A 32″ square steel duct is installed in an HVAC air distribution system that has an internal pressure of 1.7″ water column. The material used in fabrication of this duct should be _____ guage.

A 32″ square steel duct is installed in an HVAC air distribution system that has an internal pressure of 1.7″ water column. The material used in fabrication of this duct should be _____ guage.