GA diaphragm actuated altitude valves are used to prevent overflow of elevated water storage tanks, standpipes and reservoirs without the need for floats or electronic sensors. Altitude valves are installed in the fill line and measure the height of the water through a field installed sensing line, closing tight when the maximum level is reached. “Single Acting” type altitude valves control water into the tank, water is drawn out of the tank through a separate pipe. “Double Acting” altitude close when the tank is full but re-open when system head falls below tank head to allow water to flow back into the system. GA diaphragm actuated altitude valves can be supplied with solenoid shutoff, check and/or pressure sustaining optional functions. See individual Data Sheets for details.