UNITED

NATIONS	ST

Secretariat	Distr.

GENERAL

ST/SG/AC.10/1998/10

4 September 1998

Original: ENGLISH
COMMITTEE OF EXPERTS ON THE

TRANSPORT OF DANGEROUS GOODS

(Twentieth session,

Geneva, 7-16 December l998,

agenda item 2 (c))

WORK OF THE SUB-COMMITTEE OF EXPERTS

ON THE TRANSPORT OF DANGEROUS GOODS

Draft amendments to the Model Regulations

Modification of entries containing the word "inhibited"

Transmitted by the Expert from the United States of America

Introduction

1.	At the fifteenth session the expert from the United States proposed to provide an alternative proper shipping name for UN 1247, Methyl Methacrylate Monomer, Inhibited, where the word "stabilized" would be substituted for the word "inhibited". It was noted that this had already been done in the case of UN 1086. The word inhibited is commonly interpreted to mean that the substance has been stabilized to avoid uncontrolled polymerization by the addition of a chemical inhibitor. However, other means of stabilization are also possible. These include, degassing the substance to remove dissolved oxygen and inerting the air space in the package, or transporting the substance under temperature control. The purpose of the proposal was to clarify that these means of stabilization were also acceptable.

2.	In discussing the proposal, the Sub-Committee noted that in some translations of the Recommendations no distinction was made between the terms "inhibited" and "stabilized". For example, the French text uses the term "stabilise". This term is more general and covers both inhibition and other forms of stabilization. The Sub-Committee agreed that rather than addressing this substance by substance it would be more desirable to address this problem in a general way. The use of the word "stabilized" in place of the word "inhibited" in the English text would solve the problem. (See ST/SG/AC.10/C.3/30 para. 109 - 110)

GE.98-

3.	On the basis of the Sub-Committee discussion this paper proposes to replace the word "inhibited" with the word "stabilized" in each place that it appears in a proper shipping name and to provide a glossary definition for the term "stabilize".

Proposal

4. In the Dangerous Goods List in Part 3 for the following UN numbers amend the associated proper shipping names as follows:

UN

No.	Name and description
(1)	(2)
1010	BUTADIENES, STABILIZED
1081	TETRAFLUOROETHYLENE, STABILIZED
1082	TRIFLUOROCHLOROETHYLENE, STABILIZED
1085	VINYL BROMIDE, STABILIZED
1086	VINYL CHLORIDE, STABILIZED
1087	VINYL METHYL ETHER, STABILIZED
1092	ACROLEIN, STABILIZED
1093	ACRYLONITRILE, STABILIZED
1167	DIVINYL ETHER, STABILIZED
1185	ETHYLENEIMINE, STABILIZED
1218	ISOPRENE, STABILIZED
1246	METHYL ISOPROPENYL KETONE, STABILIZED
1247	METHYL METHACRYLATE MONOMER, STABILIZED
1301	VINYL ACETATE, STABILIZED
1302	VINYL ETHYL ETHER, STABILIZED
1303	VINYLIDENE CHLORIDE, STABILIZED
1304	VINYL ISOBUTYL ETHER, STABILIZED
1305	VINYLTRICHLOROSILANE, STABILIZED
1545	ALLYL ISOTHIOCYANATE, STABILIZED
1589	CYANOGEN CHLORIDE, STABILIZED
1829	SULPHUR TRIOXIDE, STABILIZED
1860	VINYL FLUORIDE, STABILIZED
1917	ETHYL ACRYLATE, STABILIZED
1919	METHYL ACRYLATE, STABILIZED
1921	PROPYLENEIMINE, STABILIZED
1991	CHLOROPRENE, STABILIZED
2055	STYRENE MONOMER, STABILIZED
2075	CHLORAL, ANHYDROUS, STABILIZED
2200	PROPADIENE, STABILIZED
2218	ACRYLIC ACID, STABILIZED
2227	n-BUTYL METHACRYLATE, STABILIZED
2251	BICYCLO[2.2.1]HEPTA-2,5-DIENE, STABILIZED (2,5-
NORBORNADIENE, STABILIZED)
2283	ISOBUTYL METHACRYLATE, STABILIZED
2348	BUTYL ACRYLATES, STABILIZED
2352	BUTYL VINYL ETHER, STABILIZED
2396	METHACRYLALDEHYDE, STABILIZED
2452	ETHYLACETYLENE, STABILIZED
2521	DIKETENE, STABILIZED
2527	ISOBUTYL ACRYLATE, STABILIZED
2531	METHACRYLIC ACID, STABILIZED
2618	VINYLTOLUENES, STABILIZED
2838	VINYL BUTYRATE, STABILIZED
3073	VINYLPYRIDINES, STABILIZED
3079	METHACRYLONITRILE, STABILIZED
5.	Modify as appropriate the entries listed in paragraph 4 in the alphabetical index of substances and articles.

6.	Modify as appropriate the corresponding entries in portable tank instruction T-50 (UN 1010, UN 1082, UN 1085, UN 1086, and UN 1087).

7.	Modify 3.1.1.4 by removing the words "or inhibited" as noted below:

3.1.1.4	Where precautionary measures are laid down in the Dangerous Goods List in respect of a given substance or article (e.g. that it shall be "stabilized" or "with x% water or phlegmatizer") such substance or article may not ...

8.	Add the following entry to the glossary:

"Stabilized in relation to polymeric monomers means that the substance is in a condition that precludes uncontrolled polymerization. This may be achieved by methods such as the addition of an inhibiting chemical, degassing the substance to remove dissolved oxygen and inerting the air space in the package, or maintaining the substance under temperature control."

9.	A dagger symbol should be placed against each substance listed in paragraph 4 to indicate that the term "stabilized" is defined in the glossary.

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