There are 2 type of calibration methods for the temperature sensor and indicator as fixed-point calibration and comparison calibration.

• Fixed-point calibration
  Using a fixed-point cell, a known specific temperature (temperature fixed point) is measured with the temperature sensor to be calibrated to find out its value.
  It is provided high accuracy calibration.
• Comparison calibration
  Using a high-temperature bath or furnace depends on arbitrary temperatures requested, are measured simultaneously with a standard temperature sensor and the temperature sensor under test to be calibrated, and it find out its value.
  It is provided calibration at arbitrary temperature.

The sensor under test values are find out by calibration to fixed-point cell or comparison calibration with standard sensor, however the fixed-point cells and standard sensor used in calibration are also a type of temperature sensor or indicator and must be calibrated these as well. In such a chain of calibrations, it eventually leads to a specific standard instrument managed by the National Metrology Institute of Japan / National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). Therefore having traceability means that we can indirectly find out the gap difference from the national standard.

The calibration certificate with the JCSS logo mark issued by Yamari Industries, Limited proves that it is traceable to Japan’s national standard and can be utilized for ISO maintenance management.

Temperature sensor has characteristics. “Characteristics” refer to the situation where a temperature sensor that should be measuring at a certain temperature displays a value that is either higher or lower than that temperature in the environment it is being measured. This temperature difference is generally called “error”. The error is typical of each temperature sensor and can also be larger or smaller at different temperatures of measurement. When you purchase a temperature sensor from us, a test report or calibration certificate is supplied along with it, which clearly states the initial characteristics of the temperature sensor. Characteristics change with use, and the factors that contribute to this change may include thermal history, vibration, oxidation, and various other factors depending on the environment in which the product is used.

The temperature of the mixture of ice and water is about 0°C. This temperature is called the freezing point. Because the freezing point is easy to make and has excellent temperature reproducibility, some types of sensor are often used for routine inspections. Insert the new temperature sensor you purchased into this freezing point and take a measurement. It most likely indicates 0℃. However, temperature sensors are instruments that characteristics may change with use. Does the thermometer you are currently using show 0°C as initially?

There is no traceability to the temperature at which these physical properties are utilized; it is only an inspection. In addition, considering the temperature range used, 0°C is probably not sufficient in many cases.

There are two possible methods for traceability at arbitrary temperature given. One is to maintain in-house temperature calibration facilities and perform in-house calibration, as we do, in this case, we can offer from the high-precision temperature calibration systems to simple calibration systems on-site. The other is to request temperature calibration from an external JCSS-accredited service provider, this case we also provide on-site calibration services for temperature sensor and/or indicator especially that are difficult to transport.

The life of the temperature sensor depends on the environment in which it is used. Operating environment includes media in contact, thermal history, vibration, etc.

Criteria such as JIS and IEC are applied to resistance temperature measurement elements and thermocouples. Type tests are required in this criteria and conform to predefined conditions. However, this type test is short-term and not a long-term test for actual operations. Deterioration of temperature sensor in actual operation still needs to be confirmed by its calibration.

Periodic calibration of temperature sensor and/or indicator are required by law, such as the High Pressure Gas Safety Act, and allows visualization of changes in temperature characteristics over time. Accumulation of calibration results is also useful for maintenance planning, such as predicting deterioration and setting calibration cycles based on risk, as well as predicting when to replace the equipment.