Engineering controls & fume hoods
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DO
Work 15 cm inside
Keep apparatus well back from the opening.
Step 3 / 6VOICE · ON
IN ONE LINE
Engineering controls remove the hazard at the source — and the fume hood is the lab's workhorse.
WHAT YOU'LL LEARN
Place engineering controls correctly in the hierarchy.
Operate a fume hood for maximum protection.
Verify ventilation before starting hazardous work.
READ THE LESSON
The hierarchy of controls
Elimination, substitution and engineering controls beat PPE because they don't depend on a person remembering. The fume hood captures and exhausts vapours before you ever breathe them.
Sash height sets the velocity
The hood is designed for a specific face velocity at a marked sash height. Raise the sash too high and the inward airflow weakens, letting vapour escape.
It's a workspace, not a cupboard
Bottles stored in a hood disturb airflow and become a hazard if a fire starts. Keep only what you're using inside, well back from the front edge.
Face velocity
Most hoods need roughly 0.5 m/s of inward air at the working sash height. The monitor tells you if you have it.
QUICK CHECK
1 / 5In the hierarchy of controls, engineering controls rank…
Select an answer to continue
OSHA · 05
KEY POINTS
Engineering controls rank above PPE.
Keep the sash at the marked height.
Work well inside; don't store in the hood.
Confirm airflow before hazardous work.
REFERENCES
NIOSH Hierarchy of Controls
ANSI/AIHA Z9.5 — Lab ventilation
ASHRAE 110 — Fume hood testing
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