The altitude control valve can control the high water level in reservoirs. Without the need for floats or other devices. It remains fully open until the shut-off level is reached. This valve is designed for one-way flow only. The water tank altitude valve is hydraulically operated and pilot controlled. The pilot control operates on the differential in forces between a spring load and the water level in the reservoir. The desired high water level is set by adjusting the spring force.The pilot control measures the reservoir head through a customer supplied sensing line connected directly to the reservoir. SHSUOTE wholesale high quality height control valve with the best price. Contact us now!