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Hydraulic Ram Pumps for Irrigation in Northern Thailand
Available online at www.sciencedirect.com
ScienceDirect Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
1st International Conference on Asian Highland Natural Resources Management, AsiaHiLand 2015
Hydraulic ram pumps for irrigation in Northern Thailand Matthias Inthachota, Suchard Saehaengb, Johannes F. J. Maxa, Johannes Müllerc, Wolfram Spreerb, c, *1 a
Department of Soil Science and Plant Nutrition, Center of Applied Biology, Hochschule Geisenheim University, Geisenheim, Germany b Faculty of Agriculture, Chiang Mai University, Chiang Mai, Thailand c Institute of Agricultural Engineering, University of Hohenheim, Stuttgart, Germany
ABSTACT First constructed two and a half centuries ago, the hydraulic ram is one of the oldest mechanical devices for water lifting. The first application utilised the principle for the water supply of a brewery. In this set up a water valve had to be manually closed. Very soon upgrades for an automatic operation of the device were adapted. With technological progress also the ram was improved, but got superseded by electric and fuel powered pumps. Today the ram constitutes a reliable and low-maintenance, sustainable alternative to motor-driven pumps. The hydraulic ram uses the kinetic energy of water flowing in a driver pipe to pump up about 10% of it to a higher elevation. Thereby, no external energy input is needed. As a lot of studies had been carried out constructing hydraulic rams with self built valves and for high water supply, the aim of this investigation was to construct a reliable and low-cost ram, made of locally available off-the-shelf parts. Different valves were tested in the lab under varying elevations of the water column in the driver pipe. The pumping pressure and water flow in the supply pipe were recorded for determining the ram's efficiency. An off-the-shelf clap check valve proved mosrt reliable with an acceptable efficiency of over 30%. One unit of a hydraulic ram was installed at a foothill location at Ban Ha, Samoeng District, Chiang Mai Province, and connected to an automatic low pressure irrigation system to irrigate a small plot of coffee trees. Soil moisture was monitored. The hydraulic ram operated maintenance free and fully automatic over six weeks, supplying the field sufficient quantities of water during this period at a pumping efficiency of 44%.
© Authors. Published Published by by Elsevier ElsevierB.V. B.V. This is an open access article under the CC BY-NC-ND license © 2015 2015 The The Authors. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University Keywords: Hydraulic ram; hydram; water lifting, gravity pump
1* Corresponding author. E-mail address: [email protected]
2210-7843 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University doi:10.1016/j.aaspro.2015.08.015
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Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
1. Introduction Nomenclature H h Q q
supply head delivery head supply flow delivery flow
Although the price of oil is decreasing recently, it is to expect that in future energy costs will tend to increase. Many farmers are dependent on fuel or electrical power for pumping water to their fields. An escape from this dependency could be provided by usage of self-powering water lifting devices. Such a device is the hydraulic ram, in short also referred to as hydram. A hydram utilises the power of falling water for pumping part of that water to a higher elevation than the origin. The hydraulic ram therefore utilises the waterhammer phenomenon. The waterhammer is a pressure surge caused by the inertia of piped moving water. Inside the pipes, water can be seen as a column. If water inside a pipework is allowed to flow out of an outlet which is closed suddenly, the water column cannot halt its movement instantly. It will go on flowing towards the outlet, where thereby pressure builds up. This pressure is then reflected at the closed outlet and will travel as pressure wave backwards the pipework, where it can give severe damage if not neutralised (Tacke 1988, Chi and Diemer 2002). In the hydraulic ram this effect is provoked intentionally, and the pressure wave is utilised to force water upwards. The ram consists of an impulse valve provoking the waterhammer, and a delivery valve that allows the pressure wave to pass through and prevents backflow of the pumped water. A typical setup of a hydram and its setup in the field is shown in Fig. 1.
Fig. 1. Typical construction of a hydram (left, according to Abate and Botrel 2002) and its set-up in the field (right, according to Tacke 1988)
The water is fed into the ram through the drive pipe. There has to be a certain fall to allow water to be accelerated by gravity. It flows into the ram and out the impulse valve, which is its centrepiece. As velocity increases, the impulse valve is pushed close by the flowing water. As the impulse valve closes a waterhammer will arise. As pressure inside the ram exceeds the pressure inside the delivery line, the delivery valve will open and pressure is released to delivery line. When pressure diminishes, the delivery valve closes. The impulse valve will open due to the low pressure in the ram and its own weight or a spring, and water will start flowing out again, so a new cycle starts. The air-filled pressure chamber represents a buffer, absorbing the waterhammer and turning the intermittent pumping into a quite steady flow (Schulz 1977, Kahangire 1984, Tacke 1988, Chi and Diemer 2002).
Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
The first hydraulic ram had been constructed by Whitehurst (1775), which had to be operated manually. The first construction working automatically was invented by Montgolfier in 1797 (Dickinson 1937). Pumping capacity of the hydraulic ram depends on size and therewith on supply water flow as well as on delivery height. Usually, around ten percent of the driving water is pumped upwards, decreasing as delivery height is increased. As most of the water is not pumped (and so to say is wasted), the system is not adequate in conditions where water is scarce. The aim of this study was to construct a reliable low-cost ram, made of locally available off-the-shelf parts. Constructional design as well as assembly and dismantling should be as simple as possible without greatly affecting its durability. The resulting hydram prototype was used to test different valves for their suitability for usage in a ram at a test stand and one ram was installed in the field for evaluating its reliability and durability. 2. Materials and Methods Layout of the ram In large parts the construction of the ram was orientated to the specifications provided by Filho and Viana (2002). Deviating from those the pressure chamber was not made of a PET-bottle but of a piece of PVC-tube with an end cap. Moreover, commercially available valves were used instead of “do-it-yourself” solutions. The constructional layout is depicted in Fig. 2. The construction was made in a nominal pipe size (NPS) of one inch, therewith inner diameter (DN) of the drive pipe was 30 mm. The brazen check valve as impulse valve was mounted in reverse direction, so the clap is initially open due to its own weight and is pushed to close by the driving water flowing out.
Fig. 2. Layout of the described low-cost hydraulic ram to be tested at a test stand and installed remote mountainous areas (in parts and assembled)
Threads were sealed by Teflon tape, PVC parts were grounded with solvent welding cement. Hose was fixed with customary hose clamps. Test stand at university For trials of the performance of the constructed hydraulic ram a test stand was established at the campus of Chiang Mai University (Amphoe Mueang Chiang Mai, Chiang Mai, Thailand (18° 47' 40.6'' N, 98° 57' 37.8'' E; 327m asl) (Fig. 3). A concrete water tank acted as the water source, height of the water column inside it simulated the supply head. Drive pipe was attached about 10cm above the bottom of the tank, so water was accelerated by
2210-7843 © 2015 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University.
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pressure instead of falling down. It was assumed, that the performance of the ram was not affected by this layout, which had already been used successfully in other investigations (Cararo et al. 2007). The drive pipe had a straight length leading to the ram of 5.3m (overall length was 6.5m) and was going horizontally along the ground. At the outlet of the tank, a water meter was incorporated into the drive pipe for observation of supply flow. The ram itself and drive pipe were fixed on concrete blocks. Delivery head was simulated by a collection vessel adjustable to different heights. Into this collection vessel a hose functioning as an automatic siphon was integrated, emptying the vessel when it was full. The volume collected was six litres, maximum supply head was 2.3m and maximum delivery head 5.65m.
Fig. 3. Photography (left) and schematic layout of a test stand used to evaluate different valve types for usage as impulse valve in the construction of a hydraulic ram
At the test stand different trials were carried out: x Different pressure chamber sizes Three different pressure chambers are put to the proof: A small one with a volume of 0.6 litres (made of 250mm 2'' pipe and analogous end cap and reducer fitting). A medium sized one, volume 2.3 litres (made of 450mm 3'' pipe, analogous end cap plus reducer fitting). Big pressure chamber with a volume of 3.6 litres (made of 700mm 3'' pipe plus end cap and reducer fitting). x Different valve types as impulse valve: There are a lot of possible types of valves thinkable to be used as impulse valve, but only two types were tested here: an off-the-shelf clap check valve and three different manifestations of inlet valves. The clap check valve (clap) was made of brass in 1'', for usage as impulse valve it had to be mounted inversely and orientated vertically, so the clap could fall open by gravity. It was also built in as delivery valve. For usage as an impulse valve, the inlet valves had to be manipulated in a way, that the valve is forced open by the spring (normally the spring is meant to close the valve unless water is soaked in). So the spring had to be put in another position. The different valves and a schematic view are shown in Fig. 4. One valve tested was a brazen inlet valve in 1'' (brass 1). A screw is put in to at which the spring can be attached. Additionally two PVC inlet valves were tested: a smaller one in the size of ¾'' (PVC ¾) and a bigger one in 1½'' (PVC 1½).
Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
Fig. 4. Different valves tested as impulse valve in the construction of a hydraulic ram, schematic view (according to Kahangire 1984) and disassembled manipulated inlet valve
Fig. 5. Different valve arrangements in the construction of a hydraulic ram (from left to right: I, IIv, IIh; with I impulse valve; D delivery valve)
x Different valve arrangements The impulse valve can be arranged in different positions as depicted in Fig. 5. In valve arrangement I, the supply flow is redirected upwards to leave the impulse valve. In valve arrangement IIv, it also has to go up, but it is directed by the pipe and does not bounce on a barrier. Spring actuated valves also can be arranged in a horizontal position (IIh), so water flow is not redirected at all and can go out quite straight through the valve in line. For determining the ram's performance, its efficiency is calculated by the following formula: ݄ڄݍ ߟൌ ܳܪڄ ǣ (1) ܳǣ ݍǣ ܪǣ ݄ǣ So η is nothing else than the ratio of the potential energy of th pumped water in the end to the potential energy of the origin water at supply head (Abate and Botrel 2002). Installation of the ram in the field For determining the ram's performance in the field, one exemplar was installed at a foothill location in a stream, fed by a small streamlet coming from slightly above the hill. The place is located in Ban Ha, Samoeng District, Chiang Mai Province, about 25km away from Chiang Mai University (Coordinates: 18° 47' 39.6'' N, 98° 50' 10.9'' E; 504m asl). The ram installed was constructed as described above, with the medium sized pressure chamber (volume 2.3l) and brazen clap check valves were used as both, impulse and delivery valve. The ram was mounted on a concrete block. Drive pipe was also fixated on two concrete blocks, positioned two and five metres in front of the ram. The
2210-7843 © 2015 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University.
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drive pipe, carried out in 1'', was quite long (80m). Its inlet was placed directly into the streamlet with a small mesh pulled over, to prevent big objects flowing in. Supply head was 3.5m, delivery head 9m above the ram. Supply and delivery flow were determined by collecting the water and measuring the time needed to fill a vessel. For the irrigation of a small test plot, delivered water was collected in a vessel. Irrigation was triggered by an integrated bell siphon, emptying the vessel at once as it was filled to capacity. The bell siphon was built in accordance to the specifications given by Fox et al. (2010). 3. Results and discussion The described ram was easy to assemble with a total cost of less than 700THB (about 20 US$) for the ram itself when made of PVC-only. Results at the test stand x Different pressure chambers Measurements were carried out with the brazen clap check valve as impulse valve and with a supply head of 2.35m and 5.65m delivery head. There was no significant difference in efficiency of the ram when operated with the large (3.6l) and medium size (2.3l) pressure chamber (33.1% and 32.6%, respectively). With the smallest pressure chamber attached, the ram did not pump water to the given height and strokes caused harder shocks on the system, because the pressure chamber was full of water and so the buffering air was lacking. From a certain size on, pressure chamber volume was hence found not crucial for operation of the ram and this aspect was not further investigated. For other trials the medium sized pressure chamber was used, providing the opportunity to spare a snifter valve, recommended by several authors for replenishing dissipated air, when using a small pressure chamber (Kahangire 1984, Cararo et al. 2007). x Different valve types and valve arrangements The different valves were tested in different arrangements, which influenced behaviour of the ram a lot (Fig. 6). Since different springs suitable for the different valves were not available, every valve had a different spring and was tested only with this.
