What is the approval condition for installing heads in closets according to NFPA 13?

The approval condition for installing sprinkler heads in closets according to NFPA 13 is primarily based on the size and dimension limitations. This specifies the requirements for the physical space where the sprinkler heads are to be installed, ensuring that they can function effectively and provide adequate coverage in the event of a fire.

NFPA 13 sets forth guidelines regarding the obstructions and dimensions of the area to ensure that the sprinkler's discharge pattern can operate without interference, which is critical for optimal performance. This includes ensuring the head is not placed too close to walls or other obstructions that might block water spray or create heat build-up, thereby compromising the effectiveness of the sprinkler during a fire event.

Other potential conditions, such as monitoring by a sprinkler installer or fire rating considerations, do not address the specific functional and spatial requirements stipulated for installations in closets, which makes adherence to size and dimension limitations the primary concern in this context.