RickRick
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| posted on 31/7/13 at 06:54 AM |
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Blowing up Fire hose
For our RC car racing club, we've aquired miles of fire hose about 4" dia in various lengths, and we want to inflate it. One end is
sealed. we also want to be able to inflate it fairly quickly, and we don't need it rock hard, just so it holds its shape so was thinking more
along the lines of an 12v airbed pump rather than a car tyre pump. we're outside too so 12v only
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snakebelly
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| posted on 31/7/13 at 07:03 AM |
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you'll be there all day with a 12v pump, if I was you I would find a local dive shop or industrial gas supplier and invest in a gas bottle and
get them to fill it for you, it doesn't need to be filled to max pressure but with some sort of regulator and a piece of hose you will be able
to fill them in seconds.....instead of hours :-).
thinking about it if you have access to a proper compressor you might even be able to fill it yourself with enough air to do the job?
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ashg
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| posted on 31/7/13 at 07:05 AM |
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bouncy castle fan.
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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Davey D
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| posted on 31/7/13 at 07:26 AM |
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As above, id go with a fan from a small bouncy castle.
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plentywahalla
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| posted on 31/7/13 at 07:44 AM |
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I doubt a bouncy castle fan will even inflate it, they are very low pressure.
I would agree with the plan of stored pressure. Get an old propane gas cylinder, vent all the gas out and pressurise it from a compressor.
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
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whitestu
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| posted on 31/7/13 at 07:51 AM |
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I was expecting an expolsion!
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Bluemoon
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| posted on 31/7/13 at 09:29 AM |
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quote:
Originally posted by whitestu
I was expecting an expolsion!
You might get one, depending on how they do it!
Compressed gas in a cylinder gets my vote (this could just be a portable compressor with a reciver of sufficient volume/pressure.
i.e. total volume of gas to fill hose = cylinder volume X preasure in bar
So long as the volume is say twice that of the hose you should get two shots at filling the hose up..
Dan
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loggyboy
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| posted on 31/7/13 at 10:01 AM |
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I doubt anything simple would create the type of pressure you would need. Could you not insert 1-2m lengths of pipe lagging that could be slid along
to the desired location, then you could fold the hose at 1/2m lenghts when clearing away.
Mistral Motorsport
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MikeRJ
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| posted on 31/7/13 at 10:06 AM |
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You'll need a big compressed air cylinder to inflate a decent length of 4" diameter pipe. e.g. A typical scuba bottle will hold around
2300 litres of air, which is only enough to inflate about 280 meters of pipe to atmospheric pressure. You'd probably want a bit more than
atmospheric pressure to make the pipe rigid as well.
Likewise using a compressor is a total non-starter as the airflow is far too low. A 240v compressor with a 3hp motor might give 11cfm, which would
take 1 minute to inflate 38 meters of pipe.
High flow and low pressure is exactly what the OP needs, and this is exactly why a bouncy castle fan or similar is the best solution. The little fans
used for inflating air beds would take hours, and probably burn out long before they finished.
[Edited on 31/7/13 by MikeRJ]
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Bluemoon
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| posted on 31/7/13 at 10:06 AM |
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quote:
Originally posted by loggyboy
I doubt anything simple would create the type of pressure you would need. Could you not insert 1-2m lengths of pipe lagging that could be slid along
to the desired location, then you could fold the hose at 1/2m lenghts when clearing away.
What do you mean by "type of pressure", if you only need it "floppy", it will be atmospheric pressure inside puss a very small
amount to hold the pipe wall up, so long as you don't have leaks it will take very little.. Also I would guess fire hose is wanted to make a
compact size when packing away...
Dan
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britishtrident
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| posted on 31/7/13 at 10:12 AM |
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As Bluemoon posted the problem is more volume than pressure what will do the job is the turbine compressor from a DIY HVLP spraygun --Earlex,
Bosch, B&Q Performance Power or similar. I use one of these compressors blow up an air bed in a few seconds.
They are all 240v and are rated about 500-600 watts so to convert from 12v you would would need a inverter rated at 1KW+ -- loads on ebay.
[Edited on 31/7/13 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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loggyboy
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| posted on 31/7/13 at 10:19 AM |
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Im talking about the weight of the hose. These things are designed to be robust, take huge water pressures, its not like a hot air baloon!
Mistral Motorsport
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gremlin1234
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| posted on 31/7/13 at 10:26 AM |
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could you fill it from a car exhaust?
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Slater
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| posted on 31/7/13 at 10:43 AM |
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quote:
could you fill it from a car exhaust?
Great idea, 2 litre engine at 2000 RPM should give 2000 litre per minute of exhaust gas, I think.
1 exhaust cycle per 2 revolutions. Is that right?
Why do they call Port Harcourt "The Garden City"?...... Becauase they can't spell Stramash.