Fig. 6. Results of the ram tested at the test stand with different valves (means and standard deviation); A, B, C, D valves; I, IIv, IIh valve arrangement, vertical/horizontal
Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
During the trials it turned out, that the spring activated valves were working more or less erratic. Especially the brazen inlet valve, did not work very well and not reliable. For an acceptable performance, adapted springs should be used and the spring tension should be adjusted, probably that would improve the reliability. The ¾'' PVC inlet valve was working only a bit less erratic, due to a too hard spring. Best results were achieved with the 1½'' PVC inlet valve. This one had a relatively soft spring and was therefore reliably closed by the drive water. However, waterhammer caused visible shocks to the valve, and as it is made of plastics, it is not believed to last very long. Surprisingly, a ram efficiency similar to th 1½'' PVC valve was achieved by usage of the brazen clap check valve as impulse valve, which was working even more reliable . Apart from that, increase of efficiency by change of valve arrangement from I to II is not surprising at all. The difference had been expected to be even greater. Both arrangements have their pros and cons: In valve arrangement II the driving water is flowing through until the end of the pipe and its flow is not disturbed apart from the outlet to the impulse valve. If the valve is orientated horizontally, water can even flow out straight in line its flow direction, decreasing friction losses even further and increasing ram efficiency. Apart from that, in valve arrangement I flow direction of water is changed to flow out the impulse valve, cushioning the flow. But there is also an advantage: waterhammer can be released straight through the delivery valve, flow of the incoming water column does not have to be redirected. It is believed, that these two effects more or less neutralize each other, so differences between the two set-ups appear to be negligible. Tension of the spring influences closing behaviour of the valve and appears to have the strongest influence on ram performance. To achieve a reliable operation of the ram, spring tension has to be adjusted to the actual conditions. There again, the clap check valve had no need for adjustment and is working most reliable. Furthermore, this valve can just be purchased off-the-shelf and does not have to be manipulated, which would constitute a possible source of misadjustment with the inlet valves. Therefore usage of the clap check valve is recommended (Kahangire 1984, Chi and Diemer 2002). As in valve arrangement I the pressure surge is released more easily, it is thought to cause less strain to the material. So this arrangement is recommended despite the slightly lesser efficiency achievable. Results of the ram in the field The hydraulic ram installed in the stream was working quite reliable. It was running continuously first for six and then eight weeks, failure was caused by heavy rain, moving the drive pipe that was not fixated well over its total length. As there was no professional strainer used, a lot of debris was present in the pumped water. But the ram itself was not influenced by that. It was delivering about 1.3 litres per minute at a wastewater flow (=supply flow delivery flow) of about 6.25 litres per minute. With the given supply and delivery head of 3.5 and 9m, this results in an efficiency of about 44%. 4. Conclusion The described construction of a hydraulic ram was quite cheap and easy to assemble. The used PVC parts and clap check valves are readily available in Thailand. With the brazen clap check valves used the ram proved very reliable working behaviour. At suitable sites it could be installed helping to increase crop safety or even make cropping at small remote sites possible. When users are introduced to the technique and familiarize themselves with the set-up, there should not be great difficulties in installation and maintenance. Hence, altogether the hydraulic ram represents a good alternative to conventional pumping devices with lower initial financial effort. References Abate, C., Botrel, T., 2002. Carneiro hidraulico com tubulacao de alimentacao em aco galvanizado e em PVC. Scienta Agricola 59 (1), 197–203. Cararo, D., Damasceno, F., Griffante, G., Alvarenga, L., 2007. Caracteristicas construtivas de um carneiro hidraulico com materiais alternativos. Revista Brasileira de Engenharia Agricola e Ambiental 11(4), 349–354.
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Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114 Chi, M., Diemer, P., 2002. Hydraulic ram handbook. Bremen Overseas Research and Development Association. Dickinson, H., 1937. Early years of the hydraulic ram. Transactions of the Newcomen Society 17, 73–83. Filho, G., Viana, A., 2002. Hydraulischer Widder. Centro Nacional de Referencia em Pequenos aproveitamentos hidroenergeticos (CERPCH), Brazil. Fox, B., Howerton, R., Tamaru, C., 2010. Construction of Automatic Bell Siphons for Backyard Aquaponic Systems. Biotechnology, College of Tropical Agriculture and Human Resources (CTAHR), University of Hawaii at Mãnao, USA, 1–10. Kahangire, P., 1984. An experimental investigation and design of hydraulic ram pumps [Master thesis]. University of Ottawa, Canada. Schulz, H., 131977. Die Pumpen. Springer Verlag, Berlin, Germany, pp. 486. Tacke, J., 1988. Hydraulic rams, a comparative investigation. Communications on hydraulic and geotechnical engineering, Delft University of Technology, Netherlands. Whitehurst, J., 1775. Account of a machine for rising water. Philosophical Transactions 65, 277–279.
