Dry run, or operating a pump without any liquid, is a simple concept, but the consequences of dry run are anything but simple. Catastrophic pump failure is possible in centrifugal and gear pumps due to dry run operation, and despite advances in preventing the failures associated with dry run, these pumps still are not as equipped to handle the issue as the Blackmer® MAGNES Series.
In centrifugal pumps, dry run can result in one of three undesirable outcomes — bearing failure, magnet coupling failure, containment failure — or a combination of these complications. Each of these conditions causes rotating elements to seize from friction caused by rotational speeds in excess of 3,600 rpm, causing aggressive friction, heat within the hardened bushings and liquid leaks.
Centrifugal pump manufacturers have attempted to prevent bearing failure by offering a variety of bushing material options, but these solutions can still be vulnerable to dry run operation. Silicon carbide can crack within seconds of going into dry run; protective coatings on traditional bushings deplete over time which may lead to failure; and composite blends provide self-lubricating benefits, but these protections may not last at the fast rotational speeds associated with centrifugal pumps. Magnet coupling failure and containment breaches are additional issues one may experience with these types of pumps.
For gear pumps, dry run often permanently damages internal components. Their internal gears, idlers, bushings and pins are contact elements that can wear and crack as a result of a dry run.
Finally, there is a more permanent solution: rotary sliding vane pumps that can accommodate indefinite dry run. An alternative to centrifugal and gear pumps, MAGNES Series Sliding Vane Magnetic Drive Pumps provide key differentiators for the prevention of damage due to dry run: reduced operational speed and a proprietary non-metallic containment shell. These new pumps from Blackmer use non-metallic, self-lubricating components, and they have no dynamic seals, an ideal feature for difficult-to-seal liquids that are too valuable, dangerous or hazardous to leak. Even during dry run operation, MAGNES can pull a vacuum, strip lines and create suction lift exceeding 25 feet (7.6 meters).
While operating at a speed of just 400 rpm, MAGNES generates the same pressures and flow rates of other pumps that operate at 3,600 rpm, with no excessive heat buildup or component wear. As a true self-priming pump, MAGNES does not require pre-flooding at startup and is well-suited for continuous-duty operation. Since MAGNES has no cumulative dry run time limit, it provides confidence that dry run events will not result in catastrophic pump failure.
Solve pump dry run events, while staying leak-free with the indefinite dry run ability of MAGNES, the Sliding Vane Magnetic Drive Pump. Learn more about MAGNES at blackmer.com.