Ammonium nitrate

Explosiveness

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

explosive properties of explosives

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

other: UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, fourth revised edition, test series 1 and 2

GLP compliance:

no

Key result

Test series:

UN Test series 1

Method:

UN Test 1 (a): UN gap test

Parameter:

fragmented length (cm)

Value:

0

Result:

negative, not sensitive to detonative shock

Key result

Test series:

UN Test series 2

Method:

UN Test 2 (a): UN gap test

Parameter:

fragmented length (cm)

Value:

0

Result:

negative, not sensitive to detonative shock

Key result

Test series:

UN Test series 1

Method:

UN Test 1 (b): Koenen test

Parameter:

limiting diameter (mm)

Value:

1

Result:

result is considered "-" (negative)

Remarks:

not sensitive to intense heating under confinement

Key result

Test series:

UN Test series 2

Method:

UN Test 2 (b): Koenen test

Parameter:

limiting diameter (mm)

Value:

1

Result:

result is considered "-" (negative)

Remarks:

not sensitive to intense heating under confinement

Key result

Test series:

UN Test series 1

Method:

UN Test 1 (c) (i): Time/pressure test

Parameter:

other: maximum pressure (kPa)

Value:

2 070

Result:

result is considered "-" (negative)

Remarks:

not sensitive to ignition under confinement

Key result

Test series:

UN Test series 2

Method:

UN Test 2 (c) (i): Time/pressure test

Parameter:

other: maximum pressure (kPa)

Value:

2 070

Result:

result is considered "-" (negative)

Remarks:

not sensitive to ignition under confinement

Results detonation test 1(a):

Apparent density [g/cm3]	Fragmentation of the tube	Effect on witness plate	Conclusion
1154	partially	none	no detonation
1146	partially	none	no detonation

Conclusion: the sample is not sensitive to a detonative shock under the conditions of UN test series 1. In test series 1, no gap is introduced and thus the substance is subjected to a more intense shock compared to the series 2 test. Consequently, a substance showing a negative result in the test series 1 test will also show a negative result in the series 2 test.

.

Results Koenen test 1(b): Down to and including an orifice diameter of 1 mm (three times) no reaction was observed. The limiting diameter for the sample is less than 1 mm.

Conclusion: the substance is not sensitive to intense heating under high confinement in the sense of the criteria of UN test series 1.

As test series 2 comprise a less severe test, this conlusion applies to test series 2 as well.

Results time/pressure test 1(c):

Sample mass	Maximum pressure [kPa]	Pressure rise time 690 -20170 kPa [ms]
5.0	>2070	7600
5.0	>2070	2913
5.0	>2070	1992

Conclusion: because the maximum pressure reached is > 2070 kPa, the sample is considered to be sensitive to ignition under confinement in the sense of the criteria of UN test series 1. The pressure rise is most likely due to gas production upon heating rather than a real deflagration. Because in every single test the pressure rise time is (much) longer than 30 ms, the sample is considered to be not sensitive to ignition under confinement in the sense of criteria of test series 2.

Interpretation of results:

GHS criteria not met

Remarks:

not explosive

Conclusions:

UN (1a) detonation: crystalline ammonium nitrate do not require classification as an explosive substance of Class 1.
UN 1(b) heating under confinement: crystalline ammonium nitrate do not require classification as an explosive substance of Class 1
UN 1(c) ignition under confinement: crystalline ammonium nitrate do not require classification as an explosive substance of Class 1.

Reference 2

Endpoint:

explosive properties of explosives

Type of information:

other: statement

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

UN numbers are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods. They are published as part of their Recommendations on the Transport of Dangerous Goods, also known as the Orange Book. These recommendations are adopted by the regulatory organization responsible for the different modes of transport and considerd as a trusted source.

Guideline:

other: not mentioned

GLP compliance:

not specified

Transported substances should be tested for explosiveness (UN test) and classified accordingly.

UN 0222, hazard Class 1 (1.1D): explosive substance

UN1942, hazard class 5.1: not an explosive substance

UN 2067, hazard Class 5.1: not an explosive substance

UN 2071, hazard Class 9: not an explosive substance

UN 2426, hazard Class 5.1: not an explosive substance

Interpretation of results:

other: not explosive according to UN recommendations on the transport of dangerous goods

Conclusions:

Based on the transport classification, it was concluded that ammonium nitrate has no explosive properties. Only in case ammonium nitrate contains > 0.2% of combustible materials, it should be classified as an explosive substance.

Reference 3

Endpoint:

explosive properties of explosives

Type of information:

other: handbook data

Adequacy of study:

supporting study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: handbook data.

Guideline:

other: not mentioned

Principles of method if other than guideline:

Method followed unknown; data from handbook.

GLP compliance:

not specified

Ammonium nitrate is capable of undergoing detonation if heated under confinement, or is subjected to very strong shocks. This decomposition may take place in at least two widely divergent manners with the formation of different products. The first reaction

             NH₄NO₃→ N₂O + 2H₂O

occurs when ammonium nitrate is heated to temperatures from 200 to 260°C can be carried out safely and is the basis for commercial preparation of nitrous oxide. The second reaction

2NH₄NO₃→ 2N₂+ 4H₂O + O₂

 takes place with great rapidity and violence and occurs when it is used as an ingredient in commercial blasting mixtures. However, ammonium nitrate fertilizers are specially made in the form of high density prills or granules of low porosity and high purity to minimize any detonation risk. This material is very resistant to detonation.

Conclusions:

Ammonium nitrate fertilizers are specially made in the form of high density prills or granules of low porosity and high purity to minimize any detonation risk.

Description of key information

From the results of UN Test 1(a)  (detonation), UN Test 1(b) (heating under confinement) and UN Test 1(c) (ignition under confinement) it was concluded that crystalline ammonium nitrate do not require classification as an explosive substance of Class 1. The test material showed explosive properties in the sense of criteria of UN test series 1 but has no explosive properties in the sense of the criteria of UN test series 2. It is too insensitive for acceptance into class 1.

Ammonium nitrate with > 0.2% of combustible substances (UN 0222) is  classified for transport as an explosive substance (Class 1). Ammonium nitrate with less then 0.2% of combustible substances (UN 1942), ammonium nitrate fertilizers (UN 2067, UN 2071) or ammonium nitrate liquid (UN2426) are not classified for transport as explosive substance.

Key value for chemical safety assessment

Explosiveness:

non explosive

Additional information

Transport classification can be used for REACH as well.

 

Experience indicates that the conditions required for ammonium nitrate to present an explosion hazard involve a combination of factors: storage in large volumes (multiple tonnes) and either contamination of the material (e.g. with metals, acids, organics) or excessive heat (e.g. under condition of fire) (from Guidance on the Application of CLP Regulation 1272/2008 (version 25/08/2009)

 

Ammonium nitrate fertilizers are specially made in the form of high density prills or granules of low porosity and high purity to minimize any detonation risk.

Justification for classification or non-classification

Based on the available information, ammonium nitrate does not need to be classified for the hazard 'Explosives' according to CLP Regulation (EC) No 1272/2008. Ammonium nitrate with > 0.2% combustible material (UN 0222) should be classified for the hazard 'Explosives'.

Based on structural features, relevant study results and on experience in handling, ammonium nitrate does not have to be classified as a self-reactive substance.