Sodium nitrate

Flammability

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

flammable solids

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Burning means a chemical reaction with oxygen releasing energy in the form of heat and light. Nitrogen is in the highest oxidation state (+5) and will not (further) react with oxygen. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt. It can not be ignited by a flame and it will not propagate combustion along a substance pile. On heating sodium nitrate melts (at 307°C) and on further heating it decomposes into sodium nitrite (NaNO2) and oxygen. The substance is concluded to be not flammable by ignition.

Reason / purpose for cross-reference:

data waiving: supporting information

Reference 2

Endpoint:

substances / mixtures which in contact with water emit flammable gases

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is known to be soluble in water to form a stable mixture

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
The substance is very soluble in water and forms a stable mixture of sodium and nitrate ions. Nitrate anion will not react with water. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt.

Reason / purpose for cross-reference:

data waiving: supporting information

Reference 3

Endpoint:

pyrophoric solids

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance is known to be stable in contact with air at room temperature for prolonged periods of time (days) and hence, the classification procedure does not need to be applied

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Nitrogen is in the highest oxidation state (+5) and will not react with atoms in the air. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt. Experience in handling confirmed that the substance does not ignite spontaneously on coming into contact with air at normal temperatures.

Reason / purpose for cross-reference:

data waiving: supporting information

Reference 4

Endpoint:

self-heating substances / mixtures

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Nitrogen is in the highest oxidation state (+5) and will not react exothermic with any atom in the air. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt.

The substance has a wide-spread use and is not known as a self-heating substance.

On heating sodium nitrate melts without decomposition and the liquid is stable in air to at least 500°C. On further heating in air it decomposes into sodium nitrite (NaNO2) and oxygen. Decomposition temperature: 600°C (from publication: High temperature properties and thermal decomposition of inorganic salts with oxyanions, Stern, K.H., CRC Press LLC, Boca Raton, 2001).

Additionally, the Ullman Encyclopedia (see the attachment) contains a chapter on nitrates that describes in particular the uses of potassium and sodium nitrates in high temperature applications, and in particular in solar technology, which implies that they are stable at those temperatures in the long term. Please refer to section 1.5 of the attachment stating the use of potassium/sodium nitrate in high temperature applications.

Nitrates are also used in the production of glass, a process that take place at very high temperatures.

Description of key information

From experience in handling and structural features, the substance was concluded to be:

-not highly flammable by ignition (the substance does not contain any atom that reacts with oxygen);

-not highly flammable in contact with water (the substance is known to be very soluble in water forming a stable mixture of ions; the anion and cation do not react with water);

-not pyrophoric (the substance does not contain any atom that reacts with atoms in the air. Experience in handling confirmed that the substance does not ignite spontaneously on coming into contact with air at normal temperatures);

-not a self-heating substance (the substance is known to be stable at high temperatures and does not contain any atom that can react exothermic with oxygen).

Based on this information, the endpoints are waived.

Key value for chemical safety assessment

Flammability:

non flammable

Additional information

JUSTIFICATION FOR DATA WAIVING

Flammability (solids)

Burning means a chemical reaction with oxygen releasing energy in the form of heat and light. Nitrogen is in the highest oxidation state (+5) and will not (further) react with oxygen. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt. It can not be ignited by a flame and it will not propagate combustion along a substance pile. On heating sodium nitrate melts (at 307°C) and on further heating it decomposes into sodium nitrite (NaNO2) and oxygen. The substance is concluded to be not flammable by ignition.

Flammability (in contact with water)

The substance is very soluble in water and forms a stable mixture of sodium and nitrate ions. Nitrate anion will not react with water. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt.

Flammability (pyrophoric properties)

Nitrogen is in the highest oxidation state (+5) and will not react with atoms in the air. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt. Experience in handling confirmed that the substance does not ignite spontaneously on coming into contact with air at normal temperatures.

Flammability (self-heating)

Nitrogen is in the highest oxidation state (+5) and will not react exothermic with any atom in the air. Sodium has a stable oxidation state (+1) and will not react with anything. Sodium nitrate is therefore concluded to be a stable non-flammable salt.

The substance has a wide-spread use and is not known as a self-heating substance.

On heating sodium nitrate melts without decomposition and the liquid is stable in air to at least 500°C. On further heating in air it decomposes into sodium nitrite (NaNO2) and oxygen. Decomposition temperature: 600°C (from publication: High temperature properties and thermal decomposition of inorganic salts with oxyanions, Stern, K.H., CRC Press LLC, Boca Raton, 2001).

Additionally, the Ullman Encyclopedia (see the attachment) contains a chapter on nitrates that describes in particular the uses of potassium and sodium nitrates in high temperature applications, and in particular in solar technology, which implies that they are stable at those temperatures in the long term. Please refer to section 1.5 of the attachment stating the use of potassium/sodium nitrate in high temperature applications.

Nitrates are also used in the production of glass, a process that take place at very high temperatures.

Justification for classification or non-classification

No classification is required for the following CLP legislation (EC) No 1272/2008 hazards:

- Flammable solids

- Substances which in contact with water emits flammable gases

- Pyrophoric solids

- Self-heating substances