7093 (purple) I just asked the Amazon Prime Fairy to send me the 60921s (magenta). Thanks! :-) – PJN Nov 8 '17 at 4:03

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