new UL Canister Burner project

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seudo_411
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Re: new UL Canister Burner project

Post by seudo_411 » Fri Feb 06, 2009 6:07 pm

Well allow me to clarify, by low pressure, I mean the large butane canister. for filling lighters. I found with the smaller refills the pressure drops very quickly.
Vibe is the refill similar to the one below. Image

The pressure on these are quite low, so when i refill my lighters I stick them in the freezer for a few minutes, then walk around with the refill in my pocket for a while, that way i can fill it properly.

Any how back on topic, been thinking of using a 15mm mixing tube, into a 15mm to 22 mm reducer to male the burner head. Does the volume (length and width) of the mixing tube make a difference to the air fuel mixing, My guesses are longer tube will give better mixing up to a point where the velocity is to low. a narrow tube will require larger air holes and lower resistance from the diffuser or mesh. A wider tube will require higher gas velocity and therefore higher gas pressure or it wont draw enough air.

note the above are just calculated guesses.

Oh, Zelph I remember i still have some epoxy "Steel" Putty, Strong stuff, have used it to repair a cracked induction hose (operating between .8 and 1 bar) So i assume it should hold up, gonna mix a block and hit it with a blow torch. I had a brilliant idea I am going to take the jet and make a wax mold of its threads. the use super glue to make a positive then when i mix the putty i can use the cast positive which is identical to the valve to make the part where the valve screws into, Add a little Loctite thread sealant and its as good as a tapped hole. :D , in theory at least.
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Re: new UL Canister Burner project

Post by Vibe » Fri Feb 06, 2009 6:57 pm

seudo_411 wrote:Well allow me to clarify, by low pressure, I mean the large butane canister. for filling lighters. I found with the smaller refills the pressure drops very quickly.
Vibe is the refill similar to the one below. Image
Yep. That's the one.
seudo_411 wrote:The pressure on these are quite low, so when i refill my lighters I stick them in the freezer for a few minutes, then walk around with the refill in my pocket for a while, that way i can fill it properly.

I'm not sure I understand that - vapor pressure is vapor pressure. It does not really depend upon volume, just temperature. The farther above the boiling point, the higher the vapor pressure.
seudo_411 wrote:Any how back on topic, been thinking of using a 15mm mixing tube, into a 15mm to 22 mm reducer to male the burner head. Does the volume (length and width) of the mixing tube make a difference to the air fuel mixing, My guesses are longer tube will give better mixing up to a point where the velocity is to low. a narrow tube will require larger air holes and lower resistance from the diffuser or mesh. A wider tube will require higher gas velocity and therefore higher gas pressure or it wont draw enough air.
Longer tube will provide better mixing, but as to the diameter???? A look at a commercial gas stove will indicate that even a large diameter tube will mix properly with a properly metered air inlet, and those are a good 18" to 2 ft between burner and jets, and they "draw" just fine with very little pressure. Home gas pressure in in the sub-PSI range measured in inches of water.
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seudo_411
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Re: new UL Canister Burner project

Post by seudo_411 » Fri Feb 06, 2009 7:30 pm

Vibe wrote:I'm not sure I understand that - vapor pressure is vapor pressure. It does not really depend upon volume, just temperature. The farther above the boiling point, the higher the vapor pressure.
My thoughts were always that, because of the smaller size it has less pressure as the volume of gas and therefore pressure changes more drastically within a canister. So going on Boyle's Gas Law http://en.wikipedia.org/wiki/Boyles_law, From what i understand for a fixed volume of gas a change in temperature will result in a change of pressure. and a change of pressure will result in a change of temperature. So I am now led to think that a drop in volume will result in a Temporary change in pressure and temperature, as the canister warms to ambient temperature so to is pressure restored.

So when I say the smaller canisters have less pressure, thats not entirely correct, what i intend to say is that because the pressure for both sizes at any given temperature would be the same, My preference for the larger canisters stems from the fact that the change in volume relative to the total volume of each canister respectively, is not as great as with the smaller of the two, so to conclude What i meant to say is that when the volume of the two canisters decrease at the same rate, the pressure and temperatures do not decrease at the same rate.
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Re: new UL Canister Burner project

Post by Vibe » Fri Feb 06, 2009 8:10 pm

OK. That makes sense. They both (large and small) START out at the same pressure, but since evaporation has a cooling effect, and there is less mass of fluid in the smaller container, the fluid temperature drops more rapidly in the smaller one - thus reducing the pressure more rapidly. The apparent solution to that would be to feed the liquid fuel to the stove with a generator line near the flame to flash that portion to gas before injecting it into the stove. That would reduce the rate of evaporation inside the canister and keep fuel canister temp and pressure more constant.
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Re: new UL Canister Burner project

