IEC 60751:2008 pdf download.Industrial platinum resistance thermometers and platinum temperature sensors
6.2.1 Tolerance acceptance test
All types of resistors shall be tested at one temperature at least. The test temperature shall be in the range from-5°C to +30°C, preferably 0°C.
Resistors of the tolerance classes 0.15 or better shall be tested at one additional temperature at least. This test temperature shall be the upper or lower temperature limit of the resistor, or spaced from the first test temperature by a minimum of 90 °C, whichever is less.
The manufacturer shall guarantee that resistances are within the specified tolerance class.
When selecting the resistors, the measurement uncertainty of the test has to be taken into account. An example is given in Figure 2: if measured by the manufacturer, only resistor No. 1 is within the tolerance class. If measured by the customer, only resistor No.4 can be rejected.
Therefore, the selection criteria for the manufacturer to use are as follows: the result of the test, expressed as a temperature deviation， when added to the corresponding expanded uncertainty, shall be totally included within the tolerance band.
The rejection criteria for the user are as follows: the tolerance value is not met if the result of the test, expressed as a temperature deviation, when added to the corresponding expanded uncertainty, is totally outside the tolerance band.
6.3.2.1 Water quench test
The thermometer shall be subjected to a minimum temperature of 300 °C for a minimum time of 5 min and then immediately plunged into water at room temperature. Then the insulation resistance shall be measured while the thermometer is immersed. The insulation resistance
shall meet the requirements of 6.5.1.
6.3.2.2 Nitrogen pressure test
The thermometer shall be externally pressurized for approximately 30s at a minimum pressure of 2.5 MPa in a nitrogen gas, after which the thermometer shall be immediately immersed in water or alcohol. There shall be no bubbling from the weld.
6.3.2.3 Liquid nitrogen test
The thermometer shall be immersed in liquid nitrogen until the temperature is stabilized, after which the thermometer shall be immediately immersed in water or alcohol. There shall be no bubbling from the weld.
6.3.3 Dimensional test
In the case for which the thermometer manufactured is covered by the scope of IEC 61152,the outside diameter and the straightness shall be tested to be in accordance with the requirements of the above-mentioned standard.
6.3.4 Tolerance acceptance test
The manufacturer has to assure that resistors of the appropriate tolerance class have been used. Thermometers of tolerance classes A and better (see 5.1 of this standard) shall be tested for resistance accuracy at one temperature in the range of -5 °C to +30 °C.Acceptance and rejection criteria are the same as described in 6.2.1 of this standard.IEC 60751 pdf download.