Pneumatic Ball Puncher

[Al Skierkiewicz]

Brandon et al,
During inspection, launchers may have to demonstrated for "dry firing" to see if they are in fact safe with no ball present. Having no external hard limit for cylinders quite frankly scares me. While the working pressure is only 60 psi, a cylinder can impart quite a bit of force on the piston and the end assy with no system resistance. I have seen enough catastrophic failures to worry about this design choice. Please prototype with extreme safety in mind.

[PVCMike]

Originally Posted by Al Skierkiewicz

Brandon et al,
During inspection, launchers may have to demonstrated for "dry firing" to see if they are in fact safe with no ball present. Having no external hard limit for cylinders quite frankly scares me. While the working pressure is only 60 psi, a cylinder can impart quite a bit of force on the piston and the end assy with no system resistance. I have seen enough catastrophic failures to worry about this design choice. Please prototype with extreme safety in mind.

While a 3/4" cylinder with good flow to it moves pretty quick, and we always make strong efforts to work and design safely, I would be amazed if an unmodified COTS piston operated at less than 50% max psi recommended by the manufacturer (125psi max, operated at 60psi per FIRST rules) failed due to dry firing. This would be a major design flaw by the manufacturer. Now if we dry fired it at 125+ psi many times and it failed that's another thing. We will of course exercise caution but a failure of this type with no other damage or modification seems implausible especially given the reliability of our product manufacturers.

[Al Skierkiewicz]

Originally Posted by PVCMike

While a 3/4" cylinder with good flow to it moves pretty quick, and we always make strong efforts to work and design safely, I would be amazed if an unmodified COTS piston operated at less than 50% max psi recommended by the manufacturer (125psi max, operated at 60psi per FIRST rules) failed due to dry firing.

Mike,
125 psi is the working pressure at which integrity with pressure is guaranteed. It does not relate to mechanical failure of the device with no load.

[PVCMike]

Originally Posted by Al Skierkiewicz

Mike,
125 psi is the working pressure at which integrity with pressure is guaranteed. It does not relate to mechanical failure of the device with no load.

Hi Al, i understand that

Originally Posted by Al Skierkiewicz

125 psi is the working pressure at which integrity with pressure is guaranteed.

I have never seen any documentation from the manufacturer or anyone else for that matter suggesting that this guarantee is under the condition that there is a minimum load applied to the cylinders. A mechanical failure of the cylinder, operated as intended and within the specified psi, unmodified and undamaged/not worn, would be a product or design failure by the manufacturer. These cylinders are designed to be operated under the specified pressure and are not subject to the condition of a minimum load to be safe. Yes they will actuate very fast (especially smaller diameter cylinders) but especially when restricted to 60psi (again less than 50% working pressure) we are well within the scope of intended and safe use specified by the manufacturer.