OT, will air hose handle propane briefly?

Fredson · Feb 28, 2019

Firstly this is not used near people or for long periods, so if it fails no safety risk. I'll be using to remotely fill basically a potato gun.

So,. How well would the pvc or standard rubber (epdm I think?) Air hose stand up to repeated say 5 minute periods of use with first propane at 4 psi and then air at 150?

BoxcarPete · Feb 28, 2019

Don't use EPDM. Absolutely not.

Neoprene/chloroprene would be fine at normal ambient temperatures, PVC would be fine, polyethylene is not recommended.

But for the love of Christ Almighty make sure you don't feed pressurized propane through EPDM.

Edit: ok, I see now that the propane isn't pressurized, but it will degrade the epdm to the tune of -60% tensile strength in a matter of hours (single-digit, maybe not even plural).

Rob F. · Feb 28, 2019

I have a weedburner that someone used red rubber air hose on and it has been fine for all the years I have used it and who knows how long before that. Granted I only use it 3 or 4 times per year. But why not just use propane hose?

Fredson · Feb 28, 2019

Got it, loud and clear no EPDM. I'll probably just go with pvc, I know the cold temperature of liquid propane can be problematic but I won't have liquid so not too concerned about that. I'd use official propane hose but need a decent length and diameter so that gets pricey.

Cole2534 · Feb 28, 2019

Fredson said:
Got it, loud and clear no EPDM. I'll probably just go with pvc, I know the cold temperature of liquid propane can be problematic but I won't have liquid so not too concerned about that. I'd use official propane hose but need a decent length and diameter so that gets pricey.

You won't have liquid, but you'll have cooling from the Joule-Thompson effect cooling. We figure 7deg F of cooling per 100psi pressure drop in natural gas, I'm not sure what it is for propane.

BoxcarPete · Feb 28, 2019

PVC should be OK in most cases, but with the propane tank cooling as Cole pointed out, you might be pushing the limit. McMaster states a temp range down to 25°F for their PVC hose, you could easily get colder than that on a modestly cool day. You'd just have to watch your tank carefully and if you see any frost, check everything over and let stuff warm up some before continuing.

McMaster also sells Nitrile rubber hose as "high pressure" hose which you don't necessarily need, but would work. They have chloroprene rubber hose as well but it's only as a specialty item, so that's out. If you look a little harder I'm sure someone sells a general purpose hose made from one of those two rubber materials.

Hazzert · Feb 28, 2019

How long is long?

You can get scuba/paintball HPA stainless braided fill "whips" 36" long with a gauge for under $50 on Amazon.

Fredson · Feb 28, 2019

100' at least and 3/4 or 1" diameter to be able to read pressure without too much drop.

Nitrile seems to be a common hose tube material (hydraulic, fuel, mine air hose are some I've seen) so if that's compatible I'll look for that.

BoxcarPete · Feb 28, 2019

Fredson said:
100' at least and 3/4 or 1" diameter to be able to read pressure without too much drop.

Nitrile seems to be a common hose tube material (hydraulic, fuel, mine air hose are some I've seen) so if that's compatible I'll look for that.

Yep, Nitrile should do just fine with propane and air, but it doesn't do so well with oxygen (at high temp) and it can't take much ozone exposure. These things are common from exposure to weather, so in general it's less reliable than EPDM for outdoor stuff long-term. EPDM doesn't care about any of those, but can't handle oil or fuel at all. Chloroprene (neoprene as a trade name) is essentially a compromise, decent on all of the above, which is why I expected it to be more common as an air hose than NBR.

Edit: this one would be perfect, comes in 3/4", NBR inner, and a CR outer.
Coilhose Pneumatics

Fredson · Feb 28, 2019

Excellent, thanks for the link.

Krutch · Feb 28, 2019

Some people like to live dangerously. "Just for fun" and potato gun/propane sure sounds like a recipe for hospital visits. If ya have to have that fun, go all out and do it properly using correct equipment. You'll live longer.

Rob F. · Feb 28, 2019

Krutch said:
Some people like to live dangerously. "Just for fun" and potato gun/propane sure sounds like a recipe for hospital visits. If ya have to have that fun, go all out and do it properly using correct equipment. You'll live longer.

You mean frozen potatoes launched with a neutral mix of accetylene and oxygen is dangerous? If potatoes aren't sized, and then frozen they just turn to powder when they clear the bore. (or so I've heard

)

Bill D · Feb 28, 2019

Note that PVC is not allowed for compressed air. Probably fine for a few shots. Left in the sun it will age faster and you get to the shrapnel stage sooner.
Bill d

Rob F. · Feb 28, 2019

Bill D said:
Note that PVC is not allowed for compressed air. Probably fine for a few shots. Left in the sun it will age faster and you get to the shrapnel stage sooner.
Bill d

They are discussing hose not water pipe.

BoxcarPete · Feb 28, 2019

Krutch said:
Some people like to live dangerously. "Just for fun" and potato gun/propane sure sounds like a recipe for hospital visits. If ya have to have that fun, go all out and do it properly using correct equipment. You'll live longer.

I agree, but there is no reason why a hose constructed with an NBR inner, fabric reinforcement layer, and CR sheath should be considered anything other than "proper equipment" for this application. I would not be surprised if the "official" propane hoses used exactly that same construction, but with a tag that says "this will be great to hook up your grill!" Those only come in short lengths/small cross sections for that reason. Chaining together 10 of those would be far more hazardous because you have more connections and therefore more possible leak paths.

sfriedberg · Feb 28, 2019

Fredson said:
100' at least and 3/4 or 1" diameter

Be aware of the volume of gas in the hose when switching between propane and air. Not sure how you'd "run a pig" through a 1" hose to get a clean transition.

adama · Mar 1, 2019

How fucking big are your spuds to need to feed this with a 1" propane hose? Pressure drop is a function of cross section and flow rate, i seriously question your hose sizing logic?

sfriedberg · Mar 1, 2019

He's actually shooting pumpkins as cannonballs and using swedes (rutabagas) as grapeshot. (Joke)

4GSR · Mar 1, 2019

If your feeding the cannon from a 5 gallon propane bottle. Go to your local propane company and get a hose assembly from them for hooking up to your regulator on your bottle. The other end will be a flare nut for a brass adapter of your choice.

What ever you do, keep PVC pipe out of the equation. Not safe or allowed by code for use.

Scruffy887 · Mar 2, 2019

3 words.
Hold my beer.
Or
Y'all watch this.

OT, will air hose handle propane briefly?

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