Ek is ‘n boer in my hart, en die here is my god. En ek is nie bereid om my siel te verkoop aan goud en roem, so ek vind vrede in my lande hier waar hy is.

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A windpump is a windmill used for pumping water, either as a source for pumping fresh water from wells, or for draining low-lying areas of land.

windpump is a windmill used for pumping water, either as a source of fresh water from wells, or for draining low-lying areas of land. Once a common fixture on farms in semi-arid areas, windpumps are still used today where electric power is not available or too expensive. 

There are manufacturers in several developing countries now producing windpumps. The uptake of wind machines for water pumping, however, has been generally very slow even though the technology is well suited to the demand of many regions of  South Africa, Asia and Latin America.

Water pumping is one of the most basic and widespread energy needs in rural areas of the world. It has been estimated that half the world’s rural population does not have access to clean water supplies. 

The Importance of a

windpump

He causes the cloud to rise over the whole earth. He sends the lightning with the rain and releases the wind from his storehouses.

The power in the wind, Worth a thought

The wind systems that exist over the earth’s surface are a result of variations in air pressure. Windspeed data can be obtained from wind maps or from the meteorology office. Unfortunately the general availability and reliability of windspeed data is extremely poor in many regions of the world. However, significant areas of the world have mean windspeeds of above 3m/s which make the use of windpumps an economically attractive option. 

The formula used for calculating the power in the wind is shown below:

PW = ½ ρ A V3

 

PW is power in watts available in the wind (W)

ρ is the air density in kilograms per cubic meter (kg/m3)

A is the swept rotor area in square meters (m2)

V is the wind speed in meters per second (m/s)

The fact that the power is proportional to the cube of the wind speed is very significant. This can be demonstrated by pointing out that if the wind speed doubles then the power in the wind increases by a factor of eight! It is therefore worthwhile finding a site which has a relatively high mean wind speed. 

wind into watts

Although the power equation above gives us the power in the wind, the actual power that we can extract from the wind is significantly less than this figure suggests. The actual power will depend on several factors, such as the type of machine and rotor used, the sophistication of blade design, friction losses, the losses in the pump or other equipment connected to the wind machine, and there are also physical limits to the amount of power which can be extracted realistically from the wind. It can been shown theoretically that any windmill can only possibly extract a maximum of 59.3% of the power from the wind (this is known as the Betz limit). In reality, for a windpump, this figure is usually around 30% to 40% and for a large electricity producing turbine around 45% maximum (see the section on coefficient of performance below)

So, modifying the formula for ‘Power in the wind’ we can say that the power that is produced by the wind machine can be given by:

PM = ½CpρAV3

PM is power (in watts) available from the machine
Cp is the coefficient of performance of the wind machine

It is also worth bearing in mind that a wind machine will only operate at maximum efficiency for a fraction of the time it is running, due to variations in wind speed. A rough estimate of the output from a windpump can be obtained using the following equation; 

PA = 0.1 A V3


where, PA is the average power output in watts over the year V is the mean annual windspeed in m/s

Principles of wind energy conversion

There are two primary physical principles by which energy can be extracted from the wind; these are through the creation of either lift or drag force (or through a combination of the two). The difference between drag and lift is illustrated by the difference between using a spinnaker sail, which fills like a parachute and pulls a sailing boat with the wind, and a Bermuda rig, the familiar triangular sail which deflects with wind and allows a sailing boat to travel across the wind or slightly into the wind. Drag forces provide the most obvious means of propulsion, these being the forces felt by a person (or object) exposed to the wind. Lift forces are the most efficient means of propulsion but being more subtle than drag forces are not so well understood. The basic features that characterize lift and drag are:

Types and characteristics of rotors

There are two main families of wind machines: vertical axis machines and horizontal axis machines. These can in turn use either lift or drag forces to harness the wind. The horizontal axis lift device is the type most commonly used. In fact other than a few experimental machines virtually all windmills come under this category.

