N991_2006

N991_2006
MODEL
N991 SERIES
BRONZE CLOSE COUPLED
ROTARY GEAR PUMPS
MODEL N991 - 1/4” NPT PORTS STANDARD
PERFORMANCE
PERFORMANCE CURV E
Model: N991
Pump
Description
N991
Standard pump with 1/4" ports
Pump with Viton(R)* lip seal
N991S5
N991R
Pump with 1/4" ports & relief valve
N991RS5 Pump with Viton(R)* lip seal & relief valve
FEATURES
•
•
•
•
•
•
•
•
Rugged corrosion resistant bronze construction
Compact close-coupled design
Stainless steel shafts
Durable bronze spur gears
Process lubricated carbon graphite bearings
O-ring cover seal for maximum leak protection
Buna Lip Seal -standard
Easy field assembly to a variety of motor frames
- For typical DC motor pump units - see N991-32 DC
- For compact AC motor pump units see Close Coupled Bronze Adapterless Rotary Gear Pumps
• For bronze pedestal pumps and mechanical seal styles - see model N1000
GENERAL DESCRIPTION
Pump housings and gears are made of top quality bronze, shafts are
303 stainless steel. Bearings are designed of high performance carbongraphite material selected for wear resistance and long service life.
Gear pumps are positive displacement pumps. Each shaft revolution
displaces a definite amount of liquid relatively unaffected by the back pressure in the discharge line. Shaft speed and flow are directly proportional.
Recommended pressure limits are 100 PSI for water and non-lubricants, 150
PSI for oil and other lubricants. The maximum shaft speed is 1750 RPM.
SHAFT SEALS
Close coupled gear pumps are normally supplied with a Buna N lip seal. A
lip seal made of Viton(R)* is available as an option. For a Viton(R)* Seal, add
S5 to the pump model number.
www.oberdorfer-pumps.com
LIQUIDS AND TEMPERATURE
These pumps are suitable for all liquids that are compatible with bronze. Most
common liquids are water, oil, and mild chemicals in the pH range of 4 to 11. Viscous
liquids require reduced shaft speeds of 1150 RPM or lower. (Consult
factory.)
Liquids containing solids, abrasives, powders, or paint pigments are definitely not recommended for gear pumps. If abrasives are unavoidable, use a very low
shaft speed.
The recommended liquid temperature range is from 32o F to 140o F for best
pump life. If more extreme temperature conditions exist, factory should be
consulted. Freezing of water-filled pumps can cause damage and must be avoided.
Oils at low temperatures are very viscous requiring a lower speed or extra power.
SUCTION LIFT
As a general rule, the suction lift should be kept at an absolute minimum by
placing the pump as close to the liquid source as possible. A gear pump in new
condition can lift 20 feet of water in the suction line. A foot valve (preferably with builtin strainer) is recommended at the beginning of the suction line. For a first start-up,
the pump should be primed to avoid dry running. MInimum size of the suction pipe
is the size of the pump inlet port. For longer suction lines (over 3 feet) or for viscous
liquids, the pipe should be at least one size or two sizes larger than the pump inlet
port.
ROTATION AND RELIEF VALVE
If the discharge line contains any throttling devices such as a shut-off valve,
a spray nozzle or other restrictive device, it is necessary to have a relief valve in the
system which returns the liquid to the suction side or to the tank. The relief valve is
also available as part of the pump itself (R-model pumps). However, built-in relief
valves are only good for intermittent service. If used continuously, the pump will overheat. A built-in relief valve is strictly a safety device against overpressure. It will not
work successfully as a pressure or flow control device. For this purpose a separate
relief valve in the pressure line must be used.
Unless otherwise specified, the pump motor unit is supplied by the factory for
shaft rotation counterclockwise from shaft end. Reversing motor will reverse “in and
“out” ports and also requires changing relief valve location. The relief valve is always
on the inlet side of this pump series. The factory pressure setting is 50 PSIG. To
increase pressure, turn the relief valve adjusting screw in a clockwise direction.
PHONE (800) 448-1668; (315) 437-0361
FAX (315) 463-9561
MODEL
N991 SERIES
BRONZE CLOSE COUPLED
ROTARY GEAR PUMPS
EXPLODED VIEW AND PARTS LIST
1
2
Screw
Pump No. 6 Req'd
3*
4
Body
O-Ring
Dowel
Pin
5*
6*
7*
Bearing
1 Req'd
1 Req'd
2 Req'd
4 Req'd
1 Req'd
1 Req'd
1 Req'd
1 Req'd
1 Req'd
Drive Gear Idle Gear
Assy
Assy
8
Cover
9*#
10
Lip Seal Coupling
11
Screw
12
Plug Nut
13
Ball
1 Req'd 1 Req'd 1 Req'd
14
15
16
17
18
Spring
Adj.
Screw
Locknut
Bypass
Nut
Fiber
Washer
1 Req'd
1 Req'd
3 Req'd
1 Req'd
1 Req'd
N991
7733
9300NB5N 9797-033
8885
5024
32149
32110
9303NN2N
5007
5604
5595
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N991R
7733
9300NB5N 9797-033
8885
5024
32149
32110
9303NN2B
5007
5604
5595
1838
5803
1840
5237
5240
5239
6533
#Seal #5007 is Standard Buna N, #7580 is Viton(R)**-Teflon (R)**
*Repair Kit contains items 3, 5, 6, 7 & 9. Repair Kit for N991(R) is #10640.
VARIATIONS
Pump No.
DIMENSIONS
1,2
9
Lip
Repair
Kit 2
Seal
1 Req'd
N991S5
7580
11318
N991RS5
7580
11318
Adapter
Kit
Kit
Number
Description
M
10562
48 Frame
N
10816
56 Frame
P
11722
S56 Frame
Q
11331
56C Frame (to ¾ HP)
F
11332
IEC71
----
-----
Adapterless- Modified 48
5/06
www.oberdorfer-pumps.com
*Viton® or equivalent FKM will be used.
Viton® is a registered trademark of DuPont Dow Elastomers.
*Teflon® or equivalent PTFE will be used. Teflon® is a registered trademark of DuPont.
Specifications are subject to change without notice.
PHONE (800) 448-1668; (315) 437-0361
FAX (315) 463-9561
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