L4W Guide to Designing and Sizing Hydraulic Ram Pump System Page 1 of 6

L4W Guide to Designing andSizing Hydraulic Ram Pump System

Published by theEngineering and Construction Services Department of

Life 4 Water, Inc.Iligan City 9200, Philippines

With Reference from:Technical Note No. RWS.4.D.5: Designing a Hydraulic Ram Pump, Water for the World Publication by USAID, 1982.

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A hydraulic ram or impulse pump is a device which uses the energy of falling water to lift a lesseramount of water to a higher elevation than the source. See Figure 1.

Figure 1. Hydraulic Ram Pump

There are only two moving parts, thus, there is little to wear out. Hydraulic rams are relativelyeconomical to purchase and install. One can be built with detailed plans and if properly installed,they will give many trouble-free years of service with no pumping costs. For these reasons, thehydraulic ram is an attractive solution where a large gravity flow exists. A ram should beconsidered when there is a source that can provide at least seven times more water than the ram is topump and the water is, or can be made, free of trash and sand. There must be a site for the ram atleast 0.5m below the water source and water must be needed at a level higher than the source.

Factors in Design

Before a ram can be selected, several design factors must be known. These are shown in Figure 1and include:

1. The difference in height between the water source and the pump site (called vertical FALL).2. The difference in height between the pump site and the point of storage or use (LIFT).3. The quantity (Q) of flow available from the source.4. The quantity of water required.

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5. The length of pipe from the water source to the ram pump (called the drive pipe).6. The length of pipe from the pump to the storage site (called the delivery pipe).

Once this information has been obtained, a calculation can be made to see if the amount of waterneeded can be supplied by a ram. The formula is: D = (Q x F x E) ÷ L, where:

D = Amount of Water delivered in liters per 24 hours.Q = Quantity of water supplied (at source) in liters per minute.F = The fall or height of the source above the ram in meters.E = The efficiency of the ram (for commercial models use 0.66, for home built use 0.33

unless otherwise indicated).L = The lift height of the point of use above the ram in meters.

Table 1 solves this formula for rams with efficiencies of 66 percent, a supply of 1 liter per minute,and with the working fall and lift shown in the table. For supplies greater than 1 liter/minute,simply multiply by the number of liters supplied.

Table 1. L4W Ram Pump Performance Data for a Supply (Q) of 1 liter/minuteLiters Delivered over 24 Hours

Lift - Vertical Height to which Water is Raised Above the Ram (m)Working Fall(m) 5 7.5 10 15 20 30 40 50 60 80 100 125 150 175 200 250 and

higher1.0 172 126 95 63 471.5 190 142 95 71 47 362.0 252 190 126 95 63 482.5 237 158 118 79 60 473.0 285 190 142 95 72 57 483.5 221 166 110 83 66 554.0 253 190 127 95 76 64 475.0 316 237 158 118 95 79 59 476.0 285 190 142 114 95 71 57 407.0 221 166 133 110 83 65 53 448.0 190 152 126 95 76 60 509.0 213 171 142 106 85 68 57 48

10.0 237 190 158 118 95 76 63 54 4712.0 Extremely High Pressure @ Drive End 228 190 142 114 91 76 65 57 4514.0 Extremely High Pressure @ Drive End 266 221 166 133 106 88 76 66 53 and lesser16.0 Extremely High Pressure @ Drive End 253 190 152 121 101 86 76 60 and lesser18.0 Extremely High Pressure @ Drive End 285 213 171 136 114 97 85 68 and lesser20.0 Extremely High Pressure @ Drive End 237 190 152 126 108 95 76 and lesser

Conversion Help1 liter = 0.26 Gallon (US)

= 0.22 Imperial Gallon (UK and Canada)

1 US Gallon = 3.79 Liters1 Imperial Gallon = 4.55 Liters

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Four Common Components of Hydraulic Ram System

A hydraulic ram installation consists of a supply, a drive pipe, the ram, a supply line and usually astorage tank. These are shown in Figure 2. Each of these component parts is discussed below:

1. Supply. The intake must be designed to keep trash and sand out of the supply since these canplug up the ram. If the water is not naturally free of these materials, the intake should be screened ora settling basin provided. When the source is remote from the ram site, the supply line can bedesigned to conduct the water to a drive pipe as shown in Figure2. The supply line, if needed,should be at least one pipe diameter larger than the drive pipe.

2. Drive pipe. The drive pipe must be made of a non-flexible material for maximum efficiency.This is usually galvanized iron pipe, although other materials cased in concrete will work. In orderto reduce head loss due to friction, the length of the pipe divided by the diameter of the pipeshould be within the range of 150-1,000. Table2 shows the minimum and maximum pipe lengthsfor various pipe sizes.

Table 2. Range of Drive Pipe Lengthsfor all L4W Ram Pumps

Length (meters)Drive Pipe Size,Nominal Minimum Maximum

¾” 3 201” 4 32

1 ¼” 4.5 401 ½” 6 50

2” 7.5 652 ½” 12 80

3” 15 1004” 20 125

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The drive pipe diameter is usually chosen based on the size of the ram and the manufacturer'srecommendations as shown in Table 3. The length is four to six times the vertical fall.

