Break tanks are utilized in fire protection systems for three main reasons:
- As a backflow prevention device between the jurisdictional water supply and the fire pump suction. In this case the jurisdiction chooses not to use backflow prevention devices.
- To eliminate pressure fluctuations in the jurisdictional water supply and provide a steady suction pressure to the fire pump. This can include where there are concerns that suction pressures on the jurisdictional water mains may become so low that main collapse can occur.
- To augment the jurisdictional water supply when the volume of water available from the jurisdiction is inadequate for the fire protection demand.
As such, break tanks will feed a fire booster pump. NFPA 20, Installation of Stationary Fire Pumps for Fire Protection, requires that the tank be sized for a minimum 15 minute duration with the pump operating at 150% of its rated capacity.
The refill system for break tanks requires at a minimum one automatic system and one manual system. If the tank cannot provide a minimum 30 minute duration, a second automatic refill system needs to be installed. Sizing of the refill systems (varies between 110% to 150% of the rated fire pump capacity), is dependent upon the duration of the break tank and the available flow from the jurisdictional water supply.
Generally design of the break tank and water mains feeding it should follow NFPA 22, Water Tanks for Private Fire Protection, and, NFPA 24, Installation of Private Fire Service Mains and Their Appurtenances, respectively.
If you would like further information regarding break tanks, please contact Risk Logic Inc.