ANALYTICAL AND LABORATORY EQUIPMENT 23
(chosen by the user) in the dry block calibrator gives the error value for each sensor at particular temperatures.
Te procedure can be repeated for alternative temperatures set on the dry block as required (for example, 70, 100, 125, 150°C).
Te design of the dry block ensures that all sensors located in its ‘well’ will be at exactly the same temperature.
Te necessary calculations can be performed in a spreadsheet by applying formulae to the relevant cells and the logged values imported into the worksheet.
On this basis, the steriliser probes are traceably calibrated (UKAS traceable) in-house for full compliance with specified testing and validation procedures.
Fig. 2 A practical, highly cost-effective alternative method is to use and in-house, portable temperature calibration system from Labfacility; this provides a rapid and simple method of sensor checking and traceable calibration “on the bench”.
A practical, highly cost effective alternative method is to use an in-house, c ‘on the bench’.
Tis comprises a thermal reference (dry block) calibrator, a UKAS certified reference thermometer (Pt100), a calibrated L200 8 channel indicator/logger and PC software: this, when used with any Windows PC represents a
complete solution for on-site accreditation which allows direct comparison of the sterilizer probes (up to seven at a time) with the UKAS certified reference sensor.
A simple calculation of difference temperature (if any) between the logged values indicated by the reference and each test probe at a given, stable temperature
System accuracy Te accuracy of a type T, Class 1 thermocouple is similar to that of a Pt100 Class B; nominally ±0.5˚C and ±0.3˚C respectively at 0˚C a Class A Pt100 will provide an order greater accuracy however.
Measurement uncertainty with such a system will be of the order of ±0.6°C for both types of sensor at a typical working temperature.
For more information ✔ at
www.scientistlive.com/eurolab
Ken Jefferies is a Technical Consultant to Labfacility Ltd, Bognor Regis
West Sussex, UK.
www.labfacilty.com
“All temperature sensors used in the sterilisation process must be routinely checked and/or calibrated in accordance with procedures described in HTM 2010 Part 3 or any other national standards.”
www.scientistlive.com
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