The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University
Irrigation Pumping Systems
A. G. Smajstria, D. S. Harrison, and J. C. Good
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
John T. Woeste, Dean for Extension
PERFORMANCE OF IRRIGATION
PUMPING SYSTEMS IN FLORIDA
A. G. Smajstria, D. S. Harrison, and J. C. Good*
An Irrigation Pumping System Performance Testing Program was
conducted as an Institute of Food and Agricultural Sciences (IFAS)
Low Energy Technology (LET) Project from 1980-84. The primary
objectives of this program were (1) to demonstrate the need for
monitoring irrigation pumping system performance, and (2) to teach
irrigators techniques for monitoring system performances so that
they could schedule repairs and implement management techniques
required to irrigate as efficiently as possible. These objectives re-
quired familiarizing irrigators with many system-specific techniques
because of the variety of both pumping and irrigation systems in
Florida and the desire for irrigators to use the most economical
testing procedures for their systems.
Other objectives concerned conducting a survey of irrigation pump-
ing system performances in Florida. These were (1) to determine the
performance ratings of irrigation pumping systems at sites
throughout Florida, and (2) to determine potential energy savings
in increasing pumping system performances to optimum levels.
This program was primarily funded as an IFAS LET project. Grants
for student assistantships were funded by the St. John's River Water
Management District (SJRWMD) and the Governor's Energy Office
(GEO), State of Florida.
Inefficient irrigation pumping systems waste fuel and increase the
cost per unit of water delivered. As pumping systems age they
become less efficient due to wear. Misapplication is another com-
mon cause of inefficiency.
Inefficient irrigation pumping systems are difficult to manage.
Pumping rates and water application rates decline with wear, thus
making irrigation scheduling difficult and less efficient, possibly
resulting in both waste of water and loss of production.
*Associate Professor, Professor, and Former Adjunct Extension Agent, Agricultural
Engineering Department, IFAS, University of Florida, Gainesville, Florida 32611
A pumping system is designed to use energy to lift water to the
desired height and to develop the required pressure for application.
The work or power output is called water horsepower (WHP) and
is calculated from
WHP = Q x H (1)
where Q = flow rate (gpm), and H = total pumping head produced
(feet of water, where 1 pound per square inch (psi) = 2.31 feet of
water). Water horsepower depends on the rate that water is lifted
and the height to which it is lifted, or to which it has the potential
to be lifted as a result of its pressure.
The performance rating of a pumping system is the ratio of the
actual performance to the performance standard for that type of
system, expressed as a percentage. Pumping system performance
is the work done (water horsepower) divided by the fuel use rate.
Performance standards were developed at the Nebraska Tractor Test
Laboratories and are given in Table- 1. They were based on WHP pro-
duced, because WHP is a characteristic of all pumps.
TABLE 1. Nebraska performance standards for irrigation pumping
Power Unit Pumping System
Fuel Performance Standards Performance Standards*
Diesel 14.75 hp-hr/gal 11.06 whp-hr/gal
Gasoline 11.30 hp-hr/gal 8.48 whp-hr/gal
Propane (LP Gas) 9.20 hp-hr/gal 6.89 whp-hr/gal
Natural Gas 88.93 hp-hr/1000 cu. ft. 66.70' whp-hr/1000 cu. ft.
Electricity 1.18 hp-hr/KW hr. 0.885 whp-h4/KW hr.
*Based on 75 percent pump efficiency and 5 percent drive loss for non-electric units.
In Table 1, performance standards are shown for the fuels most
commonly used for irrigation pumping. These standards are not the
highest theoretically obtainable values. Rather, they are values that
can reasonably be expected from a well-designed, well-maintained,
irrigation pumping system. It is possible to obtain a pumping system
performance that exceeds the standards. In that case the perfor-
mance rating would be greater than 100 percent of the standard.
The performance rating, which is a rating for the entire pumping
system, includes (1) the efficiency of fuel conversion in an internal
combustion engine or electric motor, (2) power losses in belt or gear
drives, if any, (3) pump efficiency, and (4) friction losses in the suc-
tion and discharge columns and fittings. In this manuscript, the per-
formance rating calculated using all of these components is called
the pumping system performance rating.
Performance ratings for systems tested were calculated using the
1) Calculate water horsepower from equation (1).
