sorry about that, It was a copy and paste... looked great on the clip board...
..
Anyways its air pressure, the sort of pressure you may achieve if you leave a 20 litre empty jerry painted black in the sunshine, from there down to about what 800 hpa ?...
It needs to sample pressure "sample time adjustable", and based on a no change scenario in "x" seconds release the pressure, hold open for a predetermined time, then close.
Does that help...
