Probable Cause
No Liquid Delivery
Low Liquid Delivery
Gradually Loses Prime
Motor Runs Hot or Overloads
Seal Leaks
1) Closed valves
1) Open valves
2) Plugged suction
2) Eliminate restriction
3) Air leak at suction
3) Locate and repair leak
4) Suction lift too high
4) Do not exceed vapor pressure of liquid
5) Motor wired incorrectly
5) Check wiring diagram
6) Wrong rotation
6) Correct rotation
1) Pump shaft speed incorrect
1) Check driver speed, motor wiring, pulley tension
2) Discharge pressure too high
2) Reduce downstream pressure
3) Air leak at suction
3) Locate and repair leak
4) Worn or damaged pump
4) Inspect and repair as required
5) Low viscosity
5) Verify original application conditions
1) Suction lift too high
1) Improve suction pressure
2) Air or gas in fluid
2) Eliminate air or gas from fluid
3) Air leak at suction
3) Locate and repair leak
4) Worn or damaged pump
4) Inspect and repair as required
1) Cavitating
1) Improve system suction pressure, provide adequate NPSH
2) Solid particles in fluid
2) Install suction strainer. Clean suction strainer.
3) Air or gas in fluid
3) Eliminate air or gas from fluid
4) Worn or damaged pump
4) Inspect and repair as required
1) Discharge pressure too high
1) Reduce downstream pressure. Check relief valve setting. Be sure
discharge pressure gages function correctly.
2) Shaft speed too fast
2) Reduce speed
3) Fluid viscosity higher than expected
3) Change to larger horsepower or higher service factor motor. Thin
4) Incorrectly wired motor
4) Check wiring diagram
5) Binding internal pump parts
5) Inspect and correct condition
6) Motors normally feel hot
6) Verify if actual motor amperage draw is within range
1) Dry running
1) Open valves. Prime pump
2) Solids in fluids
2) Add suction strainer
3) Damaged during field replacement
3) Inspect and replace damaged components
4) Seal material incompatible with fluid
4) Verify original application conditions. Consult factory.
For a period of 12 months from date of shipment, Oberdorfer Pumps, Inc. warrants all of their pumps to be free
from defects in material and workmanship when used in a service for which the product was designed. If any pump or part
is proved to be defective in workmanship or material on examination in our factory, and is forwarded to our factory by prepaid carrier, it will be repaired or replaced (at the factory’s option) and returned to the customer f.o.b. destination.
Oberdorfer Pumps, Inc. assumes no liability for pumps that have been altered or tampered with in any way. No
pump shall be returned to the factory for warranty service or credit without prior arrangement with the factory and the
assignment of a return goods authorization number.
This warranty is not to be construed that our product shall be deemed fit or suited for all or any particular service. Our pumps are not designed or intended for use with every known substance. If you require assurance or satisfactory
pump service life, you are urged to discuss your proposed usage with the company.
Equipment and accessories (motors, controls, etc.) not manufactured by Oberdorfer Pumps, Inc are warranted
only to the extent of the original manufacturer’s warranty.
Oberdorfer Pumps, Inc assumes no responsibility for consequential damages arising from the operating failure of
the equipment for any reason whatsoever. The company will assume no liability for service calls or expenses incurred in
the installation or removal of defective equipment and replacements.
Ductile Iron Rotary Gear Pumps
Installation, Operation, and Maintenance Instruction
Congratulations for choosing an Oberdorfer
pump, the Industry Standard for quality since 1890.
Ductile Iron Rotary Gear standard pump housings
are made of top quality ductile iron. Shafts are carbon
steel. Pumps are available with carbon bearings which
require no lubrication. Dynamic seal arrangements
include lip or mechanical seals for a variety of application
requirements. Static cover o-ring seals eliminate gasket
Application Range
Ductile Iron Rotary Gear pumps are of the external
gear positive displacement type, displacing a finite volume of fluid with each shaft revolution. As such, capacity
varies in direct proportion to pump speed. They are suited
to handle clear lubricating and non-lubricating fluids, with
PH ranging from 4 to 11, and temperatures to 400F. These
pumps handle viscous fluids to 100,000 cps (462000 SSU)
at reduced shaft speeds, with flow rates to 175 GPM (662
LPM), differential pressures to 150 psig (10.3 BAR), and
suction lift capability to 20 feet (6.1 meters) for new
Field Inspection
Ductile Iron Rotary Gear pumps may be readily
inspected in the field usually without removal from the
drive or system plumbing. Simply remove the cover
screws to pull the cover. Before attempting an inspection,
follow safety precautions and be sure to read and understand this manual.
