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Background

a1-cbiss known for their complete project management of fixed gas detection projects worked alongside a leading integrated support services company to design, install, commission, service and maintain a new fixed gas detection system within the construction site at an underground rail tunnel in North London.

Problem

During the construction of the rail tunnels, a number of vehicles are used to assist with moving materials into place and transporting workers. The vehicles' exhaust fumes can pose a threat to the safety of workers as the application is classed as a confined space. Continuous gas detection is required to ensure workers safety as stipulated by the Health & Safety Executive (HSE) and the BTS (British Tunnelling Society). they have specified the requirement to monitor Oxygen (O2), Nitrogen Dioxide (NO2), Carbon Monoxide (CO), and Nitrogen Oxide (NO), and to include data logging & reporting software.

They have specified the requirement to monitor Oxygen (O2), Nitrogen Dioxide (NO2), Carbon Monoxide (CO), and Nitrogen Oxide (NO), and to include data logging & reporting software.

Solution

The gas detection system was installed by a1-cbiss inside two 625 metre long, 6 metre diameter rail tunnels during the construction phase.

The gas detection panels are set to alarm at 19.5%, 25ppm, 30ppm and 5ppm respectively. Diesel engines used by MEWP's (mobile elevating work platforms) are to be used within the tunnels which will emit CO, NO and NO2.

To help keep the tunnels clear of contaminants, the two tunnels are constantly fed with fresh air by four 1600mm, 60kW axial flow fans. It was necessary to install six detection points, three in each tunnel, one in the middle of each tunnel and two at either end.

a1-cbiss supplied a gas detection system to continuously monitor for all four gases and log their readings every 60 seconds. The PLC controller and data logger operator is able to easily download the data on a weekly basis via a USB key and download the data to their laptop.

As soon as the alarms levels are breached during operation, the gas detection panel will activate its tunnel grade 114dB multi-tone sounder with integrated LED visual beacon. The GRP enclosure used was designed to withstand the harsh environment and plus any impact from heavy moving machinery. The gas detection system will be powered from a diesel generated 110v power supply, to guarantee the system will work. For circumstances when power is down, a1-cbiss have installed a backup battery.

a1-cbiss will provide full service and support on-site to ensure the continuous operation of the gas detection system.

Do you have a bespoke gas detection requirement?