The Blair Pump An update

Transcription

1 The Blair Pump An update Peter Morgan A publication by Aquamor-Zimbabwe. February 2014

2 Introduction The Blair Pump is a simple direct action shallow well hand pump. It was first designed in 1976 and developed further at the Blair Research Laboratory in Harare, (formerly Salisbury). The earlier models were heavy duty using 90mm PVC pipe as a cylinder. The maximum lift of these earlier models was 6m. Later in the early 1980 s a lighter duty model was designed at the laboratory for family use. Like the earlier model it was built with off the shelf fittings, which could be put together by an artisan or in the home. This later model used 40mm PVC as a cylinder. The maximum pipe length for these later models was 12m. A description of its construction was introduced into the school curriculum at the time. A mass produced version was also manufactured in Zimbabwe in the early 1980 s, using 50mm PVC pipe as a cylinder. These various models were described in detail in Rural Water Supplies and Sanitation. Peter Morgan, MACMILLAN. (the book is now out of print). This pump used an unusual method of raising water, by compressing water between two non-return valves, each fitted to the lower end of an inner and outer pipe. The outer pipe serving as a cylinder with a foot valve mounted at its base. The inner pipe fitted with a piston/non return valve at its base served as a piston, pushrod and spout. Water was delivered through the spout at the surface. Spouts could use tee pieces, but the mass produced model used spout which looked like a walking stick handle. The Blair Pump was promoted in Zimbabwe s Rural Water Supply program by the Ministry of Health and Child Welfare in the early 1980 s, to protect and improve the quality of water delivered from shallow wells. It was later replaced by the Bucket Pump, another design of the Blair Research Laboratory, which was easier to maintain, since the spare parts were not specialised. Eventually the MOHCW promoted the concept of the Upgraded Family Well a 2

3 method of improving well safety and the quality of water delivered from well-established family owned well, which are very common in Zimbabwe. The basic concept relied on improving the head works of the well and using a windlass system for raising water. This later method remains officially endorsed by the GOZ. It was an early example of the concept of Self Supply where families are responsible for dealing with their own water supply, if geological and hydrological factors are favourable. The development of both Blair and Bucket Pumps was paralleled by the development of improved well digging techniques and also hand operated tube-well drilling techniques. The Bucket Pump was specifically designed to match the small diameter tube-wells, the bucket being tubular shaped with a non-return valve fitted at the base (see other Aquamor publications). These tube-wells were first drilled by simple hand-made devices, but later by the Vonder Rig, a robust and effective hand operated drilling rig designed by the late Erwin von Elling of V&W Engineering Harare. In more recent times, when there are signs that water tables may be rising, simpler hand-made drilling rigs are being tried again, especially for use in areas where the ground water is shallow and the soil softer or sandy like. Such conditions may also revive an interest in the use of the Blair and Bucket pumps by families. This manual deals with the Blair Pump, and how after 30 years the concept still has potential for further development. Peter Morgan Harare. February

4 The Blair Pump - how it works The Blair Pump was one of many hand pumps analysed by the World Bank in a work (The Hand Pump Option) published in The report revealed that the principle of Blair Pump had been used and adapted in several countries including Malawi, Papua New Guinea and the Philippines. In Zimbabwe it has been used as a hand-made product, both heavy and light duty and also a mass produced product. Hand-made models Blair Pump how it works It is interesting to look again at Blair Pumps which were constructed 30 years ago, and have been kept in storage, and compare them with pumps which can be made today with more modern fittings. Two light duty models have been stored in the writers roof for 30 years and are described here, followed by the more recent construction of a light duty pump designed for family use. Two variants of the family model exist, one with a PVC handle and spout and one with a galvanised steel handle and spout. The latter is advocated for use at the family level. The light duty Blair Pump with PVC handle has also been adapted for lifting urine from underground tanks built as part of the schools eco-san project in Epworth, Zimbabwe. 4

5 Hand-made Blair Pumps These were made as both heavy and light duty pumps using 90mm or 40mm PVC as the cylinder pipe and galvanised steel or PVC as the pushrod pipe. Left: Lighter duty version. Right heavier duty version 5

