Altitude Valve

Greetings everybody,

would someone advise me on how to model altitude valve. I have a WaterCAD model which consists of a distillate water main from the water treatment plan conveyingwater to underground reservoirs. in order to maintain equal flow rate to each reservoir I put altitude valve on the inlet pipe to each reservoir. but my question is how to model this altitude valve, and how to put losses on it in WaterCAD.

Thank you