Plumbing valves control the flow of water, gas, and other fluids in plumbing systems. Shut-off valves start or stop the flow of water and other media in residential and commercial applications. Backflow prevention valves stop the reverse flow of polluted media in pipes and fixtures. Float valves automatically open or close when a liquid reaches a predetermined level. Flow control valves regulate fluid pressure and flow rate. Pressure control valves and temperature control valves regulate pressure and temperature in lines. Solenoid valves are electrically operated devices that use a magnetic field to open and close the valve, which starts or stops the flow of liquids or air. Air-operated piston valves have an air-powered piston that opens or closes the valve. Valve actuators are used to automate the operation of valves in the process. Valve boxes and enclosures protect pumps and valves from harsh conditions.