Viking Pump TSM420 User Manual

Electronic copies of the most current TSM issue can be found on the Viking Pump website at www.vikingpump.com

TECHNICAL SERVICE MANUAL

HEAVY-DUTY REFRIGERATION AMMONIA PUMPS

CONTENTS

Installation, General Comments . . . . . . . . . . . . 1

Pump Installation . . . . . . . . . . . . . . . . . . . . 3

Preventative Maintenance . . . . . . . . . . . . . . . 4

Safe Practices. . . . . . . . . . . . . . . . . . . . . . 5

Venting the Pump . . . . . . . . . . . . . . . . . . . . 5

Disassembly . . . . . . . . . . . . . . . . . . . . . . 7

Assembly . . . . . . . . . . . . . . . . . . . . . . . .10

Thrust Bearing Adjustment . . . . . . . . . . . . . . .11

Installation of Carbon Graphite Bushings . . . . . . . .12

Pressure Relief Valve Instructions . . . . . . . . . . 12

Troubleshooting. . . . . . . . . . . . . . . . . . . . .15

Ammonia . . . . . . . . . . . . . . . . . . . . . . . .16

INTRODUCTION

The illustrations in this manual are for identification purposes
only and cannot be used for ordering parts. Obtain a parts
list from the factory or a Viking® representative. Due to the
nature of the pump and the close manufacturing tolerances,
certain replacement parts are only available in assemblies.
Always give complete name of part, part number or material
with model number and series number of pump when ordering
repair parts. The pump or pump unit model number and serial
number are on the nameplate.

In the Viking® model number system, the basic size letters
are combined with the series (4925) indicating either an
unmounted pump or mounted pump unit.

Model Chart Number

UNMOUNTED UNITS

MECH. SEAL

HL4925

K4925
KK4925
LQ4925

LL4925

This manual deals exclusively with Series 4925 Heavy Duty
Refrigeration Ammonia Pumps. Refer to Figures 1 thru 24
for general configuration and nomenclature used in this
manual. NOTE: DO NOT OPERATE SERIES 4925 PUMPS

AT SPEEDS HIGHER THAN THOSE STATED IN CATALOG
SECTION 420 (Series 4925 Heavy Duty Refrigeration

Ammonia Pumps).

NOTE: Single reservoir sight glass is standard. Images are
shown with optional reservoir fittings.

Units are designated by the
unmounted pump model numbers
followed by a letter(s) indicating
drive style.

P = Commercial Speed Reducer

SECTION TSM 420

PAGE 1 Of 18

SERIES 4925

SIZES HL

-

LL

ISSUE E

FIGURE 1

Series 4925 Unmounted Pump

INSTALLATION,
GENERAL COMMENTS

Consideration of the following points during design and
installation of the system will help insure successful operation
of the Viking Refrigeration Ammonia Pump.

1. SUBMERGENCE - Submergence is the head of liquid
ammonia above the centerline of the pump suction port.
A liquid head is necessary to keep the ammonia from
flashing as it goes into the pump. The minimum liquid
head or submergence for good pump operation is 4 feet;
this is assuming a large, short suction line.

2. SUCTION LINE - A large, short suction line is necessary
for good operation. A good suction line:

2.1. is a suction line that is at least one size larger than
the pump suction port connection,

2.2. is connected to the pump by an eccentric reducer
(with the offset or eccentric portion down) when suction
to the pump is horizontal,

2.3. is as short as practical for the installation,

2.4. has no strainer (sometimes a temporary strainer is

used during start up to keep weld beads, etc., from going
through the pump),

2.5. uses a long sweep elbow if any elbow is
unnecessary,

2.6. has a full flow shut off valve,

2.7. and is fully insulated to prevent head pickup.

3. INSULATION - Insulation on the suction line and on the

pump helps reduce the amount of heat pickup by the
heat pickup by the liquid ammonia.

