Prepared by:
Gregory D.Jennings
Agricultural Engineering Extension Specialist
Publication Number: EBAE 161-92
Last Electronic Revision: March 1996 (JWM)
The cycle repeats between 20 and 100 times per minute, depending upon the flow rate. If properly installed, a hydraulic ram will operate continuously with a minimum of attention as long as the flowing water supply is continuous and excess water is drained away from the pump.
where:Q=pumping rate in gallons per day (gpd)
E=efficiency of a hydraulic ram pump installation, typically equal to 0.6
S=source flow rate through the drive pipe in gallons per minute (gpm)
L=vertical elevation lift from the pump to the destination in feet
F=vertical fall from the source through the drive pipe in feet.
To convert the pumping rate expressed in gallons per day(gpd) to gallons per minute(gpm), divide by 1440. The following example illustrates an application of Equation 1.
Example.
A hydraulic ram will be used to pump water from a stream with an
average flow rate of 20 gpm up to a water tank located 24 feet vertically
above the pump. The vertical fall through the drive pipe in the stream to
the pump is 4 feet. Assume a pumping efficiency of 0.6. What is the maximum
pumping rate from the hydraulic ram pump?
In this example, E = 0.6
S = 20 gpm
L = 24 feet
and F = 4 feet.
The resulting pumping rate, Q, is calculated as:
The maximum pumping rate delivered by the hydraulic ram pump operating under these conditions is 2880 gallons per day, or 2 gallons per minute.
The example shows how the pumping rate, Q, is directly related to the source flow rate, S. If S were to double from 20 gpm to 40 gpm, the resulting pumping rate would also double to 5760 gpd, or 4 gpm.
The example also shows how the pumping rate, Q, is inversely related to the ratio of vertical elevation lift to vertical fall, L/F. If L were to double from 24 feet to 48 feet, the lift to fall ratio, L/F, would double from 6 to 12. The resulting pumping rate would decrease by half to 1440 gpd, or 1 gpm.
Table 1 lists maximum pumping rates, Q, for a range of source flow rates, S, and lift to fall ratios, L/F, calculated using Equation 1 with an assumed pumping efficiency, E, of 0.6.
To illustrate the use of Table 1, consider a hydraulic ram system with
S = 30 gpm, L = 150 feet, and F = 5 feet.
The calculated lift to fall
ratio, L/F, is 30.
The resulting value for Q is 864 gpd, or 0.6 gpm.
Hydraulic ram pumps are sized based upon drive pipe diameter. The size of drive pipe selected depends upon the available source water flow rate. All makes of pumps built for a given size drive pipe use about the same source flow rate. Available sizes range from 3/4-inch to 6-inch diameters, with drive pipe water flow requirements of 2 to 150 gpm. Hydraulic ram pumps typically can pump up to a maximum of 50 gpm (72,000 gpd) with maximum elevation lifts of up to 400 feet.
Approximate characteristics of hydraulic ram pumps for use in selecting pumps are listed in Table 2. The recommended delivery pipe diameter is normally half the drive pipe diameter. For the system described in the example above, the available source water flow rate is 10 gpm. From Table 2, a pump with a 1-inch drive pipe diameter and a 1/2-inch delivery pipe diameter is selected for this system.
Consult manufacturer's literature for specific pumping characteristics.-------Pipe Diameter------- ---------------Flow rate--------------
Min. Drive Min. Discharge Min. Required Source Maximum Pumping
-----------inches---------- ---------gpm-------- ------gpd------3/4 1/221 0001 1/262
0001 1/2 3/4144 00021257
0002 1/21 1/43510 00031
1/26020 0006315072 000 Installation
The location of the water source in relation to the desired point of water use determines how the hydraulic ram pump will be installed. The length of drive pipe should be at least 5 times the vertical fall to ensure proper operation. The length of delivery pipe is not usually considered important because friction losses in the delivery pipe are normally small due to low flow rates. For very long delivery pipes or high flow rates, friction losses will have an impact on the performance of the hydraulic ram pump. The diameter of the delivery pipe should never be reduced below that recommended by the manufacturer.
To measure the available source water flow rate from a spring or stream, build a small earthen dam with an outlet pipe for water to run through. Place a large bucket or barrel of known volume below the outlet pipe, and measure the number of seconds it takes to fill the container. Then calculate the number of gallons per minute flowing through the outlet. For example, if it takes 30 seconds to fill a 5-gallon bucket, the available source water flow rate is 10 gpm. The lowest flow rates are typically in the summer months. Measure the flow rate during this period to ensure that the year-round capacity of the system is adequate.
1. Available water supply in gpm _________ 2. Vertical fall in feet measured from the source water level to the foundation on which the ram pump will rest _________ 3. Distance from the water source to the ram pump in feet _________ 4. Vertical elevation lift in feet measured from the ram pump foundation to the highest point to which water is delivered ________ 5. Distance from the ram pump to the destination tank in feet _________ 6. Desired pumping flow rate to the destination tank in gpd _________
This fact sheet adapted from materials prepared by the California, Florida, and South Carolina Cooperative Extension Services.
Columbia Hydraulic Ram
Skookum Co., Inc.
8524 N. Crawford St.
Portland, OR 97203
Blake Hydram
Ar & Do Sales Co.
4322 Mt. Vernon Rd. SE
Cedar Rapids, IA 52403
Pacific Hydro Corp.
400 Forbes Blvd.
San Francisco, CA 94080
Rife Hydraulic Engine Mfg. Co.
316 W. Poplar St.
PO Box 790
Norristown, PA 19401
C.W. Pipe, Inc.
PO Box 698
Amherst, VA 24521