2) Calculate pumping system performance from:
Performance = Water horsepower (2)
fuel use rate
3) Calculate performance rating from:
Performance Rating = Performance (3)
(from Table 1)
Fuel waste and potential energy savings depend on the pumping
system performance rating. Fuel waste was calculated from the dif-
ference between the performance standard and the actual pump-
ing system performance rating:
Fuel Waste = (100% Performance Rating) x Fuel Use Rate (4)
Using this analysis, fuel waste was calculated from the measured
fuel use rate and the rate that should have been used to obtain the
flow rate and pressure produced by the system if it had been
operating at optimum efficiency.
Performance Ratings and Pump Efficiencies
This program measured the performance rating of the entire pump-
ing system (pump, power unit, and connecting drives). That perfor-
mance rating was a comparison of the observed pumping plant per-
formance to a standard for the type of system being tested.
The performance rating was calculated as a percentage, typically
in the range of 0 percent to 100 percent. However, because the per-
formance standards were developed for a typical system in good
repair, performance ratings exceeded 100 percent when all system
components were in excellent condition and perfectly matched. It
is also possible to exceed the performance standards as new
technologies are developed. As examples, the use of turbocharged
rather than conventionally aspirated engines or the use of heat ex-
changers with irrigation water to cool internal combustion engines
both improve the fuel conversion efficiency of internal combustion
engines. For those conditions, system performances may exceed the
performance standards, and performance ratings may exceed 100
Pump efficiencies, as thought of by a pump manufacturer or in-
staller, are different from pumping system performance ratings.
Pump efficiency refers to the mechanical effectiveness of the pump
only. Because no mechanical components are perfectly efficient due
to friction losses, pump efficiencies range only up to 85 percent or
slightly greater for new pumps operated in the range of their design
conditions. Thus, pump efficiencies are expressed on an absolute
0-100 percent scale.
Advantages of Performance Rating
Irrigation pumping system performance ratings have three major
1. This rating includes the performance of components of the en-
tire pumping system (pump, power unit, and connecting drives)
rather than only the pump efficiency. Mechanical problems with
any of these system components will lower the effectiveness of
the pumping system and result in higher fuel costs per unit of
2. The pumping system performance rating gives a direct indica-
tion of fuel or dollars wasted during irrigation pumping. If, for ex-
ample, a pumping system is operating at a performance rating of
65 percent, then 35 percent (100% 65%) of each gallon of fuel
used is wasted, and 35 cents of each dollar spent for fuel is wasted.
3. The pumping system performance rating can readily be
calculated by the individual owner/operator, using only flow rate
and pressure monitoring instruments, which should be part of a
well-designed irrigation system, and water level monitoring equip-
ment, which can easily be constructed. This capability allows the
owner/operator to monitor his system on a periodic basis to deter-
mine the rate of change in performance, which will allow him to
forecast system repairs.
Disadvantages of Performance Rating
There are some limitations to pumping system performance ratings.
1. If a low performance rating is measured, the exact cause of
that inefficiency cannot be identified by the techniques used.
Rather, the performance rating is the overall rating of the pump,
power unit, and drive, and because specialized equipment and
disassembly of components is required to evaluate which compo-
nent is at fault, a pump repair company must make that evalua-
tion before the problem can be solved.
2. The performance rating concept introduces a set of terminology
that is new to many irrigators. However, the knowledge of fuel
(dollars) wasted and ease of making measurements are thought
to greatly outweigh this problem.
The primary objectives of the Irrigation Pumping System Perfor-
mance Testing Program were educational in nature. These objectives
were accomplished through (1) field meetings and demonstrations,
and (2) testing of individual cooperators' pumping systems. In both
cases a team of performance testing personnel (the pump test team)
met with program participants in the field and tested a pumping
system. Also in both cases, the system owner or manager was re-
quired to be present to operate the irrigation system and observe
test procedures. In this manner the educational aspects of the testing
program were stressed, and misunderstandings related to the
cooperators' operating procedures or equipment failures were
Field Meetings and Demonstrations
Field meetings and demonstrations were the means by which the
testing program was introduced on a regional or county basis. County
extension personnel coordinated them in cooperation with the pump
test team. Local irrigators and other interested persons were invited
to participate in the programs.
The format of the meetings stressed the educational objectives of
this program. Meetings were held at a field site so that the pumping
plant testing procedure could be demonstrated. The demonstrations
showed the need for and techniques for pumping plant performance
The meetings also provided a means of identifying cooperators for
individual tests. Individual cooperators signed up at each meeting.
