These issues, among other concerns, prompted the NFPA 72 Committee to
introduce paragraph 2-2.1.3 of NFPA 72 [1]: ‘‘Heat-sensing fire detectors shall be
marked with their operating temperature and thermal response coefficienty . The
requirement for the marking of the thermal response coefficient shall have an
effective date of July 1, 2002.’’ As of today, the issue regarding the thermal-response
coefficient (TRC) still remains unresolved