Quote:
Originally Posted by Joobacca
it is not to your advantage to not use a reservoir coming from your compressor. it allows for more pressure to be store before going out to your actuators and stores air in the system for when you aren't using the pneumatics. it's sort of standard to use tanks. you're thinking though!  |
There's another reason to use as many tanks as is allowed: You can
precharge the tanks before the round.
Consider: The total amount of
work (in the physics sense) allowed in a FIRST pneumatics system equals (A) whatever you can compress
during the round,
PLUS (B) whatever energy was
stored in the tanks
before the round.
Therefore, to maximize this value you want to go into the round with the largest storage volume allowed, prefilled with compressed air stored at the maximum PSI allowed!
Now OTOH, the compressor, its spike, the control hardware (et al) all cost you in
weight. Therefore,
IF you are using only a
tiny amount of air during the round (such as the only pneumatic device is your "end of round release trigger widget", or "pneumatic gear shifting" with tiny cylinders and little work will be done), then by all means delete the compressor and drive the pneumatic load with just the storage tanks precharged to their max pressure.
A few caveats though:
1) All FIRST supplied valves are 'piloted'. They use air to either
maintain their state (every 'spring return type' of valve in the kit), or require a minimum pressure to exist to
switch state (such as the SMC dual coil type valve).
Example - Try this out: Build up the compressor component. Attach the "grey" (Festo) valve as directed with any cylinder as a "load". Turn it on by putting 12VDC onto its contacts. NOW, slowly reduce the input air regulator's setting... You'll quickly discover that although the coil to the valve is still "on", once the pressure drops low enough (somewhere in the 20-35 PSI range) it WILL suddenly switch to the "off" state! The spring return "becomes stronger" than the "hold" pressure, and it switches off although the light is still on! With the dual coil SMC valves, you may find that you can no longer switch state once the tank pressure has dropped too far.
(I do this demo with every incoming rookie class to our team, to impress upon them the need to tinker and try things out, as some devices in the kit may
not act as you think!)
FYI, if you check the specs, most of the valves in this contest state they they need somewhere around 35 PSI minimum input pressure to operate. So, if you're contemplating a "tank only" system, your total consumption should
never allow the tank pressure to drop below that value at any time during the round, or else unpredictable behavior may occur.
2) Avoid using the vaccum generator with a tank-only system! The unit continuously consumes air to generate and maintain vacuum. That means you'll only have a VERY limited number of "grip-on" seconds in total. (I think it would be
mighty embarassing to drop your Ringer while you're still jockeying for position, and not be able to pick it up again!)
3) To maximize total actuations possible, minimize the total cylinder
volume of your loads, by picking the absolute minimum bore and stroke required to get the job done. After all, every time you actuate a cylinder (in either direction), you "throw away" it's total displacement volume of air. In an air-limited application, that could become important.
I hope this helps!
- Keith