ScienceDirect Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
1st International Conference on Asian Highland Natural Resources Management, AsiaHiLand 2015
Hydraulic ram pumps for irrigation in Northern Thailand Matthias Inthachota, Suchard Saehaengb, Johannes F. J. Maxa, Johannes Müllerc, Wolfram Spreerb, c, *1 a
Department of Soil Science and Plant Nutrition, Center of Applied Biology, Hochschule Geisenheim University, Geisenheim, Germany b Faculty of Agriculture, Chiang Mai University, Chiang Mai, Thailand c Institute of Agricultural Engineering, University of Hohenheim, Stuttgart, Germany
ABSTACT First constructed two and a half centuries ago, the hydraulic ram is one of the oldest mechanical devices for water lifting. The first application utilised the principle for the water supply of a brewery. In this set up a water valve had to be manually closed. Very soon upgrades for an automatic operation of the device were adapted. With technological progress also the ram was improved, but got superseded by electric and fuel powered pumps. Today the ram constitutes a reliable and low-maintenance, sustainable alternative to motor-driven pumps. The hydraulic ram uses the kinetic energy of water flowing in a driver pipe to pump up about 10% of it to a higher elevation. Thereby, no external energy input is needed. As a lot of studies had been carried out constructing hydraulic rams with self built valves and for high water supply, the aim of this investigation was to construct a reliable and low-cost ram, made of locally available off-the-shelf parts. Different valves were tested in the lab under varying elevations of the water column in the driver pipe. The pumping pressure and water flow in the supply pipe were recorded for determining the ram's efficiency. An off-the-shelf clap check valve proved mosrt reliable with an acceptable efficiency of over 30%. One unit of a hydraulic ram was installed at a foothill location at Ban Ha, Samoeng District, Chiang Mai Province, and connected to an automatic low pressure irrigation system to irrigate a small plot of coffee trees. Soil moisture was monitored. The hydraulic ram operated maintenance free and fully automatic over six weeks, supplying the field sufficient quantities of water during this period at a pumping efficiency of 44%.
© Authors. Published Published by by Elsevier ElsevierB.V. B.V. This is an open access article under the CC BY-NC-ND license © 2015 2015 The The Authors. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University Keywords: Hydraulic ram; hydram; water lifting, gravity pump
1* Corresponding author. E-mail address: [email protected]
2210-7843 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University doi:10.1016/j.aaspro.2015.08.015
108
Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
1. Introduction Nomenclature H h Q q
supply head delivery head supply flow delivery flow
Although the price of oil is decreasing recently, it is to expect that in future energy costs will tend to increase. Many farmers are dependent on fuel or electrical power for pumping water to their fields. An escape from this dependency could be provided by usage of self-powering water lifting devices. Such a device is the hydraulic ram, in short also referred to as hydram. A hydram utilises the power of falling water for pumping part of that water to a higher elevation than the origin. The hydraulic ram therefore utilises the waterhammer phenomenon. The waterhammer is a pressure surge caused by the inertia of piped moving water. Inside the pipes, water can be seen as a column. If water inside a pipework is allowed to flow out of an outlet which is closed suddenly, the water column cannot halt its movement instantly. It will go on flowing towards the outlet, where thereby pressure builds up. This pressure is then reflected at the closed outlet and will travel as pressure wave backwards the pipework, where it can give severe damage if not neutralised (Tacke 1988, Chi and Diemer 2002). In the hydraulic ram this effect is provoked intentionally, and the pressure wave is utilised to force water upwards. The ram consists of an impulse valve provoking the waterhammer, and a delivery valve that allows the pressure wave to pass through and prevents backflow of the pumped water. A typical setup of a hydram and its setup in the field is shown in Fig. 1.
Fig. 1. Typical construction of a hydram (left, according to Abate and Botrel 2002) and its set-up in the field (right, according to Tacke 1988)
The water is fed into the ram through the drive pipe. There has to be a certain fall to allow water to be accelerated by gravity. It flows into the ram and out the impulse valve, which is its centrepiece. As velocity increases, the impulse valve is pushed close by the flowing water. As the impulse valve closes a waterhammer will arise. As pressure inside the ram exceeds the pressure inside the delivery line, the delivery valve will open and pressure is released to delivery line. When pressure diminishes, the delivery valve closes. The impulse valve will open due to the low pressure in the ram and its own weight or a spring, and water will start flowing out again, so a new cycle starts. The air-filled pressure chamber represents a buffer, absorbing the waterhammer and turning the intermittent pumping into a quite steady flow (Schulz 1977, Kahangire 1984, Tacke 1988, Chi and Diemer 2002).
Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
The first hydraulic ram had been constructed by Whitehurst (1775), which had to be operated manually. The first construction working automatically was invented by Montgolfier in 1797 (Dickinson 1937). Pumping capacity of the hydraulic ram depends on size and therewith on supply water flow as well as on delivery height. Usually, around ten percent of the driving water is pumped upwards, decreasing as delivery height is increased. As most of the water is not pumped (and so to say is wasted), the system is not adequate in conditions where water is scarce. The aim of this study was to construct a reliable low-cost ram, made of locally available off-the-shelf parts. Constructional design as well as assembly and dismantling should be as simple as possible without greatly affecting its durability. The resulting hydram prototype was used to test different valves for their suitability for usage in a ram at a test stand and one ram was installed in the field for evaluating its reliability and durability. 2. Materials and Methods Layout of the ram In large parts the construction of the ram was orientated to the specifications provided by Filho and Viana (2002). Deviating from those the pressure chamber was not made of a PET-bottle but of a piece of PVC-tube with an end cap. Moreover, commercially available valves were used instead of “do-it-yourself” solutions. The constructional layout is depicted in Fig. 2. The construction was made in a nominal pipe size (NPS) of one inch, therewith inner diameter (DN) of the drive pipe was 30 mm. The brazen check valve as impulse valve was mounted in reverse direction, so the clap is initially open due to its own weight and is pushed to close by the driving water flowing out.
Fig. 2. Layout of the described low-cost hydraulic ram to be tested at a test stand and installed remote mountainous areas (in parts and assembled)
Threads were sealed by Teflon tape, PVC parts were grounded with solvent welding cement. Hose was fixed with customary hose clamps. Test stand at university For trials of the performance of the constructed hydraulic ram a test stand was established at the campus of Chiang Mai University (Amphoe Mueang Chiang Mai, Chiang Mai, Thailand (18° 47' 40.6'' N, 98° 57' 37.8'' E; 327m asl) (Fig. 3). A concrete water tank acted as the water source, height of the water column inside it simulated the supply head. Drive pipe was attached about 10cm above the bottom of the tank, so water was accelerated by
2210-7843 © 2015 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University.
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Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
pressure instead of falling down. It was assumed, that the performance of the ram was not affected by this layout, which had already been used successfully in other investigations (Cararo et al. 2007). The drive pipe had a straight length leading to the ram of 5.3m (overall length was 6.5m) and was going horizontally along the ground. At the outlet of the tank, a water meter was incorporated into the drive pipe for observation of supply flow. The ram itself and drive pipe were fixed on concrete blocks. Delivery head was simulated by a collection vessel adjustable to different heights. Into this collection vessel a hose functioning as an automatic siphon was integrated, emptying the vessel when it was full. The volume collected was six litres, maximum supply head was 2.3m and maximum delivery head 5.65m.
Fig. 3. Photography (left) and schematic layout of a test stand used to evaluate different valve types for usage as impulse valve in the construction of a hydraulic ram
At the test stand different trials were carried out: x Different pressure chamber sizes Three different pressure chambers are put to the proof: A small one with a volume of 0.6 litres (made of 250mm 2'' pipe and analogous end cap and reducer fitting). A medium sized one, volume 2.3 litres (made of 450mm 3'' pipe, analogous end cap plus reducer fitting). Big pressure chamber with a volume of 3.6 litres (made of 700mm 3'' pipe plus end cap and reducer fitting). x Different valve types as impulse valve: There are a lot of possible types of valves thinkable to be used as impulse valve, but only two types were tested here: an off-the-shelf clap check valve and three different manifestations of inlet valves. The clap check valve (clap) was made of brass in 1'', for usage as impulse valve it had to be mounted inversely and orientated vertically, so the clap could fall open by gravity. It was also built in as delivery valve. For usage as an impulse valve, the inlet valves had to be manipulated in a way, that the valve is forced open by the spring (normally the spring is meant to close the valve unless water is soaked in). So the spring had to be put in another position. The different valves and a schematic view are shown in Fig. 4. One valve tested was a brazen inlet valve in 1'' (brass 1). A screw is put in to at which the spring can be attached. Additionally two PVC inlet valves were tested: a smaller one in the size of ¾'' (PVC ¾) and a bigger one in 1½'' (PVC 1½).
Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114
Fig. 4. Different valves tested as impulse valve in the construction of a hydraulic ram, schematic view (according to Kahangire 1984) and disassembled manipulated inlet valve
Fig. 5. Different valve arrangements in the construction of a hydraulic ram (from left to right: I, IIv, IIh; with I impulse valve; D delivery valve)
x Different valve arrangements The impulse valve can be arranged in different positions as depicted in Fig. 5. In valve arrangement I, the supply flow is redirected upwards to leave the impulse valve. In valve arrangement IIv, it also has to go up, but it is directed by the pipe and does not bounce on a barrier. Spring actuated valves also can be arranged in a horizontal position (IIh), so water flow is not redirected at all and can go out quite straight through the valve in line. For determining the ram's performance, its efficiency is calculated by the following formula: ݄ڄݍ ߟൌ ܳܪڄ ǣ (1) ܳǣ ݍǣ ܪǣ ݄ǣ So η is nothing else than the ratio of the potential energy of th pumped water in the end to the potential energy of the origin water at supply head (Abate and Botrel 2002). Installation of the ram in the field For determining the ram's performance in the field, one exemplar was installed at a foothill location in a stream, fed by a small streamlet coming from slightly above the hill. The place is located in Ban Ha, Samoeng District, Chiang Mai Province, about 25km away from Chiang Mai University (Coordinates: 18° 47' 39.6'' N, 98° 50' 10.9'' E; 504m asl). The ram installed was constructed as described above, with the medium sized pressure chamber (volume 2.3l) and brazen clap check valves were used as both, impulse and delivery valve. The ram was mounted on a concrete block. Drive pipe was also fixated on two concrete blocks, positioned two and five metres in front of the ram. The
2210-7843 © 2015 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University.
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drive pipe, carried out in 1'', was quite long (80m). Its inlet was placed directly into the streamlet with a small mesh pulled over, to prevent big objects flowing in. Supply head was 3.5m, delivery head 9m above the ram. Supply and delivery flow were determined by collecting the water and measuring the time needed to fill a vessel. For the irrigation of a small test plot, delivered water was collected in a vessel. Irrigation was triggered by an integrated bell siphon, emptying the vessel at once as it was filled to capacity. The bell siphon was built in accordance to the specifications given by Fox et al. (2010). 3. Results and discussion The described ram was easy to assemble with a total cost of less than 700THB (about 20 US$) for the ram itself when made of PVC-only. Results at the test stand x Different pressure chambers Measurements were carried out with the brazen clap check valve as impulse valve and with a supply head of 2.35m and 5.65m delivery head. There was no significant difference in efficiency of the ram when operated with the large (3.6l) and medium size (2.3l) pressure chamber (33.1% and 32.6%, respectively). With the smallest pressure chamber attached, the ram did not pump water to the given height and strokes caused harder shocks on the system, because the pressure chamber was full of water and so the buffering air was lacking. From a certain size on, pressure chamber volume was hence found not crucial for operation of the ram and this aspect was not further investigated. For other trials the medium sized pressure chamber was used, providing the opportunity to spare a snifter valve, recommended by several authors for replenishing dissipated air, when using a small pressure chamber (Kahangire 1984, Cararo et al. 2007). x Different valve types and valve arrangements The different valves were tested in different arrangements, which influenced behaviour of the ram a lot (Fig. 6). Since different springs suitable for the different valves were not available, every valve had a different spring and was tested only with this.
