CALCULATION OF TOTAL DYNAMIC HEAD - METHOD 2

Assume that the land is a slop and the pump is installed lightly below the garden level

STEPS FOR CALCULATION 

1- Note down the required volume of water delivered per minute - (Assumption:45 Liter per minute)

2- Measure the inner diameter of the water supply line/ hose - ( Assumption 3/4 inch)

3-Measure the total length of  hose/ pipe  used for irrigation from pump to End cap- ( Assumption 50 Meters)

4-Measure the height of water emitter/ sprayer installed from the pump level( Assumption: 4 Meters) 

Based on the above assumptions, we can brief as follows :

(45 Liter Per minute-Size of pipe 3/4"-Length of pipe 50 Meters) 

For 3/4" pipe, the friction loss is 40 for every 100 meters. Therefore the friction loss for 50 meters will be 20

( you an also use the pipe- friction table to calculate the friction loss)

CHOOSING THE HEAD OF A PUMP

The formula is :

Friction loss (20)+Height of water emitter installed ( 4 Meters) + Pressure required (15 meters)

20+4+15=39 is the TOTAL DYNAMIC HEAD  required

 CHECK THE PUMP CURVE FOR SELECTING A PUMP WITH THE REQUIRED HEAD PRESSURE

Vertical axis of a pump curve indicates the head or pressure

Horizontal axis of a pump curve indicates how many liters per minute

Now draw a straight line from the point of your required head pressure( 39) on the vertical axis

Draw another straight line up from the point of your required liters per minute on the horizontal  axis

If the line drawn from point 39 on the vertical axis  meets the line drawn from point 40 on the horizontal axis,you have

selected the right pump to meet  your above requirement