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View Full Version : OT Venting Metal Self-closing Gas Cans



rws
12-07-2012, 05:27 PM
I didn't want to hijack the other thread on gas cans. I have about 10 metal self closing gas cans, and they are terrible to pour gas out of. So my question is, opposite the spout, there is a nice flat on the top of the can, where "someone" could install something that could be used to vent the can but close off too, a valve maybe of some kind? Any ideas?

I'm about to buy a length of clear fuel line and just siphon instead of the mess it makes pouring.

lakeside53
12-07-2012, 05:38 PM
I'm going to use a stock plumbing bleed valve - 1/8 npt brass male, tiny knurled knob and a fiber washer. A female npt will be brazed into the can.

metalmagpie
12-07-2012, 06:51 PM
I'm going to use a stock plumbing bleed valve - 1/8 npt brass male, tiny knurled knob and a fiber washer. A female npt will be brazed into the can.

Better blow that can out REAL GOOD before you hit it with a brazing torch ..

jeremy13
12-07-2012, 07:01 PM
I used the metal valve stems with the jam nut. Just drill hole and fish out hole and tighten.

Black_Moons
12-07-2012, 07:37 PM
I have done brazing on fuel tanks, I would never 'blow out' a gas tank and expect it to be fume/petrochem free!
rinse/wash it out with much thinner solvents that don't like to leave deposits, ie: Laqure thinner. Do that twice. then blow it out, then let dry for a day, idealy under a heat lamp. Then blow it out again and let sit.

Then *smell* the tank. Does it smell like anything but clean metal? If so, you failed to clean it.

Also consider that you can buy a $20 12oz tank of CO2 at many places ($4 to refill) and a $20 (on ebay, $50 localy for some reason) remote paintball hose and have a nice compact way to inject CO2 into something for cheap for extra percaution.

lakeside53
12-07-2012, 07:40 PM
Better blow that can out REAL GOOD before you hit it with a brazing torch ..

Na. It will be dry. If I'm concerned I'll fill them 90+% full with water.

Arcane
12-07-2012, 11:02 PM
I'm going to use a stock plumbing bleed valve - 1/8 npt brass male, tiny knurled knob and a fiber washer. A female npt will be brazed into the can.
Years ago I enlarged all the vents on my gas containers as much as possible, IIRC to 3/8"; it made a considerable difference to the time that it took to empty them.

Tony Ennis
12-07-2012, 11:23 PM
Fill the can with pure O2 first so at least it'll burn clean.

lakeside53
12-08-2012, 12:17 AM
Years ago I enlarged all the vents on my gas containers as much as possible, IIRC to 3/8"; it made a considerable difference to the time that it took to empty them.

yes... I might do that also. Depends on what i find;) The "vent" hole in the 5 gallon Blitz is tiny now - maybe only only 1/8 and it is a bit sluggish.

jdunmyer
12-08-2012, 07:36 PM
If that fitting has a through hole, soft-solder it onto the can, THEN drill the hole. I've done that several times, keeping the torch well away from any actual opening in the tank.

Black_Moons
12-08-2012, 09:29 PM
If that fitting has a through hole, soft-solder it onto the can, THEN drill the hole. I've done that several times, keeping the torch well away from any actual opening in the tank.

I hope you don't think that actualy matters much.
When you heat the tank to soldering temp you vaporise off any deposits of oil and gunk.
Red hot steel is enough to ignite some things. My last oven just used some kinda element that glowed white hot to ignite the gas. Sadly it started getting colder and colder over the years and eventualy only opened the gas valve a crack at one point.. Stupid thing.

Anyway, Point being it takes oxygen, heat and fuel to start and sustain a fire.
The heat does not need to be in the form of a spark/flame. Add (more/better) fuel and you need less heat/oxygen.
Add more oxygen and you need less heat/fuel.

Clearly, you want to try and deprive it of fuel and/or oxygen as best you can if you plan to provide plenty of heat!

Also note that a strong tank full of combustable material and oxygen is basicly the defintion of bomb.

Evan
12-09-2012, 01:11 AM
I just posted on another thread that NASA has discovered that it is possible for diesel to burn at 120C which is just above boiling. It's called a "cold flame" and it can spontaneously switch to a "hot flame" under the right conditions.

jdunmyer
12-09-2012, 09:32 AM
B_M,
You're correct, of course. It's been a while, so my memory might be getting a bit weak. Usually, if I'm working on a fuel tank, I purge it with inert gas while doing such stuff. The handiest thing for me is the Argon/CO2 bottle on my MIG welder. I might also have used my big ol' soldering iron, not a torch. Again, my memory might be fading.

rws
12-09-2012, 11:54 AM
Why couldn't a vent valve be epoxied in, like with JB Weld? The other thing is, how to cut a clean hole, and try to capture the shavings? I suppose there really wouldn't be much, but a gas can should be as clean as possible.

lakeside53
12-09-2012, 12:25 PM
You can also just use a threaded adapter, washer and nut behond. Fiddly in some cases to get the nut on.... but..

Not sure what the adversion to dealing with portable gas tanks is. Worried about residual? Just wash it out with detergent and water.

Scottike
12-09-2012, 12:58 PM
Go to your local grocery store and buy some dry ice. Drop a chunk into your gas can and wait for the CO2 fog to
start flowing out the spout of the can. You'll see gas fumes being pushed up and out of the can first and then
the fog will start coming out. Then go to work drilling and brazing/welding.
It's how we used to inertize old gas station fuel tanks before taking a torch to them to open up access holes
in them before transport.