of the important points of fit. The more extensive use of stainless-steel
shafting has helped considerably in the prevention of rusting and pitting
of the shafts. Pump shafts are usually protected from erosion, cor-
rosion and wear at the stuffing boxes, leakage joints, and inthe water-
ways, by renewable sleeves. Shaft sleeves are usually the fastest
wearing pump part and the one most frequently replaced. Once sleeves
are worn appreciably, the packing cannot be adjusted properly. Exces-
sively worn sleeves may tear and score new packing when installed.
Thus, sleeves may require replacement when no other overhaul is nec-
essary. Shaft sleeves canbe rebuilt by welding or spraying and regrind-
ing. However, unless a reliable machining and grinding shop is avail-
able the practice isnot recommended. Normally spare shaft sleeves
are furnished with the pump and when these have been used new replace-
ments should be ordered from the manufacturer.

Stuffing boxes and packing, -- Stuffing box maintenance primarily con-
sists of packingreplacement. Althotgh this sounds simple, it must be
done correctly or the pump operation will not be satisfactory. An
illustration of a conventional stuffing box is shown in Figure 6. The
procedure for repackinga stuffing box should be as follows:

(1) Remove all old packing and clean the stuffing box.

(2) Make sure the packing is suitable for the service. The
packing used should be the type and kind recommended by the pump
manufacturer, orif this has proven unsuccessful for the service,
then a packing produced and recommended for the service bya
reliable manufacturer should be installed. There are many types
of special packings that have proven to be very excellent for a given
installation, however, eachofthese must be studied and used only
on an individual basis.

(3) Insert each ring separately, pushing it as far into the stuffing
box as possible and seating it firmly.

(4) Stagger successive rings so joints are 90° or 180° apart.

(5) Be sure sealcage, ifused, is directly under sealing liquid
connection,

(6) When proper number of rings have been inserted, install
glands and tighten gland nuts firmly by hand or light wrench pres-
sure then back off until gland is loose.

(7) New packing usually has to be run in.

(8) Allow stuffing box to have slight leakage.

Mechanical seals in lieu of conventional stuffing boxes are steadily
gaining in popularity and acceptance by the pump industry. The

17



Shop Assembly and Shop Tests

Where the size of the units permits, generally in units with motors up
to 1, 500 horsepower, pumps and motors are purchased as a unit by
the Bureau of Reclamation. After manufacture and before shipment,
each unit is completely assembled and tested inthe manufacturer's
shop. Testreports, showing actual test data and characteristic
curves, are forwarded tothe Bureau for approval before shipment of
the units. This procedure assures correct fitting of parts and proper
performance of the units, as any errors or deficiencies canbe cor-
rected before aunit is shipped. If the units are toolarge tobe tested
in the manufacturer's shop, they must be tested inthe field after
installation to determine whether all warranties have been fulfilled.

Installation

The performance of all pumping apparatus is warranted by the manu-
facturer. Whenever possible he supervises the installation and con-
ducts usually under full operating conditions, such starting tests that
are possible. Afterapumphasbeen properly installed, allnecessary
precautions have been takenin alinement, andit has been checked for
proper direction of rotation; itis ready to service andstart. Servicing
usually consists of the installation of the kind and type of lubricants
recommended by the manufacturer, checking packing and stuffing
boxes, checking for free rotation, etc.

Starting

The steps necessary to start a given pump depend uponits type and use
orinstallation. The steps required in starting many pumps are unnec-
essaryinothers. The methods used are also greatly influenced by the
performance characteristics of the pump tobe started, thatis, by the
shape of the power-capacity curve, and questions such as: Can the
pump be started against a closed or open discharge valve, etc. ? For
example, the starting procedure ofa horizontal centrifugal, bottom
suction pump would be as follows:

(1) Close discharge valve.

(2) Prime pump.

(3) Start the motor.

(4) Open valves in seal waterlines to stuffing boxes.
(5) Open discharge valve slowly.

(6) Observe leakage from stuffing boxes. Some leakage is
necessary in order to insure proper packing lubrication.

(7) Check general mechanical operation of the pump and motor.

