What are you using for pressure sensors? How much current do the solenoids need to open?
The system/functionality you described requires one valve and two pressure sensors. That means information you provided is either incomplete or incorrect.
400 psi is a lot, do you have identified any pressure sensors/valves able to handle it? The 24V mentioned can mean either you already identified a valve you want to use or that is just the voltage you have available for this project. Again, incomplete, quite useless detail for someone trying to figure out what your actual problem is.
Try to provide a diagram.
Arduino can control valves and measure from sensors with the correct shields.
A hand drawn photo is fine.
Be aware that there is a limit to photo file size for upload though.