Performance Characteristics of a Small Hammer Head Pump

Many rural farming areas are located far from reliable electricity supply, hence, having a reliable source of water for crops and livestock can prove to be an expensive venture. A water pump operating on the water hammer effect requires no external power 10 source and can serve as an effective means of pumping water to a higher altitude once a reliable supply is available. A lowcost small hammer-head pump was designed to operate on the hammer head effect created by the sudden stoppage of a flowing fluid. This design consisted of an inlet section followed by the pump body, a pressure section and an outlet. The experimental set-up for testing the hammer head pump was designed with a variable head input and an adjustable head output. For each test configuration, ten samples of pump supply water and pump exhausted water were collected. The water samples were collected 15 for 30s in each case. The results showed a non-linear variation of water flow respect to pump outlet height. The pump was capable of delivering water to a maximum height of 8 to 10 times the height of the input head. The pump operated at average efficiencies of 26%, 16% and 6% when the delivery height was twice, four times and six times the input head, respectively. There was a 5% incremental decrease in pump efficiency as the delivery height increased in increments of the corresponding input head height. 20


Introduction
The first type of pumps to use the water hammer effect was the hydraulic ram pump which was reported in 1775 and was built by John Whitehurst [1]. His design was not automatic and was controlled by 25 manually opening and closing a stopcock which resulted in the device only being able to raise water to a height of 4.9 meters. This involved a significant amount of work and consumed a lot of time to operate. However, in 1797 the design was improved and the first reported automatic hydraulic ram was developed by Joseph and Etienne Montgolfier to raise water to a paper mill [2]. Although this was an improved design it still contained design flaws which caused the air in the pressure chamber to dissolve or drop. In 30 1816 this problem was eliminated when Pierre Montgolfier designed the sniffer valve that reintroduced air into the chamber. This valve was 15 cm in radius and it was reported that the pump was able to raise water to 48 meters in height [3]. The automatic hydraulic ram has been used for centuries to lift water to heights over 100 meters and was considered an effective and highly reliable machine for pumping water once certain conditions are satisfied. The pump construction was simple and consisted of a pump chamber fitted with two moving parts, an impulse valve through which the driving water was wasted and a delivery valve through which the water was delivered [4]. It worked solely on the power supplied from the water head in the source. This source could be a spring, streams, river, ponds, dam, lakes and even some wells, once the conditions existed for these water sources to create a hydraulic flow head, either by forming a dam or a naturally existing head. Basically, once a hydraulic head can be created, the pump can operate, however, the source must provide a steady and reliable supply of water [5]. The ram pump must be installed at a location lower than the water source which was used to create the flow giving the fluid (water) some velocity.
In many rural farming areas, having a reliable source of water for crops and livestock can prove to be an expensive venture. Especially in developing countries, farmland are located far from any reliable source of electricity, however, situated close to a water source. In developing and under-developed countries, farmlands are ideally located close to a reliable water source to ensure viability [6,7]. However, in many instances these locations are far from any reliable source of electricity and the cost can be prohibitive [6,8]. The alternative of diesel-driven pumps create high operation costs and are prone to service gaps due to insufficient fuel supply and technical defects. A reliable and cost-effective supply of irrigation water is therefore a core problem in many rural 50 areas in developing and emerging countries [9]. In cases where The the water source is usually situated below the level of the farmlands, and getting the water to where it is needed can be challenging [7]. Under these circumstances, A a water pump operating on the water hammer effect and requires no external power source and can serve as an effective means of pumping water to a higher altitude once a reliable source is available. Also, in under developed countries, such as Haiti, the feasibility of using small hammer head pumps to provide clean water for citizens were explored 55 by Prude University [10]. The ram pump can operate 24/7 and hence a water storage facility, such as storage tanks, at the water delivery end will be needed. This will serve as the reservoir to supply the needs when required. The major hindrance in using this established technology in third world countries is the exorbitant cost of the commercially available units. For a UK built pump the cost is US$ 1800 [11] and cheaper china made pumps range between US$500 to US$1300 [12]. One of the objectives of the 60 Prude University project in Haiti was to develop a cheaper alternative, however, the cost was US$100 [10]. Therefore, there is the need to develop a low cost alternative that can be easily built from readily available construction materials and requires minimal technical skills.
The first type of pumps to use the water hammer effect is the hydraulic ram pump which was first reported in 1775 and was built by John Whitehurst [1]. His design was not automatic and was controlled by manually opening and closing a stopcock which resulted in the device only being able to raise water to a height of 4.9 meters. This involved a significant amount of work and consumed a lot of time to operate. However, in 1797 the design was improved and the first reported automatic hydraulic ram was developed by Joseph and Etienne Montgolfier to raise water to a paper mill [2]. Although this was an improved design it still contained design flaws which caused the air in the pressure chamber to dissolve or drop. In 1816 this problem was eliminated when Pierce Montgolfier designed the sniffer valve that reintroduce air into the chamber. This valve 70 was 15 cm in radius and it was reported that the pump was able to raise water to 48 meters in height [3]. The automatic hydraulic ram has been used for centuries to lift water to heights over 100 meters and is considered the prefect machine for pumping water once certain conditions are satisfied. The pump construction was simple and consisted of a pump camber fitted with two moving parts, an impulse valve through which the driving water was wasted and a delivery valve through which the water was delivered [4]. It works solely on the power supplied from the water head in the source. This source could be a spring, however, the source must provide a steady and reliable supply of water [5]. The ram pump is ideally installed at a location lower than the water source which is used to create the flow giving the fluid (water) some velocity.
Given the long history of the hydraulic ram pump, the design and manufacture has improved considerably 80 with time and efficiency of operation increased. For commercial ram pumps the typical energy efficiency is about 60%, but can reach up to 80% [13].This is different from the volumetric efficiency, which relates the volume of water delivered to total water taken from the source. The amount of water delivered will be reduced by the ratio of the output head to the supply head. For example, if the source is 2 meters above the ram pump and the water is lifted to 10 meters above, only 20% of the supplied water will be available 85 and the other 80% being spilled via the exhaust valve [14]. These ratios assumed 100% energy efficiency. The actual water delivered will be reduced further by the energy efficiency. Hence, for an energy efficiency of 70%, the water delivered will be 70% of 20%, which yields14% [14,15]. Suppliers of ram pumps often provide tables giving expected volume ratios based on actual tests. The amount of water delivered to the end for use will depend on source flow, height of supply reservoir above pump, height of 90 delivery site above pump, length and size of delivery pipe and drive line, pump efficiency, and size of pump [15,16,17]. Considering the many combinations of these variables, the amount of water that can be delivered vary significantly. For example, delivery output from a single 2" ram pump system can range from a low of 17 gallons per day to 4,000 gallons per day or more [17].
Apart from the delivery output of the hydraulic ram pump depending on many variables the design itself 95 is complicated by the three pipe flow system and the hydraulic ram effect [18]. The delivery output is a non-linear relationship with variables of input head and output head. Therefore, for a specific hydraulic ram pump, determining the delivery output at variable input and output head heights will be a critical factor in determining the applicability, suitability and effectiveness for use. This study investigates the performance characteristics of a low cost hydraulic ram pump with input and delivery head height 100 variation and quantify the change in efficiency of delivered water.