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dinosaurjuice
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| posted on 31/7/13 at 10:45 AM |
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a slightly modified vacuum cleaner motor and a 12v inverter would be way to go i think.
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MikeRJ
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| posted on 31/7/13 at 11:24 AM |
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quote:
Originally posted by Slater
quote:
could you fill it from a car exhaust?
Great idea, 2 litre engine at 2000 RPM should give 2000 litre per minute of exhaust gas, I think.
1 exhaust cycle per 2 revolutions. Is that right?
One exhaust cycle per revolution on a 4 cylinder 4 stroke engine, and you will get rather more than 500cc per exhaust stroke.
quote:
Originally posted by dinosaurjuice
a slightly modified vacuum cleaner motor and a 12v inverter would be way to go i think.
That's not a bad idea, I have an "Earlex" shop vac that you can attach the hose to the outlet for blowing.
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coyoteboy
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| posted on 31/7/13 at 12:08 PM |
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You won't need much pressure - I have kitesurfing kites that get 4-5psi in their leading edge (about 4" diameter) and they're rigid
enough to use as an edge bumper (they're a plastic tube inside a fabric cavity (hold themselves rigid in 40kt gusts with me hanging from the
bottom of the tips).
Bouncy castle fan might do it nicely, compressed air cyl assumes you have no leaks or it'll be flat in seconds, plus you would likely need
safety certificates for it if it's an organisation.
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RickRick
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| posted on 31/7/13 at 12:24 PM |
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Wow this seems to have got you all thinking Thanks
low pressure is all we're after just enough to hold it "full" but not to make it rigid, it's also a lot lighter material
than i expected it to be.
We did think about exhausts as there's always plenty of cars, but i think it'll all get a bit of a mess after a few inflates.
i like the paintgun turbine idea, could even be hacked more to run off an rc car motor/battery there getting up towards 1kw now
also the next part of the problem is how to make a sealable opening to inflate / deflate. one end will be perminantly sealed up, but i need to
find/make a quick and easy seal for the other end ( or near the end and seal both ends up if needed) that will also allow a decent flow rate
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britishtrident
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| posted on 31/7/13 at 01:04 PM |
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quote:
Originally posted by loggyboy
Im talking about the weight of the hose. These things are designed to be robust, take huge water pressures, its not like a hot air baloon!
It is exactly the opposite a fire hose simply needs filled with fluid at a pressure very slightly above atmospheric to occupy the volume, with
a balloon you need a positive pressure differential stretch the rubber to make the balloon take up its filled shape.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 31/7/13 at 01:07 PM |
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I have used air bag jacks filled by exhaust pressure works they were very effective but do get very mucky, however my experience was back in pre-cat
thse days exhaust gas is much cleaner.
[Edited on 31/7/13 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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coyoteboy
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| posted on 31/7/13 at 04:16 PM |
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Indeed, that's a great idea BT - modern exhaust should be pretty clean and easily available. Only minor issue is you may need to
"overinflate" initially as it'll cool but with that sort of volume I suspect it'll be fine and cooled by the time it reaches
the ends anyway, meaning the drop in volume will be minor as a percentage.
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loggyboy
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| posted on 31/7/13 at 04:21 PM |
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quote:
Originally posted by britishtrident
quote:
Originally posted by loggyboy
Im talking about the weight of the hose. These things are designed to be robust, take huge water pressures, its not like a hot air baloon!
It is exactly the opposite a fire hose simply needs filled with fluid at a pressure very slightly above atmospheric to occupy the volume, with
a balloon you need a positive pressure differential stretch the rubber to make the balloon take up its filled shape.
Try blowing up a baloon with someone sat on it!
Mistral Motorsport
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loggyboy
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| posted on 31/7/13 at 04:31 PM |
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Some very basic maths
4" hose = 0.008107m2. over a 20m length thats 1621m3 of air, which is 1621000 Litres. So even trying to get half that ino to the hose so its
looks slightly inflated will be a mamouth task.
[Edited on 31-7-13 by loggyboy]
Mistral Motorsport
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RickRick
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| posted on 31/7/13 at 04:41 PM |
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Hmm that does sound like a poo ton of air!
i think i'll bodge the roll i have at home with some blocks of wood and clamps to seal the ends and try blowing it up with the 12v airbed blower
i've got, that chucks out a reasonable amount if thats going to take half hour rather than a minute or 3 it might be that it's just not
practical
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karlak
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| posted on 31/7/13 at 04:48 PM |
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Any outside taps where you are ?
Fill it with water ? Would also have the advantage of keeping it in place with the weight - although I guess fire hose is heavy anyway. Water
pressure could be an issue I suppose as well.
MK Indy - 2litre Duratec - Omex 600 - Jenvey throttle bodies - ETB DigiDash2
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