CO2 Tank for Water Rocket pressurization

I invited my neighbor to a test launch of an FTC rocket with a new parachute deployment module, and he brought along a friend.  Since I was only going to do one launch, I took along a 5 gal. air tank pressurized at home to 100psi.  This will take Big Hoss up to about 60psi (at which point point pressure equalizes between the air tank and launcher).  Then, I used the bike pump to take it up the rest of the way, to 90psi for that launch.  My neighbor’s buddy was quite impressed with the launch, and successful deployment of chute, but was amused with all the hand pumping I did.  I mentioned that I had it in future plans to get a CO2 system.  He replied that he had a 10 LB. CO2 tank at home not in use that I could have.  Great! 

Now I needed a regulator..  The CO2 regulators are mostly for feeding low psi for welding, so I was leaning toward a 500psi nitrogen regulator as some are using as discussed on Clifford Heath’s water rocket email list.  However, the welding shop I went to didn’t have one in stock, so I picked up an O2 150psi regulator for $92.  The guy at the shop swapped out the fitting on the high pressure side for a CO2 type, for a couple bucks.  In my mind I was wondering how CO2 would work through an O2 regulator.. let’s see, larger molecules, probably will not put out the full 150psi.. but how much less?  It was worth a try.  So I took it home, hooked it up.. and it squeaked out 130psi.  Good enough for me, I’m not interested in blowing myself up.  🙂  While the 10 Lb. tank is kind of big and heavy, I could trade down to a 5 Lb. if want.. I’ll decide later.  The 10-pounder came half-full so it has plenty of launches left.

Any tank full of compressed gas is very dangerous, particularly if it falls over and gets the valve knocked off – talk about a serious rocket!  This tank stand is made out of plywood, quite portable and fairly stable.  Collapses down to tote around.

I removed the fitting on the output, low pressure side of the regulator and screwed in a ball valve equipped with a quick-connect male connector.  The air hose quick connects to it.  

The red handle on the ball valve is used to pressurize the rocket.  Nice thing about this is that pressurization is done from a distance – I use a 25 foot hose.  I launch from even further back with a long cord attached to launcher.