Pump Design and Construction
The small hammer-head pump was designed to operate on the hammer head effect created by the sudden stoppage of a flowing fluid. The main components of the pump operation involved two one-way valves and a pressure tank. The one-way valves 105 were arranged such that when one closes the other opened and vice-versa. This design consists of an inlet section followed by the pump body, a pressure section and finally an outlet. A 24.5mm PVC ball valve was installed at the inlet section which allowed control of the water entering the body of the pump and facilitated priming of the pump. The pump was constructed using 32mm diameter PVC pipe and valves. The advantages of this material were the low cost, low coefficient of friction and the resistance to corrosion. The Brass one-way swing valves were used in the designof brass construction. Another The pressure tank was constructed using a 127mm long 75mm diameter PVC pipe. A PVC end caps was used on one end of the pipe and reduction PVC fittings on the other end attached to the 32mm pipe. Figure 2 is a picture of the pump components in the position for assembly. The materials/components required for the pump construction were obtained from the local hardware store. The cost of the components for the pump construction are shown in  Figure 3 shows a schematic of the experimental apparatus. The experimental set-up for testing the hammer head pump was designed with a variable head input (a) and an adjustable head output (b). The water supply of water was from a 5000L storage tankwater reservoir (c). The constant head supply tank was designed with a float (d) that maintained the constant water level as water was supplied to the inlet of the pump. The input head was the difference in height 140 between the inlet of the pump and the water level at the top of the constant head supply tank. The outlet side of the pump used variable length of 13mm diameter PVC pipe to adjust the delivery height (b). Figure 3 shows a schematic of the experimental apparatus. measuring cylinder with an accuracy of ±20ml to determine the pump waste exhausted water flow rate.

