If the drain pipe material or connections deteriorate this could cause LPG to
enter the boat and subsequently cause an explosion or fire. To minimise the risk
of this happening cylinder locker or housing drain pipes, hoses and connections
must be made of a suitable material for use with LPG. (Hose conforming to ISO
7840 is acceptable for this purpose). It should also be noted that any drain
hose will only have a limited life. They should be regularly checked and, if
necessary, replaced. (See also Check List item 7.13)

To help ensure that a drain is effective it must have an internal diameter of a
sufficient size - this must be at least 19mm (3/4ins). For boats manufactured
before 3 January 2000, which carry no more than 15kg of gas, this diameter
may be 12mm (1/2ins) - enlarged proportionally for additional gas storage. If
flexible hose is used as the drain pipe it must be connected to the cylinder
locker or housing and the hull fitting in accordance with Check List item 7.13,
which specifies the types of gas connections which must be used. [7.5]