Valve can be operated manually, both by using the handle, pedal lever and so on. Besides being operated manually, there is also a type of valve that is operated automatically, ie the control is carried out using the principle of changes in flow, pressure and temperature in the pipe. The three changes will affect the diaphragm, spring or piston so that it will automatically move the valve with the system open and close. There are many types of valves, including air valve, angle valve, ball valve, butterfly valve, check valve, control valve, diaphragm valve, float valve, foot valve / valve, gate valve, globe valve, hydrant valve, industrial valve, needle valve, plug valve, pressure reducing valve, safety valve, solenoid valve.