CompAir dealer finds niche rental business

German CompAir dealer Peter Gay Gmbh has found a niche business in renting compressors to help create protective curtains of air in water during marine operations, including bomb disposal work and subsea drilling.

The Bremen-based dealer has rented ten CompAir C 210TS-12 and C 190TS-12 compressors to hydraulic engineering company Hydrotechnik Lübeck GmbH. A single C210-TS NA is helping to create a protective curtain of air bubbles during bomb disposal work in the Baltic Sea, and the other nine units are being used by Hydrotechnik to reduce sound disturbances during foundation drilling for the FIN03 research platform being constructed off the North Sea coast of Schkleswig-Holstein in northern Germany.

In each case, the bubble curtain helps to dissipate the energy and noise created by the operations, protecting marine wildlife. There are estimated to be several hundred thousand tonnes of munitions left over from the Second World War in the North and Baltic seas and these can only be disposed of by detonating them safely. However, large explosions can be lethal to humans and marine mammals within a 4 km radius.

In the case of the bomb disposal project, Hydrotechnik lays perforated plastic pipes on the seabed in a circle around the bombs. The energy from the explosion takes the path of least resistance, which is inside the bubble curtain towards the water's surface. The result is a ‘soft' explosion that minimises harm to marine life.

For the drilling work, the scale of the operation - and the number of compressors required - is considerably larger, with the bubble curtain laid at a 70 m radius around the foundation position. The compressors were set to produce a volume flow of around 180m³/min.

"It was a real challenge to complete a project of this scale in the time available," said Cay Grunau of Hydrotechnik. "It took over six hours to drive the 315 t, 55 m long monopile around 30 m down into the seabed. This meant that the CompAir compressors ran continuously for around 20 hours".

Klaus Wreth, who is responsible for this type of application at CompAir, said; "Companies like Hydrotechnik and CompAir have the necessary technical equipment and the know-how to set all the parameters correctly - the air pressure of the compressor, the number of nozzles per metre of pipe, the shape of the nozzles in the pipe, the alignment of the nozzles, the volume flow of the compressed air, the nozzle diameter and the bubble diameter".