Hi folks. Today we will learn about Intermediate checks. This check helps us in maintaining accurate measurements of equipment in testing laboratory. As per ISO/IEC 17025 Intermediate checks is one of the fundamental checks to verify the equipment between calibrations. Many laboratories are practicing these intermediate checks to keep equipment in healthy state, in other words we can say close follow up of performance of measuring equipment. Generally, in any organization, equipment is calibrated once in a year or once in two years depending upon the usage and nature of the equipment. If we want to confirm the performance check of equipment say 8 months after calibration, in this case Intermediate checks process comes into place.
How to conduct Intermediate checks?
First of all, procedure need to be framed for intermediate checks of any equipment. Suppose XYZ laboratory is using 4 nos. of thermometers for its testing purpose. All four thermometers were calibrated 8 months back. Now we want to check the performance of these thermometers with the help of Intermediate checks. Note – in this case any one of four thermometers need be marked as Master thermometer and kept idle in the laboratory, this thermometer should not be used for general testing purpose.
Take 1000 ml water and boil it at normal pressure. Since we know that that the boiling temperature of water at normal pressure is 100 Degree centigrade. First we need to check with the master thermometer and take its reading. It should be 100 Degree centigrade
Then other three thermometers reading need to be taken with the same process. Then reading of individual thermometer need to be compared with the master thermometer reading. If the reading of Individual thermomters & master thermometer is the same, then it is confirmed that performance check is okay and it verifies the equipment. If the reading of the individual thermometer differs with the master thermometers, then in that case use of that induvial thermometer need to be stopped for further use and it needs to be sent for calibration. Likewise, we can conduct the intermediate check between calibrations.
Intermediate Checks vs Calibration
Calibration is a process of comparing a device to a measurement standard. It gives “error” of any equipment or device that how far it has deviated from its nominal value, and then verification is done whether the device is performing in or out of the tolerance defined by the published specifications. Moreover, these measurement standards itself have been calibrated by a more accurate standard, and this process is repeated until the calibrations are connected. every device used in calibration measurement can be traced back to the international standard units.
Further we need to look for changes in measurements between calibration. As we know that calibration is an absolute measurement against a known standard, but intermediate checks give an idea to look at changes between measurements. One who is conducting intermediate checks for device observes whether there is a deviation of device in comparison to the more stable measurement device. Thus in this case Intermediate checks give a signal that there is a problem with device and it needs to be replaced or aligned. If you have noticed that there exists a problem with a device at an early stage and addressed it, you have succeeded in reducing what could have led to a much larger problem if left unnoticed.
Example is illustrated below.
Very conceptual article