Gate valve is used when a straight line flow of fluid and when minimum restriction is desired. 
They are named so because the part either stops or allows flow through the valve acts like the opening and closing of a gate.
When the valve is wide open the Gate is fully drawn in to the valve leaving an opening which is same as the size of the pipe, therefore there is only a little pressure drop.

Butterfly valve is light in weight, relatively small, quick acting and provides positive shut off and can be used for throttling. 
It has a body, a resilient seat, a butterfly disk, a stem, a packing, a plate and a handle. 
To Open or Close, turn the handle only one quarter turn to rotate the disk 90 degree.

As the name implies these are stop valves that use a ball to start or stop the flow of liquid. 
When the handle is operated to open the valve, the ball rotates to a point where the hole through the ball is in line with the valve body inlet and outlet. 
To shut it requires a 90 degree rotation of the hand wheel or lever, the ball rotates so that the hole is perpendicular to the flow openings of the valve body.

As the name implies the Foot valve is fixed in the bottom of the suction line.
It prevents water flowing out of the pump when the pump is turned off so that the pump does not need to be re primed when it is restarted. 

As the name suggest it is a valve which is used to release air from the pipes. 
It releases air pockets that collect at each high point of a fully pressurized pipeline. 
ARV's can open against internal pressure, the force opens the orifice whenever air pockets collect in the valve.

When the pump starts the ball moves to open position and enables the liquid flow without any hindrance.
When the pump stops the balls takes the firm position against the metal seat because of its weight and back pressure.
Is fitted on the delivery line and the water cannot flow backwards and opens when the water flows.

ICV is installed outside the structure of the protected premises is also called as Alarm Valve.
It has NRV, Gong, Screw valve, Control valve, Pressure Gauge, Y Strainer and other fittings.
It is fixed in large sprinkler systems and is use to control the water supply and the operation of system.