Fluid handling systems often move liquids and gases that are hazardous. Avoiding environmental incidents, safety violations, and employee health risks should be a top priority.
“Special care must be taken in the specification and selection of a motor when these systems involve potentially explosive liquids and gases,” advises George Weihrauch, product manager, Baldor Electric. “Electric motors convert electrical energy into rotating mechanical energy and heat. It’s the motor’s hot internal and external surfaces caused by the internally generated heat and its potential electric arcs and sparks that could become sources of ignition. Motor application requirements that increase internal motor temperatures — such as applying a motor on an adjustable speed drive — should be carefully reviewed and accounted for in the design of the system. Likewise, special motor features, such as thermostat contacts or shaft grounding brushes or rings, that are defined as an arcing or a spark device would need to be reviewed for suitability in the specific hazardous environment.”
|Mike Bacidore is chief editor of Plant Services and has been an integral part of the Putman Media editorial team since 2007, when he was managing editor of Control Design magazine. Previously, he was editorial director at Hughes Communications and a portfolio manager of the human resources and labor law areas at Wolters Kluwer. Bacidore holds a BA from the University of Illinois and an MBA from Lake Forest Graduate School of Management. He is an award-winning columnist, earning a Gold Regional Award and a Silver National Award from the American Society of Business Publication Editors. He may be reached at 630-467-1300 ext. 444 or firstname.lastname@example.org or check out his Google+ profile.
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But safety doesn’t begin and end with the motor. “It’s critical that the right pumping equipment and shaft sealing arrangements are specified for the media that’s being transported to ensure the safety of those in the area where the pump is operating, as well as the life of the equipment,” emphasizes Nate Maguire, Americas Business Unit Director, Industry and Agriculture, Xylem. “Users should consider a variety of parameters when selecting a pump, including the flammability of the media, chemical compatibility, viscosity, amount and type of entrained gas, the atmosphere where the pump is operating — whether the pump is outside or located in an enclosed space — as well as fluid temperature, pressure and flow. Various types of pump and sealing system designs, materials, and configurations are available to meet the requirements for different applications, but to ensure a safe and reliable installation, it’s highly recommended that users consult a pump expert before selecting equipment to transport hazardous gases or liquids.”
For petrochemical applications, the pump industry has developed standards for the manufacture and supply of centrifugal pumps, notes Mark J. Cutler, applications engineering manager, SKF USA. “Two important standards are ASME/ANSI B73.1-2001 for chemical process pumps and API 610 for general refinery service pumps,” he says. “These standards define the minimum technical requirements for the mechanical design of the pumps, bearings, and seals. For pumps handling flammable or hazardous liquids, these standards outline special pump and component design features needed to be implemented in order for the pump to be used in these specific applications.”
Pumps and seals have a synergy like the transmission and engine on a car, explains Paul Wehrle, chief engineer, Meco Seals. “Align or marry the wrong two, and limitations result,” he warns. “We recommend discussing the specifics of your fluid handling system with your in-house rotating equipment specialist, pump supplier, and seal supplier. Confirming the correct equipment, environmental controls, and latest technologies available are used will maximize the performance within your system.”