Experiment sees divers put under pressure

China has completed a land-based saturation diving experiment replicating the pressures experienced 500 meters underwater, the Ministry of Transport said on Tuesday.

The country has made significant progress in the development of such technology, Wang Lei, director of China Rescue and Salvage, a department under the ministry, told an online news conference in Beijing.

Apart from the United States and France, few other countries have successfully sent divers as deep as 500 meters.

China had been conducting saturation diving tests since the 1970s.

In 2014, it successfully sent divers to a depth of 313.5 meters.

The most recent experiment started on May 22, when nine divers from the Shanghai rescue department entered a pressurized cabin.

On May 27, the pressure was increased to a level equivalent to 500 meters underwater. The pressure in the cabin was then increased to the equivalent of 502 meters.

Participants stayed in that high-pressure environment for 176 hours and carried out several experiments.

The divers returned to normal pressure and walked out of the cabin on June 25.

After three weeks of monitoring and observation, the participants were deemed physically and mentally healthy.

Saturation diving, commonly used in rescue operations at sea, enables rescuers to work at greater depths underwater for a longer period of time while reducing the risk of decompression sickness when compared with conventional techniques.

China started research in the field in the 1970s and successfully sent divers to 103.5 meters underwater for the first time in 2006.

In 2013, divers were sent as deep as 198 meters.

Wang said the development of saturation diving technologies can help China handle emergencies in offshore rescues. They also helped clean up oil that leaked from the tanker Sanchi when it sank in the East China Sea in 2018.

Wang said the next step is to carry out a 500-meter underwater saturation diving experiment in a real undersea environment.

This year marks the 70th anniversary of China Rescue and Salvage.

Wang said China will strive to build a better professional search and rescue team in the next five years that will cover a wider area and respond to emergencies more quickly.

Maritime search and rescue forces should respond to and arrive at emergency sites within 100 nautical miles (185 kilometers) of the shore in no more than 90 minutes.

Since its establishment, the team has rescued 82,783 people stranded at sea－12,703 of them foreigners.

The COVID-19 pandemic has not stopped China's rescue and search missions.

The country has prevented the spread of the novel coronavirus and carried out rescue missions at the same time, said Zhang Jianxin, deputy director of the department.

During the pandemic, rescuers are required to wear protective gowns when carrying out rescue missions to prevent the spread of the virus and avoid imported cases, he said.

After saving stranded foreigners, disinfection will be carried out in the area. Follow-up health monitoring will also be implemented.

The team has rescued 247 foreigners and 12 international vessels this year.