The Cla-Val Model CDS7-DO Altitude Pilot Control is a spring-loaded, three-way, diaphragm-actuated control that provides high-level shutoff for Cla-Val 211 Series Altitude Control Valves.

The CDS7-DO operating principle uses a differential in forces between the spring load and the hydraulic head of the fluid level in the reservoir or tank to activate the pilot valve of the control. When the force of the spring setting (or the desired high-level shutoff point) is overcome by the force of the reservoir head, the pilot valve shifts position automatically and closes the main valve. When the reservoir head is eight to ten inches less than the spring setting, the pilot valve shifts to open the main valve.

The DO feature provides an integral Delayed Opening function for independently adjusting the distance between the high and low water levels.