Question 1

How do fume hoods and laminar flow cabinets differ in their airflow direction?

Accepted Answer

Fume hoods draw air inward across the workspace and exhaust it outward to remove hazardous fumes and particles away from the laboratory. Laminar flow cabinets blow filtered air outward through the workspace to prevent contamination from entering. Horizontal cabinets direct air horizontally, while vertical cabinets direct air downward from above, then out past the sash.

Question 2

What is laminar airflow and why is it important in laboratory equipment?

Accepted Answer

Laminar airflow proceeds in parallel streamlines that do not cross, preventing cross-contamination between samples. Unlike turbulent flow, laminar flow flows smoothly around objects and removes hazardous particles efficiently. This controlled airflow is essential in both fume hoods and laminar flow cabinets to maintain a safe and sterile laboratory environment.

Question 3

What are the key safety practices when working inside a fume hood?

Accepted Answer

Always wear appropriate personal protective equipment and raise the sash only to the indicated maximum safe working height. Keep your arms inside the hood and never let your head enter the workspace. Maintain an uncluttered workspace and move all items at least six inches away from the hood face to ensure sufficient velocity throughout the hood.

Question 4

How should chemicals be stored when using a fume hood?

Accepted Answer

Do not store chemicals inside the fume hood. Instead, store them in dedicated storage locations such as a flammables cabinet. After completing work, remove all materials from the hood and close the sash to ensure a safer laboratory environment and reduce energy usage.

Question 5

What maintenance procedures are required for laminar flow cabinets?

Accepted Answer

Check for leaks by coating sensitive areas like sash edges with a soap solution, which will bubble at escaping air sites. If the cabinet is equipped with a UV-C light, turn it on to disinfect the workspace after use. Remove all items and close the sash to prevent contamination between uses.

Question 6

How does a HEPA filter protect the workspace in laminar flow cabinets?

Accepted Answer

A HEPA filter removes 99.97% or greater of 0.3 micrometer particles from the air before it flows into the cabinet workspace. This high-efficiency filtration prevents harmful chemicals and particles from entering the cabinet, maintaining a sterile environment for sensitive biological or chemical work.

Question 7

What should you do if the airflow velocity in a fume hood becomes too low?

Accepted Answer

Lower the sash until the velocity reaches the required speed. If the sash becomes too low for work to be performed at the hood, cease operations until the root cause is identified and addressed. Regular testing of flow velocity at maximum sash height helps prevent this issue.

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