What is an SPRT Probe?
Standard Platinum Resistance Thermometers (SPRTs) are highly accurate temperature measurement devices commonly used in research and laboratory settings. SPRT probes are sensitive to shock, vibration, extreme temperatures, and other environmental factors that can affect their accuracy.
SPRT probes are some of the most accurate temperature sensors available, and they are widely used in various industries, including scientific research, industrial process control, and pharmaceutical manufacturing. A close-up of a needle Description automatically generated
Fluke Calibration 5686-B Glass Capsule SPRT probe
The accuracy of your instruments is critical in temperature measurement. Any inaccuracies can lead to costly errors, production delays, and even safety issues. This is why SPRT probes require periodic calibrations to ensure that they are still functioning properly and providing accurate readings.
The Importance of Validating Your SPRT Probe
Validating your SPRT probe in your own laboratory before sending it for servicing ensures the device is still functioning properly and providing accurate readings. This will give you peace of mind and help you avoid any potential issues that may arise during calibration.
The process of validating your SPRT probe is essential for several reasons.
First, it allows you to confirm that the probe is working correctly and that it has not drifted out of spec.
Second, it helps you avoid any issues with a failed "as found" calibration.
A failed first check when it arrives at a calibration lab can raise questions. Specifically, around the validity of the measurements you took with that device since its last calibration. A failed "as found" calibration can mean the probe suffered damage during transportation. Or, it may suggest the probe was already inaccurate before you sent it in. By validating your SPRT probe in your lab before sending it for service, you can reassure yourself that a failed "as found" calibration occurred during transportation and not because of any issues with the probe itself.
How to Validate Your SPRT Probe
The process of validating your SPRT probe involves several steps that require specialized equipment.
- Visual Inspection: conduct a visual inspection of the probe.
Check the probe for any physical damage or signs of damage. Pay attention to the sheath, transition junction, lead-wires, and termination connectors. - Calibration: connect the probe to your thermometer readout or bridge.
Using an ice-bath or TPW cell check the resistance at zero or 0.01 °C (TPW). - Resistance check: ensure the resistance value of the SPRT matches the value of the calibration certificate table at zero or 0.01 °C (TPW).
This process should be repeated upon receipt of the SPRT from recalibration. In applications in which the drift needs to be known more precisely, or in cases where the risk of out-of-tolerance usage must be minimized, it is advisable to use a fixed-point cell like a Triple Point of Water vs. an ice bath. - Temperature check: for routine applications of SPRT use, a typical limit of 2-3 mK can be established for allowable drift before recalibration is needed.
Depending on the specifics of the application and QA process (risk vs. recall) will dictate the allowable drift tolerance. Long thin metal rod with black wires Description automatically generated
Fluke Calibraiton 5681, 5683, and 5684 Quartz-Sheath SPRT Probes
Validating the SPRT temperature/resistance value before sending it in for calibration is a crucial step. By validating your device before sending it in, as well as when receiving it back into process, you can have peace of mind that no damage occurred during transit to and from the calibration service.
Fluke Calibration offers a range of SPRTs with exceptional accuracy available in metal, quartz, and capsule designs. These are the ideal choice for laboratory and research settings where precision is essential.
It is important to be able to trust that your SPRTs calibration is to the highest standards of accuracy and stability. Periodically checking your SPRTs resistance at zero or 0.01 ºC (TPW) helps to ensure your measurements are reliable and is an easy way to prevent unforeseen out-of-tolerance situations.