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Accredited calibration services:
From -196oC to 1000oC ASTM thermometers, digital thermometers, PRTs, thermocouples, thermistors
Specific Gravity
hydrometers. API hydrometers, Baume hydrometers,
ASTM Class 1 and OIML E-2 and lesser specification stainless steel and brass laboratory weights. New calibrated weights and re-calibration of weights you currently have.
Thermo-hygrometers, chart recorders, humidity sensors, data-loggers
Burets, pipets, volumetric flasks, graduated cylinders, volumetric glassware
Testing and certification that an instrument complies with specified accuracy requirements...
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PRT Calibration Platinum Resistance Thermometers, or PRTs, are high quality, high precision temperature sensors. The electrical resistance of the platinum sensing element is read by a readout device connected to the sensor. The resistance of the sensor, measured in Ohms, is converted to temperature values by the software of the readout device, using characterization coefficients unique to the sensor, which are entered into the memory of the readout device. Typical PRT sensor and readout: the ERTCO-HART 850, or the Hart 1502A 'Tweener' readout and 5614 PRT sensor. The working temperature range of this pair is from approximately -196oC to 420oC (–328°F to 1764°F) with an accuracy of approximately +/- 0.028oC
ICL can calibrate the sensor only, using our Hart 1590 Super Thermometer to read it, or we can calibrate the sensor and the client's readout together for a 'system calibration'. What's involved in calibrating a PRT? ICL's PRT calibration service consists of the following services: Inspection of the sensor: We begin by inspecting the sensor visually; any damage, such as nicks, scratches, dents, or frays in the wires are reported in the 'Results of Inspection' section of the report. An insulation resistance test in accordance with ASTM E-1137 is performed to test the integrity of the internal insulation of the sensor sheath. A minimum resistance of 100 megaOhms is required. The result of this test is also reported.
The sensor is tested at the Triple Point of Water. The TPW is an intrinsic temperature point in metrology, realized in a TPW cell with ultra-pure water, where the three phases of water (liquid, solid and vapor) are at equilibrium. The temperature thus produced is defined as 0.01oC This value is used as a baseline for the stability of the sensor.
The temperature testing can be as basic or as comprehensive as the client desires. Typically, we are asked to test a series of temperatures and report 'As Found' values, and state whether those values are 'in tolerance' or not. If the 'As Found' values are determined to be out-of-tolerance, a recalibration is undertaken to obtain new characterization coefficients for the sensor. If the sensor needs to be recalibrated, we typically use the appropriate defining temperatures of the ITS-90 temperature scale (by comparison, in Hart Scientific baths):
- Boiling point of Liquid nitrogen: –195oC
(approximately) In special instances, for example if the client needs to use the device only over a limited range, we will choose calibration temperatures appropriate for that range. To accomplish the recalibration, the sensor is placed into a calibration bath at each of the (above) temperatures, permitted to come to equilibrium, and the resistance measured by the sensor is recorded. From this series of test temperatures and corresponding resistance values, we can calculate new coefficients using Hart Scientific's Tableware software.
The information used and the output of the program might look like this: Report for ITS-90 Coefficients Using those new coefficients, the series of test temperatures is repeated to yield 'As Left' values - which will be 'in-tolerance'. A final measurement is made at the triple point of water and compared with the value determined at the start of the calibration to check for sensor stability. All of this data, and all of the data used for calculation of the new coefficients, is reported to the client by means of the calibration report. Calibration order form to send us your device for calibration Our charges for this service are competitive, and turnaround times average 5 to 8 working days at our facility. |
