Tunnel construction - Working under pressure
Air pressure stops water from penetration
During the construction of a tunnel ground water can flow into the tunnel. To prevent this the tunnel is kept under pressure between partition walls. As people were working in this area the air had to be cool and clean (oil free).
100% oil free air
Because the construction labour is temporary it is attractive for the building company to rent the machines. Because of the long initial period ARD was able to deliver 100% oil-free blowers with watercoolers that are made to measure for the project. People and machines enter the tunnel via locks. When the intermediate doors open, the pressure in the tunnel has to remain. To maintain the pressure at an accuracy of 10 mbar one machine is equipped with frequency control.
Losing the pressure should bring people into danger because of the threatening water nuisance and the risc of the caisson illness. For this reason one installation is built of several machines with sufficient backup.
Scope of delivery
- 1 x BVO 5500 (29.0 - 90.3 m³/min @ 2.0 bar)
- 4 x BFO 5500 (85.0 m³/min @ 2.0 bar)
- 5 x water-air cooler