Combustible Concealed Space Upright Sprinklers TY1189 (Model CC1) ) 2.8 K-factor are fast response, upright, specific application sprinklers designed to provide protection of light hazard combustible, as well as non- combustible, concealed spaces requiring sprinkler protection. The CC1 Sprinklers comply with the criterion for the protection of combustible concealed spaces as described in NFPA 13.