
1) Underwater diving safety
Found on
https://www.crosswordclues.com/clue/freeflow

In scuba diving, a freeflow occurs when the diving regulator continues to supply air instead of cutting off the supply when the diver stops inhaling, or starts to flow when out of the diver`s mouth due to a pressure difference over the diaphragm or a bump to the purge button, and continues to flow due to the `venturi effect` of reduced internal......
Found on
http://en.wikipedia.org/wiki/Freeflow

Berghauss range of technological advancements in rucksack design to increase airflow an venting.
Found on
https://www.encyclo.co.uk/local/23307
No exact match found.