Propane meter questions

[JDP12]

Hey all,

Well after talkin it over with my dad he's agreed to let me use propane and build a meter!! Yay!

I'm going to build it according to BCPneumatic's video, but my chamber is onnly 8" long so I won't be able to mount the whole thing to my gun...

So I am wanting to use some pressure rated 1/2" ID hose for the chamber instead...So I can bend it and mount the whole meter to my gun...What should the pipe be pressure rated to???

Second question: What PSI should I fill the chamber to?? What is the ideal PSI?? I looked around but didnt find anything...My chamber volume is 110 cubic inches if that helps.....Like what would be the best PSI??

[super spuder]

um. i am confused. you wont need that big of a propane injection system on an 8 inch chamber. unless it is like over 4 inches in diameter

[JDP12]

What do you mean...I'm just followin BC's instructions.....How big would I need though?? Anyone get what I'm saying?

[super spuder]

i understand what you are saying. but can you tell me the diameter of the chamber

[JDP12]

Oooooooooooooh yea sure...It's 4" but I accounted for a little extra cuz of reducers and stuff..So the 4" part isnt 110, everything in all is......

Can I use this link to calculate how much propane I would need??

http://www.burntlatke.com/lp.html

[super spuder]

can you figure out the volume of your chamber. if it is 8" long and 4"diameter the volume is about 50. corect me if i am wrong

[JDP12]

V=radius squared x height x pi

V= 2 squared (4)x 8 x 3.14

V= 100.48

100.48 + 10 ( reducing fittings and pipe needed for those)

Total Volume= 110 cubic inches

[super spuder]

crap. no wonder i did not do so good in math. any ways, since you seem to be good in math. i i don't tonight. find 4 percent of that=4 and then what size of pipe are you using for the propane injection. or are you using pipes. if you are you just need a piece of pipe with a 4 ci volume

[singularity]

alright this is probably a stupid question but what pressure should the metering pipe be at?

[super spuder]

1 think most people run them about 30-60. i have not built one of these yet. but that is what someone told me. i am not sure thou. could someone else help

[sgort87]

The meter pressure depends on the meter's volume. I wrote out a whole explanation on how to figure propane metering <a href="http://www.launchpotatoes.com/forums/vi ... 7">here</a>.

[pyrogeek]

Just hook a regulator up inline, and experiment. That is the only way to get peak performance anyway.

[sgort87]

No it isn't. Did you not read the instructions I just gave?

[JDP12]

sgort87- So the pressure inside the meter chamber should be 98 psi ( for your example) before I release it into the gun???

[sgort87]

Thereabouts. I got 98.9 PSI. Setting the regulator at 100 would be fine though. And remember that chambers and meters have different volumes, so setting your regulator at 100 PSI most likely will not work for you.

The best way to do it is to find your chamber volume first, then design your meter to run around 60 PSI. After you plug 60 into the equations, it will give you the meter volume you need. From that, you can divide it by the cross-sectional area of the meter you'd like and it will give you the length you need. Since pipes don't come in every size, you will need to settle for a similar length and recalculate using the new volume to get your final pressure.