NFPA 820 - Recirculation of Exhaust Airflow for Unclassified Space?

[SB7685]

NFPA 820, if one was to explore using recirculation for an unclassified space, would you need to use no less than 6 air changes as stated in section 9.3.3, or would it be OK to to use NO ventilation requirement, as stated in Note (1) of Table 6.2?

Note (1) of Table 6.2 states "The NR designation (no requirement) in the ventilation column indicates that NO ventilation requirements are established for the space, and therefore, Table 9.1.1.4 also has no requirements."

Section 9.3.3 states "Recirculation of up to 75 percent of the exhaust airflow rate for unclassified areas shall be permitted, provided that the following criteria are met:
(l) The recirculated air and outside airflow rate total is not less than 6 air changes per hour.
(2) Recirculation does not occur during occupancy.
(3) Recirculation does not occur whenever a combustible gas detector senses.

Any feedback would be much appreciated, thanks!

 

[chicopee]

You should provide more information about the type of unclassified space and what would the composition of the recirculated air before anyone provides an answer, after all, common sense has to be applied when using the NFPA.