Motor shaft and ball bearing system for pumps handling hazardous liquids with containing solids

Patented Shaft and Bearing System
A Zero-emission Pump for Slurry Applications
The Lawrence Zero-emission pump is designed for handling slurries. With rolling element bearings, and a shaft that meets or exceeds API 610 design requirements, the motor can handle many times the radial and thrust loads of a standard sleeve bearing canned motor. Lubrication of the bearings and cooling of the motor are no longer dependent on the process stream.
Up to 50% by Weight Solids Our motors are designed to be used as drivers for slurry pumps handling hazardous liquids containing up to 50% by weight solids. Slurry pump components place additional loading on the pump shaft and bearings as heavier wall thicknesses are used to resist abrasive wear. Hydraulic loads are typically higher with slurry pumps due to normal wet end wear and the configuration of the impellers.
Extended Operating Range With its robust shaft and bearing design the Lawrence Zero-emission pump offers a B-10 bearing life in excess of 40,000 hrs., shaft deflection of less than 0.002" at the seal faces and a rotor assembly that remains stable under changing load conditions. Many sealless pump designs cannot tolerate dry running as critical pump components such as mechanical seals and/or bearings rely on the process fluid for lubrication and cooling. The lubrication system on the Lawrence Zero-emission pump is completely independent of the process fluid. If the pump runs dry, motor cooling and lubrication are not affected.
Lower Speeds For Lower Cost For slurry applications lower pump operating speeds provide a significantly longer operating life due to reduced casing and impeller wear. The Lawrence Zero-emission slurry Pumps with their roller element bearings and internal lubrication system are ideally suited for reduced speed operation. The lower speed capabilities of the Lawrence Canned Motors allow them to be used with Variable Frequency Drive Units for process control and improved process unit efficiencies. Typical sealless pumps use the pump product to lubricate the sleeve bearings and to provide cooling for the motor. When the pump speed is reduced, the flow of pumpage through the canned motor decreases. At low speed the circulation will stop if the pump is not putting out enough pressure to overcome the resistance in the motor cooling loop. Problems that may occur with reduced speed operation are: The sleeve bearings may overheat due to the loss of fluid film and can suffer premature failure. The pumpage in the motor may vaporize, causing additional sleeve bearing problems. Overheating of the motor can cause damage to the motor cans and windings. The Lawrence Zero-emission Pump with its self contained lubrication and cooling system will be unaffected by reduced speed operation.
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