VIKING PUMP, INC. • A Unit of IDEX Corporation • Cedar Falls, IA 50613 USA

SAFETY INFORMATION AND INSTRUCTIONS

IMPROPER INSTALLATION, OPERATION OR MAINTENANCE OF PUMP MAY CAUSE SERIOUS INJURY
OR DEATH AND/OR RESULT IN DAMAGE TO PUMP AND/OR OTHER EQUIPMENT. VIKING’S WARRANTY
DOES NOT COVER FAILURE DUE TO IMPROPER INSTALLATION, OPERATION OR MAINTENANCE.

THIS INFORMATION MUST BE FULLY READ BEFORE BEGINNING INSTALLATION, OPERATION OR
MAINTENANCE OF PUMP AND MUST BE KEPT WITH PUMP. PUMP MUST BE INSTALLED, OPERATED
AND MAINTAINED ONLY BY SUITABLY TRAINED AND QUALIFIED PERSONS.

THE FOLLOWING SAFETY INSTRUCTIONS MUST BE FOLLOWED AND ADHERED TO AT ALL TIMES.

Symbol
Legend :

!

!

!

!

!

WARNING

!

WARNING

Danger - Failure to follow the indicated

instruction may result in serious injury

!

or death.

BEFORE opening any liquid chamber (pumping
chamber, reservoir, relief valve adjusting cap fitting,
etc.) be sure that :

● Any pressure in the chamber has been completely
vented through the suction or discharge lines or
other appropriate openings or connections.

● The pump drive system means (motor, turbine,
engine, etc.) has been “locked out” or otherwise
been made non-operational so that it cannot be
started while work is being done on the pump.

● You know what material the pump has been
handling, have obtained a material safety data
sheet (MSDS) for the material, and understand
and follow all precautions appropriate for the safe
handling of the material.

BEFORE operating the pump, be sure all drive guards
are in place.

DO NOT operate pump if the suction or discharge
piping is not connected.

DO NOT place fingers into the pumping chamber or
its connection ports or into any part of the drive train
if there is any possibility of the pump shafts being
rotated.

DO NOT exceed the pumps rated pressure, speed, and
temperature, or change the system/duty parameters
from those the pump was originally supplied, without
confirming its suitability for the new service.

BEFORE operating the pump, be sure that:

● It is clean and free from debris

● all valves in the suction and discharge pipelines

are fully opened.

● All piping connected to the pump is fully supported

and correctly aligned with the pump.

● Pump rotation is correct for the desired direction

of flow.

WARNING

WARNING

!

WARNING

!

!

!

WARNING

!

WARNING

Warning - In addition to possible serious

injury or death, failure to follow the
indicated instruction may cause damage
to pump and/or other equipment.

INSTALL pressure gauges/sensors next to the
pump suction and discharge connections to monitor
pressures.

USE extreme caution when lifting the pump. Suitable
lifting devices should be used when appropriate. Lifting
eyes installed on the pump must be used only to lift
the pump, not the pump with drive and/or base plate.
If the pump is mounted on a base plate, the base plate
must be used for all lifting purposes. If slings are used
for lifting, they must be safely and securely attached.
For weight of the pump alone (which does not include
the drive and/or base plate) refer to the Viking Pump
product catalog.

DO NOT attempt to dismantle a pressure relief valve
that has not had the spring pressure relieved or is
mounted on a pump that is operating.

AVOID contact with hot areas of the pump and/or
drive. Certain operating conditions, temperature
control devices (jackets, heat-tracing, etc.), improper
installation, improper operation, and improper
maintenance can all cause high temperatures on the
pump and/or drive.

THE PUMP must be provided with pressure protection.
This may be provided through a relief valve mounted
directly on the pump, an in-line pressure relief valve,
a torque limiting device, or a rupture disk. If pump
rotation may be reversed during operation, pressure
protection must be provided on both sides of pump.
Relief valve adjusting screw caps must always point
towards suction side of the pump. If pump rotation is
reversed, position of the relief valve must be changed.
Pressure relief valves cannot be used to control pump
flow or regulate discharge pressure. For additional
information, refer to Viking Pump’s Technical Service
Manual TSM 000 and Engineering Service Bulletin
ESB-31.

