by Grant Lobdell

The current, 2017 edition of National Fire Protection Agency (NFPA) 25 Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems further explains sprinkler field service testing as required in 5.3.1.1 in the annex section A.5.3.1.1:

Sprinklers should be first given a visual inspection in accordance with 5.2.1.1.1 to determine if replacement is required. Sprinklers that have passed the visual inspection should then be laboratory tested for sensitivity and functionality.  The waterway should clear when sensitivity/functionality tested at 5 psi (0.4 bar) or the minimum listed operating pressure for dry sprinklers.

Thermal sensitivity should be not less than that permitted in post-corrosion testing of new sprinklers of the same type.

Sprinklers that have been in service for a number of years should not be expected to have all of the performance qualities of a new sprinkler. However, if there is any question about their continued satisfactory performance, the sprinklers should be replaced.

Since the permitted sensitivity in post-corrosion testing varies among various pre-market standards, Dyne’s field service testing thermal sensitivity requirements before November 4th, 2018, were based on NFPA definitions.  The 2016 edition of NFPA 13 Standard for the Installation of Sprinkler Systems defines thermal sensitivity and RTI requirements in part of section 3.6.1:

(1) Thermal sensitivity. A measure of the rapidity with which the thermal element operates as installed in a specific sprinkler or sprinkler assembly. One measure of thermal sensitivity is the response time index (RTI) as measured under standardized test conditions. (a) Sprinklers defined as fast response have a thermal element with an RTI of 50 (meters-seconds)1/2 or less. (b) Sprinklers defined as standard response have a thermal element with an RTI of 80 (meters-seconds)1/2 or more.

Furthermore, sprinklers defined as standard response were required to have a maximum RTI of not more than 350 (meters-seconds)1/2 based on various pre-market standards - the 11th edition of UL 199 and the 2006 edition of FM 2000.

During the recent NFPA 25 technical committee meeting, a revision to section A.5.3.1.1 was unanimously supported by those in attendance.  The following is the proposed language for section A.5.3.1.1 for the upcoming 2020 edition of NFPA 25:

Sprinklers should be first given a visual inspection in accordance with 5.2.1.1.1 to determine if replacement is required. Sprinklers that have passed the visual inspection should then be laboratory tested for sensitivity and functionality. The waterway should clear when sensitivity/functionality tested at 7 psi (0.5 bar) or the minimum listed operating pressure for dry sprinklers.

The thermal sensitivity should be such that the RTI does not exceed 350 (meters-seconds)1/2 for standard response sprinklers, 65 (meters-seconds)1/2 for quick response and residential sprinklers and 50 (meters-seconds)1/2 for ESFR sprinklers.

Sprinklers that have been installed for a number of years should not be expected to have all of the performance qualities of a new sprinkler. However, if there is any question about their continued satisfactory performance, the sprinklers should be replaced.

Note the pressure at which sprinklers are sensitivity/functionality tested was increased from 5 PSI to 7 PSI.  Exact RTI requirements were also defined for periodical testing purposes to address inconsistent criteria due to differences in post-corrosion test requirements.

While the 2020 edition has yet to be finalized, Dyne will begin to meet the requirements proposed at the last meeting since they are technically supported and enhance the field sprinkler testing service across multiple labs.  As of November 4th, 2018, Dyne adjusted the pressure during field service testing from 5 PSI to 7 PSI, removed the minimum RTI requirement for standard sprinklers, and increased the maximum RTI requirement for fast response sprinklers from 50 (m·s)1/2 to 65 (m·s)1/2.  Note the maximum RTI for ESFR sprinklers and standard sprinklers were left at 50 (m·s)1/2 and 350 (m·s)1/2, respectively as outlined in the proposal above.  The increased pressure and RTI changes may decrease various sprinkler failure rates.

If you have any questions regarding these requirements, please contact Dyne Fire Protection Labs at lab@dyneusa.com or (800)632-2304.

©Dyne Fire Protection Labs 2018