11



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Mr. Krauss
reports that

in the 1920's,

he reshaped

the curves of

a canal on the
North Platte
Project in
Nebraska in
accordance

with the method
outlined; and dur-
ing the years he
remained on the
project, these
curves required
no further atten-
tion. He reports
similar good re-
sults on the Mirage
Flats Project in
Nebraska during
the late-1940's. From 1950 to 1957 he treated some of the curves on
the Cambridge Canal, Frenchman-Cambridge Division, Missouri River
Basin Project, Nebraska. Figure 1 shows a curve at about Station
1245 on the Cambridge Canal. The inside of the curve (right side of
photograph) was cut to a 1/2:1 slope with the excess material being
placed on the outside of the curve to form a 4:1 slope. At the time
the photo was taken, the canal had been in service for four seasons
after the bot-
tom was re-
shaped and
there has been
no maintenance
work or clean-
ing in the mean-
time. Itis
obvious that
there has been
no noticeable
amount of either
cutting on the
outer bank or
silt deposition
on the inner
bank,

By contrast,
Figure 2isa

2


principle of mechanical sealing, simply explained, is to change the
method of using a series of conventional packing rings, compressed to
the shaft or shaft sleeve by an adjustable gland, toa principle of two
antifriction mating rings, one rotating, the other stationary, that are
held together bycompression. Mechanical sealsare built ina wide
range of sizes and pressures, using intheir construction almost any
suitable machinable materialincluding, steelorits alloys, carbon,
teflon, ceramicsorfibre. The method of lubrication and the type of
lubricant depends on service and design, therefore, the reeommenda-
tions of the pump manufacturer should be followed very closely.

Bearings. --So many different variations of the two basic types of
bearings are used inirrigation pumps that it would be next to impossible
tocover themall, The most common question asked is the time interval
between relubrication periods for antifrictionorballbearings. It is
never advisable to set up a fixed time period for adding or renewing
lubricant. Rather, let the operating conditions govern. Oil-lubricated
bearings usually have anoil gage, andthe proper level should be main-
tained, Yearly replacement of oil mightbeconsiderednormal. On
grease-lubricated ball bearings a lubrication check every 3 months is
ample. Because too much grease causes more trouble than not enough,
do not allow an inexperienced operator to add grease to ball bearings.
Generally do not fill the bearing housing more than one-third full of
grease.

Complete overhaul, --Most pump manufacturers think that a pump
should not be opened or completely overhauled unless some factualor
circumstantial evidence indicates thatit shouldbedone, That is:

(1) Factual evidence means facts, like a decline in performance,
excessive noise, high bearing temperatures, motor overload, or
similar indications.

(2) Circumstantial evidence means, past experience, similar
pumps needed overhauling, etc.

An adequate store of spare parts shoyld be maintained at alltimes for
each size and type of pump used to insure a rapid restoration to service
in the event of anunexpected overhaul, Rebuilding of worn parts or
complete replacement was covered previously under the maintenance
of pump parts.

Extended storage. --To prepare a pump for extended storage, first dry
é pump thoroughly and coat castings with a light moisture-free pro-

tective coating. Remove all packing. Adequately protect all bearings
and bearing housings from corrosion and dirt. Dismantle all readily
accessible parts such as couplings, covers, etc.; dry and coat them
with a rust-preventive compound. Wet-pit pumps should be removed
from their settings, taken apart as necessary, properly coating each
part and then stored. The winter storage problem, especially of

18



Waal OF PART

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24

Figure No. 4


explicit and normally not too difficult to follow. In addition to the
effect on the pump bearings, misalinement will usually interfere
with the proper functioning of stuffing boxes and cause undue stress
on the shaft, which could cause failure due to fatigue.

Foreign matter in the pump. --The presence of foreign matter in the
pump impeller or casing can lead to serious trouble and should be
carefully prevented. The use of the trashracks supplied and the keep-
ing clean of the sumps during shutdown periods will usually prevent
this occurrence,

Water-hammer. --A sudden change in velocity of a liquid column
causes this trouble or phenomenon. It is usually serious in long
discharge lines or in discharge lines in which the velocity is rela-
tively high. In long discharge lines with bad or abrupt changes in
profile the problem of water column separation may occur. Danger-
ous water-hammer conditions are taken care of in the design stages.
Usually water-hammer conditions can be taken care of by the instal-
lation of surge tanks, air chambers, slow-closing discharge valves,
or other means. A complete discussion of water-hammer problems
are much too long to be covered here.

Conclusions

It is not possible in a discussion of this length to fully cover all of
the many problems and considerations involved in pump maintenance.
It is hoped that this discussion has acquainted you with the types and
characteristics of irrigation pumping units and some of the many
problems one must face in maintaining them in satisfactory oper-
ating condition.

%
*
*
%

20



(3) Stuffing box packing removed and examined for wear.