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Experiments were conducted by varying the input head of the water at between 30 cm to 150 cm in increments of 30cm intervals. At each corresponding input head the pump outlet height was varied between 60cm to 600cm in increments of 60cm intervals. For each test configuration, ten samples of pump supply water and pump waste exhausted water were collected.

Analysis and Discussion
The simple construction low cost water hammer pump showed that as the delivery head increased the rate of water delivered decreased for the five input head height tested. For the lowest input head of 30 cm, the pump operated up to a maximum height of 300 cm. No water was delivered beyond this height. For input head of 60 cm, the pump operated up to a maximum height of 480 cm. No water was delivered beyond this height. For input head of 90 cm, 120 cm and 150 cm, the pump delivered water up to the maximum test height of 600 cm. A plot of the data points indicated a non-linear relationship between pump outlet height and delivered water flow rate and the regression analysis are as shown on the graph in Figure 4. This observation is in agreement with published literature [16,18,19]. The regression equations indicated the rate at which water was delivered with pump outlet height followed an x 3 variation.
This corroborated the The experimental data which showed that as pump outlet height decreased, there was a slow increase in delivered water flow rate. This was followed by an increase in delivered water flow rate with a close-to a linear variation.

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This observation is in agreement with published literature [17,18]. As the pump outlet height dropped lower than 120 cm, there was a decrease in the delivered water flow rate. The regression equations corresponding to the various input head heights are given in equations 1 to 5. The pump efficiency was determined from the ratio of the water delivered to the total water flow. The values were calculated 190 and tabulated on Table 3 4. From the data for the 60 cm and 30 cm input head, the pump was capable of delivering water be between 8 to 10 times the input head with efficiencies of 1.6% and 0.9%, respectively. This was within the range of 5 to 25 times as published 195 by U.S. department of agriculture natural resources conservation service [17]. The difference in delivery height capacity may be due to the shorter pipe length of 300 cm compared to 480 cm associated with the 30 cm and 60 cm input head, respectively. For the increased pipe length there would be increased frictional resistance to flow and the also increased gravitational force due to the higher water column. For input head ranging between 30 cm to 150 cm, the efficiency of the pump delivering water twice the input head height ranged from 23.1% to 30.6% with an average 200 efficiency of 26%. For input head ranging between 30 cm to 150 cm, the efficiency of the pump delivering water four times the input head height ranged from 19.4% to 13.3% with an average efficiency of 16.6%. From the three sets of data available for input head ranging between 30 cm to 90 cm, the efficiency of the pump delivering water six times the input head height ranged from 5.0% to 7.4% with an average efficiency of 6.4%. The trend indicated that as the delivery height increased in increments of twice the corresponding input head, there is was a 10% decrease in efficiency. This observation is in 205 conformity with the operation of the hydraulic ram pumps [19].
Conclusions  A small scale hammer head pump operated effectively without any external energy input.
 The delivered water flow rate varied according to a cubic variable showed a non-linear variation with respect 210 to pump outlet height.  The pump was capable of delivering water to a maximum height of 8 to 10 times the height of the input head.  The pump operated at average efficiencies of 26%, 16% and 6% when the delivery height was twice, four times and six times the input head, respectively.  There was a 5% incremental decrease in pump efficiency as the delivery height increased in increments of the 215 corresponding input head height. [2] De Montgolfier, J. Apart from the delivery output of the hydraulic ram pump depending on many variables the design itself is complicated by the three pipe flow system and the hydraulic ram effect [17]. The delivery output is a non-linear relationship with variables of input head and output head. Therefore, for a specific hydraulic ram pump, determining the delivery output at variable input and output head heights will be a critical 300 factor in determining the applicability, suitability and effectiveness for use. This study investigates the performance characteristics of a low cost hydraulic ram pump with input and delivery head height variation and quantify the change in efficiency of delivered water.

