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          Vibration monitoring system helps

          keep Mersey Tunnel running.

          
Mersey Tunnels
          are using a multichannel vibration monitoring system for measuring
          the vibration levels of the fan ventilation system in the tunnels
          acting as a preventative maintenance aid by providing them with
          data to plan when service and repair work can be carried out.

          

          Entrance
          to the Mersey Tunnel



          The Kingsway Tunnel has two 2.2 kilometres long tubes which connect
          Liverpool to Wallasey, providing an important traffic route for
          both commuter and heavy goods vehicles. The latest tunnel is
          now 30 years old and with its four traffic lanes links Liverpool
          with the Wirral giving fast access to the M53 motorway and the
          Freight Ferry Terminal to Ireland.

          
In the tunnel
          are eight sets of ventilation systems with both extract and blow,
          four of the sets being on standby. Each system uses extremely
          large fans with blade diameters of up to 3.5 metres. The level
          of carbon monoxide and smoke density are both monitored manually
          and at excessive levels the operator can change the fan speed
          or, in the event of fan failure, bring a standby fan on line.

          




          The multichannel
          Monitoring

          System operating on a fan

          enclosure.



          

          
Each fan is driven
          through a Radicon gearbox, the bearings of which are monitored
          for vibration levels. When these levels become excessive, maintenance
          engineers can switch over to the four standby fans and move in
          to carry out service or repair work.

          





          One of
          the eight set fans

          for both extract and blow.





          

          
Because the fan
          systems are in robust casings, the components cannot be seen
          or accessed easily, which eliminates manual monitoring with a
          portable vibration meter. Mersey Tunnels overcame this by fitting
          a permanent vibration sensor at each point on the eight fan systems,
          giving continuous simultaneous vibration readings for the

          whole tunnel.

          
All of the sensor
          signals are cabled into the multichannel vibration monitoring
          system housed in an industrial enclosure, which provides sensor
          excitation, signal conditioning, level indication and pre-set
          alarm level triggering via relay units.

          ___________________________________________________________

          
For more
          information, click here...



          March
          2005

          



                
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