New Pump Receipt Inspection
Upon receipt, check for obvious shipping damage
and completeness to purchase order requirements.
Shortages or damage should be reported immediately to
the carrier and to your Oberdorfer distributor.
Occasionally during shipment, possible misalignment or
other damage including cracked mechanical seal faces can
occur. As such, customers are advised to test the pump
with water in a convenient location prior to installing into
the intended system.
P.O. Box 4770, Syracuse, NY 13221
(shipping) 5900 Firestone Drive, Syracuse, NY 13206
Phone: 800-448-1668 or 315-437-0361; Fax: 315-463-9561
www.oberdorfer-pumps.com; Email: [email protected]
If the pump is to be stored prior to installation, it is
recommended that it be left in the original shipping carton
with all shipping plugs in place and stored in a dry environment avoiding temperature variations. Contact the motor
manufacturer for specific motor storage information.
These instructions should be kept in a convenient location for ready reference. The manual should be read carefully by
persons responsible for installation, operation, and maintenance
of the equipment. For ease of reference, a copy of the order
should be kept with the manual. Write down the pump model
number as shown on the pump nametag, and the date the unit
was placed into service.
Site Preparation
Choose a site that allows easy access to the pump for
maintenance. Consider protection from the elements. Guard
against drips and spray from nearby equipment. Choose a solid
foundation for mounting. If noise is a concern, consider a rubber pad under the pump base to dampen.
Flow Direction
Gear pumps will perform equally well in either direction however care must be taken for pumps equipped with integral pressure relief valves. To change flow direction effectively
reversing the suction and discharge ports, simply switch driver
rotation by following motor wiring diagram instructions and
change the location of the relief valve as shown below. Most
pump motor units are factory supplied with counterclockwise
shaft rotation (when viewing the pump from the shaft end).
Close Coupled
Suction Plumbing
Suction side plumbing considerations are key to desirable pump performance. Minimize head loss by assuring sufficient pipe size (especially important for highly viscous services). Generally the same size pipe as the pump ports is adequate.
For long runs (beyond 3 feet) or viscous fluids, use one or two
pipe sizes larger. Strive to keep the lines as short and straight as
possible. If flexible lines are used, they should be selected to
prevent wall collapse. To keep the pump from being starved or
running dry, be sure there is sufficient fluid supply. A flooded
suction is generally preferred. Suction lifts over 3 vertical feet
and long horizontal runs (beyond 3 lineal feet) require a foot or
check valve below the level of the liquid being pumped. When
taking suction from a tank or vessel, position the inlet above the
maximum expected level of solids. Use full-bore ball valves or
gate valves to minimize restriction. Suction strainers should be
properly sized to minimize pressure drop and positioned for easy
cleaning access. If start-up screens are used, be sure they are
removed prior to placing the system into regular operation.
Orient lines so as to prevent formation of air pockets. Be sure all
joints are tight. Flush out all suction lines prior to installing
the pump.
General Piping
For further ease of maintenance, use union fittings to
connect the pump to the system. Install a discharge priming tee
for convenience. Do not spring the piping to connect the pump.
Use piping supports or hangers as required. When necessary,
provide for thermal expansion and contraction to avoid placing
strain on the pump.
Proper alignment is key to seal and bearing performance.
Improper alignment can lead to premature pump failure. Check
the alignment carefully between the pump and the drive.
Unless the pump has been shipped directly from the
factory, it is recommended to check all bolts and nuts for tightness to eliminate possible leakage problems or destructive
Pressure Relief
Discharge lines should be fitted with properly sized line
pressure relief valves to protect both the pump and the system.
Pumps equipped with integral internal bypass relief valves are
intended as a safety device against intermittent overpressurization. They are not designed for continuous use and can lead to
overheating. In these instances, a line pressure relief valve is
required. The relief outlet should be piped back to the suction
Flow By-Pass
When a flow by-pass system is used to control output
from the pump, the bypassed fluid should be directed back to the
suction vessel to avoid recirculation heat build-up. In cases
where this is not possible, connect to the suction at least 10 pipe
diameters length away from the pump inlet. Provisions for cooling should be made in the event of recirculation heat build-up.