Fig. 6. Results of the ram tested at the test stand with different valves (means and standard deviation); A, B, C, D valves; I, IIv, IIh valve arrangement, vertical/horizontal
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During the trials it turned out, that the spring activated valves were working more or less erratic. Especially the brazen inlet valve, did not work very well and not reliable. For an acceptable performance, adapted springs should be used and the spring tension should be adjusted, probably that would improve the reliability. The ¾'' PVC inlet valve was working only a bit less erratic, due to a too hard spring. Best results were achieved with the 1½'' PVC inlet valve. This one had a relatively soft spring and was therefore reliably closed by the drive water. However, waterhammer caused visible shocks to the valve, and as it is made of plastics, it is not believed to last very long. Surprisingly, a ram efficiency similar to th 1½'' PVC valve was achieved by usage of the brazen clap check valve as impulse valve, which was working even more reliable . Apart from that, increase of efficiency by change of valve arrangement from I to II is not surprising at all. The difference had been expected to be even greater. Both arrangements have their pros and cons: In valve arrangement II the driving water is flowing through until the end of the pipe and its flow is not disturbed apart from the outlet to the impulse valve. If the valve is orientated horizontally, water can even flow out straight in line its flow direction, decreasing friction losses even further and increasing ram efficiency. Apart from that, in valve arrangement I flow direction of water is changed to flow out the impulse valve, cushioning the flow. But there is also an advantage: waterhammer can be released straight through the delivery valve, flow of the incoming water column does not have to be redirected. It is believed, that these two effects more or less neutralize each other, so differences between the two set-ups appear to be negligible. Tension of the spring influences closing behaviour of the valve and appears to have the strongest influence on ram performance. To achieve a reliable operation of the ram, spring tension has to be adjusted to the actual conditions. There again, the clap check valve had no need for adjustment and is working most reliable. Furthermore, this valve can just be purchased off-the-shelf and does not have to be manipulated, which would constitute a possible source of misadjustment with the inlet valves. Therefore usage of the clap check valve is recommended (Kahangire 1984, Chi and Diemer 2002). As in valve arrangement I the pressure surge is released more easily, it is thought to cause less strain to the material. So this arrangement is recommended despite the slightly lesser efficiency achievable. Results of the ram in the field The hydraulic ram installed in the stream was working quite reliable. It was running continuously first for six and then eight weeks, failure was caused by heavy rain, moving the drive pipe that was not fixated well over its total length. As there was no professional strainer used, a lot of debris was present in the pumped water. But the ram itself was not influenced by that. It was delivering about 1.3 litres per minute at a wastewater flow (=supply flow delivery flow) of about 6.25 litres per minute. With the given supply and delivery head of 3.5 and 9m, this results in an efficiency of about 44%. 4. Conclusion The described construction of a hydraulic ram was quite cheap and easy to assemble. The used PVC parts and clap check valves are readily available in Thailand. With the brazen clap check valves used the ram proved very reliable working behaviour. At suitable sites it could be installed helping to increase crop safety or even make cropping at small remote sites possible. When users are introduced to the technique and familiarize themselves with the set-up, there should not be great difficulties in installation and maintenance. Hence, altogether the hydraulic ram represents a good alternative to conventional pumping devices with lower initial financial effort. References Abate, C., Botrel, T., 2002. Carneiro hidraulico com tubulacao de alimentacao em aco galvanizado e em PVC. Scienta Agricola 59 (1), 197–203. Cararo, D., Damasceno, F., Griffante, G., Alvarenga, L., 2007. Caracteristicas construtivas de um carneiro hidraulico com materiais alternativos. Revista Brasileira de Engenharia Agricola e Ambiental 11(4), 349–354.
2210-7843 © 2015 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Faculty of Agriculture, Chiang Mai University.
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Matthias Inthachot et al. / Agriculture and Agricultural Science Procedia 5 (2015) 107 – 114 Chi, M., Diemer, P., 2002. Hydraulic ram handbook. Bremen Overseas Research and Development Association. Dickinson, H., 1937. Early years of the hydraulic ram. Transactions of the Newcomen Society 17, 73–83. Filho, G., Viana, A., 2002. Hydraulischer Widder. Centro Nacional de Referencia em Pequenos aproveitamentos hidroenergeticos (CERPCH), Brazil. Fox, B., Howerton, R., Tamaru, C., 2010. Construction of Automatic Bell Siphons for Backyard Aquaponic Systems. Biotechnology, College of Tropical Agriculture and Human Resources (CTAHR), University of Hawaii at Mãnao, USA, 1–10. Kahangire, P., 1984. An experimental investigation and design of hydraulic ram pumps [Master thesis]. University of Ottawa, Canada. Schulz, H., 131977. Die Pumpen. Springer Verlag, Berlin, Germany, pp. 486. Tacke, J., 1988. Hydraulic rams, a comparative investigation. Communications on hydraulic and geotechnical engineering, Delft University of Technology, Netherlands. Whitehurst, J., 1775. Account of a machine for rising water. Philosophical Transactions 65, 277–279.