(4) Coupling halves disconnected and alinement checked. (Verti-
cal units checked for runout. )

(5) Drains, seal water piping, and any other piping should be
checked and flushed.

(6) Any instruments and measuring devices checked and tested
for accuracy.

Maintenance of Pump Parts

Again, because of the wide variation in types and parts, the com-
ments regarding the maintenance of pump parts are being restricted
to six basic parts.

Pump casing. --Irrigation pump casings are not normally subject to
very extensive wear. However, the water passages should be thor-
oughly cleaned and painted during a complete overhaul. Special care
and examination should be made of the cutwater or volute tongue and
the metal-to-metal fits where the stationary wearing parts seat in the
casing. New gaskets should always be available when reassembling a
pump casing because very rarely can the old one be salvaged. Fig-
ure 4 shows a cut through a typical side-suction horizontal centrifugal -
type pump. The names of the various main parts are indicated in the
upper right-hand corner of the illustration.

Impellers. --An impeller removed from a pump should be very care-
fully inspected. All surfaces should be examined for any unusual
wear or cavitation pitting. Abnormal wear or pitting may warrant a
new impeller and possibly the use of a special metal or alloy should
be investigated. This may involve considerable expense. For
instance, an impeller made of 29-9 chrome-nickle or 18-8 stainless
alloy will be about 5-1/2 times as expensive as a standard cast-
bronze impeller. Most large impellers will give years of service
regardless of pitting and wear by treating the affected areas with
"metal build-up.'' Normally a cracked impeller cannot be success-
fully repaired and therefore should be replaced. The impeller bal-
ance should be checked each time it is out of the casing during an
overhaul. The coating of impellers to protect the metal against abra-
sive materials in the pumped water has met with varying amounts of
success in most instances. The use of neoprene paint applied in sev-
eral coats has proven quite successful on one of our projects, however,
the cost of this type of application can become quite expensive. Fac-
tory application of baked phenolic coatings is being used with a fair
degree of success by a few pump manufacturers. Experiments now
being conducted in the new field of epoxies may produce a good type of
coating which can be field applied.

Wearing rings. --This applies to centrifugal and turbine-type pumps

15



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To set up and perform
the operation described
above, as illustrated in
the photograph and draw-
ing:

(1) Obtain a drill stand
that will accommodate

the electric motor to be
used to drive the rotat-
ing shaft of the purger.

(2) Mount the motor in
the drill vice provided
in the stand and ina
vertical position with
the drive end down.

(3) Attach the purger
rotor to the drill by
means of a small shaft
inserted into the drill
jaws and into the small
shaft recess drilled into
the upper end of the
purger rotor, tighten-
ing the rotor to the

drill shaft by set screws
provided for this purpose.

(4) Place the conical-shaped cup on the drill stand in line with the
purger rotor.

(5) Place the bearing to be purged into the purger cup, making
certain it is in a horizontal position.

(6) Start the electric motor and connect a grease gun, filled with
a good grade of ball bearing grease, to the purger cup and pump
grease until it starts to flow up through the sealed portion of the
bearing.

(7) Continue rotating the bearing and at 15- to 20-minute intervals,
pump additional grease into the bearing until the grease flowing
from the bearing is clean, indicating that the cleaning operation
has been satisfactorily accomplished and the bearing satisfactorily
filled.

Two rotors for the purger are shown in the drawing. The smaller
rotor is more convenient for servicing bearings of smaller diam-
ater. Should further information be desired, write the Regional

Director, Region 7, U.S. Bureau of Reclamation, Denver Federal

Center, Denver, Colorado.


photograph of a nearby curve on the Cambridge Canal about 200 feet
above the one shown in Figure 1, which was originally a normal
section with 1-1/2:1 slopes on both banks. This curve received no
attention during the 4 years preceding the time the photograph was
taken. By comparison with the "superelevated" section in Figure 1,
there has been erosion of the outer (right) bank and there is a heavy
silt deposit on the opposite bank.

From the performance of the curves shown and the performance of
a number of other curves on the Cambridge Canal which Mr. Krauss
has given the "superelevation" treatment, we must conclude that the
procedure followed by Mr. Krauss has been effective in reducing the
erosion and silting of canal curves.

A PURGER FOR SEALED BALL BEARING

Mr. Lyle H. McIntosh, Equipment Specialist, South Platte River
Projects, Loveland, Colorado, lectured on electrical pump main-
tenance at the Irrigation Operators' Workshop held in Denver, Colo-
rado, in December 1961. One of the many items of interest to those
in attendance at the meeting related to the care of sealed ball bearings.

