Bronze Rotary Gear Pump - N991

The N991 operates as a positive displacement pump, delivering a consistent volume of liquid for each shaft rotation. This efficiency is maintained even against varying backpressure in the discharge line, with a direct correlation between shaft speed and fluid flow.

Optimal Pressure and Speed
This pump is optimized for 100 PSI (≈6.9 bar) when handling water and non-lubricants, and up to 150 PSI (≈10.3 bar) for oil and other lubricating liquids. The maximum shaft speed is 1750 RPM (≈183 rad/s). Our standard offering includes a Nitrile lip seal, with the option to upgrade to a fluoroelastomer seal for enhanced performance in more demanding environments (for this option, add S5 to the model number).

Drive Configuration
Close-coupled pumps attach directly to the motor using an appropriate adapter bracket, with a flexible coupling linking the pump and motor shafts.

Liquid Compatibility and Temperature Range
These pumps are suitable for all liquids compatible with bronze, including water, oil, and mild chemicals within a pH range of 4 to 11. For viscous liquids, a reduced shaft speed of 1150 RPM (≈120 rad/s) or less may be necessary (please consult our factory for guidance). Gear pumps should not be used with liquids containing solids, abrasives, powders, or paint pigments. The ideal temperature range for liquids is 32°F to 140°F (0°C to 60°C) to ensure the best pump life. For extreme temperatures or if freezing conditions are a concern, please consult our factory. Note that oils at low temperatures may require a lower pump speed or additional power due to increased viscosity.

Suction Lift and Installation
Position the pump as close to the liquid source as possible to minimize suction lift. In pristine condition, the pump can lift water up to 20 feet (≈6.1 meters) on the suction side. We recommend a foot valve with a strainer at the start of the suction line to facilitate priming and to avoid dry running. The suction pipe should match the size of the pump's inlet port, but for longer suction lines or viscous liquids, consider using a larger pipe.

Rotation and Relief Valve
If your discharge line includes throttling devices like valves or nozzles, ensure there's a relief valve in the system to prevent overpressure by returning liquid to the suction side or tank. Built-in relief valves are intended for intermittent use only; continuous use can lead to overheating. For pressure or flow control, a separate relief valve in the pressure line is necessary. Factory settings supply the pump for counterclockwise rotation from the shaft end, but reversing motor rotation will also reverse the "in" and "out" ports and necessitate relief valve repositioning. The factory pressure setting is 50 PSIG (≈3.4 bar). To increase pressure, turn the relief valve adjusting screw in a clockwise direction.