The Wet Pipe Automatic Sprinkler System

The Wet Pipe Automatic Sprinkler System risers are pressurized and filled with water at all times. The wet automatic sprinkler system is connected to the public water distribution system and relies on the volume of water and pressure generated by the public water distribution system. Water will discharge to the area where the fire is located by the opening of the automatic sprinkler heads. This type of sprinkler system is typically equipped with a fire department connection and in some cases, the fire department connection is considered a secondary or auxiliary source of water. The alarm check valve shall always be located upstream or below the fire department connection to prevent the auxiliary or secondary source of water from flowing into the public water distribution system. The alarm check valve is a free-swinging clapper valve that serves as both an alarm valve that indicates when water is flowing and a backflow valve that may prevent fire sprinkler water from flowing into the public water distribution system. The alarm check valve is not by today standards an approved backflow prevention device assembly used for cross-connection control. An evaluation of the system must be completed to determine the type of backflow protection required for this system, if any.

An antifreeze solution sprinkler system is an extension of the wet sprinkler system and is used for sprinkler heads installed in unheated areas of the building subjected to cold and possible freezing temperatures. If antifreeze is used in any part of the fire sprinkler system, a backflow prevention device assembly shall be installed on the pubic water system service connection upstream of the alarm check valve.