A valve that allows water to stream in one direction and will then close to prevent development of a back-flow. Check valves function on flow sensitivity in order to propel opening or closing. They are generally made up of two discs, one which allows for a forward flow and the other not allowing backward flow by shutting the valve when there is a reduction or fluctuation in the flow rate. One of the main determinants of check valves is that they are unable to be utilized in pulsating systems due to the valve being insufficient in preventing forward flow operation as a result of the vibrations.