Compressed Air Work: Experience with the use of German TBG O₂ Decompression Tables

Quelle/credit: Stephan Assenmacher

1) Obstacle removal in compressed air at the TBM cutterhead in the Herrentunnel, Lübeck |

Quelle/credit: Stephan Assenmacher

Quelle/credit: Bilfinger/Hochtief

2) Airport Light Rail Hamburg, Caisson Lot 7 |

Quelle/credit: Bilfinger/Hochtief

Quelle/credit: Kölner Verkehrsbetriebe

3) Metro Cologne, Lot North |

Quelle/credit: Kölner Verkehrsbetriebe

Quelle/credit: Stephan Assenmacher

4) Welding work in compressed air on the TBM cutterhead in the Tunnel Jenbach |

Quelle/credit: Stephan Assenmacher

Quelle/credit: XFEL GmbH

5) Schematic representation of the XFEL tunneling project in Hamburg |

Quelle/credit: XFEL GmbH

Quelle/credit: Stephan Assenmacher

6) Man lock and material lock on a typical TBM with a diameter of less than 7 m |

Quelle/credit: Stephan Assenmacher

7) Non ergonomic conditions in a man lock |

Quelle/credit: Stephan Assenmacher

8) Incorrect (left) and correct posture (right) during decompression |

Quelle/credit: Stephan Assenmacher

9) Herrentunnel: Detailed data of compressed air work |

Quelle/credit: Stephan Assenmacher

Quelle/credit : Stephan Assenmacher

10) Comparison of individual exposures with oxygen decompression and cases of Decompression Illness related to the analysed projects |

Quelle/credit : Stephan Assenmacher

Compressed air work – initially used in caissons for bridge foundations or tunnels completely excavated under compressed air conditions – has also become standard in TBM tunnelling in the last decades. As air only decompression had caused several cases of decompression illness (DCI) in the past, work in compressed air and the decompression procedures had to be reassessed. As a result oxygen decompression was implemented into the decompression procedure.

Introduction

Oxygen decompression is beneficial for a faster exchange of nitrogen which is dissolved in the exposed operative. 100% Oxygen is administered at the pressure levels of 1.0 bar and 0.5 bar via a breathing mask. The higher amount of physically solved oxygen in the blood serum and body tissues helps for a better outcome after nitrogen partial saturation of the exposed individual worker. Because of the beneficial effect, oxygen application in compressed air work (CAW) became legal standard in the German regulation “Verordnung über Arbeiten in Druckluft (DruckLV)” in 1997.

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