Bypass metering pipes?

Moonbogg · Fri May 15, 2009 1:41 am

I was thinking about bypassing metering pipes altogether. I want to have a nice, clean and simple design. I am thinking of having the cannon powered by mapp and o2. Each tank can go first to a flash suppressor/check valve and then to the ball valve that lets the fuel in the chamber. I could use gages that go from like 0-30psi since the chamber pressure will be less than a meter pipe, so an accurate reading will be easy to see on lower psi gages. SO what do you think? Is a flash suppressor/check valve and inlet valve enough of a barrier between the chamber and fuel tanks?

jagerbond · Fri May 15, 2009 2:30 am

Our McMaster check valves have held up real good. Obviously not hybrid pressures but they are rated to 300 PSI and always closed. Using O2 I would definitely proceed cautiously but I really like the idea of replacing tanks rather than pumping a bike pump or being tethered to an air compressor. I wonder how the 30 PSI gauge holds up to a 3-4 X hybrid combustion chamber spike.

Anyone got recommendations on how to record chamber spike pressure?

Mike
Sureshot Inc / http://www.ultimatespudgun.com

Moonbogg · Fri May 15, 2009 3:21 am

jagerbond wrote:Our McMaster check valves have held up real good. Obviously not hybrid pressures but they are rated to 300 PSI and always closed. Using O2 I would definitely proceed cautiously but I really like the idea of replacing tanks rather than pumping a bike pump or being tethered to an air compressor. I wonder how the 30 PSI gauge holds up to a 3-4 X hybrid combustion chamber spike.

Anyone got recommendations on how to record chamber spike pressure?

Mike
Sureshot Inc / http://www.ultimatespudgun.com

Hey there, its good to have you reply. You guys have some sweet cannons. I was going to keep the gages behind the protection of the inlet valves so they aren't exposed to combustion forces. I wanted to have a single pushbutton valve for the mapp and another for the o2. All you have to do is press the button for each and fire. So the order would go gas tank, regulator then inlet valve. I might not even need the check valve in fact. I'll have to wait and see.

Oh, I will start using o2 and mapp to fuel my current Venom cannon as well, just using my current meter pipe. Much easier than pumping all day lol.

jagerbond · Fri May 15, 2009 3:39 am

Thanks for the compliment, and yours too. I see about the gauges, makes sense now. push button metering would be trick, is this a timed electronic type concept, or mechanical?

We ran our initial prototype without a check valve on the Mapp gas with zero problems. Check valve is for extra - extra safety.

Mike
Sureshot / http://www.ultimatespudgun.com

inonickname · Fri May 15, 2009 3:41 am

Well the biggest difference between a check valve and a flash suppressor is that a check valve is intended to only allow flow in one direction while a FS is designed to stop back flow. The biggest issue with check valves during blow back (torches) is that the flame front can escape to the gas behind the valve. A flash suppressor will stop it dead by means of a porous material or bubbling through a non flammable material.

So as long as the valves are in a closed state on ignition there's no problems.

Moonbogg · Fri May 15, 2009 4:15 am

inonickname wrote:A flash suppressor will stop it dead by means of a porous material or bubbling through a non flammable material.

So as long as the valves are in a closed state on ignition there's no problems.

Flashback Arresters sound great to have implemented right behind the inlet valve or at least somewhere before the regulator. They are not TOO expensive as well. Some of them claim to have check valve functionality as well. About the valves being closed...I must assume that whoever is using the cannon indeed has a death wish and is trying to kill themselves with it. So idiot proof is sort of what i'm looking for.

jagerbond wrote:push button metering would be trick, is this a timed electronic type concept, or mechanical?

I thought about a double solenoid valve so you can electronically link the 2 valves to 1 button, but the pressures from the tanks might conflict with eachother as their regulators are set differently. I will likely have mechanical valves because of this. The valves wouldn't need to be timed, because the regulators would stop the flow when the chamber is full. First fill with mapp to about 2 PSI, then close the valve and fill with o2 to about 9PSI, then that valve closes and your done.
I will still try to find a simple way to achieve single button loading but I won't complicate the design or let the cost drive up over it.