The part number for the solenoid air valve in the 7900 Series control boxes are:
7901/ES7901 - part# 941 - marked A
7902(S)/ES7902(S) - part# 942 - (2 valves) marked A and B
7949/ES7949 - part...
Exit alarm ALK operates with 9VDC battery and doesn't required a power supply.If you choose to hard wire the exit alarm ALK use the PS902 power supply.Exit alarm ALK requires 24VDC regulated power ...