A sealed ball bearing, according to Mr. McIntosh, requires no main-
tenance other than replacement. If a motor runs continuously, bear-
ings of this type should be changed about once a year. If the bearings
are rough when removed, the change should be made more often.
Experience is the best guide as to when the bearings should be changed.

Mr. McIntosh reported that the South Platte Projects shop had made
a device for use in servicing the sealed ball bearings, that is capable
of handling bearings having diameters of from 7/8 inch up to 7 inches
as shown in the photograph on the next page and on the drawing shown
on page 5, The device consists of a 1/4-horsepower electric motor,
to rotate the inner race of the bearing; a conical-shaped leather fric-
tion plug mounted on a shaft, to insert into the inner race to fill the
inner race hole and provide for rotation of the inner race by the elec-
tric motor; a cone-shaped cup into which the outer race will fit and
which is equipped with a grease fitting, so that grease can be forced
through the bearing as the inner race is being rotated by the motor.

With the device, anyone around the shop can give the rotating bearing
a "shot" of grease periodically until the old grease and accumulated
dirt have been flushed out and replaced with new grease. After this
treatment, the bearing is as good as new, provided there is no dam-
age to bearing surfaces, and can be used almost indefinitely.



only, as abowl liner is all that is installed ina vertical propeller or
mixed-flow pump. The type and method of attaching the stationary
ring to the casing varies considerably among manufacturers, and the
impeller ring is usually either screwed or pressed on, therefore,
before attempting to remove these parts the manufacturer's instruc -
tions must be followed. Alsothe clearance and tolerance standards
vary so widely that no definite rule canbe followed. The methods to
measure clearances are also quite varied. Figure 5 illustrates the
various types of wearing ringsused. The methods of restoring worn
clearances areas follows:

(1) No wearing rings provided:
(a) Buy new parts
(b) Build up the worn surfaces by welding, spraying, etc.
(c) Install rings if sufficient metal is present

(2) Single wearing rings:

(a) Obtain a new casing ring bored undersize. Then, true
up the impeller hub to size by turning in a lathe.

(b) Build up worn casing ring by welding or spraying so it can
be bored undersize. Then, true upthe impeller hubto size by
turning in a lathe.

(c) True up the casing ring by boring oversize, build up the
impeller hub, and machine to give correct clearance.

(3) With double rings:

(a) New oversize impeller ring and use old casing ring bored
out larger

(b) New casing ring bored under size end use old impeller ring
turned down

(c) Replace both rings

(d) Build up either ring by welding or spraying end machining
other part

shaft id t sleeves. --It is unusual to replace a shaft ona
centrifugal-type pump unless it has been damaged by the failure of
other pump parts. Onvertical pumps misalinement or improper lubri-
cant can cause extensive shaft wear making replacement necessary.
During a pump overhaul the shaft should always be examined very care-
fully for any sign of wear or surface irregularities, especially at all

16


OFFSETTING LOSSES IN PUMP CAPACITY
DUE TO WATERBORNE SEDIMENT

The Office of Assistant Commissioner and Chief Engineer of the
U.S. Bureau of Reclamation has concluded from a survey of pump-
ing plants that 76 percent of all plants surveyed pump sediment in
varying amounts all or a partofthetime. It alsowas found that 84
percent of the surveyed plants reporting detectable loss of capacity
were handling waterborne sediment at least a portion of the time.

Only 3 percent of the plants showing a decrease in capacity were pump-
ing relatively clear water.

The amount of wear on moving parts of the pump coming in contact
with silty water is proportional to the sizeof sediment. Sediment
having a diameter greater than one-half the wearing ring clearance
will cause appreciable wear. Asamatterofcomparison, previous
studies of high head turbines having indicated this deleterious size to
be 0.38 millimeter. However, the damaging size sediment for small
pumps would be more nearly in the range of 0.10 millimeter. Since
this approaches the lower limit of the sand size classification (0.0625
millimeter), it canbe reasonably assumed that all water containing
sandor larger size sediments is injurious to pumping plants. Water
used to cool bearings or packing glands should containno sediment.

The attached table lists and discusses four general flow conditions of
the water sediment complex that are being handled by pumping plants.
The conditions are classified primarily upon the size and amount of
sediments. The recommended increase in pump capacities is also
indicated. These values are based on an analysis of data collected for
pumps having capacities up to 800 cubic feet per second.

