Table Of Content

DTU Ram Pump Programme DTU PSO PUMP TEONEAL | 12 sevesse_| DTU P90 ome hydraulic ram pump ‘The F9Die a ac bodied ivdoas:o ram pamp designed mast othe itiqaton af vegelabe gardens lam sreems rinha nearby, Each pump, used contruauay day and right, can iat 0.20 1.Bhectaroe (ta 12 sees ilies yom Tritisrun ony in aaygh hour, oll oniigats half the nea, “he Pod may cf ba used Yor facow “gation, hose Isgation ava wate by Buekot Soma serapp pordgrthe'ap af tele Nes pat go ovaugh prowsire Ke rrsgaton using wate: cannons a ausonehe spzmeor The P50 canal be but ony ac nigh a evenly meters. FoF tarsi ona Ts plenre shows apis) Fapidy towing saam eves water inte 9mm or*-Dmm owe presste pst feed pipe bures im Me graurd Tho Waris lta. cancre'a or Bi ve bank Astona8Cmm oasis va tank (etloasr 3 her = Class B} crops rem ie five arnt the Fume and» smaler plastic ibe nese om tho puro othe ld organ, i posse have coveral pumos, eno" wih is oun Ave pipe, jineda a ange dlvery pp. The PSC Was designe to be cheap to Bulan & sal ‘nonsrop having ro eleerely, owe, one bt the ‘uel phen the velar vai, oortas any las . Tess shoud be made uty an lac dll 227385 pap entasion age" wansep than Pe ost othe pump, "rate ums similar othe Pa have beet it by the DTU ni gevare:cauines. tough the OTL behevasthe P90 whl aparata fr tao years. oly ove pump wal Zrmbabwe) Nes been Unf tha ong [A Digg vers'on ofthis ame, made ete unser development But take nt to vom mF pru pon ‘The nol specfcans otf btu Pop ram ump aregvon he. Sarees Yusyn qprve gp ouside rsa hy may felon wel dea einen oye, See cia peor The DTU plastic irrigation pump Most som pumps being manufactured are designed to supply water for domestic use because the low flows produced and the costs gecerally make ram pump systems unsuitable for small-scale crop irrigation. Sufficient water for 1000-1500 people, for ‘example, would only irrigate s plot of around 1 hectare! Some very large bore (12") rama ‘pumps have been built ta supply water for irrigation but the capital casts of such schemes restricts their application, In many parts of the world there is a large potential for low-lit, low-cost irigation of small garcien plots to improve yields, allow alteraative crops ta be ‘grown and increase crop security in unpredictable weather conditions. ‘Tue material the DTU selected as the only viable alternative to steel is plastic pipe. PVC 10mm (4°) diameter pipe is now widely available in many developing countries and provides the scale of flow necessary for small-scaie irrigation. DTU 110mm PVC HYDRAULIC RAM PUMP ASSEMBLY ORAWING Mark 3.2 amr tue a esse, LY sen EO aT + \ ‘Tue DTU pump hss the following specification: all major parts can be manufactured from 110mm pipe (with a snivimum of other ‘muteriais such as bolts. rubber, etc.); all parts can be manufactured using hend tools in smali rural workshops; a the system can be maintained by the user and all parts are capable of simple replacement in case of wear, damage or theft, designs have been extensively tested for performuice and endurance (including extensive field tests): pumps should be easy to mune to suit a broad range of site eonditions. Ir meets the following performamve specifications: ‘The drive head (fall of water) cun be between 1 and 3 metres. ‘The drive flow available can be between 3 and 7 litres/second. ‘The maximum delivery head 1s 12m. ‘The energy efficiency exceeds 50%. ‘At2 metres drive head, maximum delivery to 15 metres is 35,000 litres per day, adequate to inrigate % of alhectare, Setting for uniimited dive fow Delivery foe — nin Daltvary had (m) DTU PYG ram pup — Typleat performance data ‘The shaded areas on the performance data chart above indicate the normull operating range for different values of drive head. Pump designs have been developed over « number of years with increasing performance and component life, Plastic pipe is more prone to fatigue failure than steel, reducing the life of some components to two years. The current design has hea extensively tested in Zimbabwe but is sill (1993) at the proving stage of development. Manufacturing notes ‘Toe int DTU ram pump to be built sing plastic materials was sted in 1986 a3 par ofan tidergeaduaie projet twas command largely from standard PVC drain pipe tings with ‘wooden tnpulae velve, The major icteest a the use of Plastic for ram pumps stemmed from the low Dostaf mates apd the exue of manufaewre using pastc components, There was some question {initlly whether the thin PVC manera! would wihstuad the cootitue! faigue loading and simply treak under the Gre cycles, Wit the auceess of ths Fst design, research was cnatinued oa is development and the Borizooeal axis impulse wave was introduced. Since then bboatery tests and Feld tial bave sipiticunty refined the design oF the pump and produced data conceraing ict durability and pampiag limitations, Plastic ram putaye can provide «cheap an sie means of supplying water t elevations of less than LScr The vale of low produced and tse hmitadious or there pumping, beed sake them ideal for local masisfcnae and use for saa scale iigation in developing Cowie. ‘This Working Paper demails the design of tbe M3.2 pump. It lists each component and describes ny significunt feapures am considerations, Drawings of all the componeats are also mciuded slang with Some graphs showing the typical peciommance of the pump. Impulse Valve ‘The design of impulse valve on the DTU M3.2 is unique amongst curreat ram pump designs. ft aims to achieve a flow afea through tie valve equal 10, or greater than, me area oF the drive pipe whilst using the drive pipe mazerial for is construction. This yrealy simplifies the materials requiral for Pump construction and reduces ihe need for steel components The M2 imauiee vatve ‘The valve operates under conditions similar ip those that canse the aerodynamic lift ofan aircraft wing, The velocity of the water flowing over the top of the tongue and out to wisi, creames a slightly lower pressure om the top side than that underneath i. As the water accelerates. this pressize differential across