Fuel Meter Questions

[spudkilla224]

hello i'm building a advanced combustion cannon and i'm planning on using metered propane.

i'm having troubles with the Fuel-Tool excel program.

my C:B ratio is: 0.84:1

my chamber is 32" long and it's made out of 3" PVC.

The barrel is 2" PVC and i plan on it being 7' long.

when i plan on using the propane it's saying that i only need a fuel meter of a total lenght of

3.870" that has to be wrong right?

Would i be ok using a 12" Long fuel meter? made out of 1/2" black threaded pipe nipples?

i'm planning on using 35 PSI for the fuel meter.

could someone please help me figure out the size of my fuel meter, like it's lenght using 1/2 pipe?

Any help would be great.

[jmeyer1022]

http://members.tripod.com/potatogunwarr ... online.htm

I'd turn up your PSI, according to this you would need 20 inches at 900ft elevation.

At 900 elevation/ 14.27 atmospheric pressure and 59 PSI (round to 60 if you'd like) you would get 4.2% fuel mixture in a 12" x 1/2" pipe. I wouldn't use nipples just get a piece of pipe.

[Radiation]

Yeah that's definately not correct. I use a 3"X14" chamber and have a 4" meter. I'm assuming you're using a 1?4" chamber?

[spudkilla224]

Yea i don't know why? i'm using a 3"X32" Chamber.

So what PSI Would i run it at with a 12" Meter? At an Elevation Of 862 Feet?

[jmeyer1022]

60 PSI at your elevation and 1/2" meter pipe, you would use 11.84" or at 59 PSI 12.06" up to you.

[spudkilla224]

thank you for the tip.

[Radiation]

Also keep in mind if your local temperature gets low (like here in Colorado) you might want to give yourself some more head room as your propane won't meter as high. For instance I actually need about a 3.25" meter at 80ish psi, but I replaced it with a 4" so I could easily meter at 30 degrees at 60 psi.

[spudkilla224]

ok, so just make it like 1.5X Bigger?

so when i make it bigger cause i figured out i'd atleast need a 6.5" pipe on each side of the galvanized tee. i'm using a pressure guage in the middle of the two 6.5" pipes.

so should i make it like two 7.0" pipes on each side of the tee?

and in the summer would i have to use less psi in the meter cause it's warmer out, and the volume would be less?

[Radiation]

No your PSI will always be about the same, what I'm talking about is that you propane tank will refuse to meter up to 75 psi or so in cold weather (and where I live at 30 dgrees I can only get about 60-65 psi). As far as making you meter bigger the answer is yes, just remember the bigger the meter the heavier. but an extra inch or so won't break your back.

Either way you will have to experiment a bit to figure out just how much psi you will need for your particular setup.