Hello grille ceiling 15 cm affects the fire spray? Need to switch to a water spray?

No. According to the fire regulations, the permeable area of the equally permeable ceiling using the grille ceiling is more than 70%, and the upper sprinkler head needs to be set, so this does not need to be changed to spray down, only the part of the ceiling with a width of more than 1 meter is not transparent, and the part of the impermeable ceiling needs to be set up and sprayed up and down (the upper and lower spray only considers the diameter of the single-layer sprinkler head).

It is best to use a sagging sprinkler head or a ceiling sprinkler in a place with a grille ceiling. According to the regulations, if the hollow area of the grille ceiling is less than 30, the sprinkler head should be installed below the ceiling, if the hollow area of the grille ceiling is greater than 70, the sprinkler should be installed above the ceiling, and the hollow area is between 30 and 70, subject to the actual measurement.