Section 13 Instrumentation (Gauging, Gas Detection)

1301. General

1. Each cargo tank is to be provided with means for indicating pressure and temperature of the cargo, and where liquid discharge is used, the liquid level must be measured. Pressure gauges and temper- ature-indicating devices are to be installed in the vapor piping systems, in cargo refrigerating in- stallations and in the inert gas systems as detailed in this Section.

2. Permanently installed instrumentation is to be provided to detect when the containment system fails.

This instrumentation is to consist of appropriate gas-detecting devices according to 1305.

3. If the loading and unloading of the ship is performed by means of remotely controlled valves and pumps, all controls and indicators associated with a given cargo tank should be concentrated in one control position.

4. Instruments are to tested to ensure reliability in the working conditions and recalibrated at regular intervals. Test procedures for instruments and the intervals between recalibration are to be approved by the Society.

1302. Level indicators and overflow control for cargo tanks (if applicable)

1. Each cargo tank is to be fitted with at least one liquid level gauging device, if liquid is used for unloading, designed to operate at pressures not less than the MARVS of the cargo tank and at temperatures within the cargo operating temperature range.

2. Cargo tank liquid level gauges may be of the following types:

(1) indirect devices, which determine the amount of cargo by means such as weighing or pipe flow meters;

(2) closed devices, which do not penetrate the cargo tank, such as devices using radioisotopes or

ultrasonic devices.

3. If liquid is used for unloading, each cargo tank is to be fitted with an independent high liquid lev-

el alarm giving an audible and visual warning when activated device of liquid pump.

and an independent automatic stop

1303. Pressure gauges

1. The vapour space of each cargo tank should be provided with a pressure gauge which should in-

corporate an indicator in the control position required by alarm and, if vacuum protection is required, a low-pressure

1301. 3. In addition, a high-pressure alarm should be provided on the navi-

gating bridge. Maximum and minimum allowable pressures should be marked on the indicators. The

alarms should be activated before the set pressures are reached.

2. Where liquid discharge is used, each liquid pump manifold is to be provided with at least one pressure gauge.

3. Local-reading manifold pressure gauges are to be provided to indicate the pressure between stop valves and hose connections to the shore.

4. Hold spaces are to be provided with pressure gauges.

1304. Temperature indicating devices

1. Each cargo tank is to be provided with at least two devices for indicating cargo temperatures. The temperature indicating devices are to be marked to show the highest and lowest temperature for which the cargo tank has been approved by the Society.

2. When a cargo is carried in a cargo containment system with a thermal protection, temperature in- dicating devices are to be provided within the insulation or on the hull structure adjacent to cargo containment systems. The devices are to give readings at regular intervals and, where applicable, audible warning of temperatures approaching the lowest for which the hull steel is suitable.

3. The number and position of temperature indicating devices are be to the satisfaction of the Society.

1305. Gas detection requirements

1. Gas detection equipment acceptable to the Society and suitable for the gases to be carried is to be provided.

2. In every installation, the positions of fixed sampling heads are to be determined with due regard to the density of the cargo gas and the dilution resulting from compartment purging or ventilation, if applicable.

3. Pipe runs from sampling heads are not to be led through gas-safe spaces except as permitted by

Par 5.

4. Audible and visual alarms from the gas detection equipment, if required by this Article, are to be located on the navigating bridge, in the control position required by 1301. 3, and at the gas de- tector readout location.

5. Gas detection equipment may be located in the control position required by 1301. 3, on the navi- gating bridge or at other suitable locations. When such equipment is located in a gas-safe space the following conditions are to be be met:

(1) gas-sampling lines are to have shutoff valves or an equivalent arrangement to prevent cross- communication with gas-dangerous spaces; and

(2) exhaust gas from the detector are to be discharged to the atmosphere in a safe location.

6. Gas detection equipment is to be so designed that it may readily be tested. Testing and calibration are to be carried out at regular intervals. Suitable equipment and span gas for this purpose are to be carried on board. Where practicable, permanent connections for such equipment are to be fitted.

7. A permanently installed system of gas detection and audible and visual alarms are to be provided for:

(1) cargo handling machinery rooms;

(2) motor rooms for cargo handling machinery;

(3) cargo control rooms unless designated as gas-safe;

(4) other enclosed spaces in the cargo area where cargo gas may accumulate including hold spaces;

(5) ventilation hoods and gas ducts where required by Sec 15; and

(6) airlocks.

8. The gas detection equipment are to be capable of sampling and analysing from each sampling head location continuously. Common sampling lines to the detection equipment are not to be fitted.

9. For the spaces listed in Par 7, alarms are to be activated when the cargo gas concentration reach- es 30 % of the lower flammable limit.

10. Every ship is to be provided with at least two sets of portable gas detection equipment acceptable

to the Society and suitable for the products to be

11. A suitable instrument for the measurement of provided.

carried.

oxygen levels in inert atmospheres is to be