Normal wear except that attributable to sediments is usually quite
smallinwell designed pumps and should not exceed 3 percentbetween
major overhaul periods. Thus, the larger recommended figure for
increase in capacity can be considered to include normal wear whereas
the small figure does not.

The table is prepared for conditions where the anticipated period
between overhaul is 3 years for small pumps and 5 yearsor greater for
large pumps. In cases where an annual major overhaul is anticipated,
the recommended increase in capacity values is probably excessive.


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Department of the Interior
Bureau of Reclamation

OPERATION AND MAINTENANCE

EQUIPMENT AND PROCEDURES
RELEASE NO. 39

January, February and March 1962

VERTICAL CENTRIFUGAL HORIZONTAL CENTRIFUGAL

Types of Pumps

CONTENTS

Preventing Erosion and Berming of Canal Curves

A Purger for Sealed Ball Bearing
Offsetting Losses in Pump Capacity due to Waterborne Sediment

Pump Maintenance--Mechanical Components


PUMP MAINTENANCE-MECHANICAL COMPONENTS

In nearly every major irrigation project, conditions occur where
water must be lifted from its normal elevation to an elevation suitable
for serving higher land of the project. Anirrigation pumping plantis
thenrequired. The plant may vary from giants suchas the Grand
Coulee or Tracy Pumping Plants constructed by the Bureau of Recla-
mation in Washington and California, which lift water from major
rivers to serve entire irrigation systems, tothe small plant at the end
ofalateral, lifting 1 cubic foot per second aheight of a few feet.

The inspection and maintenance of mechanical components of the large
and small pumps, recommended operating practices, operating char-
acteristics of va ivus types of pumps and some of their operational
and common problems were discussed during anIrrigation Operators'
Workshop heldin Denver, Colorado, by Wesley W. Beck, Hydraulic
Machinery Branch, Division of Design, Office of Assistant Commis-
sioner and Chief Engineer, Bureau of Reclamation.

Regardless of size or amount of lift, the engineer's problem is the
same, that of selecting the proper size, number and type of pumps and
determining the most feasible plantlayout. Hydraulic laws and prin-
cipals must be observed, but the designing engineer must also make
certain that the plant is economically sound and that costly features
that add little to economy of operation are avoided.

Types of Pumps

Five general types of pumps are used in Bureau of Reclamation pump-
ingplants. Theyare: propeller, mixed-flow, vertical-turbine,
horizontal centrifugal and vertical centrifugal. Construction of the
various types is shownin Figure 1.

Vertical-turbine pumps with semienclosed impellers are sometimes
used where the pumping head is 30feetorless. However, the Bureau
requires that enclosed impellers be used in all vertical-turbine pumps
with pumping heads of over 30 feet.

Propeller, mixed-flow and turbine -type pumps operate with the pump
bowl submerged, suspended in anopen sumpby the column through
which the water from the pump is discharged.

Horizontal centrifugal pumps are set ona pump floor above maximum
water surface elevation to prevent possible flooding of the motors.
Each pump is equipped witha flared suction tube extending down into
the plant sump.

Vertical centrifugal pumps usually have intake tubes and elbows lead-
ing from the plant forebay tothe pump. The pumpcasing maybe set
above or below normal water surface and maybe setona pump floor,
or, inthe case of large units, embedded inconcrete.



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wet-pit pumps, is usually a matter of individual project experience.
Each project has very valid reasons for why they should either pull the
pumps or let them freeeze in.

Operating Problems

Mechanically, anirrigation pump isa very simple machine but it would
not seem so when reading or listening to reports from the field, From
these reports it would appear that the first step when trouble develops
is topanic, then step number two isto think real fast and quick of some-
thing someone else has done wrong to cause the trouble. Some great
stories and theories of a fantastic nature develop from that point.

