AIHA Lessons Learned Reports
TitleCategoryDate of IncidentKey LearningsDescriptionsEffects of IncidentCausationCorrective Actions
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Hazardous Materials in the Cold Box/Warm Room (Copied from archived content)
O2 Displacement (Dry Ice Storage)Don't store Dry Ice in Walk-in RefrigeratorsWalk-in refrigerators (or "cold boxes") typically recirculate the chilled air in their interiors, so storing volatile materials in them can pose unique hazards--any gases or vapors may concentrate inside.
Recently on the X Campus, a walk-in refrigerator was used to store dry ice. The dry ice was stored in a standard dry ice storage locker, but the locker had been placed in the cold box to further reduce the rate of dry ice loss.
The refrigerator builds up CO2 levels of 12,000 parts per million (ppm)! In comparison, outdoor air contains only about 400 ppm CO2, and OSHA's Permissible Exposure Limit for CO2 is 5000 ppm. Although no one was affected, the incident points out the need to keep volatiles out of walk-in refrigerators.The dry ice, of course, gave off carbon dioxide (CO2) gas as it sublimedNot mentioned
Laboratory Safety Incidents: Perchloric Acid (Copied from AIHA Archived Content)
Chemical incidents – skin or eye exposure1. Always wear goggles and rubber gloves when pouring or handling perchloric acid.
2. Working with solutions of 70% or more requires a face shield, apron and special handling procedures identified in the CRC excerpt below.
3. Clean up spills immediately.
4. A preventive maintenance program must be in effect for perchloric acid hoods and other hoods where hazardous materials are used.
5. Never heat perchloric acid in a chemical hood unless the hood has been designed for use with perchloric acid and has a functioning wash-down system.
6. Flush the system for at least 20-30 minutes at the end of each work session.
7. Always store acids separately from organic solvents.
8. Consider performing testing to determine if perchloric acid or perchlorates are building up on surfaces:
Perchloric Acid Sampling and Analysis Procedure, Brookhaven National Laboratory, Safety and Health Services Division. This document describes a field procedure for taking and analyzing wipe samples from surfaces potentially contaminated with perchlorates and perchloric acid.
The following excerpts contain additional safety precautions that should be followed and describe actual perchloric acid accidents that have occurred.
Excerpt from CRC Handbook of Laboratory Safety. 4th Edition, 1995 by CRC Press LLC,
Excerpt from NFPA 45, Standard on Fire Protection for Laboratories using Chemicals.
Build-up of Dangerous Perchloric Acid Salts Due to Lack of a Hood Preventive Maintenance Program
Recently, it was discovered (see photo 1) that a perchloric acid fume hood was heavily contaminated with potentially explosive perchloric acid salts (see photo 2). Due to a malfunction in the was-down system, only the interior of the hood was subjected to a water spray. The duct from the top of the hood to the stack on the roof had not been washed down for an undetermined length of time while perchloric acid continued to be heated in the hood (see photo 3). As a result, perchloric acid salts formed on many locations along the length of the duct, particularly where the stainless steel welds were made (see photo 4). Although only visible on the outside, it is presumed contamination is worse on the interior of the stainless duct (see photo 5). Of particular concern is the wood floor in the attic (see photo 6). Wood (and other organic materials) that have been contaminated with perchloric acid can become flammable and/ or explosive with heat or friction. As a result of the non-functional wash-down system (see photo 7) the fan located on the roof was completely destroyed by the acid (see photo 8).
Build-up of Dangerous Perchloric Acid SaltsDue to the Lack of Hood Preventive Maintenance Program
Laboratory Safety Incidents: Toxic Gas Release (Copied from AIHA archived content)
Compressed gas incidentsKey Instruction Points:
1. Read the Label
2. Use Engineering Controls to Protect Against Unforeseen Hazards
3. Use Appropriate PPE as required
The Incident - An industrial research lab used arsine gas in a semiconductor- related research project. It had been decided (appropriately in the joint decision of the researcher and health and safety personnel) to use 100% arsine at 200 psig cylinder pressure rather than a 10% arsine / hydrogen mixture which had a cylinder pressure of over 2000 psig. The gas cabinet was equipped with normally-closed pneumatic shutoff valves, a flow restrictor in the cylinder valve, and in-cabinet continuous monitoring for arsine, in addition to other engineering controls. The side of the gas cylinder received from the gas supplier was stenciled with the word "arsine." The regulator had been chosen for 100% arsine gas. When the cylinder was connected to the regulator assembly (with personnel using SCBA) and turned on, the guage needle immediately pegged itself offscale on the regulator. The bourdon guage in the regulator burst and the researcher headed for the door. In moving to the door he heard the sound of the pneumatic valve closing. The gas detection system had immediately signaled for automatic shutdown of the pneumatic valve. No arsine was detected in the lab area outside of the gas cabinet and in-cabinet readings quickly dropped to zero. Subsequent examination of the cylinder contents tag (attached to the cylinder neck) indicated the researcher had actually received a 10% arsine mixture in hydrogen, at the elevated cylinder pressure of 2200 psig. The researcher had not doubled checked the manufacturers identification tag and had relied on the cylinder stenciling, which should not be considered reliable. Fortunately, the engineering controls and personal protective equipment handled the situation effectivelyResearch staff was informed to check the manufacturer's tag against their order information and not to rely on cylinder stencils. They were also reminded to utilize engineering controls and protective equipment to minimize the impact of highly hazardous materials incidents when the unexpected occurs.