Any ventilated enclosure in a lab, such as a hood or vented cabinet, creates exhaust gas. That seems easy enough to handle—just get it out of the lab. As we shall see, this process consists of two key parts, and it is a zero-sum game, more or less. Beth Mankameyer, LEED Green Associate and sales engineer at Labconco (Kansas City, MO), makes time to walk readers through the key points.

“If lab managers are looking at adding ventilated equipment to their lab space, they must understand the need for make-up air,” says Mankameyer. The air that goes out, the exhaust, must be replaced, and that’s the make-up air. Without the make-up air, a ventilated enclosure won’t work. As Mankameyer puts it: “Much like a bank account, you can’t withdraw money if you don’t have it in the first place—it’s the same concept with air exchanging in a building!”

That makes up the basic theory behind exhaust air, but what about the practice? Handling that takes a device or two. “On a ventilated enclosure, there are accessories called airflow monitors that should be added in order to continuously monitor the airflow,” says Mankameyer. Then, if the exhaust fan stops working, the airflow monitor triggers audible and visual alarms that indicate unsafe working conditions. If an enclosure system lacks an airflow monitor, a lab manager should—at the very least—install a magnahelic gauge. This gauge “works off of pressure and can be installed in the ductwork to at least give a visual indicator of air movement,” Mankameyer explains. “So, the user knows whether the exhaust fan is functioning or not.”

Keep it flowing

For any ventilated enclosure, a lab manager should set up scheduled maintenance. “It is a good idea to do an annual check on all the components of the exhaust system, including the duct work, making sure it is all still well-sealed, and check on the blower,” Mankameyer suggests. “If the blower is a belt-driven blower, check to make sure the belt is in good working condition, and make sure none of the components have rusted or corroded.”

In addition, the annual maintenance should include checking the supply side of the system. It’s easy to forget the basics of ventilation: out with the bad air, in with the good. Keeping the “good” flowing, though, depends on a functioning supply-air system. “If there are duct leaks or issues with negative pressure in the building, it will create problems with the ventilation system,” Mankameyer explains. “Having a properly balanced lab will help ensure the user’s safety by allowing the ventilated enclosures to do their job effectively.”

A 2011 report1 from the U.S. National Research Council states: “The laboratory ventilation system, whether it is the general ventilation, a chemical hood, or a specialized exhaust system, is a critical means to control airborne chemicals in the laboratory.” The report adds: “Even the best-engineered and most carefully installed ventilation system requires routine maintenance.” So, lab managers should install an effective air system—including well-designed exhaust and makeup air flows—and check them for proper performance.

Reference

  1. National Research Council. 2011. Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards, Updated Version. Washington, DC: The National Academies Press; https://doi.org/10.17226/12654.

Mike May is a freelance writer and editor living in Texas. He can be reached at [email protected]