shop air evap smoke machine safe?

[Sniper82]

I am looking at making a cheap DIY smoke machine using air compressor and am reading alot of stuff saying how air isn't safe vs nitrogen. However alot of older machines was made using air and supposedly no reports of fires. I know there risk but really how likely is it to happen? I mean if you drop your gas tank to change the pump without fully draining it first its pretty much the same risk right?

 

[phucheneh]

Displacing gasoline vapors with atmospheric air isn't safe? I'd like to hear someone's reasoning for that argument. Especially when the system you're testing already uses atmospheric air to function. When the purge valve is opened to allow vapors into the engine, it is accompanied by the opening of the canister valve, which allows air into the system to replace the vapor. If it didn't open, there would be no flow through the evap system.

Are you trying to go the glow plug + cheap tire inflator route? If so, it works fine, but is tricky to get right. Hard to get dense enough smoke coupled with the proper amount of air flow without risking too much pressure.

If you truly need a smoke test to find the problem (what DTC are you getting, and what have you done so far?) and don't foresee yourself needing this again in the near future, you may just want to pay a shop to smoke it for you.

edit: if you do make your own machine, and want to be 100%-paranoid-safe, just use a check valve to make sure vapors can't flow into your device.

 

[Sniper82]

definitely the wick/resistance wire method. Can't remember the codes right off but one was a large and the other a small evap leak. I haven't done anything yet to try and fix the problem. First thing I am going to do is buy a new gas cap just to rule that out.

Out of the research I've done on smokers I just see alot of info on how unsafe it was to pump the system full of air/oxygen.