Kistler Instruments Ltd. - PRODUCT NEWS








Kistler sensors help NPL develop dynamic pressure sensor calibration facility

Methods and standards for static pressure calibration are well established, but no accepted method or standard exists for dynamic pressure calibration.

There is growing demand within industry to ensure pressure sensors faithfully record the changes in pressure that occur during combustion or explosion events. This demand is coupled with the quality imperative within industry. The National Physical Laboratory (NPL) is working on a dynamic pressure sensor calibration method, based on shock tube techniques, which NPL hopes will be adopted as an ISO standard. The methodology uses a shock tube, in which a bursting disc separates two sections, and an increasing pressure in one section initiates failure of the disc, creating a pressure shock wave in the other section. This shock wave is used to calibrate the sensor under test mounted in the section's end wall. The shock tube performance has been validated using a Kistler Instruments Type 603B miniature piezoelectric pressure sensor with acceleration compensation, designed specifically for measuring pressure fluctuations of high frequency and short rise time, and the Type 5015 single channel laboratory charge amplifier with a wide measuring range.



The majority of pressure sensors used in industrial applications to make dynamic measurements are calibrated only for static measurements, even though it is widely recognised that the behaviour of sensors will deviate progressively from their static characteristics as the frequency is increased. The new facility provides a calibration process that extends the measurement traceability of pressure sensors into the dynamic regime by exposing them to extremely fast pressure steps of up to 1.4 MPa. This facility is particularly suited for characterising sensors used in applications such as gas turbine and internal combustion engine development.

The pressure steps are created in a shock tube using different combinations of gas, bursting disc thickness, and initial static pressure in the downstream section. The theoretical rise time for the pressure steps is in the region of a few nanoseconds making the frequency content of the pressure rise sufficient for practically all industrial applications. The calibration process extends the measurement traceability of the sensor into the dynamic regime by quantifying its resonant frequency and its amplitude and phase response over a wide range of frequencies. The SI traceability of the calibration is derived from the starting pressure and temperature, gas species, and shock wave velocity measurements. In addition to the standard tests, NPL is able to investigate the dynamic characteristics of entire measurement systems.


About Kistler
The Swiss-based Kistler Group is a leading global supplier of dynamic measurement technology for pressure, force, torque and acceleration. Kistler's technology is used to analyse physical processes, control industrial processes and optimize product quality.
Kistler has a full range of sensors, electronics and systems for engine development, vehicle technology, assembly technology, plastic and metal processing as well as for biomechanics.
The Group maintains its global presence through 26 sales and manufacturing companies, with tech centres on all continents and more than 30 agencies, enabling the Group to maintain local contact with customers and offer individualized application support.
The Kistler Group employs 1,250 people worldwide and generated revenues of CHF 285 million (GBP 193.5M) in 2013.

For more information, please contact :-

Kistler Instruments Ltd.
13 Murrell Green Business Park, London Road, Hook RG27 9GR
Tel: +44 (0)1256 741550
Fax: +44 (0)1256 741551
Email:
sales.uk@Kistler.com
Website: http://www.kistler.com

November 2014

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