THE PUMP must be installed in a matter that allows
safe access for routine maintenance and for inspection
during operation to check for leakage and monitor
pump operation.

SECTION TSM 420 ISSUE E PAGE 2 OF 18

4. PUMP SPEED - The slower the operating speed the
longer the longer the service life. This is particularly true
on refrigeration ammonia pumps where:

4.1. the liquid has virtually no lubrication value or film
strength to prevent surface to surface contact and,

4.2. the heat generated by friction can cause the ammonia
to vaporize, which in turn causes cavitation.

5. TESTING - All Viking Ammonia pumps are tested prior
to shipment, but it is good practice to pressure test the
pump along with the rest of the system before adding
the ammonia. Shipping, storage and installation all have
strange ways of producing detrimental effects on sound
equipment.

6. SYSTEM CLEANLINESS - Ammonia is a good
detergent, as such it has a tendency to remove all
the dirt, pipe scale, weld beads, and loose or foreign
material in the system. Unfortunately not all of this
material settles out in traps or can be caught in strainers;
and as a result, a considerable amount goes through the
pump, the abrasive solids going through the pump will
of course cause excessive wear during the start up of
a new system, thus the cleaner a new system is before
start up, the less wear and trouble with the pump.

7. STAND BY EQUIPMENT - Stand by equipment is always
good insurance when possible breakdown of any single
piece of equipment could be jeopardise the operation of
the entire system. Often on circulating, two pumps are
used, with operation of the pumps alternated by day or
week. Alternating operation of the pumps is not always
considered the best practice since both pumps may both
wear out at the same time. If operation of the pumps
is not alternated, the stand by pump should be run for
several hours at least once a month to make sure it is in
good operating condition. Sometimes on large systems
three pumps are used, two running continuously, with
the third for use as a standby and for peak loads.

PUMP INSTALLATION

One of the most important considerations on any circulation
Refrigeration Ammonia pump installation is proper design of
the pump inlet line. Refrigeration Ammonia, when stored in
a closed container, will exert a pressure within the container
equal to its saturated vapor pressure. The saturated pressure
of a liquid may be defined as the pressure at which both liquid
and vapor exist in equilibrium in the same container. The
vapor pressure has a different value for each temperature.
The saturated vapor pressure of water at 212ºF. (waters
boiling point) is 14.7 PSIA. In other words, when handling
Refrigeration Ammonia, we are handling a liquid, which is at its
boiling point. A slight reduction in the pressure being exerted
on the liquid will cause boiling and thus vapor formation.

With this information in mind let us examine figure 2, which
illustrates one of the most important considerations when
installing a pump to handle Refrigeration Ammonia.

The pressure (P1) in the accumulator is equal to the
saturated vapor pressure of the ammonia. When the pump
is not running the pressure (P2) at the pump inlet is equal to
the tank pressure (P1) plus the static head (H). P2 = P1 + H

ACCUMULATOR

PUMP

FIGURE 2

As soon as the pump started and the liquid begins to flow, the
pressure at the pump (P2) will drop by an amount equal to
the pressure loss in the piping between the accumulator and
the pump. When liquid is flowing: P2 = P1 + H - (pressure
loss in the piping).

In order to have an installation in which the pump handles all
liquid and no vapor, the pressure drop in the piping must be
equal to or less than the static head (H) on the pump inlet. If the
piping loss is greater than the static head, the liquid ammonia
will start to boil or vaporize and the pump will be required to
take in a mixture of liquid and vapor. Since a given weight of
vapor takes up a much greater volume than the same weight
of liquid, handling both liquid and vapor will reduce the liquid
output from the pump. The vapor is compressed back to a
liquid on the discharge side of the pump causing it to be noisy
and to wear rapidly.

Values for pipe friction losses for calculating suction line
pressure drop can be found in refrigeration hand books.

