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NPL has one of the world's most comprehensive suite of facilities for measuring the thermal conductivity and thermal resistance of engineering and construction materials. Most of these facilities have been developed in-house to achieve the highest levels of accuracy and they represent the UK national standard for thermal conductivity measurement.
Thermal conductivity ('k value') is a property of a material that determines how much heat is conducted through it for a given temperature difference. However, with a fibrous or porous insulation, which will include both solid material and gas, heat transfer is by a combination of conduction, convection and thermal radiation. 'Thermal conductivity' is still normally the quoted property for such insulation products although strictly it is an 'effective thermal conductivity'.
Thermal resistance ('R value') is a property of an object that determines the resistance to heat transfer through it a for a given temperature difference. As the 'thermal resistance' refers to an object, as opposed to a particular material, it can be used to describe the insulating effect of products that are constructed of layers of different materials. The resistance of an object to heat flow will be greater if it is thick and made from low thermal conductivity materials.
This flow meter is suitable for measuring thermal conductivity of homogeneous materials.
This flow meter is a commercial apparatus for thermal conductivity or thermal resistance of medium thermal conductivity materials such as plastics, ceramics and composites.
This hot-plate is an NPL designed and built national standard for thermal conductivity or thermal resistance of insulation and refractories at high temperatures.
A single specimen is required (Thickness: 25 mm to 50 mm, Diameter: 305 mm, flatness: better than 0.2 mm
This guarded hot-plate is an NPL designed and built national standard for thermal conductivity or thermal resistance of insulation at low temperatures.
An identical pair of specimens is required. (thickness: 25 mm to 50 mm, length and breadth: 305 mm x 305 mm, flatness: better than 0.2 mm)
The laser flash apparatus (LFA) is an instrument used to measure the thermal diffusivity (a) of materials with respect to temperature. This can then be used to calculate thermal conductivity (λ) if the density (ρ) and specific heat (Cp) of the sample as a function of temperature are already known. It has a temperature range from 25 °C to 1600 °C (or 2000 °C with modifications).
The LFA may be used to assess thermal diffusivity of a wide range of materials including metals and alloys (in solid and liquid phases), ceramics, hard metals, coated materials and MMCs.
Each transfer standard is measured in one of our national standard apparatus and is provided with a certificate showing traceability to the UK national standards and UKAS accreditation (UKAS 4002) for producing reference materials to ISO 17034:2016.
Material: EXPANDED POLYSTYRENE
305 mm x 305 mm
25 mm to 50 mm
-150 °C to 50 °C
Number of temperature:
Guarded Hot Plate:
NPL reference material specimens are cut from a batch of material that has been characterised by a series of measurements on material that is known to have stable and predictable properties. They have a higher calibration uncertainty than the equivalent transfer standard due to the contribution of variation within the batch. They are provided with a certificate showing traceability to the UK national standards and UKAS accreditation (UKAS 4002) for producing reference materials to ISO 17034:2016.
STAINLESS STEEL 304
100 °C to 500 °C
NPL batch code:
Material: PERSPEX (polymethylmethacrylate)
-10 °C to 60 °C
In addition to research on new measurement techniques and representation on international standardisation committees, we also offer consultancy and a range of measurement services providing the material data required for modelling industrial applications and the accredited measurements required for certification of construction products.
Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success. Contact our Customer Services team on +44 20 8943 7070