jrrdw wrote:Seems to me the more valve's, twist, turns and dead air in between the pressurized pilot and the port exit the longer it will take to vent the chamber, Yes? No?
All else being equal, true.
But all else is rarely equal. Just like a main valve, a pilot valve isn't instantly open and things are happening so quickly that a slow opening pilot valve may not fully open before the main valve starts to move. Also, while a 1" sprinkler valve doesn't have the same flow as a 1" ball valve, it DOES have more flow than a 1/4" ball valve.
The faster valve's should have a shorter distance and less dead air to move, Yes? No?
Not necessarily. With enough dead space in the pilot even a tiny pilot will perform adequately once the main valve starts to move... It will just take longer for that main valve to start moving. On the one extreme, it's nice to have a gun that fires the moment you open the pilot. On the other extreme, nobody wants to wait five minutes after the pilot is opened before the gun fires. But does it really matter if it takes 0.1 s to open vs 0.01? Both are quick enough in human terms.
What's important is that the pressure in the pilot stays low enough that it doesn't seriously slow down the valve piston/diaphragm. A large pilot valve OR a large amount of dead volume in the pilot will do nicely there. BOTH? Hey, that's gold (as long as it doesn't take too long for the main valve to start opening).