it's regulating volumetric flow rate, similar to the gas or water meter on your house. The short answer is no, you can't convert that to pressure. take it back and get the right regulator.
Remember Fakr and I were were messing with each other the other day about complex formulas ...you'd need a very complicated formula to do what you're after, you'd need too many unknown variables to do so, and the relationship between flow and pressure is not linear.
an example of why you can't do it - you can have zero flow yet still maintain a pressure, as inside your keg when the desired pressure is reached