GORMAN-RUPP PUMPS GMC Series User manual

OM-04384-05
March 18, 2021
GORMAN‐RUPP PUMPS
www.grpumps.com
2021 Gorman‐Rupp Pumps Printed in U.S.A.
INSTALLATION, OPERATION,
AND MAINTENANCE MANUAL
ROTARY GEAR PUMPS
MODELS
GMC SERIES
IRON PUMPS
Construction Code
3-B

TABLE OF CONTENTS
i
INTRODUCTION PAGE I - 1...................................................
SAFETY - SECTION A PAGE A - 1............................................
INSTALLATION - SECTION B PAGE B - 1.....................................
PUMP MODEL DESIGNATION PAGE B-1..................................................
PREINSTALLATION INSPECTION PAGE B-2................................................
STORAGE PAGE B-2....................................................................
Flushing PAGE B-2..................................................................
PUMP INSTALLATION PAGE B-3..........................................................
Lifting PAGE B-3.....................................................................
Positioning The Pump PAGE B-3......................................................
Mounting PAGE B-3.................................................................
Piping PAGE B-3....................................................................
Strainers PAGE B-4..................................................................
Gauges PAGE B-4...................................................................
Sealing PAGE B-4...................................................................
Valves PAGE B-4....................................................................
ALIGNMENT PAGE B-4..................................................................
ELECTRICAL CONNECTIONS PAGE B-4...................................................
OPERATION - SECTION C PAGE C - 1.......................................
PUMP OPERATION PAGE C-1............................................................
PRE‐OPERATION PAGE C-1..............................................................
Before Starting The Pump PAGE C-1...................................................
Checking Pump Rotation PAGE C-1...................................................
STARTING PAGE C-2....................................................................
OPERATION PAGE C-2..................................................................
Liquid Temperature PAGE C-2.........................................................
Overheating PAGE C-2...............................................................
Checking Gauges PAGE C-2..........................................................
Strainer Check PAGE C-2.............................................................
Leakage PAGE C-3..................................................................
PRESSURE RELIEF VALVE ADJUSTMENT PAGE C-3........................................
Cracking Pressure PAGE C-3.........................................................
Complete By‐Pass Pressure PAGE C-3.................................................
STOPPING PAGE C-3....................................................................
TROUBLESHOOTING - SECTION D PAGE D - 1...............................
PREVENTIVE MAINTENANCE PAGE D-4...................................................
PUMP MAINTENANCE AND REPAIR - SECTION E PAGE E - 1.................
PARTS KEY:
Typical GMC Pump Model PAGE E-2...................................................
ASSEMBLED GMC PUMP MODEL ILLUSTRATION PAGE E-4................................
PUMP DISASSEMBLY PAGE E-4..........................................................
Preparaing for Disassembly PAGE E-4.................................................
Pressure Relief Valve (10) PAGE E-5...................................................

TABLE OF CONTENTS
(continued)
ii
Coverplate Kit (11) PAGE E-5.........................................................
Head/Idler Kit (01 and 02) PAGE E-5..................................................
Backhead Kit Removal (06) PAGE E-6..................................................
Rotor/Shaft Removal (03) PAGE E-6...................................................
Seal Removal (05) PAGE E-6..........................................................
Housing Assembly (04) PAGE E-6.....................................................
PUMP REASSEMBLY PAGE E-6..........................................................
Cleaning and Inspection PAGE E-7....................................................
Bushing Preparation PAGE E-7........................................................
Housing Assembly (04) PAGE E-7.....................................................
Rotor/Shaft Assembly (03) PAGE E-7..................................................
Head/Idler Assembly (01 and 02) PAGE E-8............................................
Coverplate Kit (11) PAGE E-8.........................................................
Seal Installation (05) PAGE E-8........................................................
Backhead Kit (06) PAGE E-8..........................................................
SETTING END CLEARANCE PAGE E-8....................................................
RELIEF VALVE DISASSEMBLY PAGE E-9..................................................
RELIEF VALVE REASSEMBLY PAGE E-10..................................................
Relief Valve Installation (10) PAGE E-11................................................
SEAL APPENDIX - SECTION F PAGE F-1...................................
Standard Friction Drive And Optional 60A And 61J Mechanical Seals PAGE F-1.................
Standard Lip (And Optional 65A And 65C) Seal PAGE F-3....................................
BACKHEAD ADAPTOR APPENDIX - SECTION G PAGE G-1..................
Backhead Adaptor Removal and Installation PAGE G-2......................................
O‐RING APPENDIX - SECTION H PAGE H-1..................................

