An oft-overlooked and rarely considered standard feature of delivery systems is the purge valve (sometimes called “flush” as well). Simply stated, this is a toggle (or button) that is used to flush water through all of the handpieces at once. This is a procedure that should be done after every patient and at the beginning of every day.
The above illustration points out the purge toggle on a Beaverstate delivery system
Most units have air-activated valves to turn the water to the handpieces on. Most purge valves work by either by-passing this valve to force water through the lines, or by sending air to this valve to turn the water on (so it flows through your handpiece lines). The precise mechanism isn’t important, either way, the purge valve will send water through your handpiece lines as long as the unit is on. Unlike the “regular” water valve that causes water to run when the handpiece is run, the purge does not require depressing the foot control.
If you have trouble with water flowing when nothing else is running, odds are good your purge valve is on or failed. As toggles are frequently used, they are also easily bumped into the “on” position so water will flow as soon as you lift your handpiece up.