“Why Don’t We Just Put It in the Hood?”: Issues with Degrading Hood Effectiveness Due to Equipment Placement

Abstract

Placing equipment in a hood does not always guarantee a safe installation. This Article discusses the various issues associated with proper functioning of a hood with significant research equipment installed in it. The Article briefly discusses hood test methods and issues with assessing hood performance. It then highlights some common problems including storage, large solid objects, equipment which does not belong in a hood and/or will not fit in the hood, horizontal blockage, and some operational issues. The paper then suggests some approaches to avoiding these issues. The focus is understanding what reduces the effectiveness of a hood so that it can be adequately addressed as part of the hazard analysis and risk assessment to ensure a safe operation.

The Ten Most Common Laboratory Safety Issues

“…This practice is justified by a variety of spurious arguments that suggest the lab believes it has no other choice. See Figures – as well as refs and .…”

“…(1) hood doors opened past their design limits (2) packing hoods with solid equipment, equipment too large for the hood, too much equipment for the size of the hood, by placing numerous things that do not belong in a hood (3) storing too many chemicals, or incompatible chemicals and in inappropriate locations particularly in hoods (4) ventilating flammable storage cabinets (5) blocking easy exit access from the laboratory by allowing equipment and ancillary materials to be routinely placed in the exit aisles, adding equipment or casework that creates longer dead ends (aisles with only one effective exit), or installing oversized equipment in too small a space, leading to undersized and/or convoluted exit paths from the laboratory (6) providing only one means of egress from a laboratory (7) using power strips, extension cords, and similar flexible cords excessively and for routine ongoing operations (8) failing to follow NFPA 55 Compressed Gases and Cryogenic Fluids Code and NFPA 45 storage requirements for compressed gases by storing too many gases inside a laboratory, failing to separate incompatible gases properly, and/or piping the gases with no pressure relief protection for downstream components 1. HOOD DOORS OPENED PAST THEIR DESIGN LIMITS This problem includes too many doors opened at once or opened too far for a horizontal sash or a vertical sash opened past the maximum height.…”

Lessons Learned from a Short-Term Exposure to DMF

“…This placement of the ultrasonicator meant that I could not close the sash of the hood. The potential impact of this decision on my exposure to DMF is described in ref . Even though I was a full-time technician in an industrial hygiene lab, I was unaware of the concerns related to fume hood containment that are described in this article as this work proceeded.…”

Primer on Area Electrical Classification for Research Laboratories

“…For many reasons, fires and explosions can occur in hoods, − which are outside the scope of this article. Instead, I focus on what is required if a hazardous (ignitable) atmosphere could develop within the fume hood, warranting area electrical classification for safety.…”