Why am I not surpirsed by your response Trevor. I was thinking of going with the second one anyway.

I think Ill hold off on taking it apart for the moment and do a bit of testing. Mainly because restricting the flow will restrict the operating speed and power until Ive got the bones of the system sorted out.

I deal a lot with the design and testing of CO2 extinguishing systems at work, but dropping down from 3 pipe to this is a bit of a learning curve. Having almost have a client kill himself once I have developed a healthy respect for CO2.

Ill probably get one of our suppliers to take it away and deal with it when I know what I want. (Thats the advantage of not having designed anything to go on the end of it yet!!

I would be interested in just going through the CO2 system. I was thinking:

CO2 bottle, regulator, isolating valve (any requirement for gauges?), three port manual valve to purge the system from outside the bot, big bit of pipe to act as a buffer tank, five port valve and actuator.

That was about all I could think of.

Andy