At the same time, test sites were marked on county road maps to
help the pump test team locate them.
Individual Cooperator Field Tests
Most of the data to determine irrigation pumping system
characteristics in Florida were collected at individual cooperator field
tests. A potential cooperator made an appointment, and the test
team visited the field site to conduct the tests.
Field meetings, field demonstrations, and county extension per-
sonnel were the primary sources of individual participants. County
extension offices distributed test application forms. Other contacts
were established through water management districts, and directly
with cooperators by members of the test team.
Pumping system performance tests required measurements of the
physical properties that determine pumping plant performance. In
this program, testers measured gallons per minute pumped, pump-
ing lift, pressure at the discharge outlet, and the amount of fuel con-
sumed over a period of time, while the pump was operating at its
normal load. The engine and pump speeds were also measured to
ensure that the manufacturer's recommendations were being
To assure equitable distribution of educational efforts, test sites
were based on the number of irrigated acres in each county. A survey
of the five water management districts and of the county extension
agents provided this information. Acreages ranged from greater than
100,000 acres for several counties to less than 500 acres for others.
Counties with more than 3,000 irrigated acres were classified as first
priority, while those with less than 3,000 acres were second priority.
Forty-two Florida counties were classified first priority. In these,
efforts were made to schedule test sites and county field meetings
first. County field meetings for second priority counties were often
combined with those of an adjacent first priority county.
Test results for both county field meetings and individual
cooperator tests were compiled in the field and made available to
all program participants. In addition, a final formal report summariz-
ing all findings was mailed to the pumping system owners. Each
report included an economic analysis of annual fuel waste to help
the irrigator make decisions concerning system repair or
Irrigation pumping system performance testing required portable
equipment for measurements at locations throughout Florida. The
large variety of irrigation systems and pumping systems complicated
Equipment was selected to allow as many types of irrigation
systems to be tested as possible, with one exception. We were not
able to purchase equipment for testing high flow rate, low-lift axial-
flow pumps, which are often used for seepage and crown flood ir-
rigation. These pumps require special flow rate monitoring equip-
ment because of the high flow rates pumped.
Our program concentrated on the turbine and centrifugal pumps
used in sprinkler, seepage, and trickle irrigation systems where either
pumping lift or pressure was responsible for a large fraction of the
total energy requirements for pumping. The irrigation systems
associated with the pumping systems that we tested included travel-
ing and stationary guns, center pivots, solid-set sprinklers, pipeline
and open channel seepage systems, and drip and spray-jet trickle
systems. The primary factor limiting the type of system tested was
flow rate. With only a few exceptions, we tested systems with flow
rates up to 2400 gpm or with pipe sizes of up to 12 inches. A list
and approximate cost of the test equipment that we used in this pro-
gram is given in the Appendix of this circular.
Results and Discussion
A summary of accomplishments of the Irrigation Pumping System
Performance Testing Program is given in Table 2. During this pro-
gram 1,837 people participated in the field meetings and demonstra-
tions or in the individual field tests. A total of 247 pumping systems
were tested, while 506 pumping systems were visited by the test
team. Approximately one-half could not be tested because they re-
quired modifications by the system owners to allow them to be
The primary reasons that systems could not be tested were that
(1) water levels could not be measured in wells, and (2) flow rates
could not be measured. To measure water levels in wells required
an access port to the well casing. In many cases the access port did
not exist or was blocked so that pumping water levels could not be
measured. To measure flow rates in enclosed systems required an
access port for a pitot tube. In many of the enclosed systems, the
access port was not provided or was not properly situated to allow
accurate flow measurement.
TABLE 2. Summary of irrigation pump testing demonstrations, field tests,
1. Programs (Field Meetings and Demonstrations)
a. Number of programs 50
b. Number of counties participating in programs 64
c. Number of individuals participating in programs 1,331
2. Pumping System Performance Tests
a. Number of individuals applying for the pump test 419
b. Number of field sites visited by the test team* 506
c. Number of efficiency tests* 247
3. Number of Program Participants 1,837
(Sum of 1.c. and 2.b.)
4. Performance Ratings Measured
a. High Performance Rating 126.0%
b. Low Performance Rating 7.1%
c. Average Performance Rating 69.0%
*Not all sites visited could be tested.