Since Viking pumps are of the positive displacement type, be
sure that there is no obstruction in the discharge line and that
all valves are in operating position before starting the pump.
Factory assembled port will have right hand port suction and
top port discharge unless otherwise specified. Port location
is determined by looking at shaft end of pump. The pressure
relief valve on the pump provides over pressure protection.
Return-to-Tank pressure relief valves should be mounted on
the discharge side of the pump. Internal type pressure relief
valves should be mounted with the cap pointing towards the
suction side of pump. Also see formation under Relief Valve
Instructions page 12. The Viking pump mounted return-to­tank pressure relief valve (see Figure 16, PAGE 11 & Figure
17, page 12) is fitted with a pressure relief plug to keep a
valid off return line from building up excessive pressures.

SECTION TSM 420 ISSUE E PAGE 3 OF 18

DANGER !

Include provision for a pressure relief
device in any part of a pump and piping
system that can be valved off and, thus,
completely isolated. Cold liquid ammonia
when isolated will, as it warms up to
room temperature, expand and exert
tremendous pressures which may rupture
the pump or piping unless relieved.

See Viking Technical Service Manual TSM000 for additional
general installation information.

PREVENTATIVE MAINTENANCE

Series 4925 pumps are designed for long, trouble free
life under a wide variety of application conditions with a
minimum of maintenance, however the following should be
considered:

1. LUBRICATION - 1.1. Periodic external lubrication should
be applied slowly with a hand gun at all lubrication
fittings.
A good quality of general purpose grease is satisfactory
in the majority of cases, however, applications involving
very low temperatures may require other types of
lubricants. suggested frequency of lubrication is once
every 500 hours of operation. Do not over grease. Consult
the factory if you have specific lubrication questions.

1.2. Double Mechanical Seal Reservoir: After replacing
seal and/or before letting ammonia into new or rebuilt
pump, fill oil reservoir with one pint of light Refrigeration
Oil.

Before opening valves and allowing ammonia to fill the
pump be sure the hand valve on the reservoir, shown in
figure 8, is open.

Change the oil in your double seal pump reservoir after
first 200 hours of operation and then every 1000 hours
by the method mentioned below:

A. Stop pump and close hand valve on oil reservoir, see

figure 8.

B. Remove ½ inch NPT oil filler plug in top of reservoir

carefully and allow the small amount of ammonia trapped
in the reservoir to vent.

C. Open oil drain plug and allow old oil to drain.

D. Replace oil drain plug and fill reservoir with light

Refrigeration Oil to within 1½ inch of the top
(approximately 1 pint).

E. Replace ½ inch NPT oil filler plug in top of reservoir.

F. Open hand valve.

G. Wait one minute then star the pump and allow it to run

from two to three minutes before the liquid is introduced
onto the pump. This will allow the seat to seal itself
properly before the pressure is applied.

NOTE: If your pump has an automatic snap on filler valve
arranged similar to that shown in figure 3, it is not necessary
to stop the pump to add oil to the reservoir. Merely connect
lubrication pump to automatic filler valve. Open manual valve
and fill reservoir with light Refrigeration Oil to approximately
1½ inch from the top. Close manual valve and remove
lubrication pump from filler to valve. To change oil: proceed
as indicated in steps A thru G except vent pumping chamber
to atmosphere before changing oil.

2. END CLEARANCE ADJUSTMENT - After long term
operation it is sometimes possible to improve the
performance of pump, without major repair, through
adjustment of end clearance of the pump. Refer to

instruction under thrust bearing Adjustment, page
11, for information regarding this procedure.

MANUAL VALVE

FILLER VALVE

FIGURE 3

DANGER !

Be sure ammonia pressure in pump is
not above 5 PSIG when filling reservoir.
If pressure is higher, pumping chamber
should be bled down to reduce pressure
to 5 PSIG or below. (Before bleeding
pump, read SAFE PRACTICES page 4 and
VENTING THE PUMP page 4). Pressure
above 5 PSIG in the pump may cause inner
seal seat to be unseated or may force the
faces of the inner seal apart allowing any
dirt accumulated around the inner seat to
be forced between the faces. When the
pump is started the seal may leak.

