Various types of emitters

Arpit Kumar2012AE06BIV

Emitters:

• Emitters function as energy dissipater reducing the inlet pressure head ( from 0.5-1.5 atm) to zero atmospheric pressure

• Irrigate the field with continuous small droplets• Made from poly propylene or LLDPE

Classification of emitters: Emitters are classified mainly as point source emitters or line

source emitters, according to their position in their supplying laterals.

Emitter may be classified on the basis of various criteria, i.e.• Operating pressure• Discharge rates• Design• Flow regime• Cross section of flow area

Operating pressure:• Low Pressure (below 0.8 m)• Medium Pressure (2 to 5 m)• High Pressure (8 to 15 m)

Discharge rates:• Low (below 4 litres/hr)• Medium (4 to 10 litres/hr)• High (15 litres/hr or more)

Path cross section:• Low (below 0.8 mm)• Medium (0.8-1.5 mm)• Wide (1.5 mm or more)

Design:• Point source• Line source

Point Source Emitters

Line Source Emitters

Point Source & Line Source Emitters

Major Types of Emitters:

• Pressure Compensating• Non Pressure Compensating• Orifice Emitter• Vortex Emitter

1) Pressure Compensating : These are designed to obtain nearly uniform discharge from each dripper (with the help of flexible internal diaphragm), in spite of varying operating pressures. Also known as self flushing type emitters.

Advantages:i. Useful in hilly & undulating areasDisadvantages:ii. Higher investment costiii. Higher operating pressure required

2) Non Pressure Compensating: These don’t have the pressure compensation feature.

Hence, their discharge tend to vary widely with the operating pressure.

Advantages: i. Less expensiveii. Best used in fields with little or no undulationsDisadvantages:iii. Can’t be used in hilly & undulating lands

3) Orifice Emitter:• Orifice emitter employs a series of orifices to dissipate

pressure.• Flow rate of water at any given pressure is governed by

the orifice diameter.• Flow velocities are greater and the potential for clogging

is less than for laminar flow devices.• Turbulent flow devices.

4) Vortex Emitter: Vortex emitters employs the vortex effect to dissipate

pressure. The principle used is swirling of the water around the outlet hole to cause a drop in pressure and a lower flow through the hole.

Advantages: • Small in size• Less expensive• Easy to manufacture• Uniformity in discharge• Resistant to clogging

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