Limiting Oxygen Concentration (LOC) Testing

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Our UK laboratory generates flammable & explosive test data for your combustible dust and powders. The Limiting Oxygen Concentration test determines provides data for the design of nitrogen inerting systems or to confirm if combustible dusts or powders are appropriate for processes with a limited oxygen atmosphere.


The Sigma-HSE Advantage

Sigma-HSE is your single solution provider for a full range of combustible dust testing & explosion analysis testing. Our dedicated team of experts are committed to helping you ensure that your dusts and/or powders will not generate a combustible dust explosion so you can maintain workplace safety and comply with the regulators.

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Frequently asked questions

What are your Standards & Schedule of Accreditation

BS EN 14034 part 4

What is the Limiting Oxygen Concentration (LOC) test?

The Limiting Oxygen Concentration (LOC) test determines the minimum quantity of oxygen, within an atmosphere, that would be sufficient to enable combustible dust, when dispersed in the air, to ignite when in contact with an ignition source.

How does the Limiting Oxygen Concentration (LOC) test work?

Working through a range of concentrations, a powder is dispersed into a 20L explosion vessel (sphere) using dry compressed air and an inert gas i.e., nitrogen. Using partial pressures, oxygen content within the sphere at the time of ignition is controlled.

These suspended dust clouds are then exposed t a large 2 kJ chemical ignition sources and the following dust explosions are monitored, measured, and recorded, using high-accuracy piezoelectric transducers.

Once ignition occurs at a specific oxygen concentration, oxygen concentrations are reduced, and powder concentration is varied, until the hightst oxygen concentration is established. This, in essence, means that ignition is not possible, and the ‘LOC’ is established.

What does Limiting Oxygen Concentration (LOC) data do?

Data obtained by the Limiting Oxygen Concentration test is predominantly used for either the design of nitrogen inerting systems or to confirm if combustible dusts or powders are appropriate for processes with an established limited oxygen atmosphere.

As many ventilation systems now are set at a much lower oxygen level than required, this can result in large nitrogen costs. This can be avoided or reduced, by knowing a combustible dust’s specific limited oxygen concentration and then setting the concentration of oxygen levels accordingly.

How to get your materials tested

Receive quick and accurate testing data in just a few simple steps

Contact us

Get in touch with one of our experts so we can learn more about your specific process, unit operations and combustible dust testing requirements. We'll then generate and send you a customised quote.

Prepare & ship

Prepare your material samples and ship them to one of our globally accredited laboratories (UK or India).

Analysis & Reports

Once we've received your dust samples, we'll begin testing and analysing. We'll then create and send you an actionable in-depth report detailing the potentially hazardous properties of your materials.

Post-project support

If you need support after receiving your report, our after-project support team will be on hand to assist you with any questions you may have.

Discover our range of combustible dust testing solutions

We undertake the following combustible dust and powder tests to simulate full scale process, and process upset conditions. ​

Test your explosive dust and powders for their minimum ignition energy

Whether your process uses grain dust, coal dust or metal dust, getting your hazardous materials tested is an important step to prevent a combustible dust explosion, flash fire or other process-related hazards. Get in touch to learn more about how we can assist you in keeping your process plant and unit operations safe from combustible dust and powder explosions.
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