Hi guys and Gals.
I was hoping for a little advice.
I have now updated the water flow arrangement for the ballast tank of my Submarine build. It has worked generally but has highlighted a problem when it come to emptying. The system of switches works well and the pump reverses correctly and the solenoid valves switch over. Unfortunately as before, the tank fills well, and with the additional non return valve, holds the fill well, but will not empty. I have now added a pressure gauge to the tank to see which pressure switch I need to fit for safety. At 60% full it is holding 2 Bar. I have checked the solenoid valve and it is rated at 0.05Mpa. (0.5 Bar) Not enough which is why it will not operate to empty. I have now purchased a 0.4Mpa valve, (4 Bar) which should overcome this problem. My long awaited question is: Should I fit relays to the solenoid valves even though they work, and if yes, could I ask why.
I have drawn the system as I have it and added a picture.