For the 247 pumping systems tested, performance ratings ranged
from a low of 7.1 percent to a high of 126.0 percent. The low value
represents a waste of 93 cents ($1.00 $0.07) for each dollar of fuel
cost. In this case, the economics of repair are very readily apparent
because the pumping system performance rating relates directly to
The high performance rating of 126 percent occurred because a
supercharged diesel power unit, which used a heat exchanger rather
than radiator and fan, produced fuel conversion efficiencies that ex-
ceeded those of the Nebraska standards for a conventionally
operated system. This was one of 24 systems observed to operate
at an efficiency greater than the Nebraska standards. It
demonstrated the feasibility of exceeding the Nebraska standards
by application of currently available energy-efficient technology in
the operation of power units.
The average performance rating measured was 69.0 percent. This
indicated that the average pumping plant tested wasted 31 cents for
each dollar of fuel cost. Although a detailed analysis including pump-
ing time and repair costs would need to be made for each individual
site to determine the need for repair, the average performance rating
of 69 percent indicates that the average pumping system is probably
in need of repair or adjustment.
The frequency distribution of irrigation pumping system perfor-
mance ratings is shown in Figure 1. From this figure, it is evident
FIGURE 1. Frequency distribution of performance ratings.
Average = 69.0%
* 30- -
o Fl I l I 'III l^
0 20 40 60 80 100 120 140
Performance Rating (%)
that these data are normally distributed with a mean of 69.0 per-
cent and a standard deviation of 24.1 percent.
Pumping System Characteristics
In Table 3, pumping systems that we tested are classified by crop
type, power source, irrigation system type and water source. Most
of the systems tested (47.8 percent) were citrus irrigation systems.
These were followed by field crops (18.6 percent), nursery (13.0 per-
cent), vegetable (12.5 percent), and other (8.1 percent) systems.
Power sources were almost entirely electric motors and diesel
engines. Statewide, 55.1 percent were electric, 42.5 percent were
diesel, 2.0 percent were gasoline and 0.4 percent were propane.
The distributions of sizes of electric and diesel power units are
shown in Figures 2 and 3, respectively. From Figure 2, electric
powered pumps were found to be exponentially distributed with the
greatest number of units being small in size. The average electric
motor size observed was 25 horsepower. From Figure 3, diesel
powered pumps tested were normally distributed with an average
power unit size of approximately 58 horsepower.
TABLE 3. Summary of number of systems tested classified by crop types,
power sources, Irrigation systems and water sources.
3. Field Crops
2. Large Gun
5. Center Pivot
1. Surface Water
2. Ground Water
20 ( 8.1%)
5 ( 2.0%)
1 ( 0.4%)
FIGURE 2. Horsepower ratings and fuel use rates for the electrically
powered pumping systems tested.
0 5O 100
40 80 120
40 8 120
150 20 250 300
Electric Power Use Rate (kwlhr)
- l -
FIGURE 3. Horsepower ratings and fuel use rates for the diesel-
powered pumping systems tested.
0 50 100
I I I
0 4 8 12 16 20
Diesel Fuel Use Rate (gal/hr)
FIGURE 4. Horsepower ratings and equivalent diesel fuel use rates
for all pumping systems tested.
0 50 100 150 200 250 300
. 15 -
Figure 4 shows the distribution of power unit sizes for all pump-
ing units tested in this program. Both horsepower and fuel use rates
are given on the horizontal axis. For this figure, fuel use rate data
for all types of power units were converted to their equivalents in
gallons of diesel fuel. The average size was 40 horsepower, and the
average fuel consumption rate was 3.4 gallons of diesel fuel per hour.
Types of irrigation systems were distributed as follows: 30.0 per-
cent of the systems were sprinklers, 22.7 percent were large guns,
20.2 percent were surface (including seepage), 16.6 percent were
trickle, and 10.5 percent were center pivots.
Most systems tested pumped ground water. Statewide the propor-
tions were 87.4 percent groundwater and 12.6 percent surface water.
