A shanghai engineer has developed a rappel-like device that could help people escape fires in high-rise buildings.

The device, invented by Zeng Jingxiong, has passed the country's fire equipment tests and been granted a patent, Xinmin.cn reported yesterday.

It can be installed near the window of an upper-story apartment and used to lower two people at once "dozens of meters" to the ground, the report said.

Zeng said that if his invention had been used at Shanghai Business School, where four young women died on Friday when they jumped or fell escaping a blaze in their sixth-floor dorm room, the tragedy might have been averted.

The device consists of a roller framework with a reel of steel tape and a sling. The user attaches the sling around his waist and drops from his window in an emergency.

A drag mechanism slows the descent to 1 to 1.5 meters per second. A hand crank allows the steel tape to be re-rolled for future use.

Zeng said his invention costs 300 yuan (US$43.96) to make and he is seeking potential investors to help him go into production.

"Some companies have shown an interest in my device, and I'm looking for someone to turn my invention into a real product and launch mass production to serve the people living in the city's thousands of tall buildings," Zeng said.

The building escape device could play an important role in future fire safety, according to the head of the Shanghai Association of Inventions.