Cla-Val Pacific 210-03 and 610-03 Altitude Valves control the high water level in reservoirs without the need for floats or other devices. They are non-throttling valves that remain fully open until the shut-off point is reached. These valves close at a high water level. Water is withdrawn from the reservoir through a separate discharge line or through a check valve located in a by-pass line around the altitude valves. The valves delay opening until the water in the reservoir lowers to a desired level. The low level is adjustable from 1 to 15 feet from the high water shut-off point.