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Each summer, heat stress is a problem that affects more than 10 million outdoor workers in the United States. By Michael W. Michelsen Jr. |
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| Workers who perform their jobs in hot temperatures are all too familiar with the signs and effects of heat stress and other heat-related problems. Even their equipment isn't immune. Summer heat, especially when accompanied by dust and poor maintenance, can overtax workers and drastically reduce the life of even the toughest equipment. The effects of summertime labor on workers can range from thirst and discomfort to loss of strength, energy, and endurance. In severe cases, heat stress can lead to nausea, fainting, collapse, or even unconsciousness and death. At any stage in the heat stress continuum, workers' productivity and alertness suffer. Other problems commonly caused by heat stress include increased accidents, absenteeism, and low employee morale. Heat stress can also cause a significant decrease in motor skills, judgment, and concentration, jeopardizing not only the individual but also the group with whom he or she is working. The human body seeks to maintain a constant internal temperature, despite environmental conditions. To keep the internal temperature within safe limits, the body must rid itself of excess heat, primarily by varying the rate of blood circulation, which controls the release of sweat onto the skin by the pores. As sweat evaporates, the body is cooled. When humidity is high, the evaporation of sweat from the skin decreases, and the body's efforts to maintain an acceptable body temperature can be affected dramatically. Keeping People Cool and Safe One key to preventing excessive heat stress is educating supervisors and workers to the hazards of working in heat and the benefits of implementing proper controls and practices. Employers should establish programs to acclimatize workers to hot environments and provide necessary work-rest cycles and water to minimize heat stress. While working in heat-stress conditions, a worker might produce as much as 2-3 gal. of sweat in just two hours. Because so many heat disorders involve excessive dehydration, it is essential that workers be provided with relief from heat in as many ways as possible, including water intake, which should be as nearly equal as possible to the amount of sweat produced. Most workers exposed to heat drink much less fluid than needed for optimal performance because of an insufficient thirst drive. A worker, therefore, should not depend on thirst alone to signal when and how much to drink and should instead drink 5-7 oz. of fluids every 15-20 minutes to replenish the necessary fluids in the body. The clothing worn in environments prone to heat stress can have a dramatic effect on worker health and productivity. Clothing can inhibit the transfer of heat between the body and the surrounding environment. When air temperature is lower than skin temperature, clothing reduces the body's loss of heat into the air. When air temperature is higher than skin temperature, clothing helps prevent the transfer of heat from the air to the body. This advantage may be nullified, however, if the clothes interfere with the evaporation of sweat. In dry climates, adequate evaporation of sweat is seldom a problem. In a dry work environment with very high air temperatures, protective clothing could be an advantage to the worker. The proper type of clothing depends on the specific circumstance. Certain work in hot environments may require insulated gloves, cooled or insulated suits or vests, reflective clothing, or infrared-reflecting face shields. For extremely hot conditions, thermally conditioned clothing is available from appropriate manufacturers. One such garment carries self-contained cool packs, while another gives users a cool drink, anytime, anywhere. Bullard of Cynthiana, KY (www.bullard.com) sets high standards for head protection for a wide variety of applications, from classic fire helmets to industrial hardhats. Bullard hardhats provide comfortable protection from rain, snow, dust, and harmful ultraviolet rays. Suspension is achieved by six 1-in.