Can you mix different lot numbers of CO2 scrubbing material into your canister?

• A. Yes
• B. No
• C. Only if same batch
• D. Only for long dives

Answer: (B)

Mixing CO2 scrubber material from different lot numbers creates variability in the absorbent bed, which can make its performance unpredictable. Lot numbers reflect batches that may differ slightly in chemical composition, moisture content, and particle size. When you blend materials from different batches, some granules may scrub CO2 more quickly and others more slowly, leading to channeling where gas bypasses parts of the bed. This can cause uneven absorption, higher CO2 partial pressure, and potential CO2 buildup—dangerous in a closed-circuit system. To maintain a predictable, uniform scrubber performance, only material from a single batch should be used in a canister, and mixing different lots should be avoided. The other options don’t address the stability and predictability of the scrubbing reaction, and one is irrelevant to the question of batch safety.