sprinklernotes Window Sprinkler Within A Dwelling Unit
“We have designed and installed an NFPA 13R sprinkler system in a three-story apartment building. The system has been installed, and it has come to our attention that the architect designed a firewall that cannot have openings within 4 ft of the firewall and there are windows within 4 ft of the firewall. The local building code allows the use of a water curtain per NFPA 13 in front of the windows with this application. This application will have quick-response sprinklers installed in the compartment of a dwelling unit with residential sprinklers. Does this meet the NFPA 13 and 13R standards by installing quick-response sprinklers (for the water curtain) in the same dwelling unit compartment as the residential sprinklers?” We have reviewed the 2019 editions of NFPA 13, Standard for the Installation of Sprinkler Systems, and NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, that you indicated as the applicable standards. Our informal interpretation is that residential and quick-response window sprinklers can be within the same compartment. There is no residential type window sprinkler; thus, a special quick-response window sprinkler has to be used. The issue is the thermal element where the compartment has to be either residential or quick-response sprinklers. The residential sprinkler and the quick-response window sprinkler are both fast-response type sprinklers so that shouldn’t be an issue for this application. Section 1.6 of NFPA 13R for new technology addresses this in section 1.6.1 which states that nothing in this standard shall be intended to restrict new technologies or alternate arrangements, provided the level of safety prescribed by this standard is not lowered. The materials or devices not specifically designated by this standard shall be utilized in complete accord with all conditions, requirements, and limitations of their listings per section 1.6.2. Section 5.1.1.4.2 of NFPA 13R also addresses special sprinklers. Special sprinklers shall be permitted to be listed for protection of a specific construction feature in a portion of an occupancy classification. Some other practical reasons this could be allowed is that the window sprinkler would likely be located at a lower elevation than the ceiling or sidewall sprinklers. In addition, the window sprinkler may be located behind a curtain, window shade, or blinds. A fire exposing on the window would likely activate the window sprinkler first before the room sprinklers would activate. If the room sprinklers did activate first, the effects of that are not expected to be adverse. There are larger issues occurring on the outside of the window. An incorrect application of these two sprinkler types would be using the window sprinkler to cover part of the dwelling unit in lieu of residential sprinklers. That is not the case for this application. NFPA 13 in section 12.1.4 does address residential sprinklers installed in a compartment as defined in section 3.3.38 that all sprinklers within the compartment shall be residential sprinklers. The Automatic Sprinkler Systems handbook commentary indicates that when mixing sprinklers that are not of the same make, caution is needed to avoid the possibility of reverse operating order or spot operation of sprinklers. It is important that all residential sprinklers be of similar thermal sensitivity when they are installed in a compartment. The use of bulb-type and solder-type sprinklers or residential and other types of sprinklers is acceptable, as long as all of the sprinklers in the compartment are fast-response sprinklers as defined in section 3.3.205.2(1)(a). Section 12.1.4 changed from fastresponse type in the 2010 edition to residential sprinklers in the 2013 edition. However, the commentary has remained unchanged since the 2010 edition until the 2019 edition, where it was deleted from the handbook during the