There are three basic areas in which pump troubles canoccur. Oneis
hydraulic, one is mechanicaland the last is electrical. The hydraulic
problems can be divided into two groups, the first being suction and
intake problems before the liquid passes through the impeller and the
second being system problems after the liquid has passed through the
impeller, Figure 7 is a pump trouble-shooting check list to be used to
try tolocate trouble inapump. A schedule or list of pump operating
symptoms are shown along witha group of possible causes for each
symptom. Whenisolated the cure for each trouble is usually self-
evident. The basic idea for this check list was prepared by an engineer
of one of the larger pump manufacturers in 1960. Startingfrom this
idea it has been reworked toa single drawing size for inclusion inthis
discussion,

Common Pump Troubles

Pump noise. --Basically two types of noise ina pump are expressed by
the words "crackling" and "rumbling." A "crackling" noise usually
means suctiontroubles, whichare causing the pumptocavitate. This
condition exists in flowing liquids when the pressure at any point falls
below the vapor pressure of the liquid at the prevailing temperature.
To check this simply throttle the discharge from the pump; if the crack -
ling stops, the diagnosis is correct. Tocorrect this symptom one
must find a way of increasing the pumps NPSH (Net Positive Suction
Head), The other noise symptom "rumbling" means troubles inthe
discharge system usually caused by operation of the pump at partdoad
capacity or by operating the pump at capacities well in excess of those
for which it was designed. The correction for this symptom is rather
obvious,

Direction of rotation. --Ina centrifugal-type pump the reverse direc -
tion of rotation, commonly produced by reverse mounting of the impeller
on the shaft, causes a large drop inhead and capacity, a great rise in
power demand, anda large loss inefficiency.

Misalinement of parts. --Misalinement troubles should not be per-
mittedtoarise. The manufacturer's instructions are usually very

19



€ Pump Shoft-~..

_--7Pump casing--__

-

A
Wearing ring-- J
—-~--Impeller------ y
NO WEARING RINGS SINGLE RING
ON IMPELLER

€ Pump Shaft~

_--7-Pump casing.

SINGLE RING DOUBLE RINGS
ON CASING

TYPES OF WEARING RINGS

Figure No. 5

25



PREVENTING EROSION AND BERMING OF CANAL CURVES

The erosion of the outside of canal curves in earth sections com-
bined with the formation of berms or silt bars on the inside of the
curves constitutes one of our more troublesome O&M problems

in the maintenance of canals and laterals. This erosion and depo-
sition process is, also, one which aggravates itself rather than
reaching a balanced condition. That is, increased erosion tends
to throw more water towards the outside of the curve, where the
water is deeper, and this aggravates the erosion. As more mate-
rial is eroded, there is more to deposit on the inside of the curve
thus throwing more of the water towards the outside. This process
is not likely to develop a dangerous condition overnight; but over a
period of time, the outer bank is weakened and the canal section
assumes such shapes that it must be corrected.

Mr. Fred C. Krauss, Chief, Nebraska Irrigation Maintenance
Branch in the Bureau Office at McCook, Nebraska, has tried what
appears to be a good solution to this problem and his solution is
being passed on to those who may wish to try his corrective meas-
ures,

In cleaning a canal that is badly eroded on the outside of the curve
with a silt deposit on the inside, Mr. Krauss moves the silt directly
across the canal into the eroded area and even overexcavates the
inside of the curve, so that the slope of the inside bank is 1/2:1,

or flatter if that appears to be too steep. However, Mr. Krauss
believes the siope should not be flatter than 3/4:1. The material

is used to build up the outside slope to a 4:1 slope, so that the final
section is modified similar to that shown in the sketch below.

_--7Shallow water
Fa reduces velocity

Outside of curve-~

Because the amount of silt in canal water varies and because of
differences in the ability of soils to resist erosion and differences in
canal velocities, the suggested slopes may not be exactly the right
ones to use in all instances, but this can be determined by trial.

The degree of curvature will also have some influence on the slopes
that should be used. This procedure should not be attempted ina
canal lined with a buried membrane as the overexcavation would
very likely result in removal of or damage to the membrane.



If the pump is to be started against a closed check valve with the dis-
charge gate valve open, the steps would be the same, except the dis-
charge gate valve would be opened some time before the motor is
started. The pump manufacturer's instructions usually give a
detailed procedure for starting a given pumping unit.

Stopping

The procedure for stopping a pump also depends on the type and use;
for example, the procedure to stop the pump used in the previous illus-
tration wouldbe as follows:

(1) Close discharge gate valve.
(2) Stop the motor.
(3) Close valves in seal waterlines to stuffing boxes.

The manufacturer's operating instructions usually give adetailed
procedure for stopping a given pumping unit.

Discharge Valves

In asingle unit plant with short discharge lines the flap gate in the dis-
charge structure is all that is needed or required for discharge regula-
tionor control. However, with more than one unit or with long dis-
charge lines other means must be used to prevent recirculation, etc..
One of the following three systems is most generally used inthe dis-
charge lines from centrifugal and vertical turbine-type pumps:

(1) Check valve with associated guard valve. --This is used in
relatively small discharge lines and where Simplicity of operation
is desired.

