Tunnel solutions for the extractive areas
In some countries they do not allow tunnel atmosphere monitors to be mounted on the tunnel wall; also, where there is a single bore it is very difficult to gain access for maintenance purposes. The TunnelTech 400 series are extractive gaseous pollutant and visibility monitors and extract a gas and dust sample from the tunnel bore and carry to a remote analyser. This allows maintenance to take place without affecting tunnel traffic flow.
The NO2 analyser is a highly efficient transmissometer configured for the continuous measurement of Nitrogen Dioxide in road tunnel atmospheres. This extremely stable and reliable monitor incorporates a high-power blue LED to utilise the capacity of nitrogen dioxide to absorb UV and blue light to provide accurate readings in parts per billion. Visibility is monitored in the same sampling chamber using a standard opacity technique. The other optional gases are monitored using electrochemical cells.
One advantage of extractive analysers is that they can be regularly calibrated using bottled audit gases. There are four versions of the TunnelTech 400 series:-