I was wondering whether it would be possible to open an indiana ball valve directly with a solenoid, rather than needing an intermediate pneumatic actuator. The short answer seems to be 'no', assuming 100psi and a 0.5" diameter valve, and a solenoid of reasonable size and cost. Would a smaller valve diameter work? And if so what throw would it need?
It's all a matter of leverage. If you used a longer throw solenoid to operate a lever that then opened the valve, the mechanical advantage may make it feasible.
In general, a given solenoid can pull a lot harder if you use it with a shorter throw, so this may not be an out. And of course with leverage the motion at the valve will be slower. So what are the requirements for throw/diameter? Or, to put it more fundamentally: what flow rate do you need between accumulator and cannon base? If you have a 100ml accumulator (that's 6 cubic inches), at 7 bar (c. 100 psi), would a valve with a 200 lpm (6.7 cfm) flow rate work? In theory that would get the 100ml through in 30 ms -- but of course the accumulator pressure is decreasing, so it isn't that simple... If that was OK, then a Clippard MME-2PDS could replace the buna ball valve, the actuator and the servo which presses the actuator valve.
I never measured flow rates but the best cannon builders maintain at least a constant cross-sectional area through the entire cannon. So you've got the same cross-sectional area at the tips of the barrels as you do in the buna ball valve. As far as electrical triggers go, I have seen people use high-torque servos for some of the smaller cannons. The downside to that is it eases the valve open, rather than the sharp "crack" you want for best power/efficiency.
It's been pointed out that the MJV-2 is rated at 25 scfm @ 100 psi, and that that isn't enough for a multi barrel cannon, so the 6.7 cfm of an MME-2PDS would definitely nopt work. There are other members of the MME family with flow rates of 49, 93 and 171 cfm (at increased cost) which might work -- it might be worth paying for the releative simplicity.
