SOLAS Chap. II-2 Part B Reg. 4
INTENDED TO SECONDARY MEANS
CONNECTION : FREE SIZE, ANSI, JIS, DIN etc FLANGE

This device is designed to maintain constant pressure
inside the inert gas system. Since the sealing method is
decided by the level of water, the correct effectiveness of
sealing can be attained within the extent of supplemented
and completed pressure. This device is usually use to a
secondary means according to SOLAS Regulations