My excuses in advance for the probably-bad wording of the question, I'm just an hobbyist without much knowledge in engineering. To the point I can't google for information on my problem since I don't even know the applicable terms... So please bear with me :-)
I want to automatize my DIY ultrasonic LP cleaning machine by adding automatic fill/drain of the ultrasonic cleaner (see drawing).
After the cleaning is done, the ultrasonic cleaner is emptied to the solution tank below; dirt will settle at the bottom of the tank. The cleaning solution has a bit of alcohol in it and is heated during the cleaning process so I want the solution tank to be sealed to reduce evaporation that would change the solution's alcohol/water ratio.
Of course, air has to flow in and out of the tank during pumping or draining, and during cooling of the solution in the tank so I need a form of relief valve? Or is it another type of component, perhaps a kind of pressure regulator? I thought about simply using a valve but that wouldn't be practical as I don't want to have to periodically open the valve during the cooling of the solution to let air in.
I know of two requirements, 1) it has to allow bi-directional flow and 2) it has to work at very low pressure, as the solution tank will likely be a plastic water dispenser which is not able to withstand much pressure.
I hope I explained the problem clearly enough. If not feel free to ask for mode details. If you could recommend products that would be nice. Thanks for your help and please don't make fun of me :-)