Fire Damper Installation

Q: Do you need a fire smoke damper at floor level in an open duct shaft? Or where the duct comes out through the shaft wall?

A: Section of the 2000 edition of the Life Safety Code requires compliance with section 9.2. Section 9.2.1 requires compliance with NFPA 90A Installation of Air Conditioning and Ventilation Systems, 1999 edition. If you have a copy of that standard, take a look at Figure A-3-3 in the appendix of the book, and there is a real nifty diagram that points out all of the possible locations where fire and smoke dampers would be required. But, to directly answer your questions, section 3-3.2 of NFPA 90A requires a fire damper at the floor level of any HVAC duct that penetrates a fire-rated floor if the duct is not enclosed within a fire rated shaft. But section 3-3.4.1 says an air duct that pass through floors of buildings that require the protection of vertical opening (such as a hospital would), must be enclosed with walls with 1-hour fire resistance rating if the shaft penetrates 3 or less stories, and 2-hour fire resistance rating if the shaft penetrates 4 or more stories. The exception to 3-3.4.1 says you do not need a fire rated shaft if the air duct passes through only one floor, or if the air duct passes through only one floor and an air-handling equipment penthouse floor, whereby the air duct would require a fire damper where the duct penetrates the floor. In reply to your second question… According to section 3-3.4.4, fire dampers are required in any opening into or out of a shaft required in 3-3.4.1, whether or not the shaft opening contains an air duct or is ductless. A fire damper is required, even if the shaft is only 1-hour fire rated. So, in conclusion, you do need fire dampers if the duct is not enclosed in a fire rated shaft and penetrates one floor (but only one floor), and you do need fire dampers where the duct exits a rated shaft.