All solenoid valves normally closed, open with electrical current. All pneumatic operated valves, normally closed (by spring) opens by air. Failsafe all: closed (by no air and/or no current). Each valve operated by one common electrical control switch with four positions: all off, current to either of solenoid valve 1, 2 or 3. Suggestion 2. Manual and/or electrical by 5/3 valve. Open or closed for each main valve electrically by 3/2 valve, generally as above, or separately for each In addition is installed a manual or electrical operated 5/3 valve for the operating air. In end positions the 5/3 is connected as to give air to for instance main valve 1 and 3 separately (one each end position) In the mid position the 5/3 is selected with function 'airaition' air return for valve 1 and 3. You put in addition a pneumatically operated spring return valve (2/2 pneumatical) for the airline for mainvalve number 2 between mainvalve 2 and the mid position of 5/3 valve operater of the 2/2 connected to airaition (air return posrts) in this position. If the 2/2 pneumatical operater is given air (connected to) both airlines for for mainvalve 1 and 3, and the 2/2 is closed by air it will always remain closed when 1 and 3 is open (has operating air pressure). Only way to open the 2/2 wich is controlling the airline in to mainvalve 2's solenoid valve is mid function of the 5/3, where mid position is air airaition (return). In this way you can use all the three positions of the 5/3 as selector for operation of one dedicated single of your main valves.

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