-wide nylon straps, offering increased balance and comfort. The full profile shell enhances ventilation, cooling the wearer's head. The ES-ULTRA self-sizing suspension and the ESTRSL Sure-Lock nonslip ratchet suspension feature a Sportek terry cloth like removable brow pad for absorbency and comfort. Vertical adjustment hanger keys on the front and rear positions of the headband allow a custom fit. Accessory slots accept face shields, hearing protection, welding helmets, or communication devices. All Bullard helmets meet or exceed American National Standards Institute 289.1-1997, Type A, Class E, G, and C requirements. Bullard helmets are available in 23 colors and can be customized with company logos or Scotchlite reflective strips. Bullard also sells the Isotherm Cool Vest, a cooling work vest that helps reduce the chance of heat-related illnesses. Unlike ice or gel packs that steadily lose their effectiveness, Bullard's cool vests will remain at a constant 55ºF for hours of cooling and are available in two designs and in either flame-retardant or nonflame-retardant material. Simply submerge the vest's cool packs in a cooler with ice water, and they are fully energized in 20 minutes. Extra cool packs can be kept ready for instant onsite changes. CamelBak Products Inc. in Petaluma, CA (www.camelbak.com), produces backpack-style and waist-mounted hydration products that carry up to a 2-lit. capacity and that can be worn all day, keeping water cool and giving workers hands-free access to drinkable water while working. The result is healthier, safer, and more productive workers, no matter what the weather. CamelBak offers a wide variety of hydration systems. For industrial users, the HotShot, the newest in a line of hydration systems, delivers 72 oz. of water and has several accessories, including different harness styles and Velcro attachments. It can be slipped into a jacket pocket or vest straps. Other CamelBak products are available when safety and visibility are concerns. The Hi-Viz Hydration System, available in orange or lime green, also features reflective straps on packs and harnesses. The 70-oz. insulated reservoir makes filling and cleaning fast and easy. Other products include Big Bite Valves, clips that attach drinking tubes to clothing or other gear, tube extensions, a chest strip, and the CommPocket, which attaches to any CamelBak system to hold a cell phone, a two-way radio, or a global positioning system. Extreme heat can affect concentration, making falls more common. Dennington Safety Gear Inc. in Shreveport, LA, manufactures the Dennington Safety Harness (www.ldlunitedunion.com), which provides for a higher standard in fall protection. According to the US Bureau of Labor Statistics, there were 303,817 nonfatal injuries and 640 deaths caused by falls in private industry in 2000 (2001 data were not yet released as of this writing). The Dennington Safety Harness provides three advantages over standard harnesses:
The company says its harnesses, when incorporated into a comprehensive fall prevention program, will significantly reduce the number and severity of workers' compensation claims and reduce serious injuries and deaths. Federally mandated OSHA standards provide additional incentives for such programs. Exceed Safety Products in Minneapolis, MN (www.exceedsafety.com), recently introduced The Flap, a detachable sun protection screen that easily can be clipped to a baseball cap or a hardhat. The Flap is lightweight with a breathable fabric that prevents up to 99% of the sun's ultraviolet rays (UVA: aging, UVB: burning - the most dangerous) from contacting the skin. It can be customized with company colors or a logo screen print, it is machine-washable, and one size fits all. Hammond Air Conditioning Ltd. of Brantford, ON (www.hammondac.com), offers factory-style new system installations and kits for all makes and models of new and used machines. The equipment carries a one-year parts and labor warranty for new systems and installations and a one-year parts warranty for kits. Helping Engines Keep Their Cool Heat is hard on engines. Proper maintenance (checking fluid levels, performing oil changes, and other common steps) eases its effects, and equipment makers are developing higher-performance, more reliable engine designs. "The key," states Dan Rafferty, product manager for Takeuchi in Buford, GA, "is proper maintenance. I've seen it all. I've seen owners of our equipment who buy a piece of equipment and hardly ever even change the oil. I've also seen the guy who babies his equipment to the point where it looks and performs better than the day he took it from our offices. He even washes and waxes it. Needless to say who gets a longer life out of his equipment." Flexxaire Manufacturing Inc. in Edmonton, AB (www.flexxaire.com), produces fully automatic, adjustable, and reversible fan systems that change blade pitch while in motion, preventing radiator plugging, engine overheating due to excessive debris, and engine overcooling from operating heavy equipment in freezing weather. Flexxaire offers two fan series: the FX and the Mark III.
