1. Pumps and Pumping in Irrigation applications
Basic Pump Theory
John Starke: Irri – Gator Products

2. What do Pumps pump? Slurry - Liquids - Gases - etc
oils
petroleum
water
fertiliser
liquid foods
sewerage
air
etc-etc

3. What type of pumps are there?
Centrifugal – single or multi stage
Positive displacement
Rotary
Peristaltic
Axial flow
Turbine
Vacuum
Piston
etc-etc

4. Pumps Commonly found in Irrigation
Centrifugal = used for pumping water
Positive displacement rubber screw (Mono) =
lower volume high pressure = pumping water
Piston type very low volume – precise =
fertiliser injection
Turbine = pumping water
Submersible – multistage – low to med volume + higher pressures = borehole
Submersible – single stage – high volume + low pressure = dewatering

5. Concentrate on Centrifugal Pumps for pumping Irrigation water
Concentrate on Centrifugal Pumps for pumping Irrigation water. What is a Centrifuge or Centrifugal force?

6. A Centrifuge is: a piece of equipment - generally driven by a motor -
that puts an object in
rotation around a fixed axis
applying a force -
perpendicular to the axis.

7. Centrifugal & Centripetal Forces

8. Centrifugal Pumps
A centrifugal pump is one of the simplest types of pump that uses centrifugal force to move fluid into a pipe.
The basic purpose of the pump is to convert energy of an electric motor , or engine into velocity or kinetic energy and then into pressure of a fluid that is being pumped.
Centrifugal pumps are the most commonly used pump and their operating cost is low compared to other pumps.
They are reputed for high reliability and ensure smooth operation.

9. Centrifugal Pump Delivery Flange Backing Plate Suction Flange
Gland Packing
Bearings
Shaft
Impeller
Volute Casing
Pedestal

10. Pump Terminology
Duty Point = a certain flow of water at a certain pressure to fulfil the system requirement – constant or varying
Pump Efficiency = how effectively the pump converts the input energy into water pressure
Rotational Speed = Speed at which the Impeller turns
Positive Suction = The water flows into pump on its own e.g. below dam wall

11. Pump Terminology
Negative Suction = The pump has to “lift” the water from a source lower than itself e.g. river
NPSH = refers to the maximum “lift” capability a pump has to extract water from a source lower than itself
Cavitation = Noise in the Volute Casing of a Pump due to the presence of undesirable air particles imploding

12. Pump Identification & Pump Curves
Pump Manufacturer – e.g. KSB; Rapid Allweiller; Grundfos
Pump Type - Single Stage /250; 80/40; 150/315 etc
Multistage /40 – 2 stage; WKLN 65/4 etc
Impeller Size – e.g. 250mm; 185mm
Motor Size – kilowatts or horsepower
Speed of Motor – 2 / 4 Pole or 29?? / 14?? RPM
Efficiency of motor – ?
Power factor of motor – cos ?

13. Typical Motor Identification Plate

14. Typical Pump Identification Plate

15. What is a Pump Curve?
This is the characteristics of the pump when operating at a specific speed and giving the following info:
Pressure / Head Developed
Flow rate of liquid
Power Duty point and Non overload
NPSH required
Efficiency of pump

16. 65 / 250 Centrifugal Pump 82m Head in Metres Flow rate in m³ per hour
120m^3/hour

17. 80
120
37kW Power
17kW Power

18. 82 meters head
71% efficiency
Nett pump suction head required is 4,6m
Motor size required for non overload is 45 kW
120 m^3/hr

19. Laws of Affinity They are as follows:
The affinity laws express the mathematical
relationship between the several variables
involved in pump performance.
They apply to all types of centrifugal and
axial flow pumps.
They are as follows:

20. Volume Capacity
The volume capacity of a centrifugal pump can be expressed as:
q = (n1 / n2) x (d1 / d2)        
Where:
q = volume flow capacity (m³ / hour)
n = wheel velocity - revolution per minute - (rpm)
d = wheel diameter – (mm)

21. Head or Pressure
The head or pressure of a centrifugal pump can be expressed as:
h = (n1 / n2)² x (d1 / d2)²       
Where:
h = head or pressure  (metres)

22. Power The power consumption of a centrifugal pump can be expressed as:
P = (n1 / n2)³ x (d1 / d2)³       
Where:
P = power (kilowatt)

23. Changing the Impeller Speed
If the Impeller diameter is constant - change in Impeller speed can simplify the affinity laws to:
Volume Capacity
q1 / q2 = (n1 / n2)
        
Head or Pressure
dp1 / dp2 = (n1 / n2)²
          
Power
p1 / p2 = (n1 / n2)³        

25. If the speed of a pump is increased with 10% then:
the volume flow increases with 10%
the head increases with 21%
the power increases with 33 %
If we want to increase the volume of an existing system with 10% we have to increase the power by 33%.

26. How NOT to do it !!

27. How many of these do we see ? !!

28. Pump House or Store Room?
Time for an Upgrade ??!!

29. Rather do THIS !!!

30. Or This !

31. Sell some of these!!!!

32. Thanks