There are several technical parameters that are used to characterize windmill rotors. The tip speed ratio is defined as the ratio of the speed of the extremities of a windmill rotor to the speed of the free wind. Drag devices always have tip-speed ratios less than one and hence turn slowly, whereas lift devices can have high tip-speed ratios (up to 13:1) and hence turn quickly relative to the wind. The proportion of the power in the wind that the rotor can extract is termed the coefficient of performance (or power coefficient or efficiency; symbol Cp) and its variation as a function of tip-speed ratio is commonly used to characterize different types of rotor. As mentioned earlier there is an upper limit of Cp = 59.3%, although in practice real wind rotors have maximum Cp values in the range of 25%-45%. 

Solidity is usually defined as the percentage of the area of the rotor, which contains material rather than air (see Figures 1 & 2 below). High-solidity machines carry a lot of material and have coarse blade angles. They generate much higher starting torque (torque is the twisting or rotary force produced by the rotor) than low-solidity machines but are inherently less efficient than low-solidity machines. The windpump is generally of this type. Low-solidity machines tend to be used for electricity generation. High solidity machines will have a low tip-speed ratio and vice versa.

The choice of rotor is dictated largely by the characteristic of the load and hence of the end use. Some common rotor types and their characteristics are shown in Table 1 below.

He causes the cloud to rise over the whole earth. He sends the lightning with the rain and releases the wind from his storehouses.

Matching rotor and pump

When installing a windpump it is important to match the characteristics of the pump and the wind machine. A good interaction between pump and rotor is essential. The most common type of pump used for water pumping (especially for borehole water pumping) in conjunction with a windmill is the reciprocating or piston pump.

 

The piston pump tends to have a high torque requirement on starting because, when starting, the rotor has to provide enough torque to overcome the weight of the pump rods and water in the rising main – once the rotor is turning, the torque requirement decreases because of the momentum of the revolving rotor. The windspeed can then drop to about 2/3 of the start-up windspeed before the windpump will stop.

Other common pump types used for wind pumping are the progressive cavity or ‘Mono’ pump and the centrifugal pump.

Both have advantages in certain circumstances but both also tend to be expensive and less commonly used. 

Poldaw Engineering

water pump

Figure 3. illustrates a typical example of a modern multi-bladed windpump. The high solidity means high starting and running torque and low running speed which is desirable for use with the piston pump.

It is obviously important to match the water pumping demand with the available wind and hence decide upon a suitable rotor size. To calculate the demand we need to know the following data:

 

Water pumping is one of the most basic and widespread energy needs in rural areas of the world. It has been estimated that half the world’s rural population does not have access to clean water supplies. 

For water at sea level the approximate energy requirement can be calculated using the following equation:

 

E = 0.002725 x volume x head (in kilowatt-hours)

Typically pumping heads can vary between a few meters and 100m (and occasionally more), whilst the volume of water required can vary from a few cubic meters a day for domestic use to a few hundred cubic meters for irrigation.

Wind pumping with electricity

Although the multiblade windpump is by far the most common windpump in use, it is not the only option available. Another option, especially where there is a requirement for the pump to be sited remote from the wind machine, is to use an aerogenerator to provide electricity for an electric pump. Although they tend to be more expensive, they do have the advantage that the electricity can be used for other applications when not pumping and also that the electricity can be stored in batteries for use when the windspeed is insufficient for direct electricity supply.

He causes the cloud to rise over the whole earth. He sends the lightning with the rain and releases the wind from his storehouses.

References And

resources

Poldaw Windpump originally designed and Developed by Neale Consulting Engineers Ltd. (NCEL) UK, when it was introduced into South Africa. Poldaw Windpumps are intended principally for applications in developing countries.

Poldaw Windpumps are manufactured today in Mpumalanga South Africa by a Company called Poldaw Engineering situated in Eloff, Delmas.

About

Poldaw

They are a truly “appropriate technology” for rural water supply in many situations.

The Poldaw Windpumps are a range of medium sized low cost machines.

Although the multiblade windpump is by far the most common windpump in use, it is not the only option available. Another option, especially where there is a requirement for the pump to be sited remote from the wind machine, is to use an aerogenerator to provide electricity for an electric pump. Although they tend to be more expensive, they do have the advantage that the electricity can be used for other applications when not pumping and also that the electricity can be stored in batteries for use when the windspeed is insufficient for direct electricity supply.

From their experience they have identified the importance of certain design criteria which are applicable to windpumps anywhere in the world.

