Performance of a water ram built with disposable bottles

The hydraulic ram is a device that makes use of the energy of a “water fall” to raise part of the water flow to a higher elevation by merely using the energy of the water hammer. Even though a small water volume is compressed, the device may be a solution for water supply on family farms, for home use, animal drinking troughs and watering of vegetables. Current study evaluated the performance of a hydraulic ram constructed with disposable bottles replacing the conventional air chamber model made of cast iron. Experiment was conducted at the College of Agronomic Sciences in Botucatu SP Brazil. Equipment ́s performance was assessed by employing different volumes of air chambers (0.25; 0.6; 1.0 and 2.0 L) at the following pumping pressures: 70, 105, 140, 175, 210 and 245 kPa. Results showed that 0.6 and 1.0 L bottles showed higher pressure flow. Within the conditions given for polyethylene tubes, the effectiveness of the device occurred only at a maximum 1:7 ratio (slope/elevation).


INTRODUCTION
The hydraulic ram is a simple and inexpensive device that was introduced for water supply to the rural and deprived areas of the third world countries.The use of these pumps, it is hoped that it can solve the problems of lack of adequate water for drinking, agriculture and animal husbandry, etc. and therefore be useful in preventing rural to urban migration (Fatahi-Alkouhi et al., 2015).
A hydraulic ram functions by a water hammer caused by closing a valve that interrupts the water flow from a supply to a higher hydraulic head (Abate and Botrel, 2002), with the lifting of water through no outside power source.According to Horne and Newman (2005), the hydraulic ram does not need any external power source; *Corresponding author.E-mail: marconibt@gmail.com.Tel: (0xx64) 3620-5636.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License maintenance and function are simple, without any need of specialized manpower; costs and deployment are low; and it may be run 24 h a day.The hydraulic ram is used in low-head hydropower and highly suitable on small farms.Hydraulic rams may be manufactured at nonindustrial very low costs with PVC tubes and polyethylene (PET) bottles as alternatives for the normally cast iron air chamber (CERPCH, 2002).
PET-built hydraulic ram is a relatively very recent device.Although there is scanty information on the device, it is highly relevant in situations where no other type of water pumping is available.Analyses evaluate its performance according to the characteristics of its construction and supply flow, water pressure, loss and yield.Needless to say, the latter factor is the most important item for users.The function of the hydraulic ram during the whole day, continually repeated in 20 to 100 beat cycles per min, depends on the supply flow which pressurises the water intermittently (Jennings, 1996).Thus, there is a continuous water supply without any sort of interruption.The apparatus is self-starting and no oiling is required (RHM, 2014).Supply flow rates or available flow for the hydraulic ram depend on the characteristics of its construction and on the material used.Cararo et al. (2007) employed alternative PET material and reported flows between 21.28 and 46.81 L min -1 .The authors emphasized that variation was due to the device´s construction type.Hydraulic rams manufactured in Brazil function with a flow between 5 and 150 L min -1 (Azevedo Netto and Alvarez, 1988).Compressed water volume is related to the ratio between low and high-head water and on the material used in the supply.Abate and Botrel (2002) used PVC and galvanized steel supply tubes and had the highest yield with a hydraulic ram featuring PVC tubes up to 4.2 m level difference.They underscored that galvanized steel tubes are the most efficient.Mohammed (2007) noted at the development of a hydraulic ram pump that it would conveniently alleviate the problem of water supply to the mass populace; ideally, verifying different combinations of the supply and delivery heads and flows, stroke length and weight of the impulse valve, volume of the air chamber and size of the snifter valve, etc.
When compared to steel ones, PVC tubes have two different characteristics that affect yield: the first favors yield and is characterized by low internal roughness, with low flow loss; the second, unfavorable to yield, is characterized by the tubes´ elasticity which absorbed the water hammer impact (Abate and Botrel, 2002).
CERPCH (2002) reported that in PET bottle hydraulic rams, the elevation height must be 2 to 8 times the height of the fall of the source water, proportionate to the diameter of input and output tube.The device must be placed at a sufficient level difference so that it may operate, in other words at a minimum of 1 m and a maximum of 10 m (the support pressure of the PET bottle should be taken into account).As a rule, level difference is produced artificially by a small dam and using the river´s level difference.
The iron-manufactured air chamber has a greater rigidity with regard to the impact of the water hammer when compared to that in PET bottle air chamber.In fact, the former has low attenuation to the hammer impacts and thus a better yield than the latter.PET bottles have only a relative resistance since they normally support a 200 kPa pressure from its normal contents (Cararo et al., 2007).
Current assay evaluates the hydraulic characteristics of a hydraulic ram made from PET bottles with different volumes and submitted to several pressures while employing polyethylene tubes for supply.

