I am regulating air pressure in a pressure vessel. When filling, let's say from 0-70psi I want the valve to open 100% and gradually strict the flow so it does not get over pressured above 80psi. Once it's pressurized to 80psi I need to maintain it with a tolerance of +-10% anywhere from 1-24hrs. If in case the pressure goes above 10% the proportional valve opens and vents it out gradually and maintains air pressure. I spoke with my local AB distributor and he's setting me up with the material list. I know this is a difficult project and I appreciate all inputs. I'm also buying the Process Control Solutions book by John Shaw. Thanks, TioPaeng