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Keeping light at the end of the tunnel

One of the most critical fan types are those used in road or rail tunnels. During normal operation the fans are used for pollution and control and to manage carbon monoxide levels throughout the tunnel. However, should a fire break out, the fans need to operate rapidly to extract the smoke from the tunnel.


Maintaining these fans to the highest standards is equally as critical, and Gibbons HVAC Services is one of a few companies capable of carrying out such work.




“We were recently asked to undertake routine maintenance of 24 jet fans that serve a major road tunnel,” says Andrew Knight, Business Manager – HVAC Services and Refurbishment at Gibbons. “The fans are clearly life-critical and as such are rated to operate under smoke duty at 300 degrees Celsius for a period of one hour.”

Each fan is mounted from a cradle hung from the tunnel ceiling and is fitted with a pair of perforated lined silencers. Maintenance involved a series of routine tests on all the fans during a planned night time tunnel closure. The Gibbons team managed the complete process, from delivery of access equipment on site, to detailed method statements and risk assessments.


“We designed a record sheet for the service, such that all information was logged and a passport for each fan was created,” explains Andrew. “Our engineers completed a series of visual inspections on every fan. We also took condition based readings using portable monitoring equipment. These readings allowed us to identify any problems relating to bearings, looseness, balance and overall vibration.”



Thermal images of key system components were carried out to provide a complete picture of current plant health. The service visit was followed up with a detailed written report and a record of readings for each fan, so that the data can be trended on subsequent visits. 


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If you have a HVAC services enquiry, contact Andrew Knight on 07850204915, email him at or visit the divisional page here.

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