Dimension reference temperature
The reference temperature is the temperature for which the dimensions apply. In order to ensure the comparability of linear dimensions, the standard DIN EN ISO 1: 2016-12 (as the successor to the standard DIN EN ISO 1: 2002-10) sets the reference temperature for geometric product specification and testing at 20 ° C. The reference temperature therefore applies to the specification of all linear dimensions, in technical drawings, other specifications and also measurement reports.
This does not necessarily mean that measurements or calibration (and ultimately also manufactured) must be carried out at 20 ° C. For example, in the test instructions for gauge blocks VDI / VDE / DGQ 2618, sheet 3.1 (January 2004) under "2.5 Temperature control": "The temperature difference between the calibration item and the standard must be observed. With different materials, the difference to the reference temperature and the Thermal conductivities to be considered. " The supplement to DIN EN ISO 1 dated February 2004 with the title "Systematic deviations and contributions to measurement uncertainty in length measurements due to thermal influences" provides information on this in the event that "the mean temperature is not equal to the standardized reference temperature, with the averaging over the Time and space takes place ".
Test and measuring equipment , but also the test items , change their properties with changing temperature. Variable properties can include lengths and volumes ( thermal expansion ), electrical resistance , hardness or toughness . In length measurement technology, the thermal expansion of the individual components is particularly important. For example, the handles of outside micrometers or limit gauges are made of insulating plastic in order to minimize the influence of body temperature. The influence of temperature on the measurement result and the measurement uncertainty are reduced if the measuring equipment and the test object are made of the same material or of materials with the same expansion coefficient . The influences due to deviations of the test object and measuring device temperature from the reference temperature must be estimated and taken into account depending on the respective requirement.
To ensure constant temperature and humidity, measuring rooms are usually air-conditioned.
See also
Individual proof
- ↑ DIN EN ISO 1 Geometrical Product Specifications (GPS) - Standard reference temperature for geometrical product specification and testing (ISO 1: 2016); German version EN ISO 1: 2016. DIN, December 2016, accessed on November 15, 2018 .