Shutoff valves can help prevent combustion system loss and catastrophe.
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The fuel delivery system uses electromechanical automatic safety shutoff valves. |
Now that the industrial economy seems to be recovering, many positive trends are leading the news: productivity is up, capacity utilization is improving and corporate profits are healthier. Manufacturing is on the rebound and order levels are getting stronger.
Unfortunately, some less positive trends also are being exposed: workforces are increasingly thin and the average experience level of workers has fallen, all while the average age of capital equipment is increasing. Left unchecked, these negative trends can magnify a company’s liability and risk associated with processing equipment such as ovens, dryers and heaters.
In every fuel-fired heating device, an array of safety devices works in combination with the burner to produce safe, reliable heat. After the flame safeguard relay, perhaps the single most important safety device on a combustion system is the shutoff valve.
The purpose of a shutoff valve is to immediately (less than one second) interrupt the supply of fuel to a burner when the control system requires an “off” condition. The cause may be a loss of flame, a loss of a safety permissive or simply a power-off condition on the heating equipment.
Shutoff valves earn their “most important device” designation because they serve a function in a combustion system that is not unlike a parachute. For this reason, most codes require two valves for redundant safety, depending upon the burner size and application.
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On this pipe train, digital fuel/air ratio controls and electromechanical shutoff valves help maximize efficiency and safety. |
The use of shutoff valves is governed by several bodies, including the National Fire Protection Association (NFPA), Canadian Standards Association (CSA), Industrial Risk Insurers (IRI), Factory Mutual (FM), Underwriters Laboratories (UL), Fire Safe, and regional and industrial codes. Make sure you understand the applicable codes and standards for your location, your industry and insurance provider. Additionally, make sure your system is properly applied with regard to the National Electrical Manufacturers Association (NEMA) rating, area classification, pressure rating and valve trim.
Remember, too, that education prevents accidents. For any employee who operates or maintains combustion systems, provide some degree of basic training on shutoff valves for identification, operation and maintenance. Damaged or bypassed shutoff valves are common when untrained employees are charged with operating or maintaining heating equipment.
Most shutoff valves on the market today offer very good durability. Regardless, some codes require annual inspections and leak tests. Minimize your company’s risk by performing and documenting these important checks and making them part of a continuing maintenance program.
Regular partial-stroke testing is one method of checking for proper valve operation without requiring a shutdown period. Develop a partial-stroke testing plan and create a documented, repeating inspection and maintenance program to provide an optimal level of loss prevention with shutoff valves.
When functional checks or leak checks expose weak or slow shutoff valves, replace the valve, but do not purchase based on price alone. There is no such thing as a “bargain parachute.”
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