Table 3. Drive Pipe Diameters by Model NumberRam Pump Size RP75 RP100 RP125 RP150 RP200 RP250 RP300 RP400

Dripe Pipe Size (NPS/DN)* ¾” / 20 1” / 25 1 ¼” / 32 1 ½” / 40 2” / 50 2 ½” 65 3” / 80 4” / 100* NPS = Nominal Pipe Size, (inches, U.S.); DN = Diametre Nominal (metric, Europe)

3. Ram. Rams can be constructed using commercially available check valves or by fabricatingcheck valves. They are also available as manufactured units in various sizes and pumpingcapacities. Rams can be used in tandem to pump water if one ram is not large enough to supply theneed. Each ram must have its own drive pipe, but all can pump through a common delivery pipe asshown in Figure 3.

In installing the ram, it is important that it be level, securely attached to an immovable base,preferably concrete, and that the waste-water be drained away. Since the ram usually operates on a24-hour basis the size can be determined for delivery over a 24-hour period.

Table 4. L4W Ram Pump Capacity by Model NumberRam Pump ModelParameters

RP75 RP100 RP125 RP150 RP200 RP250 RP300 RP400Volume of Drive Water Needed(liters/min) 9-12 11-16 12-25 27-55 45-96 68-137 136-270 180-410

Maximum Lift @ 5 Meters Fall, Meters 35 50 50 75 75 75 75 75Maximum Lift @ 10 Meters Fall, Meters 75 100 100 100 100 100

High Lift Ram Pump ModelRP200H RP250H RP300H RP400H

Maximum Lift @ 15 Meters Fall, Meters 150 150 150 150Maximum Lift @ 20 Meters Fall, Meters 200 250 300 300

Note: Customized ram pump design can be ordered/made to fit specific field need.

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4. Delivery Pipe. The delivery pipe can be of any material that can withstand the water pressure.The size of the line can be estimated using Table 5.

Table 5. Sizing the Delivery Pipe(HDPE Pipes recommended)

Delivery Pipe Size (mm) Flow (liters/min)30 6-3640 37-6050 61-9080 91-234

100 235-360Note: Must have a rating of at least SDR11 resist pressure

specially at high lift

5. Storage Tank. This is located at a level to provide water to the point of use. The size is basedon the maximum demand per day.

How to size your ram pumpSuppose you want to provide water to a small village, say, 20 homes or households with a total of100 people. There is a spring 30m lower than the village which drains to river which is 15m belowthe spring. The spring produces 60,000 liters of water per day. There is a location for a ram on theriver bank which is safe should the river overflows at rainy season. This site is 5m higher than theriver and about 40 meters from the spring. A ground water tank or reservoir is planned for thevillage 400 meters from the ram site. The lift required to the top of the storage tank is 45 meters.

The following are the steps in design.

Identify the necessary design factors:1. Maximum vertical fall is 15m. You can use 6 meters of FALL.2. LIFT is 45m to top of storage tank.3. Quantity of flow available equals 60,000 liters per day divided by 1,440 minutes per day

(30,000/1,440) = 41.6 liters per minute.4. The quantity of water required assuming 40 liters per day per person as maximum use is 100

people x 40 liters per day = 4,000 liters per day.4,000/1,440 = 2.77 liters per minute (use 3 liters per minute)

5. The length of the drive pipe is 40m.6. The length of the delivery pipe is 400m.7. The above data can be used to size the system. Use Table 1, for a FALL of 6m and a LIFT

of 50m, 114 liters can be pumped a day for each liter per minute supplied. Since 4,000 litersper day is required, the number of liters per minute needed can be found by dividing 4,000by 95:

8. 4,000/114 = 35.08 liters per minute of water required.

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From item 3 above, the water supply available from the source is 41.6 liters per minute so the watersupply is sufficient. The volume of driving water or supply needed is only 35.08 liters per minute.From Table 4, an RP150 requires from 27 to 55 liters per minute. An RP150 Ram pump can liftwater to a maximum height of 75-100m at 5-10 meters of FALL according to Table 4.This will be adequate since the lift to the top of the storage tank is only 45m. Thus, a RP150 Rampump would be selected.

Table 3 shows that for a RP150 Ram pump, the drive pipe diameter is 1 ½” nominal. Table 2indicates that the minimum and maximum length for a 1 ½” pipe 6m-50m. Since the spring is 40maway, the length is all right. Table 5 can be used to select a delivery pipe 30mm in diameter whichfits the supply needed, 35.08 liters per minute.

Summary of Design:Size of Ram Pump : L4W Ram Pump Model RP150Drive Pipe Diameter : 1 ½ inchDrive Pipe lengths : 30 meters (6 meters Fall x Ratio of 5)Delivery Pipe Lengths: 400 meters, diameter 30 mm

Check Ram Pump Deliverable in liters per 24 hours:Formula: D = (Q x F x E) ÷ LDischarge (Delivery) = (Quantity of water x Fall x Efficiency) ÷ Lift

D = (41.6 lpm x 6m x .66) ÷ 45mD = (164.74lpm) ÷ 45mD = 3.66 liters per minute (multiply further by 60 and then by 24 to get liters per 24hours). So,D = 3.66 liters per minute x 60 minutesD = 219.60 per hour x 24D = 5,270.40 liters per 24 hours >> meaning you are much much over the requiredvolume of only 4,000 liters

For more info, contact us:Tel/Fax: (063) 492-3567

Email: life4water@yahoo.comhttp://life4water.webs.com/rampump.htm

Note:Life 4 Water, Inc.

is a registered non-profit organization in Iligan City, Philippines having a SEC Reg No. 200322741It provides water services to areas where government services barely reach.

Sales from ram pumps and fees collected from construction and other services are utilized tofinance its operations.

Life 4 Water helps poor families improve their livelihoods and help them transform livelihoods intoenterprise – Thus, alleviating poverty.

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