Post by seudo_411 » Sat Feb 07, 2009 2:02 pm

Vibe wrote:OK. That makes sense. They both (large and small) START out at the same pressure, but since evaporation has a cooling effect, and there is less mass of fluid in the smaller container, the fluid temperature drops more rapidly in the smaller one - thus reducing the pressure more rapidly. The apparent solution to that would be to feed the liquid fuel to the stove with a generator line near the flame to flash that portion to gas before injecting it into the stove. That would reduce the rate of evaporation inside the canister and keep fuel canister temp and pressure more constant.
Yeah thats pretty much it. Been having an up hill battle trying to find some 1/8" anything. No silicone fuel line, no copper tubing, just some macroline, thats sold in 1 foot lengths only. :evil: Not very conducive to stoving...

EDIT: If there is any board member that owns a Jetboil GCS/PCS, and that is able to give me any information on the Jet, i.e. The hole size, and the thread on it would be greatly appreciated. I have to pass this info onto the engineering shop that is making my mixing tube. To find out if the are able to make a female adapter for the jet that leads to the hose barb for my gas line.
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Re: new UL Canister Burner project

Post by Vibe » Mon Feb 09, 2009 12:31 pm

http://www.harborfreightusa.com/usa/com ... ingle=true
Image
I'm going to try and play around with this. It's got an on/off/throttle built in, as well as some premixing...if I don't cut the nozzle off. The burn time is a bit limited at an advertised 15 minutes.
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seudo_411
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Re: new UL Canister Burner project

Post by seudo_411 » Mon Feb 09, 2009 12:59 pm

The JetBoil jet is 0.21mm, Got the info from the company, but not much else, was gonna try and hustle them to send me a stove so i can see for myself,

I have also considered a torch like that, its just the valve that is a bit inconvenient as you have to rotate the body, I like little knobs and wheels . Great price though. Just had a thought, Buy 3or 4 of those cut the nozzles, and braze them together, get the brunton stand or similar and you could have a three to four jet burner. Like a little blue flower.
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Re: new UL Canister Burner project

Post by zelph » Mon Feb 09, 2009 5:38 pm

Vibe wrote:http://www.harborfreightusa.com/usa/com ... ingle=true
Image
I'm going to try and play around with this. It's got an on/off/throttle built in, as well as some premixing...if I don't cut the nozzle off. The burn time is a bit limited at an advertised 15 minutes.
Heads-up!!! I had a couple of the cheepee's clog up on me shortly after using them. I did cut them up to see how they worked and use them in my experiments.
I found that here was small particles of machining debri inside the fuel chamber that may have been the cause of clogging.
I suggest you have the torch in an upright position to burn off the fuel or just let it go up into the air outside without lighting it up. That's if you were considering cutting the section off that contains the adjustment control.
http://www.woodgaz-stove.com/

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seudo_411
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Re: new UL Canister Burner project

Post by seudo_411 » Mon Feb 09, 2009 6:33 pm

zelph wrote:
Vibe wrote:http://www.harborfreightusa.com/usa/com ... ingle=true
Image
I'm going to try and play around with this. It's got an on/off/throttle built in, as well as some premixing...if I don't cut the nozzle off. The burn time is a bit limited at an advertised 15 minutes.
Heads-up!!! I had a couple of the cheepee's clog up on me shortly after using them. I did cut them up to see how they worked and use them in my experiments.
I found that here was small particles of machining debri inside the fuel chamber that may have been the cause of clogging.
I suggest you have the torch in an upright position to burn off the fuel or just let it go up into the air outside without lighting it up. That's if you were considering cutting the section off that contains the adjustment control.
Hey could you see that, A stove with three individually adjustable flames. Take that Eurogas...
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Re: new UL Canister Burner project

Post by Vibe » Mon Feb 09, 2009 6:36 pm

Yeah Zelph. I just ran into the same thing today. But I didn't have to cut it up. The small "bump" on the valve cap is really the turn limiting pin. It pulls out fairly easily with a pair of wire cutters, and the whole top will screw off for cleaning. I'm going to take one of the nozzle assemblies into work tonight and look at it under one of our 25x stereo microscopes, and possibly a MicroView examiner. I should be able to measure the diameter of the jet in it. I might just enlarge that jet to get a stronger flow while I'm at it. I'll let you guys know what I find.

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