Incompatible Storage and Hood Deficiency in a Metallography Lab
An internal audit of a small metallographic laboratory finds: a 2.5 L bottle of 68% nitric acid stored on an open shelf next to 1 L of acetone and a box of magnesium ribbon; the eyewash station is 18 m away in the corridor and its weekly activation log is missing for the last three weeks; the fume hood face velocity is 0.30 m/s with the sash at 45 cm, while the manufacturer specifies at least 0.5 m/s. Two technicians work in the room, and one reports headaches after using the hood. The audit is tomorrow, and the lab manager asks whether the findings can be closed by updating the log and moving the acid to a different shelf. Production requires the hood to stay in service for a scheduled analysis.
1. Rank the findings by risk and explain which ones require immediate action before the audit.
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The incompatible storage is the highest immediate risk. Nitric acid is a strong oxidizer, acetone is a flammable solvent, and magnesium ribbon is a reactive metal. A leak, breakage, or fire could produce an energetic reaction, toxic nitrogen oxides, and a metal fire. The acid, acetone, and magnesium must be separated immediately into compatible, labeled storage: acid in an acid cabinet, solvents in a flammable-solvent cabinet, and magnesium in a dry, isolated location away from oxidizers.
The hood deficiency is the second immediate risk because it affects worker exposure now, not just at audit. A face velocity of 0.30 m/s at a 45 cm sash is below the manufacturer's 0.5 m/s specification, and the headache report is a possible exposure symptom. The hood should be removed from service, labeled, and investigated before further use; the scheduled analysis should be moved or postponed.
The eyewash and log issue is also serious but is primarily an emergency-response and documentation deficiency. The eyewash must be unobstructed and reachable within the required travel time; 18 m may exceed a 10-second access criterion depending on the route. Missing weekly activation records mean the unit's function is unverified. Updating the log and moving the acid alone would not close the findings.
2. Prepare a corrective-action plan that addresses root cause, interim controls, and verification, and state whether the hood can remain in service.
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The hood cannot remain in service. Interim controls: lock out or tag the hood, stop work that requires it, relocate the scheduled analysis to a verified hood or postpone it, and arrange a temporary ventilation or exposure assessment if any work must continue. Provide the technicians with information about the symptoms and arrange occupational health follow-up for the affected worker.
Immediate controls for storage: move the nitric acid to a dedicated acid cabinet, move acetone to a flammable-solvent cabinet, and place magnesium in a dry, isolated location. Inspect the shelf for corrosion, provide secondary containment, and verify that containers are closed and labeled. Restore eyewash access by clearing the route, verifying the unit, and resuming weekly activation with signed records.
Root cause and corrective action: the findings indicate weak chemical inventory, storage segregation, and equipment-verification systems. Update the chemical inventory and compatibility matrix, retrain staff, add monthly storage inspections, and add hood face-velocity checks to the preventive-maintenance schedule. Verify the hood with a calibrated anemometer or tracer test after repair, document the as-left face velocity at the specified sash height, and only then return it to service. Close the audit findings only after objective evidence of each correction, not after a log update.