GMC SERIES OM-04384
PAGE I - 1INTRODUCTION
INTRODUCTION
Thank You for purchasing a Gorman‐Rupp pump.
Read this manual carefully to learn how to safely
install and operate your pump. Failure to do so
could result in personal injury or damage to the
pump.
Because pump installations are seldom identical,
this manual cannot possibly provide detailed in
structions and precautions for every aspect of
each specific application. Therefore, it is the re
sponsibility of the owner/installer of the pump to
ensure that applications not addressed in this
manual are performed only after establishing that
neither operator safety nor pump integrity are com
promised by the installation. Pumps and related
equipment must be installed and operated ac
cording to all national, local and industry stan
dards.
If there are any questions regarding the pump or
its application which are not covered in this man
ual or in other literature accompanying this unit,
please contact your Gorman‐Rupp distributor, or
The Gorman‐Rupp Company:
The Gorman‐Rupp Company
P.O. Box 1217
Mansfield, Ohio 44901-1217
Phone: [phone]
or:
Gorman‐Rupp of Canada Limited
70 Burwell Road
St. Thomas, Ontario N5P 3R7
Phone: [phone]
For information or technical assistance on the
power source, contact the power source manufac
turer's local dealer or representative.
HAZARD AND INSTRUCTION
DEFINITIONS
The following are used to alert maintenance per
sonnel to procedures which require special atten
tion, to those which could damage equipment, and
to those which could be dangerous to personnel:
Immediate hazards which WILL result in
severe personal injury or death. These
instructions describe the procedure re
quired and the injury which will result
from failure to follow the procedure.
Hazards or unsafe practices which
COULD result in severe personal injury
or death. These instructions describe
the procedure required and the injury
which could result from failure to follow
the procedure.
Hazards or unsafe practices which COULD
result in minor personal injury or product
or property damage. These instructions
describe the requirements and the possi
ble damage which could result from failure
to follow the procedure.
NOTE
Instructions to aid in installation, operation, and
maintenance or which clarify a procedure.

OM-04384GMC SERIES
SAFETY PAGE A-1
SAFETY - SECTION A
This information is specific to Gorman‐Rupp GMC
Series Rotary Gear Pumps. It applies throughout
this manual and any manual or literature ac
companying the pump.
In addition to this manual, see the separate litera
ture covering the drive unit used to operate this
pump.
Pumps and related equipment must be in
stalled and operated according to all na
tional, local and industry standards.
This manual will alert personnel to
known procedures which require spe
cial attention, to those which could
damage equipment, and to those which
could be dangerous to personnel. How
ever, this manual cannot possibly pro
vide detailed instructions and precau
tions for each specific application or for
every situation that might occur during
maintenance of the unit. Therefore, it is
the responsibility of the owner, installer
and/or maintenance personnel to en
sure that applications and/or mainte
nance procedures not addressed in this
manual are performed only after estab
lishing that neither personal safety nor
pump integrity are compromised by
such applications or procedures.
Before attempting to install, operate, or
service this pump, familiarize yourself
with this manual, and with all other liter
ature shipped with the pump. Unfamil
iarity with all aspects of pump operation
covered in this manual could lead to de
struction of equipment, injury, or death.
The standard version of this pump is de
signed to handle a wide range of light,
medium, and heavy viscosity liquid, de
pending on design and components,
and a range of temperatures when fitted
with different seals. Do not apply at
higher temperatures that the seal will
handle. Do not attempt to pump liquids
which may damage the pump or endan
ger personnel as a result of pump fail
ure; consult the factory for chemical
compatibility.
Death or serious personal injury and
damage to the pump or components
can occur if proper lifting procedures
are not observed. Make certain that
hoists, chains, slings or cables are in
good working condition and of suffi
cient capacity and that they are posi
tioned so that loads will be balanced
and the pump or components will not be
damaged when lifting. Suction and dis
charge hoses and piping must be re
moved from the pump before lifting. Lift
the pump or component only as high as
necessary and keep personnel away
from suspended objects.
After the pump has been installed, make
certain that the pump and all piping or
hose connections are secure before op
eration. Loose connections can result in

