9.3.7 Vent Outlet Closing Devices
9.3.7(a) General. Where vent outlets are required by 4-6-4/9.3.5(a) to be fitted with automatic closing devices, they are to comply with the following:
9.3.7(b) Design.
i) Vent outlet automatic closing devices are to be so designed that they will withstand both ambient and working conditions, and be suitable for use at inclinations up to and including ±40°.
ii) Vent outlet automatic closing devices are to be constructed to allow inspection of the closure and the inside of the casing, as well as changing the seals.
iii) Efficient ball or float seating arrangements are to be provided for the closures. Bars, cage or other devices are to be provided to prevent the ball or float from contacting the inner chamber in its normal state and made in such a way that the ball or float is not damaged when subjected to water impact due to a tank being overfilled.