It is a device for reducing the line water pressure to atmospheric pressure providing water at a low controlled discharge (2 to 4 lit/hr).
They are Classified According to Various Criteria
1. Emitter principle (Principle of operation): Office, long path, perforated pipe, doubled wall pipe, etc.
2. Flow regime: Laminers or Turbulent. This is related to emitter principle.
3. Operation pressure: Low ( 2 to 5 mm), High ( 8 to 15 mm).
Low (Below 4 lit/hr), Medium ( 4 to 10 lit/hr) , High ( 15lit/hr and more)