The Poldaw designs meet these criteria, and at the same time achieve the lowest cost possible without compromising                  robustness and reliability.

Benefits of Poldaw Windpumps

Poldaw Windpumps were designed and developed using modern engineering design know-how, achieving:

Product Description:

How much water do the Poldaws produce?   The performance of the Poldaw Windpumps depend on pumping head (i.e. total lift required) and windspeeds. The two most popular models are the 3.5m machine (the diameter of the rotor is 3.5 meters) and the 5m machine. For a moderate pumping head of 20m, in a medium wind speed of 4m/s, outputs are:

 

Poldaw 3.5 m:  21,000 liters per day

Poldaw 5.0 m:  43,000 liters per day

 

There are also smaller models, 2.2m

 

The 3.5 meter machine can pump from depths of up to 90m, whilst the 5 meter machine can pump from 140m, now extended to 200m max by means of a spring counterbalance system.

 

Are there siting or wind condition constraints?  The Poldaw can start up under load in the lightest of breezes and operates in wind speeds as low as 3 meters per second (approx. 7 mph). A simple test with an anemometer will confirm local wind speed conditions.

A range of tower heights is available, selected to suit local topography and wind conditions, for example a sheltered site may require a tall tower. If there is doubt about the suitability of a site for a windpump, Poldaw and/or its local licensees will advise.

Cost effectiveness of the Poldaw Windpump:-   The Poldaw Windpumps costs 30% less to manufacture than other similarly sized windpumps and, being made with local materials and labor, have no import duties.

 

Running costs are negligible due to no fuel and minimal straightforward maintenance.

Who manufactures Poldaw Windpumps?  The Poldaw is a modern appropriate technology windpump design, which can be made easily in any country using readily available materials with basic engineering tools and equipment.

Easy maintenance:  Poldaw Windpumps have been designed to need very little maintenance. All that is required is the greasing of bearings once a year, with a general inspection of other components.

 

Routine maintenance and pump washer replacement can easily be carried out with the tower standing. To simplify installation, and for any major borehole or windpump maintenance, the tower has been designed to hinge on two of its three feet so that the whole machine can be laid down by use of a winch.

What happens when the wind doesn’t blow?  Windpumps are suitable for any location with an average wind speed of 2.5 m/s or more and with no prolonged windless periods.

 

In such locations, on most days there is sufficient wind for the windpump to operate for at least part of the day. However, to provide against windless days, the Poldaw Windpump is usually installed with a water tank or reservoir. Generally a tank with three days of water supply is adequate.

What happens when there is a storm?  The Poldaw Windpump is designed, through the use of a hinged tail vane, to turn (or “furl”) automatically to minimize the area facing into the wind. By means of this mechanism it will withstand storms of up to 180 kilometers per hour (= 50 m/s, 110 miles/hr.)

 

They are a truly “appropriate technology” for rural water supply in many situations.

Technical Details

Traditional Concept + Modern Design

Technical Data

Design for low cost and high reliability:-The Poldaw Windpump has a very simple but elegant design. Most successful small windpumps with a deep well capability use a speed reduction gearbox to avoid dynamic problems in the pump and pump rods. However, gearboxes are expensive, difficult to manufacture, and require good lubrication and therefore high maintenance. The Poldaw transmission uses a simple crank and rocker arrangement, with a specially developed rotor which develops high torque at low speed. The elimination of the gearbox thus reduces the cost and improves reliability.

Lubrication only once a year:   For the continuously moving joints, self-aligning ball bearing units are used, which are universally available, very reliable and only require greasing about once a year.

Pumps and pipelines:  The pump itself consists of a simple cylinder incorporating a non-return valve at the bottom and another in the piston. The pumps vary in diameter, depending on the required pumping head. For pumping a long distance to a remote tank, an air chamber may be incorporated. This evens out the pulsing water flow from the pump and thus reduces the stresses on the windpump mechanism.

Automatic Storm Protection:  Poldaw Windpumps protect themselves from damage in very strong winds, by turning the rotor edge-on to the wind. This takes place automatically in wind speeds of over 50 km/h, and enables the windpump to withstand storms of up to 180 km/h (50 m/s). When the wind drops again the rotor resumes its normal position facing the wind.

