This a meter that measures pressure/temperature/flow. The reason you want to know flow is to assure your get turbulent flow through the water circuit. Temperature when measured absolutely tells you if the temperature is set properly. When measured from the Inlet and Outlet of the same circuit can should you the efficiency of the circuit or whether the cavities in that circuit are all seeing different temperatures. Pressure is related to flow. A dramatic pressure difference between the Inlet and Outlet pressures imply some kind of blockage in the circuit.

The right way to optimize a molding cycle is to cool the mold properly. To most people this means run cold water through it. Right?? Not quite. The secret is both temperature and flow. It not only has to be cool, you have to pump it through the mold so that it exchanges heat via turbulent flow. Generally, the rule of thumb for turbulent flow is 1.5 GPM per circuit. This does not mean dribbling the water into a bucket and measuring it with a stopwatch because you only accounted for the pressure going in, and not the resistance of the return circuit.