What is the maximum volume of antifreeze allowed in NFPA 13D and NFPA 13R?

In NFPA 13D and NFPA 13R, the maximum volume of antifreeze that is permitted in a fire protection system is set at 40 gallons. This limitation is established to ensure that the fire suppression system maintains its efficacy while preventing the potential for hazardous conditions that could arise from using large amounts of antifreeze.

Antifreeze is used in sprinkler systems primarily to prevent water from freezing in low-temperature environments, especially in residential settings where the risk of freezing pipes is a concern. However, the use of antifreeze comes with specific guidelines due to its chemical properties, which can impact fire suppression effectiveness and may introduce environmental or health risks if not managed properly.

By establishing a maximum volume, the NFPA provides rules that help maintain the integrity of the fire protection system while balancing safety and practicality. Therefore, the 40-gallon limit serves as a standardized benchmark across installations covered by these codes. This approach helps ensure that the advantages of utilizing antifreeze do not outweigh the safety considerations and potential complications associated with its use.