Hi I have tried searching for more information. But above is all I can find for these valves. They are more then twenty years old. The solenoid is definitely 24vdc 0.3 Amp and is a plunger type solenoid that uses a spring return. I can make some tests directly on the solenoid if this would help. This type of solenoid is sold as a dc or ac variant but costs approx 30 Euros each which would be quite an investment for 20 zones. There are also two types of diaphragm valves that I know of using these solenoids. That is the Elmeco and the Rain Bird 11/2″ valves.
Please let me know if there are any checks I can make to clarify any necessary details.