MATERIALS AND METHODS
Assay was conducted in the Laboratory of Irrigation Equipments of the Department of Rural Engineering of the Faculdade de Ciências Agronômica (UNESP), Botucatu SP Brazil.Tested treatments comprised of four volumes (disposable bottles): 0.25, 0.6, 1.0 and 2.0 L and five pressure levels: 105, 140, 175, 210 and 245 kPa.Bottle lids had a 22 mm diameter.
Supply reservoir comprised a 200 L metal tank with water level kept at a height of 3.5 m relative to the hydraulic ram.Water flowed from the reservoir through a polyethylene tube with internal diameter 22.5 mm, so that the equipment could be tested.Part of the total water volume was deployed to the hydraulic ram and was pressured through a tube with internal diameter 10.68 mm; the remaining water or excess water overflowed through the safety valve.Gauges for pressure control were installed and pressure was monitored by digital manometer with 0 -7 kgf cm -2 range.
Figure 1 shows the hydraulic ram, developed with a PET bottle, its components are: 1 -inlet; 2-pressure flow; 3-PET bottle; 4vertical retention valve; 5-bottom valve.Water volume in the pressure tube and safety valve were collected with 10 L pails during 1 min.
Samples were weighed and rates transformed into discharges.Supply discharge of the hydraulic ram with PET bottle was obtained from pressure and excess discharges.The sum of the two discharges was equal to total supply discharge.Discharges were necessary for the functioning and the elevation of a section by the water hammer.
A chronometer determined the number of impacts by the safety valve in 1 min.The spring was calibrated so that the number of impacts would be between 50 and 60.Each bottle type had three replications at same pressures 70, 105, 140, 175, 210 and 240 kPa, while measuring discharge in liters per minute for pressure and excess water.Yields were calculated by Equation 1.
Where: η% = yield in %; q = pressure discharge in m 3 s -1 ; Q = discharge in safety valve in m 3 s -1 ; h = height of supply water in m; H = pressure height in m.
Analysis of variance was performed to verify data dependence using F-test at 5 % probability.R 2 rate was the parameter to verify adjustments of regression curves to reported data.

RESULTS AND DISCUSSION
Collected data were analyzed and compared taking into consideration the performance of the hydraulic ram of the PET bottle for volumes 0.25; 0.6; 1.0 and 2.0 L and pressures 70, 105, 140, 175, 210 and 245 kPa (Table 1).
The hydraulic ram pumped between 0.24 and 5.1 L min -1 .On the other hand, Cararo et al. (2007) reported rates between 0.58 and 11.76 L min -1 , with a 4.36 m level difference relative to the level of the hydraulic ram.Abate and Botrel (2002) studied galvanized steel and PVC supply tubes in a commercial hydraulic ram and reported rates between 2.39 and 6.68 L min -1 .Variations were caused by the material (galvanized steel and PVC) and water supply heights employed (2.1; 3.8 and 4.7 m).
The four different volume-sized bottles evaluated decreased pumped pressure discharge as pressure increased.When pressures were analyzed separately for the different volumes under analysis, no statistical difference was registered among the flows, with the exception of the volumes 0.6 and 1.0 L at pressure 240 kPa.Variable volumes of excess water did not have any significant difference in the treatments under analysis.Table 2 shows the water volume which has not been used in the pressure pump, or rather, excess discharge.Variations of water loss from excess water during the assay reached 67% (pressure at 70 kPa, with 1 L bottle) and 97.47% (pressure 245 kPa and 0.25 L bottle) respectively.Rates demonstrate high water loss by the equipment, characteristic of its deployment.Results corroborated those by Cararo et al. (2007) with loss rates between 64.72 and 98.16%.
During laboratory assays, the handling of the equipment did not always permit the precise adjustment of preestablished pressures by gauges and manometers since the equipment had pressure variations during work caused by the water hammer.Table 3 shows mean pressures (for the desired pressures) for each volume.
According to Zárate Rojas (2002), yield the hydraulic ram mainly depends on the relationship between fall height from the reservoir to the hydraulic ram, on the height of the equipment elevation to the upper reservoir and to the preciseness of the manufactured apparatus.Tests with the PET bottles used as air chambers at different volumes and pressures provided the relationship between rates of pumped water caused by level difference and the relationship between level difference PET bottles with 0.6 and 1.0 L provided the highest rates of pumped flow, with the best performance among the others being a 1:3 ratio.Thus, it may be inferred that air chambers with 0.6 and 1.0 L at 245 kPa had the best yield when submitted to the highest level difference/ pumping pressure ratio, evaluated in the experiment., following proper construction conditions and height of pressure flow, maximum discharge could be higher if the supply tubes were made of more rigid material.High elasticity of the polyethylene absorbed the impact of the water hammer and reduced its efficiency.
According to Suarda and Wirawan (2008) the back head pressure caused by the water hammer in the drive pipe decreases from 103.87 m without air vessel to 37.85 m with air vessel.Moreover, pressure shock in delivery pipe increases from 0.29 m without air vessel to 2.9 m with air vessel.Therefore, they showed that fixing an air vessel could increase sharply the efficiency of the hydraulic ram from 0.72 to about 19.45%.The 0.6 and 1.0 L polyethylene bottles had the best results, mainly for the highest-level difference/pressure flow ratios.Hammer impact failed to occur at pressures over 245 kPa on the water flow.The air in the bottle was released and the system stopped functioning.The developed hydraulic ram pumped up to 739.15 liters of water a day for a 1:6 ratio level difference/pressure flow ratio, with the 0.6 L PET bottle.

Figure 1 .
Figure 1.Hydraulic ram made of a PET bottle.
Figure 2 shows the linear regression for pressures 70, 105, 140, 175, 210 e 245 kPa and evidenced the device´s hydraulic behavior.Although, current hydraulic ram pumped flows between 0.06 and 5.37 L min -1

Table 1 .
Mean rates for pumped and excess water flow in treatments with PET bottles of different volumes under different pressures.

Table 2 .
Percentage of total volume of water used in pressure and excess pump, yield and discharge in supply (pressures).

Table 3 .
Mean rates of pressures and yields for different volumes of PET bottles.

Table 4 .
Rates of pumped water discharge according to the different pumped water heights verified in current assay.