We have all worked in stuffy indoor environments. These places have a detrimental effect on our morale, demeanor and quality of work. Healthy air in a laboratory is essential, not just for worker morale, but for their safety.
The first and primary line of defense for laboratory technicians are fume hoods and safety cabinets. “A fume hood is basically a box with a movable sash and some baffles on it that pulls air through it. A fume hood really doesn’t do anything it is the blower that pulls the air through it that does the work,” said Tony Kopidlansky, senior design engineer with Thermo Fisher Scientific Inc. “A biological hood has to protect both the operator and the experiment that is being worked on whereas the fume hood just expels fumes – it is just for operator protection, not for product protection.”
The air from fume hoods exits outside the lab which provides challenges, not the least is that a tremendous amount of energy is blown out of the building and wasted. “I don’t think the concept of ducted included a thought process – let’s dilute the air until it is below the parts per million concentration for any given chemical,” said Karl Aveard, vice president of GFA Technologies USA at Erlab. Filtering the air and recirculating it back into the lab saves on energy cost and is now a safe option because of the sophisticated filtering systems that have been developed. “The process of chemical filtration is adsorption. This is actually a process that takes advantage of the minute gravitational fields that are around the grains of charcoal and it captures the toxic molecules in the airstream. And they are locked to the surface of the carbon. If you remove all the contaminate out of the air, the air is totally filtered and you put it back into the space as air that is cleaner than the air that went into the hood in the first place,” said Aveard.
There is no compromise when dealing with healthy air in a laboratory. The first step is identifying what substances will be used in the laboratory and then selecting the appropriate ventilation. “The lab planner or architect knows up front what hoods are needed, and what types of chemicals are going to be used,” said Terry Thompson, Polypro sales manager for NuAire. “They then do their due diligence, by finding the best hood for the right application.”
“One of the biggest contributors to poor fume hood performance is supply air grille type and location,” said Andrew Sinnamon, technical specialist for Mott Manufacturing Limited. “A good rule of thumb is that a standard six foot hood should have a minimum of two supply air grilles, each measuring two by four feet.”
Positioning of fume hoods is critical. If there is a problem in a fume hood where someone is working, you do not want other technicians accidentally exposed. “Ideally, you want someone to be able to move away from that fume hood and nobody else then having to go by that fume hood when exiting the room,” said Russ Chernoff, principal with Chernoff Thompson Architects. “It seems like a simple idea but you would be surprised that it does not get thought about. Quite often the fume hoods are located near the corridor so you have to go past the fume hood to exit the space.”
All the safety measures in place will not help if people routinely ignore them. “The design of the enclosure is such that it encourages proper use of the enclosure,” said Luke Savage, LEED green associate, sales engineer, Labconco Corporation. “In a chemical fume hood there are a lot of things that we can do to try to promote the use of the sash as a physical barrier between the operator’s breathing zone and the hazardous chemicals inside. One of those ways is with a sash stop. Another way is with a sash positional alarm, which is an audible signal that goes off when the sash is raised above a certain height. We have auto return features that when a sash is raised above a specific height it will automatically return back to that height. We have full sash intelligence, where there are proximity sensors on the fume hood. When you approach the hood, the sash will open to a programmed height which is just above the user’s elbows and then when you walk away, the sash will close completely. Through the design and engineering of the product there are a lot of ways we can try to encourage the proper and safe use of the enclosure.”
This article originally ran in the June 2012 issue of Lab Product News