I am making a prototype of automatic irrigation. I am controlling irrigation of four fileds with a single water pump. To maintain the proper watering I need to install electeic water valve that can controll the flow of water. As I am designing a prototype so I need a valve that's work without pressure. What type of valve I can use.? It will be cost effective for me if you suggest a recycle product or a source of device from where I can recycle this kind of product
You will find it difficult to find such a valve. Most solenoid valves for irrigation are "pilot" types. That means the solenoid is actually quite small because it only opens and closes the pilot line which actually opens the valve with the water pressure.
There are solenoids available for pumped systems where the pressure may be lower. They are still pilot valves.
If you are making a small desktop model, then perhaps the solenoids that drive the pilots is all you need to demonstrate that it works. Buy some cheap valves and pull them apart.
If you are just using the valve as a load for the circuit, then inexpensive sprinkler solenoid valves should do. Wiring a led in parallel with the valve circuit to demonstrate the valve is actuated. Try Toro or Rainbird. They run on 24v ac and can be controlled with triacs or mechanical relays.
You need an electric ball valve to do what you want.
Something like this.
http://www.aliexpress.com/item/1-2-Electric-motor-valve-Brass-DC12V-Motorized-valve-with-5-wires-CR05-DN15-Electric-valve/1938495319.html?spm=2114.40010208.4.2.L5v1W0