A primary objective of the irrigation pump testing program was
to provide irrigators with sufficient information so that they could
personally conduct performance tests on their systems using the most
economical equipment. This objective helped limit the number of
tests we could conduct. Because of the time requirements for travel,
teaching, and pump testing, an average of only 2.8 systems were
visited daily. However, upon completion of the tests we felt that
each irrigator had a basic understanding of the test procedure. Each
system manager also was provided with a bound booklet that ex-
plained the test procedure and described equipment required for per-
In formal reports made to system owners, we recommended con-
tacting repair specialists for specific information on the nature of
repair and costs. Our testing program did not allow us to determine
the exact cause of low efficiencies. In most cases, specialized test
equipment or "pulling" the pump from the well is required to make
To make individual performance tests on their pumping systems,
irrigators must measure the pump output (flow rate and head
delivered) at the same time that they measure energy input to their
power unit. The primary limitations we encountered were in measur-
ing pump discharge rates for totally enclosed systems and the pump-
ing lift (a component of the pumping head) when pumping from
To minimize difficulties when testing individual systems, irrigators
should have flow meters installed on their systems to provide con-
tinuous records of both volumes and rates of pump discharge. They
should also have their wells equipped with a means of measuring
pumping water levels. This may be done by assuring that the access
port on the well casing is free from obstructions, but it can be ac-
complished more easily by having a copper tube air line installed.
Such a system will initially be the more expensive option (approx-
imately $60 plus installation costs), but it will provide a means of
continuously monitoring both static and pumping water levels.
Survey of Program Effectiveness
To evaluate the effectiveness of the Irrigation Pumping System
Performance Testing Program in increasing pumping efficiencies and
conserving energy, an anonymous written survey of program par-
ticipants was conducted. The primary reasons for the use of the writ-
ten survey were that (1) retests or revisits of field sites would have
been expensive and (2) revisits would have detracted from time and
travel funds available for initial contacts. The written survey ap-
proach was also used because of the lag time between decisions to
repair or replace systems and the actual work. Typically, to avoid
"down-time" during the irrigation season, systems are repaired on-
ly during those times of the year when crops are not being produced,
or when irrigation is not critical. Also, repairs or replacements must
be coordinated with local repair companies, which may cause fur-
For this report, performance ratings of repaired or replaced
systems were assumed to be 100 percent. A limited number of retests
demonstrated the validity of this assumption. Three systems that
were repaired or adjusted were retested by the pump test team. In
all three cases, performance ratings after modifications equalled or
exceeded the performance standards.
In the following analyses, survey responses were assumed to be
representative of all Florida irrigators. Responses to each survey
question are discussed in the following paragraphs.
Criteria for Repair:
The first question asked if system repair, replacement, or other
changes would result from this testing program. Responses then were
correlated with the anticipated energy savings estimated by the pro-
gram participants. All respondents with performance ratings above
78 percent indicated they would continue to operate their systems
as before. Of those with performance ratings below 78 percent, 62.2
percent responded that system changes of some type would be made,
while 37.8 percent responded that their systems would be operated
The correlation between the decision to repair and the operating
cost savings anticipated from repair was clear. Of those surveyed
who had an annual expected operating cost savings of less than $440,
97.4 percent decided to continue to operate their systems as before.
Of those with expected annual operating cost savings of more than
$830, 100 percent decided to have repairs made. Of those in the
range of $440 to $830 ($635 average) annual operating cost savings,
exactly 50 percent decided to have repairs made, while 50 percent
decided to continue to operate their systems as before.
Irrigators with pumping systems having low performance ratings
but whose systems are operated relatively few hours per year decid-
ed not to have repairs made because cost savings under those
operating conditions would be minimal. Likewise, those with systems
using little energy decided to delay repairs because expected sav-
ings were minimal.
The second survey question asked cooperators how repairs would
be made if required. Most (72.2 percent) indicated that local pump
repair companies would be called upon. 27.8 percent responded that
they would personally make repairs. These responses demonstrate
the need for support from the irrigation industry, as well as the
economic potential for companies to provide pump repair services
on an active basis.
The third survey question asked cooperators who had previously
responded that their systems would be operated as before to indicate
the potential energy savings per year at which repairs would be
made. Of these, 42.1 percent responded that they would make
repairs before $1,000 per year were wasted. Fifty percent indicated
that repairs would be made if $1,000 to $3,000 per year were wasted.
Only 5.3 percent indicated that repairs would be delayed until fuel
wasted per year was in the range of $3,000 to $5,000. These data
further support the need for an active irrigation pump repair in-
dustry. They also indicate that the average irrigator is very sensitive
to the need for pumping system performance evaluations and to the
need for periodic repairs, if these data are presented in economic
terms for easy interpretation.
Other questions requested information on the nature and cost of
any repairs that were made. For systems repaired, 61.5 percent of
the repair costs were less than $500, 23.1 percent spent $500 to
$1,000, while those who replaced major system components spent
$3,000 to $5,000. The average repair cost was approximately $895.
