Fueling multiple chambers without need for valve on each one

Harness the power of precision mixtures of pressurized flammable vapor. Safety first! These are advanced potato guns - not for the beginner.
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CS
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Mon Feb 18, 2013 6:20 pm

I'm working on a belt fed hybrid, and up to now I planned a spool valve on each cartridge to fill them. That is a lot of work/o-rings/fittings/cost so this is my solution:

Side note:
Would 5 minute epoxy hold these poly, drip line, fittings to pvc?
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jackssmirkingrevenge
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Tue Feb 19, 2013 12:40 am

What do the cartridges look like? And how do they attach to your device?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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Zeus
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Tue Feb 19, 2013 1:51 am

I've used the same type normally at 200psi, and the hose stated to swell. You'll have no worries.
/sarcasm, /hyperbole
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CS
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Tue Feb 19, 2013 4:02 am

I've already built the cartridge. Cross section below.

Zues:
Good to hear! Guessed that they would handle hybrid pre-mix since they have a small diameter, but I was still unsure.

Did you use the drip fittings?
Does the hose have to be clamped to the barb?
Did you epoxy them in?
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cartridge.png
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Zeus
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Tue Feb 19, 2013 4:17 am

I've used the 3/4 hose barb to 3/4 threaded hose fitting, similar to garden tap fittings. I used it for a vacuum pump, and it held until my leaky setup bottomed out at 30mmHG. Then I took it up pretty high, without jubilee clamps on the hose. Not sure how long it'll last without them, but it worked for me.
/sarcasm, /hyperbole
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jackssmirkingrevenge
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Tue Feb 19, 2013 4:37 am

What kind of a check valve are you using?

Here's a thought:

Image

Say your cartridges are 1" OD and 5 inches long. The easiest thing to do is get a 50 inch long section of 1" ID pipe, pop the cartridges inside and fill the whole pipe with a hybrid mix. Open it up, the mix around the cartridges escapes but that inside the cartridges stays inside because of the check valve. No messing with pipes and connections to fill.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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CS
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Tue Feb 19, 2013 7:17 pm

What kind of a check valve are you using?
No check valve. The "multiple cartridge fill valve" seal each chamber at the same time. So the drip lines from every cartridge are part of the chamber. The hole from chamber to drip line would be so small the energy would hopefully be dampened.

Here's a thought:
I never understood how you keep the check valve from falling into the chamber...
Say your cartridges are 1" OD and 5 inches long. The easiest thing to do is get a 50 inch long section of 1" ID pipe, pop the cartridges inside and fill the whole pipe with a hybrid mix. Open it up, the mix around the cartridges escapes but that inside the cartridges stays inside because of the check valve. No messing with pipes and connections to fill.
Good idea, but that won't work once the cartridges are in a belt config.
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this was my #1 design, seal is great. didn't like that each cartridge had to indiviually be filled though.
this was my #1 design, seal is great. didn't like that each cartridge had to indiviually be filled though.
spool.png (15.41 KiB) Viewed 3889 times
this type of design I tried, however it didn't seal. (it might of been the glue getting on the face...)
this type of design I tried, however it didn't seal. (it might of been the glue getting on the face...)
flat pvc from pipe heated and flattened (sdr-21 that doesnt fit golf balls)
flat pvc from pipe heated and flattened (sdr-21 that doesnt fit golf balls)
belt.png (20.3 KiB) Viewed 3889 times
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MrCrowley
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Tue Feb 19, 2013 7:21 pm

CS wrote:I never understood how you keep the check valve from falling into the chamber...
I was wondering that too, maybe you could use a magnet with a hole drilled in the middle for the valve as long as the initial flow from the fuel meter isn't too high.
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Wed Feb 20, 2013 2:04 am

CS wrote:I never understood how you keep the check valve from falling into the chamber...
Gravity :) hold it upright before filling, then the mix pressure does the rest.
Good idea, but that won't work once the cartridges are in a belt config.
Use a bigger diameter pipe :) sure you would be wasting a lot more propane, but that would be in relative terms.

Filling a 2.5" diameter 50" long pipe for a 10x mix of propane costs around 5 cents (calculation based on a 14.1 oz. container of propane costing $6.59...) so even if you double the volume, it's costing you double, but 10 cents... see what I mean?
I was wondering that too, maybe you could use a magnet with a hole drilled in the middle for the valve as long as the initial flow from the fuel meter isn't too high.
You could also bolt on a small piece of wire to keep it from falling out, or just screw on a piece of neoprene and make a flap valve.

Image

An airsoft BB coupled with an o-ring in a hole would also make a good check valve, with a bit of imagination and research of existing systems there are tons of options out there.
hectmarr wrote:You have to make many weapons, because this field is long and short life
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CS
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Wed Feb 20, 2013 8:14 am

I should take pictures to prove I have in fact tried out several different systems.

I've tried the flap check valve, and it didn't work. I did a lot of searching to find someone who has done it, because I know people have, but can't find anything. Pictured below:

Was thinking it might be necessary to have the flap part seal against another piece of rubber. Rubber on rubber instead of rubber on pvc.
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jackssmirkingrevenge
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Wed Feb 20, 2013 8:19 am

As with most valves of this type, you need a raised lip for it to work effectively:
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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