Taizer:
thanks Lefty for the help.I didn't finish my first post. Meant to also mention that the basics of the programming would be based on pulse signals sent from the meter to the board. In turn, the programming of the board would allow me to control when the valve opens and closes based on the number of pulses received.
Sure sounds like a classic industrial controller type application. There is even a full P&ID software library avalible if you wish to try and implement it. You will have to create and adapt the basic measurement functions and output control functions to the P& ID library, but it's all doable.
http://www.arduino.cc/playground/Code/PIDLibrary
Good luck;
Lefty