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September 2024

Partial Volume Deflagration (PVD)

A deflagration explosion developed from a flammable cloud of gas, aerosol, or dust that occupies only part of the volume in a confined space.

Oxygen

The oxidizer; sufficient oxygen must be present in the atmosphere surrounding the fuel for fire to burn.

Oxidizing Gas (NFPA 55)

A gas that can support and accelerate combustion of other materials.

Oxidizing Agent

A chemical or substance which brings about an oxidation reaction. The agent may (1) provide the oxygen to the substance being oxidized (in which case the agent has to be oxygen, or contain oxygen), or (2) it may receive electrons being transferred from the substance undergoing oxidation. DOT...

Oxidizer

Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials. Examples of other oxidizing gases include Bromine, Chlorine, and Fluorine. Oxidizers can be further classified as follows; Class 1 - An oxidizer whose...

Oxidation

Depending on the context, oxidation can either refer to; a) a reaction in which oxygen combines chemically with another substance, or b) any reaction in which electrons are transferred. For the latter definition, oxidation and reduction always occur simultaneously (redox reactions), and the...

Oxidant Concentration Reduction

The technique of maintaining the concentration of the oxidant in a closed space below the concentration required for combustion to occur. This is commonly called inerting.

Oxidant

Any gaseous material that can react with a fuel (either gas, dust, or mist) to produce combustion. Oxygen in air is the most common oxidant.

Override

A control action which overrides the normal control action to prevent exceeding a process limit. Overrides normally are part of the POCS rather than the ESD. To manually or otherwise deliberately overrule an automatic control system or circuit and thereby render it ineffective. To cancel the...

Overpressure

Any pressure above atmospheric caused by a blast.

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