Referee comment: A clear objective (and knowledge gap) at the end of the introduction is missing. It should be stated what the drawbacks of the previous designs was, what the research gap is and thus the research question -
Author response: (marked up manuscript lines 54-63) 310 Also, in under developed countries, such as Haiti, the feasibility of using small hammer head pumps to provide clean water for citizens were explored by Prude University [9]. The ram pump can operate 24/7 and hence a water storage facility, such as storage tanks, at the water delivery end will be needed. This will serve as the reservoir to supply the needs when required. The major hindrance in using this established technology in third world countries is the exorbitant cost of the commercially available units. The automatic hydraulic ram has been used for centuries to lift water to heights over 100 meters and was 325 considered an effective and highly reliable machine for pumping water once certain conditions are satisfied.
Referee comment: explain how with "ponds", "lakes", and "wells" , "a form of flow can be created" This source could be a spring, streams, river, ponds, dam, lakes and even some wells, once the conditions existed for these water sources to create a hydraulic flow head, either by forming a dam or a naturally existing head. Basically, once a hydraulic head can be created, the pump can operate, however, the source must provide a steady and reliable supply of water [5].

Referee comment: delete "construction"
Author response: (marked up manuscript line 110) Brass one-way swing valves were used in the design 340 Referee comment: Figure 1 the word "exhausted water" and in Figure 3 "waste water" is used. Please synchronize and avoid the word "waste water" since this has another connotation. -Author response: In the marked up manuscript version; the word waste water was replaced with exhausted water throughout the manuscript.

Referee comment: explain to what reference the "input head" is related.
Author response: (marked up manuscript lines 139-141) The constant head supply tank was designed with a float (d) that maintained the constant water level as water was supplied to the inlet of the pump. The input head was the difference in height between the inlet From the data for the 60 cm and 30 cm input head, the pump was capable of delivering water be between 8 to 10 times the input head with efficiencies of 1.6% and 0.9%, respectively. This was within the range 360 of 5 to 25 times as published by U.S. department of agriculture natural resources conservation service [16].

Referee comment: explain if this was to be expected (and give reference)"
Author response: (marked up manuscript lines 204-206) 365 The trend indicated that as the delivery height increased in increments of twice the corresponding input head, there is was a 10% decrease in efficiency. This observation is in conformity with the operation of the hydraulic ram pumps [18]. (marked up manuscript lines 108-110)

The comments from reviewer 2 were constructive and served to improve the quality of the manuscript. The comments are addressed below.
The pump was constructed using 32mm diameter PVC pipe and valves. The advantages of this material were the low cost, low coefficient of friction and the resistance to corrosion. The Brass one-way swing 395 valves were used in the designof brass construction.
(marked up manuscript lines 95-101) Apart from the delivery output of the hydraulic ram pump depending on many variables the design itself is complicated by the three pipe flow system and the hydraulic ram effect [17]. The delivery output is a 400 non-linear relationship with variables of input head and output head. Therefore, for a specific hydraulic ram pump, determining the delivery output at variable input and output head heights will be a critical factor in determining the applicability, suitability and effectiveness for use. This study investigates the performance characteristics of a low cost hydraulic ram pump with input and delivery head height variation and quantify the change in efficiency of delivered water.
pumps range between US$500 to US$1300 [11]. One of the objectives of the Prude University project in Haiti was to develop a cheaper alternative, however, the cost was US$100 [9]. Therefore, there is the need to develop a low cost alternative that can be easily built from readily available construction materials and requires minimal technical skills.

