A ceramic disc faucet uses a single cartridge to operate two functions: the temperature of the water and the water flow rate. This cartridge is cylinder shaped and fits inside the handle. It is self contained, so if the seals inside fail, and the faucet leaks, the whole thing is simply replaced with a new one. There are no small parts to contend with or change.
Design and Function
The ceramic disc cartridge is made from two ceramic pieces. One of them does not move and is positioned on the bottom of the cartridge. The other one is a moving piece and it sits on top of the other one. When the stem, the small rod on the end of the cartridge which connects to the handle, is turned one way, the non-fixed disc in the cartridge turns against the fixed disc and aligns holes in the disc. These holes allow either hot or cold water to flow through the cartridge, depending on which way the disc is turned.
Assembly and Construction
The ceramic disc faucet pieces have flat sides on top and bottom, so the two pieces fit together perfectly. This allows for a water tight seal when the pieces are placed together. This is the key to the functionality of the part. The ceramic disc cartridge is just one part of the faucet, however. The cartridge itself must sit inside of a water tight body and it is usually secured with a bonnet or dome cap, screwed to the base of the faucet. Several gaskets surround the ceramic disc cartridge, preventing water from escaping through the body of the faucet.
Operating the cartridge is fairly simple. When you turn the handle one way, the holes in the two discs line up, allowing hot or cold water through. The further clockwise you turn the handle, the farther open the hot water hole becomes, and the cold water hole shuts. This means all hot water is coming through the cartridge, so the temperature increases. The reverse is true if you turn the faucet counterclockwise. Lift the handle up on a single level faucet and both holes open wider, allowing more water to flow and increasing the total flow rate.
Leaks will occur when the cartridge valves wear out. Small sediments may cause scratches or cracks in the discs, thus damaging the watertight seal between the two discs. This results in water leaks because water seeps through the cracks and into the base or handle of the faucet. As mentioned earlier, this problem is corrected by replacing the cartridge with a new one. A fresh disc cartridge has a perfectly flat, watertight seal between the discs and will not leak.
Clogs also affect the operation of the disc cartridge. Sediments and minerals collect in the holes, even though the ceramic is supposed to be impervious to sediment build-up. Over long periods of time, it may reduce the water flow. This is also solved by replacing the cartridge.