Improving the installation efficiency of fire safety systems. By Nicola Anderson

Fires on rolling stock have the potential to be catastrophic and a number of tragic events have served to highlight the importance of fire safety controls and prevention over the years.

Incidents such as the 2000 Kaprun disaster in Austria, the 2002 El Ayyat disaster in Egypt, the 2003 Daegu Metro fire in South Korea and most recently, the 2019 Tezgam disaster in Pakistan, all resulted in a tragic loss of life, serious injury to people, and extensive damage to assets and infrastructure.

Over the years, rail industry safety standards have significantly improved in order to mitigate the risk of fire in rolling stock and ensure vehicles are configured to be as fireproof as possible. Safety approaches include the use of incombustible or fireproof material, use of fire barriers to separate areas of risk, use of emergency equipment such as fire extinguishers and use of fixed protection systems consisting of fire detection and suppression to prevent a potential fire and stop it from spreading.

Fixed fire protection systems that include suppression often have a sprinkler system that delivers a fire-extinguishing agent to help put out any fires that might break out within rolling stock. Such systems usually include a high-pressure tank, complete with pipework, which includes a series of nozzles attached at certain sections. The pipework forms a channel through which the fire-extinguishing agent is sprayed into each part of the railway vehicle via the nozzles.

Such sprinkler systems are generally installed during the manufacture of rolling stock, although they can be fitted retrospectively. The pipework for the delivery of the fire-extinguishing agent is usually attached to the bodywork/chassis of the rail vehicle, most commonly on the roof structure, and then concealed behind ceiling panels. In order to ensure that the nozzles effectively deliver the fire-extinguishing agent, they are exposed to the interior of the vehicle by means of an opening cut through the ceiling panels.

As ceiling panels and pipework are fitted to the chassis of the rail vehicle, and the location and size of the openings used for the nozzles are predetermined by dimensional drawings or during fitment, there is a risk of dimensional or tolerance errors. This means that fitment of pipework, nozzles and ceiling panels to the chassis is not always possible first time, and some rework may be required. For example, a nozzle might not fit within an opening in a ceiling panel due to a combination of errors, e.g. a dimensional error of the roof structure, a positioning error of the pipework attached to the roof structure and/or an attachment error of the ceiling panel. Such rework results in increased time and effort required in installing the system.

To solve this problem, Hitachi Ltd has built on existing technology and been granted a UK patent GB2533486 for an invention that focuses on the pipe structure for delivering the fire-extinguishing agent into the vehicle.

Specifically, the patent protects fire-extinguishing equipment including a channel, which is formed by pipes, which are connected and fixed to a ceiling panel inside the roof structure of the rail vehicle. The adjacent pipes on the respective ceiling panels are coupled using a flexible joint, which can be easily accessed via an opening on each ceiling panel. The nozzle is then fitted into this opening.

The flexible joints protected by the patent allow the fire-extinguishing system to be fitted despite any dimensional and tolerance errors. Installation can be completed at the first attempt and with fewer steps than was possible previously, thus increasing the operating efficiency of the technology.

Nicola Anderson is a patent attorney at European intellectual property firm, Withers & Rogers. She advises innovators in the rail sector about how to protect their inventions