NPL can measure the attenuation and speed of sound in liquids and solids, typically over the frequency range 1 to 20 MHz. Solid or solid-like samples are normally required in the form of right-circular cylinders of minimum diameter 50 mm and thickness 5 mm or greater.

For liquid samples special liquid reference cells can be used for measurements which are made using a through transmission immersion technique by interposing the sample between a broadband hydrophone and transducer.

For measurements where the temperature variation of the acoustic properties of materials is required, this can be carried out over the temperature range 5 °C to 50 °C.

For the most accurate measurement of speed-of-sound in liquids, an ultrasound pulse-echo facility exists which monitors the change in arrival time of a reflected pulse when the distance between a transducer and polished reflector is accurately altered.

The technique is appropriate for application to relatively small liquid volumes and measurements can achieve an uncertainty as low as ±0.01%. Again, the temperature dependence of the speed of sound in liquids can be measured over the range 5 °C to 50 °C although with slightly degraded uncertainties.

Contact

Customer Service tel: +44 20 8943 8631
E-mail: acoustics_enquiries@npl.co.uk