(2) Electrically operated discharge valves. --These are suitable
for any size and type of installation but become inoperable in the
event of a power failure.

(3) Hydraulic cylinder valves. --These are suitable for any size
and type of installation and when used in conjunction with an accum-
ulator tank they ''fail-safe'' in the event of any malfunction of the
pumping unit.

Valves in the discharge lines from mixed -flow or propeller-type pumps
are usually avoided. The most satisfactory arrangement is tohavea
separate discharge line with flap valve on the end of each pump.

Throttling

Discharge capacity of centrifugal and vertical turbine pumps can be
reduced simply and usually safely by throttling the discharge. In

12



Maintenance and Inspection

Because of the wide variationintypes, sizes, parts, and design ofirri-
gation pumps, comments regarding maintenance and inspection are
necessarily rstricted to the most commonly used types and sizes. The
manufacturer's instruction books shouldbe very carefully read and
studied before attempting to start, operate or service any given pump-
ing unit. However, inall plants daily, semiannual and annual inspec-
tion and maintenance are required.

In large attended installations an hourly record is kept of the equipment.
Card files are maintained and any change in unit characteristics readily
found. However, mostirrigation pumping plants do not fallin this class,
therefore, the daily inspection usually consists of anoperator, andin
some instances the ditchrider or watermaster, visiting the plant twice
daily. He checks the lubricant, bearing temperatures (usually by feel),
and would probably note any change in sound of a running pump or vibra-
tion ofthe unit. A sudden rise inthe temperature of a bearing or stuffing
boxis more indicative of trouble than one which constantly runs warmer
than usual.

Inirrigation pumping plants the semiannual inspection is somewhat
of a misnomer in that we usually have a complete shutdown of the pumps
anywhere from 3 to 5 months during the winter season. Roughlyafter
about 1, 000 hours of operation or 6 weeks of continuous pumping a so-
called semiannual inspection should becarriedout. This inspection
should consist of:
(1) Stuffing box:
(a) Free movement
(b) Clean and oil gland bolts and nuts
(c) Inspect packing to see if it needs replacement
(2) Check pump and drive alinement and correct ifnecessary

(3) Drain and refill oil-lubricated bearings

(4) Check grease lubricated bearings for correct amount and
kind of grease

A thorough inspection of each pumping unit should be made once a year
by anexperienced mechanic and crew. In addition to the semiannual
inspection the following should be checked annually:

(1) Bearings should be removed, cleaned, and examined for wear.

(2) Bearing housings cleaned.

14



OPERATION AND MAINTENANCE
EQUIPMENT AND PROCEDURES
Release No. 39

January, February, and March 1962

INTRODUCTION

Several of the articles appearing in this issue of the bulletin
describe procedures used in the operation and maintenance of irri-
gation equipment and systems by project operators in attendance

at the Irrigation Operators' Workshop in December 1961. In some
instances, there was a request for additional information not then
available in published form. Information requested on other opera-
tion and maintenance practices and procedures will be included in
future releases of the bulletin, as they can be prepared.

This bulletin, published quarterly, is circulated for the benefit of
irrigation project operation and maintenance people. Its principal
purpose is to serve as a medium of exchanging operation and main-
tenance information. It is hoped that the labor saving devices or
less costly equipment developed by the resourceful water users
will be a step toward commercial development of equipment for use
on irrigation projects in a continued effort to reduce costs and
increase operating efficiency.

To assure proper recognition of those individuals whose suggestions
are published in the bulletins, the suggestion number as well as

the person's name is given. All Bureau Offices are reminded to
notify their Suggestions Awards Committee when a suggestion is
adopted.

Division of Irrigation Operations
Office of Assistant Commissioner and Chief Engineer

Denver, Colorado



€ ‘ON Pan3ry

WV¥OVIC NOILOIJT3S dWNd

“S.¥'0 ‘ALIOWaV
0001 008 oof _oos _—om1_—cop a» of ow. o

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41334 ‘OW3H W1oL

201

23



Cover Sheet. Irrigation pumps used by the Bureau of Reclamation
on projects in the 17 western states vary from giants such as those
used on the Columbia Basin Project at Grand Coulee Dam which
have a capacity of 1, 600 cubic feet per second with a lift of 280 feet.
to those required at the end of a small lateral to lift 1 cubic foot of
water per second a height of a few feet. The five general types of
pumps employed for this work are shown. 328-701-7609

2


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26



Typical Characteristics

Typical characteristics of the various types of pumps are shownin
Figure 2. The characteristics of the vertical-turbine-type pump are
essentially the same as forthe centrifugal. Characteristics of pumps
in each type may vary considerably, however, the general shapes of
the curves willbe similar to those shown.