GMC SERIESOM-04384
PAGE A-2 SAFETY
damage to the equipment and serious
injury to personnel.
Never operate the pump without a pres
sure relief valve installed on the pump
or in the discharge piping. Make certain
that pump‐mounted pressure relief
valves are installed with their adjusting
ends toward the suction port. If bi‐rota
tional operation is required, a pressure
relief device must be provided for both
directions of flow. Operation without a
pressure relief valve or with an improp
erly installed relief valve could cause
the pump to explode, resulting in seri
ous injury or death to personnel.
Before attempting to open or service the
pump:
1. Familiarize yourself with this man
ual.
2. Lock out incoming power to the
drive unit to ensure that the pump
will remain inoperative.
3. Allow the pump to completely cool
if overheated.
4. Close the discharge and suction
valve (if used).
An overheated pump can cause severe
burns and injury. If overheating occurs:
1. Stop the pump immediately.
2. Allow the pump to completely cool.
3. Refer to the instructions in this
manual before restarting the
pump.
Do not remove plates, covers, gauges,
pipe plugs or fittings from an over
heated pump. Vapor pressure within the
pump can cause parts being disen
gaged to be ejected with great force. Al
low the pump to completely cool before
servicing.
This pump may be used to handle liq
uids which may cause serious illness or
injury through direct exposure or
emitted fumes. Wear protective cloth
ing, such as rubber gloves, face mask
and rubber apron, as necessary, before
disconnecting or servicing the pump or
piping.

GMC SERIES OM-04384
PAGE B-1INSTALLATION
INSTALLATION - SECTION B
Review all SAFETY information in Section A.
Pumps and related equipment must be in
stalled and operated according to all na
tional, local and industry standards.
Since pump installations are seldom identical, this
section is intended only to summarize general rec
ommendations and practices required to inspect,
position, and arrange the pump and piping. If there
are any questions concerning your specific instal
lation, contact your Gorman‐Rupp distributor or
the Gorman‐Rupp Company.
Most of the information applies to a flooded suction
installation where liquid is supplied under pres
sure.
If the pump is positioned above the liquid in a static
lift installation, information such as mounting, pip
ing configuration and priming must be tailored to
specific conditions.
These pumps are not recommended for
use with water. Some models when fitted
with specific options may be used with wa
ter; consult the factory.
PUMP MODEL DESIGNATION
Following is a description of the model numbering
system for Gorman‐Rupp rotary gear pumps.
Rotary gear pump model numbers include design
style, port size, hydraulic size and construction
code.
Typical Pump Model
GHS 1 1/2 GF 32
Design
Style
Port
Size
Hydraulic
Size
Construction
Code
Design Style: Gorman‐Rupp rotary gear pumps
are available in five basic designs:
GMC - Medium Duty - Compact
GMS - Medium Duty
GHC - Heavy Duty - Compact
GHS - Heavy Duty
GHA - Abrasive Duty
Port Size: Gorman‐Rupp rotary gear pumps are
available in port sizes from 1 to 6 inches, depend
ing on the design style. Consult your Gorman‐
Rupp distributor or the factory for additional sizes.
Hydraulic Size: The first letter in the hydraulic size
is a rotor diameter code. The second letter indi
cates tooth length.
Construction Code: Construction Codes for Gor
man‐Rupp rotary gear pumps are as follows:
Code Description
3 Iron w/Mechanical Seal(s)
4 Iron w/Packing or Lip Seal(s)
9 316 SST w/Mechanical Seal(s)
10 316 SST w/Packing or Lip Seal(s)
32 Steel w/Mechanical Seal(s)
38 Steel w/Packing or Lip Seal(s)
Theoretical Displacement: Table B‐1 indicates
theoretical displacement values for each hydraulic
size.
NOTE
Actual capacities and recommended shaft speeds
vary according to application. Consult your Gor
man‐Rupp distributor or the factory for additional
information.

