Many laboratories have fume hoods installed. A chemical fume hood is a significant safety device that is critical to maintaining acceptable laboratory air quality and preventing user exposure to potentially harmful chemicals. Yet, the fume hood is the most misunderstood and misused safety device in the laboratory. So much mystery and myth exist regarding how a fume hood works and how to use it safely. It starts with the perception that a fume hood is a standalone device and if there is a fume hood in your laboratory and you use it, you will be safe. The reality is that a fume hood is only a small component in the mechanical ventilation system of a laboratory. It is the point of interface between the user and the laboratory ventilation system (LVS).
The fume hood does very little alone. Yes, there are good hood designs and not so good hood designs, but until connected to a properly designed and maintained laboratory ventilation system, the fume hood is just an enclosure that does nothing. The primary purpose of the fume hood is to protect users from exposure to harmful chemicals that are being used inside the hood. To do this, a fume hood must capture, contain, dilute, and exhaust those dangerous substances. None of this is possible without a ventilation system. Secondarily, the fume hood should provide some physical protection in the case of fire or explosion.
This book was written for informational purposes, it provides a background and explanation of how a fume hood works and how to use it in an effective way. The whole subject of fume hoods is full of misinformation, confusion and even controversy. Do a search for “fume hood books” and the only book you are likely to find was written by G. Thomas Saunders back in 1993. Why is there so little written about a subject as important as fume hoods? While there are standards and best practices, web posts and media articles that reference fume hoods, there is nothing from the 21st century that offers a comprehensive, factual discussion of the subject.
Having been in the industry for over 40 years, I have seen it all — the good, the bad, and the ugly. I have designed seven major fume hood product lines. I have worked for companies that have collectively built nearly 500,000 fume hoods over those years. Some of my later fume hood designs were truly world class and had great performance in the test laboratory. But it is possible to take that fume hood out of the test laboratory, install it in a working laboratory, and the same fume hood that performed so brilliantly in the test laboratory may fail to adequately protect users in a working environment. Users see the brand name and the test laboratory reports and understandably believe they are safe while using the fume hood.
In the post sales visits to laboratories, I often saw my world class fume hood not working properly. I spent a lot of time educating all stakeholders about fume hoods and how they must be integrated with the whole building to work properly. What I found, was that due to the complexity of fume hood operation and the lack of understanding about how a fume hood works, no one really wanted to tackle the problem.
Through this book I hope to provide a needed source of accurate and timely information about fume hoods and their use in the laboratory environment. My goal is to cover the following points:
- the purpose of a fume hood is to capture, contain, dilute and exhaust harmful chemicals;
- fume hoods are simply a component of a laboratory ventilation system and do nothing alone;
- laboratory ventilation systems are about airflow;
- adequate testing – as manufactured (AM), as installed (AI), and as used (AU) is the only way to know if a fume hood is performing effectively;
- users are a major factor in fume hood performance and safety.
During the past ten years, I have worked mostly internationally outside the United States. Much of my time has been in India and China. It has been an eye-opening experience to see what is being done in these countries where there are few standards or regulations. Without government oversight such as we have in the U.S. with the Occupational Safety and Health Administration (OSHA), almost anything goes. One of the major problems in these countries is that many laboratories are designed and operated with no mechanical air supply systems. They use natural ventilation. In other words, they open the doors and windows when they operate the hood. It is impossible to manage air pressure and airflow balance without a mechanical supply air system. The other major issue is chemical storage. There are lots of chemicals in the open laboratory and it is common for many owners to shut the laboratory ventilation system off when users are not in the laboratory in order to save energy. The problem is that with no ventilation the chemicals in the fume hood and in the laboratory contaminate the laboratory air overnight and the users arrive back to a highly polluted laboratory the following day. The pollution is evident by the corrosion seen in these laboratories. I am quite certain that users have no idea of the hazards associated with these practices.
The last decade has been a real change for me. I went from being a supplier of fume hoods to being an independent consultant, trying to help companies make better products and to do more to protect users.
A while back, I was meeting with a laboratory owner who was preparing to build a new laboratory. The owner had been talking to several well-known suppliers about fume hoods. The plan was to use natural ventilation to save money. After some discussion, I said to him, “you do realize that these hoods will not perform safely without mechanical air supply?” His response was, “it doesn’t matter if the hoods work, it only matters that we have them and that people assume they work.” The indifference to user safety was shocking and convinced me to become a user advocate. It is the right thing to do.
Since 2010 I have given dozens of conference presentations and seminars on fume hood safety. I have worked with many companies helping them to improve their products and understand what it takes for a fume hood to perform effectively. I am compelled to share what I know with the hope that this information will help make a difference and that in the years to come laboratories around the world will be safer and healthier places to work.