SECTION TSM 420 ISSUE E PAGE 4 OF 18

3. CLEANING THE PUMP - It is good practice to keep the
pump as clean as possible. This will facilitate inspection,
adjustment and repair work to help prevent over looking
a covered grease fitting.

4. STORAGE - If the pump has to be stored or not used for
an appreciable length of time it should be drained and
a light coat of lubricating and preventive oil should be
applied to the internal parts. Lubricate all fittings.

MAINTENANCE

IMPORTANT: READ THE FOLLOWING BEFORE
REMOVING A PUMP FROM AN AMMONIA SYSTEM OR
BEFORE STARTING REPAIR WORK ON A PUMP.

DANGER !

Before opening any Viking pump liquid
chamber (pumping chamber, reservoir,
etc.) Be sure:

1. That any pressure in the chamber has
been completely vented through the
suction or discharge lines or other
appropriate openings or connections.

(See detailed procedure for venting

the pumps, pages 4, 5 and 6).

2. That the driving means (motor,
turbine, engine, etc.) has been
“locked out” or otherwise made non­operational so that it cannot be
inadvertently started while work is
being done on the pump.

3. That you know what liquid the
pump has been handling and the
precautions necessary to safely
handle the liquid. Obtain a material
safety data sheet (MSDS) for the
liquid to be sure these precautions
are understood.

Failure to follow above listed
precautionary measures may result in
serious injury or death.

AMMONIA (Anhydrous Ammonia, NH3)

Ammonia is a colorless gas or liquid, has a pungent odor, as
a gas is lighter than air, is easily liquefied by pressure alone
and is very soluble in water. It boils at -28º F.; vapor pressure
is 16 PSIG at 0º F., 45 PSIG at 30º F., 93 PSIG at 60º F., and
138 PSIG at 80º F.

A listing of safe practices and equipment are available from
many sources, including those listed below. A copy of such
a listing and safe practices and equipment should be made
available to everyone working where ammonia is used.

Safety Department. The Safety Department of any company
using ammonia should have information about the basic
safety practices and equipment to use when working with
ammonia. The supplier of the ammonia should always have
the same information.

ANSI - American National Standard Institute, Inc.
1430 Broadway
New York, New York 10018
Bulletin ANSI-K61.1

CGA - The Compressed Gas Association, Inc.
500 Fifth Avenue
New York, New York 10036
Pamphlet G-2 on Anhydrous Ammonia

IIAR - International Institute of Ammonia Refrigeration
1 Illinois Centre
111 East Wacker Drive
Chicago, Illinois 60601

The above references give specifics on safety practices and
equipment. In addition to those, some general precautions
include:

WORK CAREFULLY.

DO NOT HURRY.

LOOK AT ANY PRESSURE GAUGES TO DETERMINE
CONDITIONS IN THE SYSTEM.

HAVE PLENTY OF WATER AVAILABLE.

VENTING THE PUMP

1. Stop the pump (some maintenance people close the

inlet shutoff valve before stopping the pump; but, this is
not recommended practice).

2. Close the inlet (suction) side shutoff valve. A in figure 4.

3. Close the discharge side shutoff valve. B in figure 4.

ACCUMULATOR

SEE THE “ * ”

ON PAGE 6.

DANGER !

Exposure to ammonia causes intense
irritation to the surface tissue of the eyes,
nose, throat and lungs. Exposure to high
concentrations of ammonia may blind,
burn, strangle or kill.

SAFE PRACTICES

Basic safety practices and equipment should always be used
when working with ammonia. Only personnel familiar with
ammonia systems should work on these pumps.