These data indicate that repair costs, in most cases, could quickly
be recovered by energy savings resulting from improved pumping
When major component replacement is required, costs will be
greater and will require longer periods of time to recoup. The data
from this survey demonstrate the difficulties involved in determin-
ing the performance rating at which repairs should be made. In the
final analysis, that becomes a decision which the system manager
must make based upon his economic situation.
Pumping Hours of Operation:
The survey of program participants asked how many hours the
pumping systems were operated annually. These data are given in
Figure 5. The average for all systems was 1,045 hours per year.
FIGURE 5. Distribution of annual pumping times (hours of operation)
from survey of program cooperators.
0 2 3 46 7
Pumping Time (Hours x 1000)
The general effectiveness of the pump testing program was
evaluated by responses to four questions. In response to the first
question, 100 percent of the respondents indicated that the program
was effective and should be continued, including 84.7 percent who
thought the program should be continued by IFAS and 15.3 percent
who thought the program should be continued by commercial firms.
In response to another question, 76.4 percent indicated a will-
ingness to pay $100 or less for a pump test. 12.7 percent indicated
they would pay $200, while 10.9 percent were undecided.
When questioned concerning their ability to perform a pump test,
59.0 percent thought they could perform a test on their personal
pumping equipment, while 41.0 percent thought they would not be
able to test their own equipment. These data imply that, despite our
general success in teaching testing techniques, there is a need for
commercial firms to test pumps.
A final survey question asked if pump tests would become part
of an individual's irrigation management program. Yes responses
were given by 69.8 percent, although only 49.1 percent indicated
that their systems would be tested annually. The pump test program,
according to 30.2 percent, would not be a part of their irrigation
management program. Of the latter 30.2 percent, one-half had
previously indicated that they would not be able to perform an effi-
ciency test personally and, therefore, evidently also do not plan to
employ commercial firms to perform such tests. The remaining one-
half were all operating irrigation systems that were performing ef-
ficiently. The maximum energy cost wasted per year by these in-
dividuals was $450. This perhaps indicates that this group sees no
need for periodic performance tests because they have managed
their systems adequately without them in the past. This group,
however, represents only a small portion of the total number of
systems tested. Most systems are not operating efficiently, as shown
in Figure 1. The average system is operating at only 69.1 percent
of the level at which it should be operating, and based upon the
above survey responses is probably in need of repair.
Energy Savings Achieved Through Testing
Energy savings resulted from the Irrigation Pumping System Per-
formance Testing Program as irrigators made decisions to change
management practices or to repair or replace systems in response
to low performance ratings. Those savings were documented by field
data and the survey of program cooperators whose systems were
Other energy and water savings undoubtedly occurred but were
not documented. We were not able to document water-use savings
that might have occurred due to an individual's increased awareness
of his pumping costs or his irrigation system pumping rates, if that
increased awareness occurred through this program. We were also
unable to document the effectiveness of county field meetings and
group demonstrations in reducing energy and water use. A total of
1,331 individuals participated in 50 meetings and demonstrations of
the pump testing program. They received pump testing procedures
and other publications, but we had no means of evaluating the im-
plementation of those materials. Likewise, publications were
distributed through county extension offices, but without feedback
on implementation. Finally, the pump test team visited 506 field
sites, but only 247 (49 percent) were tested because of site limita-
tions. Although energy and water savings may have resulted from
partial tests and discussions with irrigators on those occasions, we
were not able to document energy savings for these individuals.
In the pump testing program, we were only able to document
energy savings for the 247 successful field tests that we conducted.
Assuming that this sample was representative of irrigation pump-
ing systems in Florida, we estimated potential energy savings for the
state's irrigation industry.
Energy savings resulting from the pump test program are analyz-
ed in Table 4. In this analysis, energy savings were calculated only
upon those 247 systems we were able to test completely. Those
systems with performance ratings above 78 percent did not result
in energy savings, our survey results indicated, because they would
continue to be operated as before. From the frequency distribution
of systems tested, those represented 35.5 percent of all systems
tested. Thus, 64.5 percent of the systems tested had performance
ratings of less than 78 percent.
TABLE 4. Documented energy savings through the pump testing program.
