Hong Kong Regulations

FACTORIES AND INDUSTRIAL UNDERTAKINGS (WORK IN COMPRESSED AIR) REGULATIONS - REGULATION 13

Entrance to and exit from a working chamber

When no lock attendant is inside a man-lock or working chamber, the
arrangements shall be such as to enable any person employed in compressed  air
inside the man-lock or working chamber to control the doors of the man-lock or
working chamber in order to leave or enter the working chamber in the case of
an emergency.