GMC SERIES
OM-04384
PAGE B-2INSTALLATION
Table B‐1. Theoretical Displacement
Hydraulic
Size
Theoretical Displacement
Per Revolution
Gallons Centimeters3
DC 0.00568 21.486
DE 0.00704 26.646
GC 0.00967 36.619
GF 0.01405 53.186
GH 0.01915 72.479
GJ 0.02317 87.700
JG 0.03579 135.49
JJ 0.05159 195.28
JL 0.07078 267.94
JP 0.10078 381.48
NK 0.10665 403.71
NM 0.14173 536.51
NP 0.17681 669.31
RM 0.24030 909.65
RP 0.29979 1134.8
RR 0.35927 1360.0
RS 0.41876 1585.1
SR 0.65752 2489.0
SU 1.10240 4173.2
TU 1.91280 7240.7
PREINSTALLATION INSPECTION
The pump assembly was inspected and tested be
fore shipment from the factory. Before installation,
check for damage which may have occurred dur
ing shipment. Check as follows:
a. Inspect the pump assembly for cracks, dents,
damaged threads, and other obvious dam
age.
b. Check for loose attaching hardware. Since
gaskets tend to shrink after drying, check for
loose hardware at the mating surfaces.
c. Carefully read all tags, decals, and markings
on the pump assembly, and perform all duties
indicated.
STORAGE
Due to the extreme close machining toler
ances within rotary gear pumps, proper
storage before installation is essential to
prevent damage to the pump.
If the pump will not be immediately installed, follow
these procedures or damage to the pump will oc
cur.
a. Do not flush the pump. Ensure that the port
plugs shipped with the pump remain in place
until piping is installed to help prevent dust or
other foreign objects from entering the pump.
b. Pumps that will not be installed for an ex
tended period should be stored indoors if
possible. The factory‐installed port plugs will
not ensure protection from excessive humid
ity, splash water or rain. In very humid or wet
conditions, install air‐tight plugs in the ports
and fill the pump completely with a lubricating
preservative liquid that is compatible with the
liquid to be pumped.
c. Pumps stored outdoors must be fully pre
served as described above, completely cov
ered with plastic or other water‐tight material,
and the covering anchored to ensure that it
will not be blown off.
Flushing
Clean piping is essential because of close‐
tolerance moving parts in this pump. Flush
all dirt, grit, weld beads or scale from the
suction piping before installing the pump.
Damage to the pump because of debris in
the suction line is not covered by the pump
warranty.
Before shipment, the pump may have been tested
using a petroleum‐based preservative. If flushing is
required, do not do so until just before installation;
the test oil protects close‐tolerance pump parts
from corrosion.
Most cleaning solvents are toxic and

