While sealed pumps can perform admirably in the manufacture, transfer and handling of dangerous chemicals and other hazardous materials, the shortcomings that are inherent in their sealed design can make them insufficient for the job.
Fortunately for the operators of chemical-manufacturing facilities, there is an alternative technology that can help eliminate some of the major concerns associated with achieving full containment: seal-less sliding vane, internal gear and eccentric disc pumps.
Let’s take a look at the advantages of a few specific seal-less pumping technologies:
SLIDING VANE
Seal-less sliding vane pumps constructed of corrosion-resistant stainless steel generally feature a magnetic coupling consisting of samarium-cobalt magnets and a unique bearing and head design that allows a small quantity of the pumpage to circulate through the containment can and onto the bearing surfaces. This positive flow of fluid minimizes temperature rise during operation, which helps maximize bearing life. Replaceable 316 stainless-steel end discs allow easy rebuilding of the pumping chamber to like-new condition without having to remove the pump from the piping. Additionally, carbon-graphite sleeve bearings help ensure no metal-to-metal contact during operation. Operationally, seal-less sliding vane pumps offer the same advantages as their sealed cousins: volumetric consistency, self-priming and limited dry-run capability, drain plugs that allow easy draining and easy replacement of worn vanes.
Featured Image: Seal-Less Sliding Vane Pumps feature a magnetic coupling consisting of samarium-cobalt magnets and a unique bearing and head design that allows a small quantity of pumpage to circulate through the containment can, which minimizes temperature rise and maximizes bearing life.
Above: Next-generation Seal-Less Internal Gear Pumps feature only one fluid chamber, which not only enhances product containment, but eliminates product entrapment, especially when transferring high-viscosity liquids.
INTERNAL GEAR
Technological advancements in internal gear pump design and operation now offer to the market models that have only one fluid chamber. This method of construction removes the adapter plate that is a staple of traditional two-chamber magnetically coupled internal gear pumps, which eliminates product entrapment concerns, especially when transferring high-viscosity liquids. One-chamber operation is achieved through a between-the-bearings design that places the magnets directly on the pump rotor, resulting in a simpler flow path and full leak-free product containment. Some seal-less internal gear pump models are also constructed of as few as seven parts, which helps contribute to an estimated 50 percent reduction in maintenance costs when compared to sealed pumps. There are also seal-less internal gear pump brands and models that are interchangeable with 95 percent of competitive sealed or packed-gear pump brands, making time-saving drop-in replacement a reality.
ECCENTRIC DISC
Seal-less eccentric disc pump models feature no mechanical seals, packing, couplings—or even magnets, with the shaft sealed instead by a unique double stainless-steel bellows. Operationally, seal-less eccentric disc pumps can still offer self-priming, dry-run and low-shear operation, very high suction and discharge pressures, the ability to pump both low- and high-viscosity liquids and clean-in-place/sanitize-in-place (CIP/SIP) capability. Additionally, by virtue of the unique eccentric disc operating principle that allows them to pump air, seal-less eccentric disc pumps can achieve product-recovery rates of 90 percent or more on the suction side and 60 percent to 80 percent on the discharge side of transfer lines. This enhanced product-recovery capability can result in thousands of dollars in cost savings annually from the retrieval of still useable raw materials and saleable end products.
These varying types of seal-less pump technologies check all of the right boxes when it comes to overcoming the four major challenges in handling dangerous chemicals or hazardous materials: optimized Safety; full product containment; reduced maintenance; and streamlined operating costs.
Seal-less Eccentric Disc Pumps feature no seals, packing, couplings or magnets, which translates to full product containment coupled with the added benefit of optimized product-recovery rates.
CONCLUSION
Sealed pumps have been performing sufficiently in chemical-manufacturing operations for many years. However, operators who are looking for a better alternative should look to upgrade their facilities with seal-less pumps. These types of pumps will reduce leakage events and improve containment of dangerous or hazardous materials. Maintenance costs can also be lowered to such a level that the lifetime cost to operate the seal-less pump may be half that of a sealed model. Most important to the operator, the use of seal-less pumps can increase the peace of mind that comes with knowing that not only is personal and environmental safety being optimized, but that the bottom line is receiving a boost, as well.
ABOUT THE AUTHOR
Chrishelle Rogers is the global gear pump product manager for EnviroGear® and PSG®. Ms. Rogers can be reached at 909.222.1309 or chrishelle.rogers@psgdover.com. Nicholas Ortega is the engineering manager for EnviroGear® and PSG and can be reached at 909.512.1230 or nicholas.ortega@psgdover.com. PSG is comprised of several leading pump brands, including Abaque®, Almatec®, Blackmer®, Ebsray®, Griswold™, Maag Industrial Pumps, Mouvex®, Neptune™, Quattroflow™, RedScrew™, and Wilden®. For more information on EnviroGear and PSG, visit www.psgdover.com.
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MODERN PUMPING TODAY, February 2016
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