Average pumping performance rating measured 69.0%
Standard deviation of performance ratings 24.1%
Performance rating at which systems will be repaired 78%
(If annual fuel cost wasted exceeds $635)
Proportion of systems to be repaired 56.7%
Average performance rating of systems to be repaired 52.5%
Average annual hours of operation 1045 hrs.
Annual diesel fuel consumption by systems to be repaired 495,000 gal.
Annual diesel fuel savings per system repaired 1,680 gal.
Average annual diesel fuel savings per system tested 952 gal.
Average annual dollar savings per system repaired $2,016
Average annual dollar savings per system tested $1,142
Florida estimated average annual diesel fuel equivalent
for irrigation 76.3 million gal.
Florida potential annual energy savings if systems are repaired
using the criteria determined from our survey 20.4 million gal.
Also from our survey, 50 percent of tested systems that had per-
formance ratings lower than 78 percent, but with annual expected
energy savings in the range of $440 to $830 (average of $635), would
be operated as before. These systems represented 15.6 percent of
the total tested, and 50 percent of them were 7.8 percent of the total
tested. Thus, 56.7 percent (64.5% 7.8%) of the systems tested were
assumed to be repaired.
From the normal distribution of performance ratings observed
(Figure 1), the average performance rating for the systems to be
repaired was 52.5 percent. We assumed that repair would restore
the system to a 100 percent performance rating. Thus, documented
energy savings were based on improving the rating of each system
to be repaired by an average of 47.5 percent.
We used all field test data to evaluate the average fuel use rate
for irrigation pumping. For this report, data were transposed to
gallons of diesel fuel equivalent using the University of Nebraska
Tractor Test Laboratory performance standards for the various fuels.
This resulted in an average diesel fuel equivalent of 3.38 gallons per
hour. From our survey results, the average time of operation for each
system was 1,045 hours per year. Thus, the expected total fuel use
was more than 870,000 gallons of diesel fuel equivalent per year.
The expected annual fuel consumption by the 56.7 percent of
systems to be repaired was equivalent to 495,000 gallons of diesel
fuel, approximately 47.5 percent of which will be saved by repairs
to the pumping systems. Total fuel saved, therefore, was approx-
imately 235,000 gallons annually. This is an average of 952 gallons
for each system tested. It also represents an average fuel savings
of 1,680 gallons for each system on which repairs were to be made.
Approximating diesel fuel cost at $1.20 per gallon allows the ef-
fectiveness of this testing program to be evaluated on an economic
basis. The benefit of each test, in terms of fuel dollars saved, was
approximately $1,142. The average annual fuel dollars saved by each
system repaired was approximately $2,016.
From our survey of cooperators, the average system repair cost
was approximately $895, indicating that, on the average, repair costs
will be recovered in less than one year by savings in pumping costs.
These figures should be applied with caution, however, because
systems requiring extensive repairs or component replacement will
probably require more than one year to repay costs. Every decision
to repair a pumping system also depends upon the availability of
funds, labor, and perhaps other inputs, making it an economic deci-
sion for each system manager. Pump performance testing provides
information on potential energy savings, which is necessary for mak-
Potential Impact of Continued Testing
Assuming that the average pumping system performance rating
of 69.0 percent is representative of overall pumping system perfor-
mances in Florida, an energy savings equivalent to 23.6 million
gallons of diesel fuel per year could be realized by increasing pump-
ing plant performances to optimum levels. This is based upon an
estimated annual irrigation energy requirement equivalent to 76.3
million gallons of diesel fuel and a potential increase in efficiency
of 31 percent.
It is not economically feasible to repair pumping systems until a
critical efficiency level is reached. That critical level is specific for
each system and occurs at the point at which economic losses due
to inefficiencies in pumping, plus those of repair costs, are equal to
the potential monetary savings of increasing pumping plant perfor-
mance to optimum levels. It is not desirable (nor economically feasi-
ble) to attempt to maintain all pumping systems at maximum effi-
ciencies. Thus, the potential increase in efficiency of 31 percent is
unrealistically large. Based upon our survey responses, systems will
be repaired when performance ratings of below 78 percent are reach-
ed or when anticipated annual fuel savings exceed $635. Conse-
quently, a realistic estimate of the potential energy savings from
pump performance testing in Florida is equivalent to 20.4 million
gallons of diesel fuel annually.
