UNITED

NATIONS	ST

Secretariat	Distr.

GENERAL

ST/SG/AC.10/1998/4

22 July 1998

Original: ENGLISH
COMMITTEE OF EXPERTS ON THE

TRANSPORT OF DANGEROUS GOODS

(Twentieth session,

Geneva, 7-16 December l998,

agenda item 2 (b))

WORK OF THE SUB-COMMITTEE OF EXPERTS

ON THE TRANSPORT	OF DANGEROUS GOODS

Packing Instructions */

Transmitted by the expert from Germany

1.	Background

Paragraph 4.1.1.8 of the Model Regulations requires a vent for packagings with contents which can emit gas (as a result of temperature increase or other cause), provided that the gas emitted will not cause danger on account of its toxicity, its flammability, the quantity released, etc. The vent shall so be designed that, when the packaging is in the attitude in which it is intended to be transported, leakages of liquid and the penetration of foreign substances are prevented under normal conditions of transport.

Paragraphs 6.5.3.3.6 and 6.5.3.4.10 require pressure relief devices for rigid plastics IBCs and for the inner receptacles of composite IBCs. The opening pressure of these devices shall not be greater than the hydraulic test pressure, a lower pressure limit is not specified indicating difference to metal IBCs. Therefore, it is possible that pressure relief devices are applied, whose opening pressure is even below the maximum allowable working pressure according to paragraph 4.1.2.11.2. As a result these devices will open even under conditions likely to occur under normal conditions of transport.

The opening of pressure relief devices should not be acceptable under normal conditions of transport following paragraph 6.5.1.5.2. However, this paragraph (under "normal conditions of transport") is written in general terms and is open for interpretation.

2.	Proposals

It is proposed to amend paragraphs 6.5.3.3.6 and 6.5.3.4.10 as follows:

"A vent shall be fitted to each IBC intended for the transport of liquids only when a vent is required according to special provision B5 in column 9 of the Dangerous Goods List in Chapter 3.2. The vent shall be so designed that, ...(see 4.1.1.8)".

It is proposed to add a new sentence in paragraph 4.1.8:

"IBC special provisions are designated using the abbreviation B (IBC special packing provisions) and are assigned to specific substances in column 9 of the Dangerous Goods List in chapter 3.2.

B5 IBCs shall be provided... (see ST/SG/AC.10/C.3/1998/21, page 7).

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