Pump Driver Mounting
Adapter kits (including bracket, coupling components, and hardware) are available for Ductile Iron Close
Coupled Gear pumps allowing connectivity to NEMA and
IEC motor frames. Assembly instructions are included with
each kit. Adapterless motors, carbonator mounts, and electric clutches are available for some models. Contact your
Oberdorfer representative for additional information.
Follow National Electrical Code. Verify that electrical
service is properly grounded, fused, and adequately sized
for motor nameplate requirements. Check to be sure that
motor wiring connections are correct referring to the
wiring diagram on the motor nameplate or inside the terminal box.
Prior to start-up, recheck installation as described
above. Verify desired rotation by jogging the motor and
make corrections if necessary. Before initial startup, pre-wet
the gears and make sure the pump is adequately primed.
Failure to do so could cause immediate damage to pump
components. Make sure that discharge valves are open.
Start pump and check for proper operation. Lip and
mechanical seal versions require no adjustment. If the
pump’s bearing areas or seal area runs hot, shut the pump
down and determine the cause. For units equipped with integral pressure relief valve, the factory setting is usually 50
psig. It is recommended that the setting should be 5 psig
above the operating pressure in the discharge line. To
increase the set point, turn the by-pass valve adjusting screw
clockwise. If start-up screens were used, be sure they are
removed prior to placing the system into regular operation.
Depending on suction conditions, it may be necessary to
reprime the pump for subsequent restarts.
Dry running leads to immediate damage to pump components. Due to tight running clearances, liquids containing solids and abrasives will accelerate pump wear.
When possible, flush the pump after each usage.
Allowing liquid to freeze in the pump can cause damage.
Since each installation differs, the frequency and
extent of pump maintenance is best established based upon
past performance. Keeping detailed maintenance records of
past performance aids in determining future preventative
maintenance intervals. During routine operating inspections,
pay particular attention to seal and bearing areas of the pump.
Consult the motor manufacturer for motor maintenance
Before attempting to service the pump: Disconnect motor
power and release all pressure within the system. Flush
the pump thoroughly with a neutralizing fluid before
attempting to disassemble. Wear appropriate personal
protection equipment and handle the equipment with
Changing Applications
Verify that all wetted parts of the pump are compatible with the new fluid to be handled and that the motor is
adequately sized. Check with your Oberdorfer distributor if
in doubt.
Inspect for Wear
If your Iron Gear Pump exhibits reduced flow, an inability to maintain pressure, is noisy or performs otherwise abnormally, first refer to the Troubleshooting Matrix on back. If the
problem persists, the pump should be inspected for wear or
damage. Oberdorfer Iron Gear pump internals may be readily
inspected in the field usually without removal from the drive
or system plumbing. Simply remove the cover screws to pull
the cover. Full pump removal and complete disassembly may
be needed for a comprehensive inspection. Contact your local
authorized distributor or the Oberdorfer factory.
Mechanical Seals
Pumps equipped with mechanical seals are of the
standard pusher bellows type or wedge style. They can be
expected to provide long and troublefree service provided:
1) Seal materials are compatible with pumped
fluid and properly applied to the service.
2) Adequate cooling and lubrication is provided
3) Dry running is avoided
4) Abrasives are kept away from the seal area
5) Pump and driver are properly aligned
Detailed mechanical seal inspection and replacement instructions are included with Oberdorfer Repair Kits.
Lip Seals
Pumps equipped with lip seals are of the metal cased,
spring energized, single lip style. These are intended to provide minimum friction drag with positive sealing and again
should be maintenance free provided the same conditions for
mechanical seals are met as well as:
6) Avoid scouring of the shaft in the lip seal area due
to contaminated abrasives
7) Avoid excessive seal lip contact pressure on the
pump shaft due to excessive pump pressure.
These are readily replaceable by pressing out the old
seal and pressing in a new replacement.
Pumps equipped with teflon or graphoil packing require
periodic adjustment as described above in the Startup section
to avoid excessive leakage. Eventually all the packing in the
pump will become deteriorated and will have to be replaced.
Recommended Spares
Repair kits are available for all Oberdorfer Ductile
Iron Gear Pumps. Each kit comes with detailed instructions.
For the proper kit, contact your Oberdorfer Distributor or the
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