London Underground Extension
As part of London Undergrounds Northern Line Extension, they have installed a large scale under platform ventilation system at Nine Elms, Battersea and Kennington stations. The ventilation systems at all three stations work in concert to ensure the platforms and tube tunnels are always supplied with fresh air, dust extraction and effective cooling. In the event of a fire in the tube tunnels or platforms, this system can be used to evacuate smoke and supressing the fire.
We installed differential pressure transmitters in the fan rooms. With the ability to accurately measure relatively low pressures both positive and vacuum, these instruments provide information required to determine ventilation pressure, fan direction of rotation and an indication of the operational efficiency of the fan.
The major challenge we had was finding an atmospheric reference for these instruments. For the most part the area around the fan rooms and adjoining spaces are subject to fan ventilation pressure. This meant long pipe runs, at times through multiple walls and spaces to reach an area exposed to normal atmospheric pressure.