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(marked up manuscript lines 128-133) The materials/components required for the pump construction were obtained from the local hardware store. The cost of the components for the pump construction are shown in Author response: (marked up manuscript lines 46-59) In developing and under-developed countries, farmlands are ideally located close to a reliable water 460 source to ensure viability [6, 7]. However, in many instances these locations are far from any reliable source of electricity and the cost can be prohibitive [6,8]. In cases where The the water source is usually situated below the level of the farmlands, and getting the water to where it is needed can be challenging [7]. Under these circumstances, A a water pump operating on the water hammer effect and requires no external power source and can serve as an effective means of pumping water to a higher altitude once a 465 reliable source is available. Also, in under developed countries, such as Haiti, the feasibility of using small hammer head pumps to provide clean water for citizens were explored by Prude University [9]. The ram pump can operate 24/7 and hence a water storage facility, such as storage tanks, at the water delivery end will be needed. This will serve as the reservoir to supply the needs when required. The major hindrance in using this established technology in third world countries is the exorbitant cost of the 470 commercially available units. electricity source yet close to a water source. Maybe a word like "usually" or "mostly" could fit, as long as evidence is provided for such an affirmation.
Author response: (marked up manuscript lines 44-51) In many rural farming areas, having a reliable source of water for crops and livestock can prove to be an expensive venture. Especially in developing countries, farmland are located far from any reliable source 485 of electricity, however, situated close to a water source. In developing and under-developed countries, farmlands are ideally located close to a reliable water source to ensure viability [6,7]. However, in many instances these locations are far from any reliable source of electricity and the cost can be prohibitive [6,8]. The alternative of diesel-driven pumps create high operation costs and are prone to service gaps due to insufficient fuel supply and technical defects. A reliable and cost-effective supply of irrigation water 490 is therefore a core problem in many rural areas in developing and emerging countries [9]. In many rural farming areas, having a reliable source of water for crops and livestock can prove to be an expensive venture. Especially in developing countries, farmland are located far from any reliable source of electricity, however, situated close to a water source. In developing and under-developed countries, 510 farmlands are ideally located close to a reliable water source to ensure viability [6, 7]. However, in many instances these locations are far from any reliable source of electricity and the cost can be prohibitive [6,8]. The alternative of diesel-driven pumps create high operation costs and are prone to service gaps due to insufficient fuel supply and technical defects. A reliable and cost-effective supply of irrigation water is therefore a core problem in many rural areas in developing and emerging countries [9]. In cases where The the water source is usually situated below the level of the farmlands, and getting the water to where it is needed can be challenging [7]. Under these circumstances, A a water pump operating on the water hammer effect and requires no external power source and can serve as an effective means of pumping water to a higher altitude once a reliable source is available. Author response: (marked up manuscript lines 24-35) The first type of pumps to use the water hammer effect was the hydraulic ram pump which was reported 525 in 1775 and was built by John Whitehurst [1]. His design was not automatic and was controlled by manually opening and closing a stopcock which resulted in the device only being able to raise water to a height of 4.9 meters. This involved a significant amount of work and consumed a lot of time to operate. However, in 1797 the design was improved and the first reported automatic hydraulic ram was developed by Joseph and Etienne Montgolfier to raise water to a paper mill [2]. Although this was an improved 530 design it still contained design flaws which caused the air in the pressure chamber to dissolve or drop. In 1816 this problem was eliminated when Pierre Montgolfier designed the sniffer valve that reintroduced air into the chamber. This valve was 15 cm in radius and it was reported that the pump was able to raise water to 48 meters in height [3]. The automatic hydraulic ram has been used for centuries to lift water to heights over 100 meters and was considered an effective and highly reliable machine for pumping water 535 once certain conditions are satisfied. The automatic hydraulic ram has been used for centuries to lift water to heights over 100 meters and was considered an effective and highly reliable machine for pumping water once certain conditions are satisfied.

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Referee comment: L. 41: It mentions "water was wasted", whereas the Fig. 1  Author response: In the marked up manuscript version; the word waste water was replaced with exhausted water throughout the manuscript. This source could be a spring, streams, river, ponds, dam, lakes and even some wells, once the conditions existed for these water sources to create a hydraulic flow head, either by forming a dam or a naturally 560 existing head.
Referee comment: L. 44: The ram pump installed at a lower location than the water source is not an ideal scenario but a mandatory one. Otherwise the pump will not operate whatsoever.
Author response: (marked up manuscript lines 41-43) 565 The ram pump must be installed at a location lower than the water source which was used to create the flow giving the fluid (water) some velocity. put that in the introduction, so in this section the specific parts and assembly methods of your prototype 570 are directly described.
Author response: In my opinion, I would prefer this paragraph to remain as is.
Referee comment: L. 61: Figs 1 and 2 could be put side to side, so the reader can make a quick correspondence between the scheme and the actual prototype.
Author response: This change was made.

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Referee comment: L. 73-76: I recommend to match the parts of the experimental set-up, as described in this paragraph, with those of the Fig. 3, to make sure all of them can be identified in both graphic and text. A good way of achieving it could be by assigning letters or numbers to each part.
Author response: (marked up manuscript lines 137-142) 580 Figure 3 shows a schematic of the experimental apparatus. The experimental set-up for testing the hammer head pump was designed with a variable head input (a) and an adjustable head output (b). The water supply of water was from a 5000L storage tankwater reservoir (c). The constant head supply tank was designed with a float (d) that maintained the constant water level as water was supplied to the inlet of the pump. The input head was the difference in height between the inlet of the pump and the water level at  single one, due to their similar structure. In that case, each cell must be divided in two parts, for the pumped flow and wasted flow, respectively. Moreover, this can give the chance to include a third part: the pumped/wasted ratio; it can be eventually related to the pumping efficiency.
Author response: An attempt was made to combine the tables, however, the data was too much to fit properly side-by-side on one table. Hence, the tables were left as is.