mcmaster is expensive... clippard should be cheaper (note that it is a ss air cylinder so it's a little bit more expensive than regular ones)
http://clippard.com/store/byo_cylinder/ ... -10-2-|||H
It is going to be rather difficult to find air cylinders rated to more than 250psi. To be honest I didn't feel very safe at pressures higher than 500 psi and that was because of the air cylinder
so..800psi with standard stuff ??
naaah I wouldn't even comes close to it
either you can make your own air cylinder or you use one of these
to have a seperate air circuit
(the fitting reduces air pressure by 8bar max, but when you pilot the input side air can escape via inbuilt check valve... so it's exactly what you want)
EDIT
ohh if you are wondering where to get them... I have no idea
but you could build it with a pressure reducing valve (ie shrader valve) and a check valve (ie another shrader valve but inserted the other way round and without the spring)
there is one more option to pull this off...
you could use two 3 way valves instead of one:
one for the QEV one for the air cylinder (and have a seperate regged down air supply for it)
lol this is getting a bit ridiculous
JSR posting in 3... 2... 1... >>>> 'your pathetic 3 way valves are no match for my lathed parts and epoxy..... muhhahahaha!'
probably the easiest and cheapest way is to build your own air cylinder... a pipe, threaded rod, some washers & orings and a spring