the tongue increases until itis sufficiem to begin to cluse the valve. As che tangue rises the velocity over tis increased, which in em increases the pressure differential, causing the ‘valve to close faster and further increasing the velocity In this way the tongue azcelerates and closes ‘very rapidly producing the sudden deceleration of the water necestéry to raise the pressure ix the pump body to the delivery pressure “The vave design works well sing PYC materials doe ots sight leniiity. When te vave closes ‘esubssquent presure soe aruuly epee ne eesury tp seal gree ough Ge tonne {ay tot ft periecly o ce valve body. The sarae valve design has heen tied using swel pe maverial ot ws (ound oro work well aie tongoe could notesny be cootaued tote exact shupe of he Eide ofthe valve bocy and didn’t ave silent leiby vo defonm andr ihe cormal wecang Pressure. Provide tha ie ongue of 2 PVC pani is sufficiady well ost pera wl deform {era numberof days of operon nl eens reper. ‘The development of the this design from the basic concept has iken some time in using different configuranons: hole sizes. spacing, valve length and in finding a design with sufficient strength ‘withstand the continual loading. PVC is uot a material recommended for use in simations where a ‘high farigue loading is likey. its use would therefore not normally be advisabie in ram pumps where there isa bighly fluctuating load from the pressure ransienc in the pump and drive pipe. Research hhas shown that provided the delivery pressuve is kepe within recommended Limit. the pump and pipe rmaberial are sufficiently thick. and the pump weil manufarnared with 09 ponestial stress ‘concentrators. hat the normal fatigue loading expervenced is well wishin the tolerance of the material. A Working Piper's walle from me DTU deniling se researc and findings of work undertaken (on fatigue in PV Impose Valve Design and Mamutacture Notes 1)Great care is meesed in the manufarture of the holes in the valve body 1a ensure that here ‘re n0 smal cus, indentations or cracks from the initial shaping of the holes. Once the boies have beew oughly sbaped they should be carefally Gled wat they are completely smnboth to te touch and show no visual defects. This wil help prevent the formation and propagation of cracks, 2) The tongue hinge tsa potential source of rapid wear of the PVC material used both for the ‘image and the valve body. The binge is simply a bolt about which the tongue bas some ‘freedom wo move. To prevent wear of the’ the hole that goes through itis lined ‘with a piece of metal, either a small section of pipe with the correct UD or 8 specially fabricated liner made from sheet see, 3}.On pve oocasions impulse valve cracks were found running dows the valve ro the pipe axis atthe upstreamn end that was pushed into the te piece. These crac ‘caused by the valve being wedged too hard into the te pieve socket, This created a significant addidonal hoop sees at thgt end of the valve and ied to a crack propagating ‘fom some sinall imperfection in the first valve hole back to the end of the pipe. The main ‘cause of this problem was the mazthod of wedging the impulse valve into the te piece. ‘apmins. the concrete end block. [ts possible 0 prevent this type of cracking by wedging the impulse valve more careful. However this does aot provide a foal proof solution ‘and stil allows the possibility of valve failure. The simplest method of preventing this problem isto shorn the length ofthe pipe that cax fit ino the te sockar so that the double kn of he mpalse valve bors op agains the tee Before the ave pushed i too Delivery Vaive Design The delivery valve fora low cost ram punip mus sassy all ofthe folowing requirements; 1) produce gue pefimmance by: apening quskly with slow pressure diferentil across have low reanvare to ow tough ie allow Unde backflow By closing quickly Wiha sital pressure different. 2) have an acepmale working fe with any dispose rubber pars astng minimum ot mo 3) be cheap and simple o manufacture, Position ofthe Delivery Vale Laboratory tests have been carried out on a number of different rypes of defivery valve to assess their performance. These were simply designed 10 compare tbe throughput ofthe valve under a controled set of conditions. Backflow of water through the valve from the air vessel during the period af recoil ‘nad been found to be significant on tests of steel raca pumps. reducing the delivery flow by up tn 40% in the worst cases. With ideorical impulse valve seuings. the delivery bead and flows were measured for S diferent delivery vaives. The results ofthe tests are shown in the fallawing graphs. ‘The original flap type delivery valve proved to give the best performance over a widermpe of conditions with two thickaesses of nzbber io increase the rigidity of che valve, The Tubber Used in the ‘ests was Jum thick commercial sheet. One thickness of rubber gives lower performance de (0 its lower response to closure allowing more backflow ro occur. Increasing the auraber of rubbers above Zalso reduces the delivery flow as the resistance of the valve to opening ineneases and the Friction ‘throwah the valve during delivery reduces che flow. Linforruneately the quality and availabiliey of rubber sheer varies enormously around the world and iti imiporiantm be able to make use of locally available materials to guarantee access to spare part, Good quality inner tube from truck wheels is often the most available znd reliable source of rubber. iris recommended that a umber of thicknesses be used to atake the total thickness of rubhe herween 4 and Gmm. Some experimentation with the maerials available is advised. measuring perfoomunce with vmrying amounts of rubber to find an optimum and assess the robber vulnerability in teasing and stretching. M3.2 DELIVERY | Flap 2 robbers VALVE COMPARISON eee POWER Nib "OO eee = a SN Le “ Paap 6mubter ~ \ _— ae Lo ™ ; CA ™ — | j j Drive Head — 15m Stroke = 40mm Weigh =4 | | , © Delivery Head (m) M3.2 DELIVERY VALVE COMPARISON EFFICIENCY Efficiency (%) Drive Head = Sm Suoks = 4000 Weights = 4 Delivery Head (m)