5.2.1 Sounding
pipes or other approved devices, which may permit a limited amount
of vapour to escape to atmosphere when being used, would be accepted
for those tanks which are not required to be fitted with closed sounding
devices, see
Pt 5, Ch 15, 5.3 Closed sounding devices.
The devices are to be so designed as to minimise the sudden release
of vapour or liquid under pressure and the possibility of liquid spillage
on deck. Means are also to be provided for relieving tank pressure
before the device is operated.
5.2.2 Separate
ullage openings may be fitted as a reserve means for sounding cargo
tanks.
5.2.3 Arrangements
which permit the escape of vapour to the atmosphere are not to be
fitted in enclosed spaces.