Page 50 - OHS, May 2021

TRAINING: CONFINED SPACES
are made from either molded plastic or cast aluminum, and the two types serve difffferent purposes.
Plastic units are lightweight and cost-effffective, but they’re only designed for light to moderate use. Although plastic does well at resisting scratches and dents, the housing may crack easier if abused or operated in cold weather.
Blowers that incorporate cast aluminum housings come with higher price tags as well, however, these units also have a demonstrated reputation for withstanding much more abuse and should be expected to last longer than plastic blowers.
Ducting
Airflow depends heavily on the duct. The standard diameter for portable ventilation blowers is eight inches, although larger sizes are available, and the most popular duct lengths are 15 and 25 feet. Duct lengths that exceed 25 feet significantly decrease the airflow that can be delivered to a confined space. If more than 25 feet of duct is needed, consider other options to place the blower closer to the confined space opening. Otherwise, one can invest in a larger, more powerful blower, add another blower inline (mid-duct run), or set up separate duct runs with multiple blowers to compensate for the reduced airflow.
Bends in the duct — especially those with an angle of more than 90 degrees — also reduce the airflow rates produced by any
blower. Manufacturers understand that providing airflflow in a confifined space environment oftften requires making a minimum of two 90-degree bends in the duct, so they oftften account for the airflflow loss when rating the CFM of their products. Be sure to check the specififications provided by the manufacturer for an explanation of how each specific blower was rated.
Price
While everyone must deal with meeting budget requirements, worker safety always comes first. If a blower doesn’t meet the requirements of a confined space, it will not be able perform adequately and will put workers at risk with the possibility of causing serious injury or even death. Conversely, don’t think that purchasing the most expensive blower automatically means it will be the best one for a particular space. The biggest thing to keep in mind is that a price tag can’t be placed on employee safety and wellness.
Despite the several factors that go into the process, properly selecting and using a ventilation blower for a confined space isn’t terribly complicated. While it does require some thought and preparation, meeting regulatory compliance and ensuring worker safety is well worth the effort.
Jan Wienczkowski is the Marketing Manager for General Equipment Company, a manufacturer of ventilation blowers since the 1970s.
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