Antifreeze solution is allowed in systems with ESFR sprinklers under which of the following conditions:

• A. The antifreeze solution is ethylene glycol based
• B. The antifreeze solution is propylene glycol based
• C. The ESFR sprinkler is listed for use with the antifreeze solution
• D. Antifreeze can be used with any ESFR sprinkler

Answer: (C)

Antifreeze can be used in ESFR systems only when the sprinkler and the system are specifically listed by the manufacturer as compatible with antifreeze solutions. This listing ensures that the materials, sealants, gaskets, and the sprinkler’s spray pattern and flow characteristics won’t be adversely affected by the antifreeze, and it sets the approved type (such as propylene glycol) and concentration. Without such a listing, using antifreeze can compromise performance and violate code requirements, even if the antifreeze type itself seems suitable. So the key condition is that the ESFR sprinkler is listed for use with the antifreeze solution.