FAT32 works for both OSes, but has a 4GB size limit per file, so it isn't ideal. However there is a 4GB file size limit. You could use NTFS but you will have to install additional software on the Mac in order to read AND write to the volume. exFAT then is the best option.
The riser duct is a problematic zone due to: -build-ups, alkali infiltration and chemical attack to the steel anchors. Following the general rule, we suggest lining the duct with bricks in the round sections and with castables in the square sections.
Ducts are used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, supply air, return air, and exhaust air.Ducts commonly also deliver ventilation air as part of the supply air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort. A duct system is also called ductwork. Planning (laying out), sizing, optimizing, detailing, and finding the pressure losses through a duct system is called duct design.