Summary and Conclusions
An Irrigation Pumping System Performance Testing Program was
conducted to demonstrate to irrigators the need for testing irriga-
tion pumping systems and to teach them to test their systems. Ma-
jor components of this program were field meetings and group
demonstrations, typically conducted on a county basis throughout
the state. A total of 50 field demonstrations with 1,331 participants
Another major program component was individual pumping system
performance tests conducted for cooperators throughout the state.
The test team visited 506 field pump sites, and 247 of those were
tested. The remainder required modifications to be made by the
system owners before they could be tested. The main problems were
lack of access ports for flow measurements in enclosed systems and
for water level measurements in wells.
Performance ratings of systems tested were normally distributed,
averaging 69 percent with a high of 126 percent, a low of 7 percent,
and a standard deviation of 24.1 percent. Ratings were calculated
by comparing a system performance level with performance stan-
dards developed at the Nebraska Tractor Test Laboratories. Thus,
low ratings indicated a need for repair, while ratings above 100 per-
cent demonstrated the possibility of exceeding test standards by us-
ing energy-efficient technology.
A survey of cooperators documented the energy savings through
this program. This survey showed that the average irrigation system
is operated 1,045 hours per year, and that irrigators repair systems
when they are observed to operate at performance ratings below
78 percent, if annual fuel-cost waste exceeds approximately $635.
That information and the measured distributions of performance
ratings and fuel-use rates were used to calculate energy savings. As
a result of this program, a total energy saving equivalent to 235,000
gallons of diesel fuel per year was realized. That is an average of
952 gallons for each pumping system tested, or 1,680 gallons for each
system on which repairs were made. The benefit of each test in terms
of fuel dollars saved was $1,142 (at $1.20 per gallon for diesel fuel),
while that for each system repaired was $2,016. The average pump
repair cost was $895, indicating that it can be offset by energy sav-
ings in less than one year.
The statewide potential energy savings through the continuation
of a pump testing program is 20.4 million gallons of diesel fuel an-
nually. This was based upon the estimated consumption of 76.3
million gallons of diesel fuel annually, observed performance ratings,
and the decision to repair systems when performance ratings
dropped below 78 percent if annual fuel-cost waste exceeded $635.
Test Equipment for Irrigation Pumps
I. Fuel Monitoring
A. Diesel: Volumetric Cylinder, Tripod, Hoses,
Valves and Connectors
B. Gasoline: Positive Displacement Piston Fuel
Flow Meter (Conameter)*
C. Electricity: Volt-Amp-Power Factor Meter
D. Portable Multitester
II. Flow Measurement
A. Large Guns: Nozzles and Orifice Rings
(Rainbird, Nelson, Rainbow)
B. Surface Discharge: Low Pressure Impeller
Meters, 6- and 10-inch diameters (Sparling)
C. Enclosed Systems: Integrating Pitot Tube,
Accutube (Meriam Instrument)
III. Pressure Measurement
Standard Pressure Gauges, 1/2%
IV. Water Level Indicators
A. Electrical Water Level Indicator (Soil Test)
B. Steel Tape (200 feet)
V. Pump Speed
Portable Digital Optical Tachometer
(Graham and White)
VI. Tools and Supplies
A. Mechanic and Plumbing Tools
B. Supplies: Hose, Clamps, Pipe Fittings
VII. Safety Equipment
First Aid Kit, Electrician's Gloves, Rubber
Boots, Hard Hats, Goggles, Rain Suit
VIII. Miscellaneous Equipment
Pickup Truck Topper, Equipment Boxes,
Easels, Posters, Two-Wheel Trailer
Total Equipment Cost
*No endorsement is implied. Brand names provided for information
This publication was produced at a cost of $1175.61, or 56 cents per
copy, to inform Florida irrigators of potential energy savings through
pump efficiency testing. 5-2.1M-85
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORI-
DA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, K. R.
Tefertiller, director, In cooperation with the United States Department
of Agriculture, publishes this information to further the purpose of the
May 8 and June 30, 1914 Acts of Congress; and is authorized to pro-
vide research, educational Information and other services only to Indl-
viduals and Institutions that function without regard to race, color, sex or national ori-
gin. Single copies of Extension publications (excluding 4-H and Youth publications) are
available free to Florida residents from County Extension Offices. Information on bulk
rates or copies fdr out-of-state purchasers Is available from C. M. Hinton, Publications
Distribution Center, IFAS Building 664, University of Florida, Galnesvllle, Florida
32611. Before publicizing this publication, editors should contact this address to deter-