6 Commercially made Blair Pumps These were manufactures by Prodorite (Zimbabwe) and pumps can still be made to order. The pump was promoted by the MOH in the early 1980 s and large numbers were put to use.. The Blair Pump had a walking stick handle which served as a spout. Parts of the commercial pump The concept of the Blair Pump was taught at schools and also staff of the Ministry of Health, including nurses 6

7 The early hand-made family Blair Pumps The first hand family Blair Pumps were smaller and much cheaper copies of the more robust heavy duty model. Two antiques, fabricated by hand 30 years ago were taken from the archives and photographed in detail. They used 40mm PVC as cylinder pipes and 25mm PVC as pushrod pipes. Both had foot-valves which could be extracted through the cylinder pipe. Two hand-made family Blair Pumps made in There were slight variations in which the piston and handle were made. The tee handle was easier to make from standard off-the-shelf fittings. 25mm class 26 PVC pipe was used for the pushrod/handle and 40mm class 16 PVC pipe for the cylinder. The walking stick handle was made by heating a pipe filled with sand and bending. 7

8 Piston valves type 1. 25mm standard PVC fittings were used with a brass washer and small rubber ball. A small brass or galvanised rod was used to retain the ball valve. Piston valve type 2 with glass marble The piston was made longer to reduce loss of water between the piston and cylinder wall. PVC parts could be resized to fit within the cylinder pipe. A glass marble sitting on a washer was also used as a valve. The washer was best made of brass. The ball was retained by a small brass or galvanised iron rod. 8

9 The foot-valve Foot-valves on these early pumps were extractable and could be withdrawn through the cylinder. The lower anchor for the foot valve is secured by a small screw. The valve push fits into the anchor with 25mm PVC pipe A rubber ball sitting on a washer is used as a valve. The valve retained by a small galvanised steel rod. The base of the cylinder was fitted with a stainless steel screen. Glass marbles were also used and make excellent valves. 9

10 Mounting on the well These family Blair Pumps also used galvanised steel sockets mounted in concrete blocks which were mounted themselves on to the concrete slab covering the well or tube-well. Left: The original 30 year old demonstration pump in use. Also the up to date 2014 hand-made model described in this manual, demonstrated on the same site. 10

11 Assembling a new family Blair Pump Since 1983 some of the standard PVC fitting available in Zimbabwe have changed. The following account describes the construction of a family Blair Pump in The same principles have been used throughout. Whilst PVC can be used above the ground, steel is the preferred option. A steel handle and spout is shown in this demonstration. The following components are required to fabricate a family light duty Blair Pump. Components 1. Steel components cost USD 40mm to 25mm reducing bush (1) mm to 32mm reducing socket (1) mm tee (1) mm barrel nipple (4) mm socket (1) mm elbow (1) m 20mm galvanised steel pipe 6.50 Small piece 3mm galvanised wire 0.10 Brass or galvanised washers (2) PVC components PVC 50mm thread to 50mm PVC pipe (1) mm PVC socket (2) including cylinder joint mm PVC socket (4) including pushrod joint + extra mm PVC pipe to thread (5) including 1 extra mm class 10 $2.00/m for 6m mm class 10 $1.50?m for 6m Adhesives etc Packet hard setting adhesive putty (small) 3.50 Packet hard setting liquid epoxy adhesive 7.00 Marbles 10c 0.20 TOTAL (approx.)

