Hi Chris,

This may not answer all the questions, but this is what can be found in NFPA 99, 2015.

14.2.10.2*

Exhaust from all classes of chambers shall be piped outside of the building.

14.2.10.2.1

Each Class B chamber shall have an independent exhaust line.

14.2.10.2.2

The point of exhaust shall not create a hazard.

14.2.10.2.3

The point of exhaust shall not allow reentry of gases into the building.

14.2.10.2.4

The point of exhaust shall be protected by the provision of a minimum of 0.3 cm (0.12 in.) mesh screen and situated to prevent the intrusion of rain, snow, or airborne debris.

14.2.10.2.5

The point of exhaust shall be identified as an oxygen exhaust by a sign prohibiting smoking or open flame.

14.2.10.3

The supply piping for all air, oxygen, or other breathing mixtures from certified commercially supplied cylinders and portable containers shall be provided with a particulate filter of 66 microns or finer.

14.2.10.3.1

The particulate filter shall meet the construction requirements of ANSI/ASME PVHO-1,

Safety Standard for Pressure Vessels for Human Occupancy, and be located as close as practical to the source.

A.14.2.10.2

Exhaust piping extending from the building can create a lightning risk. Lightning protection should be considered.