GMC SERIES OM-04384
PAGE B-3INSTALLATION
flammable. Use them only in a well ven
tilated area free from flame, sparks, and
excessive heat. Read and follow all pre
cautions printed on solvent containers.
To flush the pump, use an approved solvent com
patible with the liquid being pumped. Make cer
tain that the solvent will not attack pump com
ponents, particularly seals and gaskets.
PUMP INSTALLATION
Pump dimensions are shown in the separate
Pump Specification Bulletin.
Never operate the pump without a pres
sure relief valve installed on the pump
or in the discharge piping. Make certain
that pump‐mounted pressure relief
valves are installed with their adjusting
ends toward the suction port. If bi‐rota
tional operation is required, a pressure
relief device must be provided for both
directions of flow. Operation without a
pressure relief valve or with an improp
erly installed relief valve could cause
the pump to explode, resulting in seri
ous injury or death to personnel.
Lifting
Death or serious personal injury and
damage to the pump or components
can occur if proper lifting procedures
are not observed. Make certain that
hoists, chains, slings or cables are in
good working condition and of suffi
cient capacity and that they are posi
tioned so that loads will be balanced
and the pump or components will not be
damaged when lifting. Suction and dis
charge hoses and piping must be re
moved from the pump before lifting. Lift
the pump or component only as high as
necessary and keep personnel away
from suspended objects.
Remove suction and discharge hose and piping
before attempting to lift the pump. Use lifting equip
ment with a capacity of at least five times the total
weight of the equipment being lifted.
Positioning The Pump
Locate the pump as close as possible to the liquid
being pumped. Locating the pump below the liq
uid source will help self‐priming and reduce the
possibility of cavitation.
Mounting
The pump may be shipped alone, mounted on a
base, or with pump and motor mounted on a base.
Install the pump and motor on a base before
mounting the base on a foundation.
Mount the base on a foundation that will provide
permanent, rigid support for the pump, and will be
heavy enough to absorb any vibration, strain or
shock.
Piping
Before establishing suction and discharge lines,
determine pump port positions and rotation. Fig
ure B-1 shows typical port positions for the stan
dard 180housing; if you have selected a 90
housing port option, your port positions will be dif
ferent.
Begin piping layout at the pump, and work toward
the source of supply and the point of discharge.
Either hose or rigid pipe may be used to make con
nections. If rigid piping is used, install expansion
joints to protect the pump from vibration and ther
mal expansion in the piping. Do not use expansion
joints or flexible connectors to adjust misaligned
piping.

GMC SERIES
OM-04384
PAGE B-4INSTALLATION
Housing Position Std. 180 Pump
(3-9 O'clock) Housing Mounted Relief Valve
STD.
OPT.
Rotation Clockwise
Drive End Front End
Rotation Counter-clockwise
01A S
SS DD
DD S
Figure B‐1. Typical Port Positions & Rotation
The discharge and suction lines must be inde
pendently supported to avoid vibration and strain
on the pump. For maximum pumping capacity,
keep the lines as short and straight as possible. El
bows and fittings used in the lines increase friction
losses; minimize their use. Reducers used in suc
tion lines should be the eccentric type installed
with the flat part uppermost to avoid creating air
pockets.
Before tightening a connection or flange, align it
exactly with the pump port. Never pull a pipe line
into place by tightening the flange bolts and/or
couplings.
Strainers
Because of the close‐tolerance moving parts of
this pump, it is recommended that a strainer be in
stalled in the suction line. The strainer should be
large enough to prevent excessive vacuum, and
capable of operating under high vacuum without
collapsing. The net open area of the strainer
screen depends on liquid viscosity and desired
flow rate; in any case, the sum of the area of all the
holes in the screen should be three to five times the
area of the suction pipe.
Gauges
To monitor operation and assist in troubleshooting,
a vacuum gauge and a pressure gauge should be
installed on the pump.
Sealing
Even a slight leak will affect priming, head, and ca
pacity, especially in a suction lift application. Seal
all piping joints, valves and gauges with pipe dope
or teflon tape. The sealing material should be com
patible with the liquid being pumped.
Valves
To avoid air pockets, install piping valves with the
stem horizontal.
To prevent leakage during shutdown, install a shut
off valve in the discharge line, particularly on a
flooded suction application. Shutoff valves are not
recommended for suction lines.
It is not recommended that a foot valve be installed
at the end of the suction line. If desired to install a
foot valve, consult the factory.
When handling very hot or cold liquids, install a
pressure relief valve in any part of the system that
can be valved off or isolated; this will protect piping
against damage from liquid thermal expansion or
contraction from temperature changes during
shutdown.
ALIGNMENT
Make certain that power to the drive unit
is disconnected before attempting to
connect the pump drive; otherwise, per
sonal injury may result.
NOTE
See ROTATION in Section C before mounting the
pump on the base.
Because this pump is designed to be driven by a
close‐coupled motor, it is imperative that the user
make certain that the motor drive shaft is parallel
and concentric with the rotor/shaft assembly.