12 Photos of components used in light duty Blair Pump The basic components (PVC and steel) available in hardware shops 40mm PVC class 10 as a cylinder, 25mm class 10 as a pushrod Left: The main steel socket which is embedded in concrete and PVC thread to pipe adaptors (thread to 50mm and 40mm PVC socket). Right: the components of the steel handle, spout and upper push-rod) Components of the piston valve (left) and foot-valve (extractable type) and anchor (right) 12

13 Assembling the piston valve The piston valve is made up of 5 components (25mm PVC socket, length of 125mm PVC pipe 36mm, marble (d=16mm), Washer (ID 13mm. OD 24mm) and 25mm PVC pipe to thread adaptor. The washer is inserted into the plain end of the pipe to tread adaptor and bonded with a fast setting epoxy adhesive ( Pratleys white was used in this case). The marble is then placed inside the valve chamber and the 25mm PVC pipe added. Then the 25mm socket is added. The washer is inserted into the 25mm PVC to thread adaptor. It is best bonded in position with epoxy adhesive. The marble is placed inside. A short length (36mm ) of PVC is added to the adaptor (using solvent cement or epoxy adhesive as a bonding agent). The 25mm PVC connector (socket) is then added and bonded to the pipe A 4mm hole is drilled through the pipes at the point shown and a short length of 4mm galvanised rod is pushed through (tight fit). This retains the marble. 13

14 Assembling the foot-valve Two types of foot-valve arrangements are possible. Type 1 is extractable through the cylinder pipe. Type 2 is attached to the end of the cylinder pipe. The extractable type is preferred. Extractable foot-valve This is made up of 2 X 25mm PVC pipe to thread adaptors, 2 X 36mm lengths of 25mm PVC pipe, a 25mm PVC socket, a marble (d=16mm) and a washer (ID 13mm. OD 24mm). One of the 25mm PVC pipe to thread adaptors serves as an anchor which is bonded into the end of the cylinder pipe. The components of the foot-valve and anchor. The washer is best made of brass or galvanised steel. The washer is bonded securely into the plain side of the 25mm PVC pipe to thread adaptor. 14

15 The short length of 25mm PVC pipe is bonded into adaptor. Then the 25mm PVC connector is fitted. A short length of 4mm galvanised wire is prepared. A 4mm hole is drilled through the assembly at the point shown. The marble is added and the wire (pin) is pushed through the hole. This secures the marble (which acts as the valve) in place. 15

16 Filing components The foot-valve and foot-valve anchor are shown here. Parts of the adaptors of each must be filed down so they will enter the cylinder pipe. Left: The foot-valve and the anchor with threaded foot-valve puller (a 20mm steel barrel nipple). Right: The foot valve is extracted by attaching the foot-valve puller to the lower part of the piston valve and screwing it into the foot valve. The foot-valve anchor is coated with epoxy and tapped into the base of the cylinder pipe. A water-tight seal is made by adding a little extra epoxy. 16

17 Adding a stainless steel screen It is a wise to add a stainless steel screen to the base of the cylinder pipe. This will exclude grit and other materials from entering the valves The alternative foot-valve and anchor This version of the foot-valve pushes into an anchor which is bonded to the base of the cylinder pipe, and is added from the outside of the pipe. This unit is also made up of 2 X 25mm PVC pipe to thread adaptors, 2 X 36mm lengths of 25mm PVC pipe, a 25mm PVC socket, a marble (d=16mm) and a washer (ID 13mm. OD 24mm). One of the 25mm PVC pipe to thread adaptors serves as an anchor which is bonded into the lower part of the cylinder pipe. The parts are fitted together as previously described. The parts of the non-extractable foot-valve A 25mm PVC pipe to thread adaptor is pushed and bonded into the base of the cylinder pipe. An extra length of (36mm) 25mm pipe is bonded to the footvalve arrangement. This will be pushed and pinned into the foot valve anchor. 17

18 The steel to PVC joints The large steel reducing socket is embedded in a strong concrete anchor (see later). The 40mm PVC cylinder pipe is bonded to a 40mm PVC socket which is itself bonded within a 50mm PVC pipe to thread adaptor. This adaptor is threaded into the steel reducing socket The joint between steel and PVC pushrods is made with a single adaptor. Assembly of push-rod The steel pipe of the push-rod is 1m long. The various part of the steel handle/pushrod are assembled as in the photo. 18

