Standard Fire Code Rules for Storage of Commercial Lithium Batteries
Standard fire codes cap bulk lithium battery storage at 600 kWh per control area unless protected by dedicated ESFR sprinklers and 2-hour fire barriers
K-25.2
Meaning
Sprinkler performance ratings identify a specific flow coefficient for fire suppression heads that indicates the volume of water discharged relative to the pressure applied at the nozzle. The designation k-25.2 refers to an extra large orifice sprinkler that is capable of delivering a very high volume of water at lower pressures compared to standard industrial heads. These sprinklers are primarily used in high ceiling warehouses where the goal is to suppress a fast growing fire before it can involve the structural roof members.
This specific rating is a measurement of hydraulic efficiency and does not describe the thermal sensitivity of the device.
Flow Calculation
Hydraulic engineers use this value to determine the total water demand of a fire protection system and to size the pumps and storage tanks accordingly. When a k-25.2 head is selected, the system must be able to provide the massive volume of water required to sustain the discharge over the entire design area. This coefficient is part of a mathematical formula where the flow rate is equal to the k factor multiplied by the square root of the pressure.
Accurate calculations are necessary to ensure that the water pressure at the most remote sprinkler is sufficient to achieve the desired suppression effect.
Hardware Selection
Mechanical properties of the sprinkler head are designed to produce a specific drop size and distribution pattern that can penetrate the heat of a battery fire. Choosing a k-25.2 sprinkler allows the facility designer to protect taller storage heights without the need for in rack piping which can be expensive and prone to damage. These heads are usually part of an early suppression fast response system that activates at a lower temperature than conventional industrial sprinklers.
The large orifice reduces the likelihood of the head being clogged by small particles in the water supply.
System Demand
Total water requirements for a building equipped with these high flow heads are significantly higher than those for a standard light hazard occupancy. A system utilizing k-25.2 sprinklers may require a dedicated fire pump and a large on site water reservoir to meet the flow duration requirements of the fire code. This investment in infrastructure is justified by the ability to store high hazard commodities like lithium ion batteries in dense configurations.
The performance of these sprinklers is a critical factor in the overall risk assessment of a modern logistics facility. Ensuring that the water supply can meet the demand is the most important part of the fire protection design.