To pressurize the rockets I use the pumping station, a starter aid type portable battery and a 12V air-compressor. The advantage of this set-up is that it is easy to carry into the field for my launches but it has also some drawbacks.

First the maximum pressure a portable compressor can deliver is limited to around 200 psi / 14 bar. As far I know there is no portable 12V compressor available that is able to deliver pressures well over 200 psi with some reliability.

The other limitation lies in the available power, the starter-aid power source is able to deliver about 10 Amps over half an hour or so, but not much more. This limits the delivered volume a compressor can deliver and limits the volume of the rocket.
As I am able now to build larger rockets that can withstand higher pressures, i ran into the limits of my pumping station. The 14 liter rocket @ 170 psi is the maximum the pumping station with the starter aid can deliver.

I needed more pressure and volume.
The pressure and volume stored in a 4 Liter / 200 bar air-pressure cylinder exceeds the capability's of the pumping station and can also be carried. In theory the cylinder is able to pressurize a 14 liter rocket to about 40 bar (580 psi) on a single fill.
Well over the current capability's of my wrockets!!

These type of cylinders are used by fire fighters for their breathing equipment.

On the picture you can recognize the yellow 4 Liter cylinder, a pressure regulator.

(--->The one I have now goes up to 13 bar, i'am still looking for a regulator that is able to go above 20 bar, someone out there?<---)

Also some bottles for the water fill can be carried and there are supporting brackets for the wrocket (not visible, its on the backside) . On the right hand side there is a manual pump I made, which is used to pump water into the wrocket on the launching platform.

I intend to use this set-up for my launches in 2006 and i will keep you informed on the experiences with the pressure station.