19 The rear barrel nipple must be filled with material to stop water passing through it. An epoxy putty can be used or a very strong sand cement mix left to harden and cure. All the components are tightened up together The steel push-rod moves up and down within the steel bush threaded into the steel socket, which is embedded in very strong concrete. These parts will eventually wear and can be replaced. The various parts of the pump can be replaced when worn. When the pump is made by a do-it-yourself member of the family, he or she may make extra parts like valves to be kept for use, when the originals have worn out. In a family setting this may take some time. Head-works The Blair Pump works best when mounted over a strong head-works made of bricks and cement, with a good water run-off which allows waste water to drain away from the well head. The foot valve should rise at least 300mm above the base of the well. 19

20 Final assembly Suitable lengths of 40mm and 25mm PVC pipe are cut to suit the installation. This will normally be up to 6m length. The upper PVC adaptors and the cylinder pipe are bonded together. The PVC push rod pipe is bonded to the piston. The upper steel push rod is bonded through the adaptor to the PVC push rod. The PVC adaptor is filed down to fit within the 40mm pipe.. The foot-valve (if non-extractable) is pushed and pinned into the anchor. Note stainless steel screen on foot-valve. All upper PVC pipes are bonded together. 20

21 Adjusting pipe lengths The pipe lengths (pushrod and cylinder pipe) must be adjusted and cut so that the two valves (piston and foot-valve) come close to one another but do not touch when the push rod is in its lowest position. Foot-valve extraction. This is particularly important when the extractable foot valve system is used. The two valves should not meet when the pump is being used to pump water. However the two valves should come to within 2cm of each other when the pushrod is at its lowest. When the foot-valve extractor (20mm barrel nipple) is screwed into the piston valve, and lowered down the cylinder pipe, it should be able to engage with the thread in the foot valve. The push-rod is rotated in a clock wise direction and the lower end of the barrel nipple screws into the foot-valve. It can then be pulled out, and the foot valve brought to the surface for inspection. When the foot-valve is fitted back, the barrel nipple is screwed by hand more tightly on the piston and more loosely on the foot-valve. The valves are sent down the cylinder pipe, the foot-valve pushed home in the anchor, and the push-rod turned anti-clockwise and realised from the foot-valve. The push rod is then brought to the surface and the barrel nipple taken off. The pump can then be fitted together for normal operation. The push-rod length should be adjusted so that the piston valve lies about 2 cm above the foot-valve. 21

22 The concrete head block The concrete head block is cast in very strong concrete around the large steel reducing socket. A mix of 1 part PC15 cement and 3 parts sharp clean river sand is used. The block is reinforced by steel wires within. After a few days curing the block is transferred to the well head. In this case the well head designed for the bucket pump has been extended to accommodate the oblong shape of the Blair Pump head block. Overflow hole A small hole is drilled in the upper part of the cylinder pipe to allow any water that rises very high in the cylinder pipe (above the piston) to run back into the tube-well. Overflow hole 22

23 Fitting the pump to the well or tube-well The cylinder pipe is screwed tightly into the steel socket normally by lowering the pipe down the well first and then attaching the pipe when the block is held up. Then the pushrod pipe is lowered down the cylinder pipe and handle guide screwed into position. The pump is ready to use. The pushrod is moved up and down to lift the water. 23

24 Use and maintenance The Blair pump as described here should lift water easily from 6m and up to 12m with a reduced output. The system used by the Blair Pump does not use tightly fitting seals and in fact the piston is leaky against the cylinder wall. If the handle is lowered slowly no water will pass up the push-rod. Water will be forced up the push-rod when the handle is pushed down more quickly. The valves can be inspected easily if the volume of water delivered is reduced. Anything stuck in the valves can be removed. The pump become less efficient as the depth of water becomes greater. The pump is not designed for heavy duty use, although mass produced Blair Pumps were used in heavy duty settings for some years in Epworth, near Harare. However, eventually they became worn out. Some were rehabilitated. A hose pipe can be fitted to the spout of the pump for watering vegetables nearby in the garden. This is because a high pressure builds up in the pushrod when it is pushed down smartly. The Blair Pump principle can be used in several other applications like lifting paraffin and other liquids. When the pump is worn out build another! One of the first Blair Pumps to be put to use at Henderson Research Station north of Harare 24