 

PUMPING PERFORMANCE   The output capacities for the range of possible Poldaw Windpump applications can be seen in the following tables:

They are a truly “appropriate technology” for rural water supply in many situations.

Easy and safe installation procedures:  Installation can be performed by two or three people and takes less than three days under normal circumstances.

Day 1. The foundations are dug and filled with concrete, using a template to position the steel anchor points.

Day 2. The windpump is completely assembled with the tower lying horizontally supported on a trestle.

Day 3. Using a cable winch and gin-pole, the windpump is raised to its vertical position, as shown below. The pump and pipework etc. are assembled and connected.

Poldaw Windmill

Installation

Traditional Concept + Modern Design

Why Windpumps?

Handpumps   These are preferred for relatively modest water needs but are usually limited to depths of up to about 50 meters. The Poldaw Windpumps can pump from as much as 140m.

 

Electric / diesel pumps  Either requiring a mains supply (not always available in remote locations) or a diesel engine with a regular fuel supply, these pumps have high servicing and maintenance overheads. Poldaw Windpumps run on free energy and only require simple annual preventative maintenance. They do not require operator attention on a day-to-day basis.

 

Solar pumps  These can be an attractive option in good sunlight locations but they are an expensive investment (usually imported) and also are prone to damage and theft. Poldaw Windpumps can be manufactured locally with local materials and are robust and difficult to steal!

Poldaw Windpumps are a practical solution and will operate in winds as light as 2.5 to 3 meters per second (approx. 5 to 7 mph).  A reasonable sized storage tank ensures water is available even on windless days. (Other powered pumping methods also usually employ storage tanks).

The original Climax windpump was manufactured by Thomas and Son of Worcester in England. After the second world war Stewards and Lloyds were allowed to, under license, manufacture the Climax at their Tosa works in Vereeniging. The first were manufactured in 1942 but after some modifications the 1944 model were made. Further modifications were made to the windvane to improve efficiency and the 1957 model saw the light. This model has S & L on the one side of the vane and Climax with the C partly encircling the rest of the name.. The lettering on the windvane changed again in 1969 with S&L within a white disk on the one side and Steward and Lloyds on the other.

Stewards and Lloyds also built a number 18 windpump. It is a direct-acting windpump. It can be distinguished by the wheel construction that has three concentric rims where the other models only have two. The windvane was orange. These models are not manufactured anymore.

Steward's and Lloyd's

Climax

 In 1985 Dorbyl Limited bought Stewards and Lloyds and the windmill devision was moved to Duncanville in Vereeniging in 1989. The later models have a wind vane with white lettering on an orange background. The date of manufacture of the specific windpump is stamped on the oilbath.

As from 1997 the factory was moved and the Climax windpumps are now manufactured in Bloemfontein.

Our Director Pieter Kruger and his Father are known in the Mpumalanga region as “Piet Pomp”, install, repair and maintained all kinds of Wind pumps for 50 years as a family. Pieter Kruger works with Wind pumps now for 28 years.

Turbex

 The Turbex rotor windpump was designed and manufactured in Harrismith in South Africa. Full details about this pump can be found at www.turbex.co.za.

Turbex rotor windpump photographed on the D826 near Sossosvlei in Namibia.
Turbex photographed in the Langkloof.
Turbex on farm Klipheuwels between Vosburg and Pampoenkraal.
Turbex on the N1 near the Vaalrivier bridge
Turbex photographed near Van Zyl's Rus.
Turbex photographed in Namibia.
Turbex near Coligny, North West province.
Turbex in the Tankwa National Park.

Gilmer

Mr Jean Gillmer of the farm Droekloof between Hanover and Middelburg designed and built the Gilmer windpump.

Gilmer windpump photographed near Gariepdam.
Gilmer langs Gariep dam op Bethulie pad.
Gilmer windpomp op Soebatsfontein naby Hondeklipbaai.
Gilmer op plaas Middelka naby Marydale.

Vetsak

Vetsak windpump photographed on farm Brandfontein district Loxton.
Gilmer langs Gariep dam op Bethulie pad.

Ek is ‘n boer in my hart, en die here is my god. En ek is nie bereid om my siel te verkoop aan goud en roem, so ek vind vrede in my lande hier waar hy is.