See http://www.fightingrobots.co.uk/discus/messages/9/1332.html?1077738986http://www.fightingrobots.co.uk/disc...tml?1077738986 for a more detailed explanation but in summary:

A failure mode of a regulator is to let by, thus pressurising the downstream low pressure components to full bottle pressure. This can be caused by foreign matter on the seat, a seat failure, scored seat etc. There are numerous manufacturers and types of pushfits, it would not be possible with any degree of confidence state at what over-pressure they will fail at. I have tested an 18 bar pushfit at 50 bar without failure. So, lets assume M2 has a regulator failure, the LP side pressure rises to 50 bar and the pneumatic system does not fail, I then fire the ram and no doubt a big bang as the ram explodes from mechanical failure. This is why M2 has always had a LP relief valve from day 1.

Another reason for the LP relief valve is to avoid the need for test pressure points. How does the tech checker know what pressure you are operating at? Simply by checking the LP relief valve certification.

Hope that helps explain some of the thinking behind the LP relief valve.

Paul