Lessons Learned: Monitoring of Aging Equipment Reminder Due to Hood Sash Cable Failure

Summary

Workers in the lab had finished up removing chemicals from the hood they were working in and were in another part of the lab when they heard a loud crash. The crash was the result of the cable supporting the sash failing and the sash dropping.

The manufacturer of the fume hoods involved in the event, Clean Air Products, does not have a suggested preventative maintenance schedule for the cable system on their hoods. However, as equipment is pushed to be used for longer, it needs to be more closely monitored for signs of failure.

Event Details
The cable supporting the sash on a fume hood in NREL’s Solar Energy Research Facility (SERF), broke, causing the sash to suddenly move from a working height of 18 inches to a fully closed position. The force generated when the sash contacted the working surface popped the side panel of the hood loose and caused the laminated safety glass inside the sash to crack. There were no injuries or exposures that resulted from this event.

An inspection of the failed cable showed evidence of a compromised outer protective sheath and corrosion of the cable. There are two other identical hoods located in SERF. These hoods were inspected; one had a corroded support cable and compromised protective coating. The other hood passed inspection but will have the support cables replaced. An additional hood in another lab from the same manufacturer with a similar installation date was also inspected and found to have one of its support cables frayed; this hood was deemed safe to continue operations but will also have its cables replaced. All SERF hoods are scheduled to be replaced as part of the SERF Ventilation and Restoration project, estimated to be completed during the fiscal year 2026.

Lessons Learned

The lessons learned below are aligned with one of NREL’s eight safety principles:

Hazards are identified and evaluated for every task, every time - Procedures and safety components are constantly reevaluated to ensure they still provide the protection assumed.

Aging equipment often needs to be monitored closer than newer equipment, especially those pieces of equipment that serve a safety/hazard mitigation function. Utilization of the preventive maintenance program or ensuring research staff more closely monitor these types of equipment during their daily laboratory operations is seen as a value-added opportunity.

The manufacturer doesn't have a recommended maintenance schedule or definition of end-of-life. It was determined that the failure in this event was a result of the normal aging process for this component. Without a preventive maintenance program and a plan for monitoring aging equipment these types of events are more likely to occur.

The Research Operations Community of Practice (CoP), which includes members from NREL, Los Alamos National Laboratory (LANL), Brookhaven National Lab (BNL), Idaho National Lab (INL), Pacific Northwest National Laboratory (PNNL), Oakridge National Laboratory (ORNL) and Savannah River National Laboratory (SRNL) reported no history of this type of failure in their hoods. Of these labs, only LANL has a maintenance program-focused effort in addition to the required annual reviews/testing for LEV/alarming and the like.

As part of the action plan for this event, NREL benchmarked Los Alamos National Laboratory’s Fume Hood Preventative Maintenance Program they put in place in 2018. They have seen great results of fewer hood failures and more streamlined repairs and replacements. NREL is currently developing a schedule for preventative maintenance and a program to make sure critical failures like this event don't occur again.

SME for additional information: John Morris, John.Morris**At_Symbol_Here**nrel.gov

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