Digital Drip Designer

Coefficients of Variation and Emitter Exponents

for Various Types of Emitters

Type Coeffecient of Variation Emitter Discharge Exponent
Single vortex 0.07 0.42
Multiple-flexible orifice
0.05
0.70
Multiple-flexible orifice
0.07
0.70
Ball and slotted seat,nc1
0.27
0.50
Ball and slotted seat, pc2
0.35
0.15
Ball and slotted seat, pc
0.09
0.25
Small tube
0.05
0.70
Small tube
0.05
0.80
Spiral long-path-nonflushing
0.02
0.65
Spiral long-path-manual flushing
0.06
0.75
Long-path--pc
0.05
0.40
Long-path--pc
0.06
0.20
Tortuous long-path
0.02
0.65
Groove and flap, short-path
0.02
0.33
slot and disk, short-path
0.10
0.11
slot and disk, short-path
0.08
0.11
Porous pipe
0.40
1.00
Twin-wall lateral
0.17
0.61
1non-pressure compensating
2pressure compensating

Note - emitter discharge exponents: the lower the value, the more pressure compensating the emitter. A value of 0 is fully pressure compensating, while a value of 1.00 would be totally non-pressure compensating.
 
 

Emitter Classification based on Manufacturer's coefficient of variation

(from ASAE Standard EP405, 1985)


Emitter Type
Coefficient of Variation
Classification
Point source
<0.05
Good
 
0.05-0.10
Average
 
0.10-0.15
Marginal
 
>0.15
Unacceptable
Line source
<0.10
Good 
 
0.10-0.20
Average
 
>0.20
Marginal-Unacceptable

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Lateral Pressure Losses