RP-01638

More documents

Recommendations

Info

kPascal), respectively. In the fatigue test, the mechanical properties of PVC were considerably influenced by the temperature rise that was induced by repeated loadings. During field operation, however, the PVC piston is not subjected to continuous repeated loading as simulated by the servo-pulsator. The leakage test was carried out by completely filling the riser pipe with water and allowing it to leak through the foot valve for 1 day. Test results indicated that there was no water leakage by the modified foot valve for a water head of 5.00 m (16.4 feet). Both rubber and plastic seals were tested and the same results were obtained. The variation of strength with curing time for joints in 3-inch (7.5-cm) and 3/4-inch (2-cm) PVC pipes was also tested. The tensile strength of 3-inch (7.5-cm) joints reached over 120 kglcm2 after curing for 15 minutes, which can be regarded as the initial setting time of the solvent cement. During laboratory tests, it is impossible to simulate the actual field conditions to which the handpumps will be exposed, especially using the head simulation system. Other relevant factors such as the quality of the water in the wells, the rate of pumping or speed of the piston, the direction of the force exerted on the pump rod, and the condition of the above-ground components must also be taken into account. Therefore, the Waterloo piston and foot valves were monitored under field conditions. Field Testing The wells that were selected for field testing of the Waterloo pump were used daily by the villagers in the community. Normally, the selected well was equipped with either a DMR or ARD handpump and only the below-ground components (cylinder, piston, and foot valve) were replaced by the Waterloo components. If the replaced components did not perform as well as the old ones, or the pump did not function normally due to the replacement, the villagers had to find a new source of water and complained. It was, therefore, important for the working team to ensure that the components that were installed in the well functioned properly. Hence, the following modifications were made to the PVC components, based on the laboratory tests, before the pumps were installed in the field. Modifications PVC cylinder The cylinder suggested by the University of Waterloo was ordinary PVC pipe that could be obtained in the local market. When the PVC cylinder was installed for testing in the laboratory, failure occurred at the joint between the steel cap and the PVC cylinder. One solution was to increase the thickness of the PVC cylinder, but it was found that the new cylinder was too costly. The solution that was adopted incorporated a steel casing with a PVC lining. Figure 5 shows the details of the modified 3-inch (7.5-cm) diameter cylinder together with its steel cap. The steel casing strengthens the upper and lower joints and the PVC lining is required to reduce the wear of the polyethylene piston rings. PVC piston The details of the original piston are shown in Fig. 1. However, problems were encountered with breakage of the top and bottom ribs of the piston, which are the weakest parts of the piston. Failure was due mainly to the ribs hitting the wall of the cylinder repeatedly when the pump rod moved eccentrically. To prevent this, the thickness of the top and bottom ribs was doubled from 1/4 inch (6 mm) to 1/2 inch (12 mm). The details of the modified piston are shown in Fig. 6. Foot valve The foot-valve assembly of the Waterloo handpump is shown in Fig. 1. This foot valve was originally attached to the cylinder wall with a polyethylene adapter that sealed tightly against the cylinder wall. However, because the inner surface of the PVC cylinder was not perfectly round and smooth, water leakage occurred at the foot valve. Another problem was that sand particles often became trapped between the PVC plate valve and the upper face of the piston, resulting in additional water leakage. The first attempt to solve this problem was to replace the polyethylene adapter with drilled stainless-steel plates, place a compression spring on top of the plate valve, and glue a thin piece of rubber to the PVC plate. One problem that remained after the first modification was that sand particles trapped inside the grooved portion of the piston caused wear. To solve this, the idea of using 26
0 4 A B OF inch 1 cm 4 10 01 1 inch T cm 3 t i 1 8 Fig. 5. Modified 3-inch (7.5-cm) diameter cylinder (A) and steel cap (B): (1) steel cap; (2) rubber O-ring; (3) steel casing; (4) PVC living; and (5) threaded section. (Total height of cylinder is 27 inches (68.6 cm).) the foot valve as a spare piston was eliminated. In the second modification, the contact area between the PVC plate valve and the stainless steel plate was kept to a minimum by means of two small ridges. This foot valve performed satisfactorily in the field. To reduce the production cost, however, a third modification was made by eliminating the compression spring and changing the PVC plate valve to a 1/4-inch (6-mm) solid rubber plate. The moving distance of the rubber Fig. 6. (A) Top and (B) side views of modified piston of Waterloo handpump; (1) 7/16-inch (1.11-cm) holes; and (2) PVC piston ring. plate valve was kept at 1/4 inch (6 mm). The third modification of the foot valve is shown in Fig. 7. In total, 54 wells in three regions used this type of foot valve. Site selection and installation of PVC pumps The sites of the field tests were in central, northeastern, and northern Thailand. The 27
Page 1 and 2: ARCHIV SHARP no. 1
Page 3 and 4: IDRC-204e Village Handpump Technolo
Page 5 and 6: Contents Preface ..................
Page 7 and 8: Preface Many factors are involved i
Page 9 and 10: Introduction The precise links betw
Page 11 and 12: The primary objectives of these stu
Page 13 and 14: Sri Lanka Pathirana Dharmadasa, lJp
Page 15 and 16: m O C O x 00 N .,y D+ O G+ CL C n Q
Page 17 and 18: 13 8 -6 7 9 10 A B C Fig. 4. (A) LI
Page 19 and 20: in the village can easily make a ne
Page 21 and 22: Table 2. Overview of performance da
Page 23 and 24: Thailand Pichai Nimityongskul and P
Page 25 and 26: L -' 0 inch 3 cm 8 A B Fig. 1. (A)
Page 27: The tensile strength of the PVC pip
Page 31 and 32: water per 10-cm stroke, changes in
Page 33 and 34: Fig. 11. Below-ground components of
Page 35 and 36: Philippines Antonio Bravo This repo
Page 37 and 38: 2 Fig. 3. Modified version of above
Page 39 and 40: At a standard frequency of about 40
Page 41 and 42: Malaysia Goh Sing Yau The populatio
Page 43 and 44: AP. AP (FU + FD) (WW1 + WW2 + BP +
Page 45 and 46: Optimum Design It is difficult to s
Page 47 and 48: 10 4 1 A B Fig. 6. (A) Piston assem
Page 49 and 50: made from a 0.5-inch (1.27-cm) thic
Page 51 and 52: PK 006S2 312181 717181 60 1019181 0
Page 53 and 54: was found only in: (1) the top wood
Page 55 and 56: Overview of Technical Performance G
Page 57 and 58: Ln Country and model Pedestal Table
Page 59 and 60: Economic Analysis and Potential Mar
Page 61 and 62: program is being curtailed by the l
Page 63 and 64: cylinder: PVC is one-third the cost
Page 65 and 66: about 50% of the cost of the existi
Page 67 and 68: Table 7. Summary of important handp
Page 69 and 70: Conclusions In an era of rapid deve
Page 71 and 72: Malaya proposes to address this que
Page 73 and 74: Participants ZAINUDDIN ARSHAD, Mini

RP-01638

Create successful ePaper yourself

Delete template?

Save as template?