technology
High-performance, cost-effective solution Extensive testing led to the selection of a specially developed sprinkler system for Stockholm’s Northern Link road tunnels. Based on a unique sprinkler, the system offers robust fire performance and greatly reduced costs, reports Henrik Johansson
When the Swedish Transport Authority (STA) started to compare technologies and systems around 2010 for protecting the Northern Link and Stockholm Bypass tunnels, they could not find any existing system and technology that matched their criteria – performance, redundancy, resistance to the environment, robustness, maintenance and lifetime cost. STA involved the well-reputed fire engineering firm Brandskyddslaget and the RISE Fire Research laboratory to help them investigate technologies that protect the same type of hazards in other applications. Early in the project, Brandskyddslaget sprinkler engineers understood that the main risks are similar to those in high rack storage. The project team also looked at how the installation cost may be reduced without interfering with the system performance. Brandskyddslaget then turned to Johnson Controls as the world leader in both storage protection and horizontal sidewall sprinkler technology. It was also determined that the cost of a fixed firefighting system (FFFS) is
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mainly driven by the amount of pipe. The horizontal sidewall type of nozzle technology was found to reduce the pipe demand by up to 70%, which resulted in significant cost savings.
Ro-Ro ships and warehouses The research by RISE/ Brandskyddslaget showed that 10 mm/min was the optimal water
density for road tunnels. This conclusion was mainly based on laboratory testing for RO-RO ships (SP Report 2009:29) and the few official FFFS road tunnel test reports available. The risk on a RO-RO ship is more or less identical to the risk in road tunnels. The difference is the air velocity and shape of the room. The ideal nozzle type and water density was now identified; however, the solution did not exist. Johnson Controls was assigned to develop a large K-Factor horizontal sidewall nozzle. This product line is known as Tyco Model TN and is offered in two sizes, K240 and K360. TN is a technology with its origin in the sprinkler fire protection of high rack storage. In the late 80’s, the increased performance of sprinklers creating bigger droplets began to be recognised by the fire protection industry as an effective way to protect warehouses. Inventions like the Early Suppression Fast Response (ESFR) sprinklers and similar designs that created big droplets changed the market substantially. These technologies made it possible to protect rack storage with a ceilingonly sprinkler system design. Today this technology is used for