Section 6 Cargo tank level gauging equipment and arrangements against overfilling

6.1.1 Each cargo tank is to be fitted with suitable means for ascertaining the liquid level in the tank.

6.1.2 Ullage openings or sighting ports may be fitted to the cargo tanks on Type N-open ships. See Pt 5, Ch 13, 5.2 Pressure/vacuum and venting systems for various tanker types 5.2.1 for requirements of openings in cargo tanks.

6.1.3 Arrangements which permit the escape of vapour to the atmosphere are not to be fitted in enclosed spaces.

6.1.4 Sounding information is to be available at the position where the valves of the cargo tank are controlled.

6.1.5 The maximum allowable filling limit of the cargo tank is to be indicated at each sounding device.

6.1.6 The sounding devices are to be legible under all weather conditions.

6.2.1 The cargo tanks of all types of ships are to be fitted with a closed level indicating device of an approved type. Except for Type N-open and N- with flame arrestors, the level indicating device is to be of the closed type which does not permit the escape of vapour or cargo when being used. For all types of tankers, the device is to be so positioned that it can be easily read from the operating position for the closing valve on the relevant tank.

6.2.2 Proposals to use indirect sounding or measuring devices, which do not penetrate the tank plating, will be specially considered.

6.3.1 Cargo tanks of each type of tanker are to be provided with a mark on the inside showing the level for the following maximum percentage of filling permitted, see also Pt 5, Ch 13, 6.3 Precautions against overfilling 6.3.4:

6.3.2 Cargo tanks of each type of tanker are to be provided with a high level audible and visual alarm set at the following percentage of filling, see also Pt 5, Ch 13, 6.3 Precautions against overfilling 6.3.4:

6.3.3 In addition to the high level alarm required by Pt 5, Ch 13, 6.3 Precautions against overfilling 6.3.2 the tanks are to be provided with an independent automatic device for shutting off the supply of cargo, set at the following percentage of filling, see also Pt 5, Ch 13, 6.3 Precautions against overfilling 6.3.4:

6.3.4 Filling percentages are to be determined in relation to the total capacity of the tanks including any expansion trunk and are to have an accuracy of ±0,5 per cent.

6.3.5 For the maximum allowable cargo related filling limits see ADN Table C, Column 11, see Pt 5, Ch 13, 1.3 Materials 1.3.9 for reference.

6.3.6 Pressure vessels for Type G tankers may not be filled to more than 91 per cent for uncooled and 95 per cent for cooled cargoes. See ADN, Part 3, Table C, column 11, see also Pt 5, Ch 13, 1.3 Materials 1.3.9 for reference.

6.4.1 Cargo tanks of all ships are to be provided with suitable connections for a device capable of taking samples of the cargo.

6.4.2 On cargo tanks of Type G ships these devices are to be of the closed type.

6.4.3 On cargo tanks of Type C and N ships these devices are to be of the closed or restricted type. Conform with the requirements of ADN, Table C, Column 13, see Pt 5, Ch 13, 1.3 Materials 1.3.9 for reference. The sampling opening is to be in compliance with Pt 5, Ch 13, 6.4 Cargo sampling arrangements 6.4.8.

6.4.4 The closed devices are to be so arranged that loss of pressure and appreciable loss of gas is not possible.

6.4.5 The restricted devices are to be so arranged that during sampling only a minor quantity of gaseous or liquid cargo will come into the atmosphere. The arrangement of the device is such that it is completely closed when not used.

6.4.6 On cargo tanks of Type N-with flame arrestor a closed or partly closed sampling device is not required. However, sampling openings are to be in compliance withPt 5, Ch 13, 6.4 Cargo sampling arrangements 6.4.8.

6.4.7 Closed or partly closed sampling devices and sampling openings are not required for Type N-open ships.

6.4.8 The diameter of sampling openings may not exceed 0,30 m. They must be provided with a flame arrestor and are to be so arranged that the opening time can be limited and the wire gauze could not remain in the open position without external influence.

6.4.9 On ships of Type N-Open sampling openings are not required to be fitted with a flame arrestor.

6.4.10 Sampling devices are not required for Type N bunker ships.

6.4.11 The cargo sampling devices are to be of an approved type, accepted by the applicable National Authorities.