The FX Series is an automatic self-cleaning, reversible, self-adjusting (in-motion variable-pitch), hydraulically activated fan system for heavy equipment. The fans range from 20 to 78 in. in diameter and come with six, eight, or 10 blades. FX Series fans are designed to replace existing fan systems and meet the same cooling requirements, with added advantages of stopping and reversing airflow automatically or on demand. FX fans can save users many hours each week in downtime by eliminating the need to manually clean debris from the radiator. Further, when a temperature control is used, the fan will move into a neutral position when engine cooling is not required, reducing horsepower and fuel consumption. For example, a fan that would normally use 60 hp (3 gal. of fuel) when spinning in full pitch with closed shutters will use 6 hp when spinning in neutral without shutters. In one hour this can represent a fuel savings of approximately 2.7 gal. Many users have also reported that the FX has extended the engine life of their equipment, adding thousands of hours of operation between engine repairs. The Mark III Series is a fully automatic self-cleaning, reversible, full-range self-adjusting (infinite in-motion variable-pitch), electrically/mechanically actuated fan system for heavy equipment. The fans range in size from 24 to 78 in. in diameter and come with six, eight, or 10 blades. Mark III Series fans are designed to replace existing fan systems and provide the same cooling requirements, with the added advantage of keeping engines operating at an optimal temperature (by making infinite blade pitch adjustments) and stopping and reversing airflow automatically or on demand. Both series of fans have three hydraulically activated blade positions: pull air, stop air (neutral), and push air. When a fan is in the pull-air position, it pulls air from outside through the radiator, as normal fans do. The stop-air position prevents air from entering the engine compartment, and the push-air position pushes air out of the engine compartment, through the radiator. All three blade positions are achieved without work stoppage, change in engine speed, or additional wear to the engine, fan belts, pulleys, or bearings. The two fan systems prevent engine overheating by keeping the radiator, screen, and guards free from debris. In environments where dirt, debris, and other materials can plug radiators and cause overheating, the fans purge debris from the radiator by temporarily reversing the blade pitch position while reversing the airflow. FX and Mark III fans are used in a variety of applications, including forestry, mining, construction, demolition, waste handling, wood recycling, and several other debris-related operating conditions. Machines that can be fitted with Flexxaire fans include Austoft, Byron, Case, Caterpillar, CMI, Cameco, John Deere, Komatsu, New Holland, Prentice, Risley, S. Madin, Tigercat, Timbco, and Timberjack. Huber Reversible Fan Inc. in Erie, PA (www.huberfan.com), offers more than 700 models or fans for nearly three dozen equipment manufacturers. Huber fans are available as standard and/or optional equipment directly from several equipment manufacturers. They also may be purchased as aftermarket attachments. In addition, Huber can customize fans for special needs. Horton Inc. in Roseville, MN (www.hortoninc.com), is a supplier of engine cooling systems and other components for a variety of equipment applications. It recently introduced VMaster, a viscous air-sensing fan drive that operates at variable speeds, resulting in economical operation and increased engine performance for off-highway equipment. The fan drive is available for select construction and agricultural applications, including tractors, backhoes, cranes, lift trucks, crawler dozers, excavators, and articulated dump trucks. Horton plans to expand the line by this spring and is working with original equipment manufacturers (OEMs) to develop first-fit applications. The VMaster viscous direct-sensing fan drive will also be available this year. The VMaster helps OEMs comply with noise-reduction legislation in Europe and the US. The lightweight modular VMaster viscous air-sensing fan drive has a precision bimetal sensor that automatically adjusts fan speed based on air temperature from the engine's heat exchangers. The fan operates at optimum speed, cooling only as needed, which reduces noise and fuel consumption. The flat-plate bimetal design improves performance and durability by preventing debris buildup. Summer problems can dramatically affect the performance of both humans and machines. Proper maintenance of both will result in higher productivity and profits. Based in Riverside, CA, Michael W. Michelsen Jr. specializes in business and technology subjects.
GEC - May/June 2003
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