The brake horsepower input and head of mixed -flow and propeller
pumps increase sharply as the flow from the pumpsis decreased, and
at zero flow the pumping head and brake horsepower input amount to
several times the values at designflow. These characteristics make
these types of pumps unsuitable for installations where throttling of
the pumpsis required. They are generally used for comparatively
large capacities at low pumping heads and operate most satisfactorily
with a short discharge line, preferably with no valves inthe line other
thana flap valve onthe end. If regulation ofthe discharge is desired,
it is accomplished by bypassing part of the discharge back to the sump
rather than by throttling.

The brake horsepower input of centrifugal andturbine-type pumps, on
the other hand, decreases as the flow from the pumpis decreased, and
at zero flow the head of the pumpisnotexcessive. These characteris-
tics make these types of pumps adaptable for many kinds of installations.
They can be throttled to provide the desired flow, witha corresponding
saving inhorsepower input, and with little loss in pump efficiency.
They are started against a closed discharge valve, thus simplifying
starting procedure when two or more pumps are manifolded into one
discharge line. Vertical turbine-type pumps are well adapted for
small pumping plants where extensive regulation of flow is desired.
They have been used by the Bureau in the smallest sizes at pumping
heads as low as 10 feet, and in sizes up to 25 cubic feet per second at
pumping heads as highas 275 feet.

In selecting the type of pump to be used, pumps normally available
from manufacturers should be considered inorder to avoid units that
will involve specialdesigns. Figure 3 shows a PumpSelection Dia-
gram that has been developed by the Bureau based on the types of pumps
used in existing installations. The diagram shows the range of capacity
and head over which each type of pump would normallybe selected. To
illustrate, the diagram shows that for vertical turbine -type pumps the
normal head range is between 10 and 275 feet and the capacity range can
vary from 1.1 cubic feet per second to about 25 cubic feet per second.
In those areas not covered by a specific pump type we are inthe realm
of special design and the type of pump selected will depend upon several
factors other than head and capacity, suchas, overall efficiency, plant
layout, pump setting, operating restrictions or requirements, etc.

10


this manner, artificial friction losses are introduced by throttling, and

a new head curve is obtained which intersects the head-capacity curve
atthe desiredflow. By an examination of the brake horsepower curves
in Figure 2 we can determine which type of pump may be safely throttled
without exceeding the motor horsepower limitations of the prime
movers. Normally, throttling of a centrifugal type of pump to 50 per-
cent of rated discharge can be done for extended periods without harm-
ful effect to the pump.

When throttling below the 50 percent limitation it is usually imperative
to consult the manufacturer to find if the pump is suitable for operation
at this reduced flow. Such operation usually means heavier shafts,
possibly a double-volute in the case of centrifugal type pumps, to with-
stand the increased radial thrust, etc.

Another problem arises when a pump is operated for any length of time
against a closed discharge, that is the thermodynamic problem caused
by the heating of the liquidinthe pumpcasing. The difference between
the horsepower input to the pump and the water horsepower developed
by the pumpislostinthe unit. These power losses are converted into
heat and transferred to the liquidin the pump. When operating at shut-
off, power losses equal shutoff horsepower. Low-capacity, high-head
pumps should be watched most closely for this occurrence.

Power Failures

If a check valve protects a pump from reverse flow after power failure,
there is generally no reason why the pump should not be restarted imme-
diately upon restoration of power. The electrical control used at the
plant will determine if this will be automatic or if an operator must visit
the plant to get itback onthe line. Withboth the electrically operated
and hydraulic-cylinder-operated discharge valves, limit switches are
used which require that the valves must be in the closed position before
the electrical circuit to the motor may be energized after a power inter-
ruption. Again, the electrical control used will determine if the restart
willbe automatic or manual. A pump that requires priming before start-
ing generally cannot be restarted automatically after a power failure
because of the possibility of loss of prime.

Dry Operation

Most pumps have close running clearances and cannotbe run dry at all,
or in some cases for longer than a few seconds without being seriously
damaged. A centrifugal pump with excessive clearances between the
stationary and rotating elements couldbe run dry for an indefinite period
but even then the risk of galling and seizure is present.

13