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Crowcon’s gas monitoring systems have been installed in the world’s fourth longest rail tunnel to detect flammable and toxic gases before they reach hazardous levels.

The 28km-long Guadarrama Tunnel in Spain and the 8.5km San Pedro Tunnel form part of the recently-opened Madrid-Valladolid high speed rail link.

The Guadarrama Tunnel comprises two parallel tunnels connected by cross-passages every 250 metres, as well as a 500 metre-long emergency room, located equidistant from both tunnel entrances.

The San Pedro Tunnel, which also comprises parallel tunnels, is connected by cross passages every 400 metres.

More than 500 Crowcon detectors are installed throughout the tunnels, including Xgard detectors (validated to IEC61508 SIL2/3) for detecting carbon monoxide (CO), nitrous dioxide (NO2) and oxygen (O2) levels, and flameproof (Exd) infra-red Nimbus units for detecting methane (CH4) levels.

Signals from these detectors are processed by more than 70 Vortex rack-mounted controllers, which are connected to PLCs via RS485 and provide operators with all gas readings and alarm/fault information.

If the detectors register dangerous levels of gas, ventilation and exhaust systems are automatically triggered by the Vortex control panels, which also pinpoint which detector is in alarm mode.

They then immediately transmit this information via PLC to a Scada system that transmits the information to control rooms in Madrid and Segovia.

Internal combustion engines emit exhaust fumes that contain significant quantities of CO and NO2 (both highly toxic).

If a tunnel is inadequately ventilated, these gases can accumulate to dangerous concentrations.

Oxygen depletion is also a risk where a fresh-air supply is limited.

In the absence of adequate ventilation, oxygen levels can be quickly depleted by breathing, combustion and dilution by other gases such as carbon dioxide (also a toxic gas), nitrogen, argon or helium and chemical absorption by corrosion processes.

Under EU regulations, fire and gas safety systems are obligatory in tunnels longer than 500M.

Crowcon Detection Instruments

Crowcon Detection Instruments specialises in the development, manufacture, sale and support of flammable and toxic gas detection equipment. For over 40 years and all around the globe, our products are relied upon to protect people and plant against gas hazards, from oil platforms to steel mills and water treatment works to automobile manufacturers.

Headquartered in the UK and with our own significant local facilities in  Erlanger, USA, Singapore, China and the Netherlands supported by carefully selected distributors, we are proud to uphold our reputation for reliability, technological innovation and equipment that is properly suited to its task.

Crowcon products are sold throughout the world, serving oil, gas and petrochemical companies, public utilities, clean water and sewage treatment companies, fire brigades, construction companies and other organisations where accidental leakage of gas or vapour can become a toxic or explosive danger.

Crowcon has been a part of the Halma Group since 1985. Halma is listed on the Midcap London Stock Exchange (FTSE 350) and is recognised as one of the most successful engineering groups in the world.

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