Temperature and Humidity Calibration

Calibration provides confidence that the temperature displayed on devices is reflective of actual temperatures in the areas being monitored. It is an essential process for environments storing temperature sensitive goods.

Yes we can issue UKAS certificates for both temperature and humidity data-loggers.

Manufacturers of sensors will have a recommended re-calibration period; for Tek Troniks temperature and humidity probes we recommend annual re-calibration.

However, the manufacturers recommended period cannot override any legislative, performance, contractual or audit defined calibration requirement.

If you're using probes for critical applications more frequent calibration would be the norm.

If the probe is damaged, dropped or is generally mishandled then a calibration to check performance should be completed.

Periodic checking of the probe against a known source to sense check performance should also be completed.

If you have any concerns over performance of the probe then calibration should be carried out.

The acceptable deviation of a temperature or humidity probe will depend on; your specific application requirement, legislation for your industry/sector, performance defined internally, by your regulatory body or by your customers.

As a manufacture we are commonly asked by customers for temperature probes that are accurate to within ±0.5°C.  This implies that if you have an area that is at 5°C then your happy with a temperature probe reading of between 4.5°C and 5.5°C.

Understanding deviation

When calibrating a probe at 5°C the calibration house will specify the error seen in the probe and their uncertainty in the measurement they have taken.

If the measured reading is 5.3°C and their uncertainty is ±0.3°C then they are saying that they are 95% confident that the accuracy of the reading taken is between 5°C and 5.6°C.

At 5°C the deviation would be acceptable, at 5.6°C it would fail the ±0.5°C requirement.  Therefore with this measurement and this uncertainty the probe would be deemed to be beyond the acceptable deviation level.

Common mistakes (Based on the above area at a temperature of 5°C)

In industry it is often assumed that when an employee tests a probe against a known source (hand held thermometer) and they get a reading of 5.5°C then all is good, the probe is within its deviation limit.

However this may not be the case, unfortunately they have not allowed for the uncertainty of the reading being taking and have little or no knowledge of how the uncertainty is calculated. See the next FAQ for more about Measurement Uncertainty.

Self checking using a known source is great for checking performance of probes periodically, however to know your true deviation, calibration is required and you should use a UKAS calibration house, like Tek Troniks..

Traceability is the term used to refer to an unbroken history of comparisons relating to the calibration equipment's measurement to a known standard.

To calibrate with confidence and to calculate our uncertainty budgets, it is imperative we have accurate knowledge of the performance of our equipment.  This is done by comparison to the national standard.

Our UKAS 17025 calibration processes document how these traceable comparisons are completed and is audited to show our strict compliance.

The UKAS 17025 accreditation provides tractability of measurement to the SI system of units and/or to units of measurement realised at the National Physical Laboratory or other recognised national meteorology institutes.

The standard of adherence for calibration will depend on your application, industry, sector and audit requirements.

The honest answer may be you require calibration but not the UKAS standard. Though we supply non-UKAS calibration services we always ask why you want to take this option?

The compliance to the UKAS ISO/EC 17025 standard should give you confidence that the calibration being completed is done to;

• the highest standard
• to strictly audited processes
• with equipment that meets the needs to complete comparisons accurately
• with calculated uncertainties that can be trusted
• the work completed by audited, trained professionals.