9.2 Sounding pipes
9.2.1 Principle
a) Sounding devices are to be fitted to tanks intended to contain liquids as well as to all compartments which are not readily accessible at all times.
b) For compartments normally intended to contain liquids, the following systems may be accepted in lieu of sounding pipes:
• a level gauge of an approved type efficiently protected against shocks, or
• a remote level gauging system of an approved type, provided an emergency means of sounding is available in the event of failure affecting such system