propane meter

sprayandprayboy · Sun Jun 05, 2011 7:57 pm

hi all im new here. i have a gun that was "spray and pray" but i changed it to propane and it doesnt work

i used the fuel tool

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

and it still doesnt work

it was fine as a spray and pray ,this is my first serious gun , my chamber volume is 85 cubic inches ,and my barrel is 32 cubic inches.
any of your help would be very well helpfull

thank you

ramses · Sun Jun 05, 2011 9:46 pm

You may need to change the pressure based on the vapor pressure of propane at whatever temperature.

I would make the meter to work on 50 psi or so, and use an air compressor regulator to maintain that pressure. They were on clearance for $5.00 at Harbor Freight a little while ago, but I think they may have been discontinued. I should have bought more.

Crna Legija · Sun Jun 05, 2011 10:08 pm

whats the volume of your meter? what pressure you filling it to?

sprayandprayboy · Mon Jun 06, 2011 1:16 am

I am using like a half of a tank, and my hose is 4 3/8" long not counting the fittings and vaulves and is 3/8" ID, its not working very well, now that i shortened the hose i must blow a little air into the chamber... do u suggest making the hose about 3/4" shorter. thanks o yeah i dont have a regulator should i try to get one

Crna Legija · Mon Jun 06, 2011 2:28 am

sprayandprayboy wrote:I am using like a half of a tank, and my hose is 4 3/8" long not counting the fittings and vaulves and is 3/8" ID, its not working very well, now that i shortened the hose i must blow a little air into the chamber... do u suggest making the hose about 3/4" shorter. thanks o yeah i dont have a regulator should i try to get one

What??????

saefroch · Mon Jun 06, 2011 5:38 am

sprayandprayboy wrote:half of a tank

Is not a unit of pressure... Please try again

sprayandprayboy · Mon Jun 06, 2011 11:54 am

the propane tank is half full

Crna Legija · Mon Jun 06, 2011 12:10 pm

sprayandprayboy wrote:the propane tank is half full

we get that but what pressure are you filling you meter pipe to and how much volume is that pipe?

sprayandprayboy · Mon Jun 06, 2011 4:47 pm

my meter pipe is the hose it is a high pressure fuel line i dont know how mutch pressure a half full propane tank holds i do not have a regulator, sorry i should have said that my "meter pipe" was a hose.

saefroch · Mon Jun 06, 2011 5:11 pm

You've been filling the meter to whatever pressure the tank is? You don't have a gauge on the meter?

Fuel tool says you only need your meter pipe 3.1" long. I HIGHLY recommend manometric fueling, because you will not have potentially massive errors because of a change in temperature.

Fnord · Mon Jun 06, 2011 6:21 pm

Uhh, saefroch, I don't think manometric is ideal for a non-airtight gun.

S&P:
As long as you have liquid propane sloshing around in the tank, the pressure inside will be the same (around 120 psi, but varies with temperature).

You don't absolutely need a regulator or a pressure gauge, but it may make life easier. If you could post a picture of your rig that would help us trouble-shoot.

ramses · Mon Jun 06, 2011 6:30 pm

I HIGHLY recommend volumetric metering with a pressure gauge or regulator over manometric metering, especially for a 1x combustion. Unless you want to have a completely air tight chamber that you fill to precisely 0.62 psi for every shot.

Regulator.

several more

sprayandprayboy · Mon Jun 06, 2011 6:54 pm

yes i still have liquid propane sloshing ... i cant get a piture until friday

saefroch · Mon Jun 06, 2011 7:27 pm

Well I guess I don't understand what "manometric fueling" means. To me, it just means "fueling based on pressure," which would indicate the use of a gauge, but the use of an independent metering volume or pipe is optional. I take it that this term normally refers only to chamber fueling?

sprayandprayboy · Mon Jun 06, 2011 8:19 pm

i dont understand "manometric fueling" is either