Required section · Section 5 of 6

Choose the controls and sequence the response

This screen asks for two kinds of decision. The first is choosing which controls belong in a bundle for a routine LN2 transfer room and a dry-ice receiving bay: which are engineering or administrative controls that catch a hazard a person cannot sense directly, and which are inadequate on their own. Personal protective equipment (PPE) matters, but PPE alone does not answer the question a fixed oxygen monitor answers, and it does not substitute for ventilation, segregation, or a defined evacuation and re-entry procedure.

The second decision is sequencing: when the alarm activates, what happens first, second, and last. The guided example already showed the correct order once. This screen asks the learner to reconstruct it without the narrative walking them through it, and to justify why the order matters (stopping the transfer before exiting keeps a hazard from getting larger while the room is being vacated, and confirming a calibrated reading at the doorway before re-entry is what actually clears the space, not the elapsed time since the alarm or a return to the earlier wall-display number).

Neither decision asks the learner to attempt a rescue, silence an alarm from inside the room, or re-enter to investigate. If the required monitor is missing, failed, overdue, unavailable, or unverified, do not begin or resume the transfer; hand off to the monitoring and re-entry procedure. Hands-on cylinder, oxygen-monitor, and cryogenic procedures follow site EHS, fire code, and manufacturer requirements.

When in doubt about whether a room, a vial, or a shipment is safe, the answer is to use the instrument reading and the written procedure, not a guess based on how the room looks or how routine the task usually is.

Ordering exercise

Put the response to the 08:13 low-oxygen alarm in the correct order, from the moment the alarm activates to the room being cleared for normal work again.

1. Confirm a calibrated doorway reading

Use a calibrated instrument check at the doorway to confirm the room has returned to a safe oxygen level; the wall display alone is not sufficient.
2. Exit and close the door

Leave the room without attempting to silence or investigate the alarm from inside, and close the door behind you.
3. Resume with authorized re-entry

Only after the doorway reading is confirmed safe does authorized staff re-enter and resume the transfer or retrieve equipment.
4. Stop the LN2 transfer

Stop adding LN2 to the freezer bank immediately so the source of the oxygen displacement is no longer active.
5. Notify and let ventilation run

Notify the supervisor or EHS contact and let mechanical exhaust continue running with the door closed.

Knowledge checks

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Knowledge check 1

Where should a shipment box marked "Dry ice, UN1845" be opened after it arrives at the receiving bay?

Choose one option.

In a ventilated area, not in an enclosed vehicle cab or small closed room

Inside the delivery van cab before unloading, to save time

In a small closed closet, away from foot traffic

It does not matter, since dry ice itself is not a hazardous material

Knowledge check 2

Which combination of controls best reduces oxygen-deficiency risk from routine LN2 transfers into a room like the one in the guided case?

Choose at least 3 options.

A fixed oxygen monitor with an audible alarm at the room entry

Mechanical ventilation for the room

A written evacuation and re-entry procedure with defined doorway testing

Relying on PPE alone, without monitoring or ventilation

Assuming staff will notice symptoms of low oxygen before it becomes dangerous

Section status

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The module finishes after every required section is marked done and every check in those sections is correct.