Norgren should sell the switch you are looking for or possibly SMC. There is a Norgren rep in every state apparently.

i ran my bottle @ 1400 psi, you will see pressure drop after a run.
i re did all solinoed re build kits etc every 12 months.

purge kits do work even on low hp systems.
well it worked on my 120hp one.
get one and see how long after you press the button before you can see the gas come out white.