Quality Control & Testing

Stobart Wood Fuel understands the importance of high quality, consistent fuels to ensure a reliable running of your biomass boiler throughout the year. With access to testing facilities at the company’s dedicated laboratories, along with the stringent programme of testing for all fuels, you can be sure that material supplied by Stobart Wood Fuel is of consistent high quality.

Controlling moisture content, material composition and particle size distribution are vital to a smooth running of your biomass boiler. Overall water content and the makeup of the material can significantly affect a fuel’s burn profile and the calorific value it delivers. These factors also play an important role in the levels and types of deposits that can build up within the boiler and its exhaust system. This is why we are so exacting when it comes to ensuring our high quality standards never drop.

Ensuring quality and consistency

Moisture Content


Different Biomass boilers are designed to work most efficiently at different moisture contents, meaning moisture content is incredibly important for biomass fuels. Moisture content is measured by baking a sample of material (100g) for 18 hours in specialist drying ovens. By subtracting the initial weight to the final weight can show you how much of the sample has been lost in heating, giving you the amount of moisture in the sample, thus a percentage.  These tests ensure accurate measurements so you can be confident that your material is of the right specification.

Particle Size Distribution


An Endecott’s sieve shaker is used to measure the particle size distribution of the biomass fuel to ensure conformity to specification. Many biomass boilers have a feeding system that is suited to a particular particle size, meeting this specification is crucial to minimise blockages and increase efficiency. Sieves with a series of different sized apertures are available to be used in any combination which is determined by the specification of the biomass fuel.

Material Makeup

In addition to the particle size distribution, the range of different materials contained within a fuel must also be determined to enable the most efficient running of biomass boilers. Makeup is calculated simply by hand sorting a representative sample into its constituent parts. Each element is then weighed against the total sample weight to produce a percentage. Stobart Wood Fuel uses regular testing of makeup to ensure that the biomass fuel supplied matches a customer’s specification.

Accredited Testing Facilities

Stobart Wood Fuel utilises own testing facilities for specialised analysis and more detailed testing of biomass fuel. These tests typically include ash levels following incineration, net and gross calorific value, precise biomass content and chemical composition, all factors that affect quality of burn.