N991_2000

N991_2000
BRONZE CLOSE COUPLED
ROTARY GEAR PUMPS
OBERDORFER PUMPS
MODEL
N991
SERIES
A Subsidiary of Thomas Industries Inc.
MODEL N991 - 1/4” NPT PORTS STANDARD
Pump
Description
N991
Standard Pump with 1/4" ports
N991S5
Pump with Viton(R)* Seal
N991R
Pump with 1/4" ports and Relief Valve
N991RS5
Pump with Relief Valve & Viton(R)* Seal
3/8" NPT Ports are available.
FEATURES
n Compact design eases installation and use in limited space areas.
n Construction is bronze and stainless steel wetted components.
n Close tolerance design allows for consistent performance.
n Helical gears for quiet operation.
GENERAL DESCRIPTION
Pump housings and gears are made of top quality bronze, shafts are 303
stainless steel. Bearings are designed of high performance carbon-graphite material selected for wear resistance and long service life.
Gear pumps are positive displacement pumps. Each shaft revolution dis places 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.
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.)
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PERFORMANCE
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 32 o F to 140 o 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
BRONZE CLOSE COUPLED
ROTARY GEAR PUMPS
OBERDORFER PUMPS
N991
SERIES
A Subsidiary of Thomas Industries Inc.
EXPLODED VIEW AND PARTS LIST
Pump
No.
1
Screw
6 Req'd
2
2
2
Body
3
O-Ring
4
Dowel
Pin
1 Req'd
1 Req'd
2 Req'd 1 Req'd
2
5
6
Bearing Drive Gear
Assy.
2
7
Idle Gear
Assy.
8
Cover
1,2
9
Lip
Seal
10
Cap
Plug
11
12
Coupling Screw
13
Plug
Nut
14
Ball
15
Spring
16
Adj.
Screw
17
18
Locknut Bypass
Nut
19
Fiber
Washer
1 Req'd
1 Req'd
1 Req'd
N991
5013
9300NB5N 9797-033
8885
5024
32980
32979
9303NN2N
5007
9346
5604
5595
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N991R
5013
9300NB5N 9797-033
8885
5024
32980
32979
9303NN2B
5007
9346
5604
5595
1838
5803
1840
5237
5240
5239
6533
1
2
1 Req'd 1 Req'd 1 Req'd 1 Req'd 1 Req'd 1 Req'd 1 Req'd 1 Req'd 1 Req'd 1 Req'd 3 Req'd
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
Seal
Kit
2
1 Req'd
N991S5
7580
11318
N991RS5
7580
11318
*Viton(R) or equivalent FKM will be used.
Viton(R) is a registered trademark of DuPont
Dow Elastomers.
Teflon(R) or equivalent PTFE will be used.
Teflon(R) is a registered trademark of DuPont.
7/00
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Specifications are subject to change without notice.
PHONE 800-448-1668; (315) 437-0361
FAX (315) 463-9561
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