Residential Fire Sprinklers

• Passive Purge System
  This system will contain water supplied by the potable water meter and is plumbed so that as a designated water fixture flushes stagnant water as it is used in the household.
   
• Antifreeze System
  This system will contain a percentage of propylene glycol or glycerin and water is supplied by the potable water meter. All antifreeze solutions shall be a listed factory premixed solution and approved in accordance with NFPA 13D and the California Fire Code which allows only propylene glycol solutions of no more than 40% or glycerin solutions of no more than 50% by volume.
  
  

The antifreeze system requires a backflow prevention device.  Minimum protection for this application is an RP.  Location of said backflow device will need to be approved by Water District representatives. 

See examples below of RP backflow devices previously installed in garages for residential fire sprinkler protection.  This is a common location for residential fire sprinkler systems with antifreeze or glycerin.