4’

PUMP

FIGURE 4

Schematic of Piping and Valves For a Liquid Ammonia

Recirculating Pump in a Refrigeration System

SECTION TSM 420 ISSUE E PAGE 5 OF 18

4. Close all other shut off valves in lines connected to the
pump. Typical would be valve C in line E* in figure 4
from the pump mounted return-to-tank type relief valve
to the accumulator or the valve from an in line mounted
safety relief valve to the accumulator or the valve in a
pressurizing line 2 in figure 5, from the high pressure
side of the system to the pump double sea oil reservoir.

5. Allow ice on pump to melt. This process can be speeded
up by running cold water over the pump.

Start the venting process as soon as convenient after the
ice has been removed from the pump. This will prevent
venting the ammonia at the lower pressures of a cold
pump rather than at the high vapor pressures in a room
temperature pump.

For systems with vent (purge or bleed) valves (e.g. D
figure 4) go to step 6; for systems without a vent valve,
go to step 7.

6. A hose should be connected to any vent valve (e.g. D
in figure 4) in the blocked off portion of the system. The

open end of the horse should be placed under water in a
tank containing at least 10 times as much water as there
is ammonia in the blocked off portion of the system or the
end of the hose should be lead to a safe, well ventilated
area. After the hose has been attached to the open end
properly located, then open the vent valve. Check the
open end of the hose to make sure the ammonia is
venting. After ammonia has stopped venting, continue
with step 8.

②

⑤

⑥

If there is no line from the bracket to the reservoir, carefully
loosen the pipe plug (drain), 3 in figure 6 towards the
bottom of he bracket. This pipe plug is found only on the
“K”, “KK”, “LQ” and “LL” 4925 pumps. The small “HL”
4925 does not have one. When working on the “HL”
4925 that has no trouble fitting between the bracket and
double seal oil reservoir, carefully loosen the pipe plug,
4 in figure 6, in the suction port of the pump.

*This segment of line, (E in figure 4) between the return
to tank pressure relief valve and the shutoff valve, C,
should include a pressure relief valve vented to a safe
area.

8. Carefully loosen any unions or tubing fittings in any other
lines to the pump that have been blocked off by closing
the shutoff valves, so that venting from these segments
of the system can be accomplished. Typical of such lines
would be that from the pump mounted return-to-tank
relief valve to the accumulator, E* in figure 4, or a line, 2
in figure 5, from the high pressure side of the system to
the double seal oil reservoir.

ALWAYS LISTEN FOR THE “PSST” AT ANY POINT
LOOSENED TO PROVIDE VENTING.

9. Carefully loosen the fill plug. 5 in Figure 5, in the top of

the double seal oil reservoir.

10. After the ammonia has stopped venting turn the pump
shaft, 6 in figure 5, over for at least 10 complete
revolutions. This will make sure that there is no pocket of
accumulated ammonia that has not been exposed to a
venting point.

11. Carefully loosen the plugs, 4 in figure 6 and 7 in figure
5, in the suction and discharge ports of the pump. If

ammonia continues to vent, wait until the venting stops.
When venting from all the loosened connections stops,
then complete the loosening of the fittings and complete
the removal of the plugs.

⑦

①

FIGURE 5

Viking K4925

Refrigeration Ammonia Pump with Return-To-Tank

Pressure Relief Valve

7. If there are no vent valves in the blocked off piping, the

Viking Model 4925 ammonia pump should be vented by
carefully loosening the fitting (1 in figure 5) on the lower
end of the tubing that runs from the pump bracket to the
double seal oil reservoir.

THERE SHOULD BE A DISTINCT “PSST” SOUND
WHEN THE AMMONIA VAPOR LIQUID STARTS TO
VENT. LEAVE THE AREA UNTIL THE VENTING IS
COMPLETE.

If there is rigid pipe instead of tubing running from the
pump bracket to the double seal oil reservoir, the pipe
union should be loosened carefully until the “psst” is
heard.

SECTION TSM 420 ISSUE E PAGE 6 OF 18

④

③

FIGURE 6

Viking K4925

Refrigeration Ammonia Pump with Internal

Pressure Relief Valve