A calibration test is a procedure in which an instrument, tool, or device is tested to confirm that it conforms with the standard. Calibration is very important, as it ensures that objects are working properly. There are a number of reasons to conduct a calibration test, ranging from concerns that something is not working as it should to preparations for an event in which very precise calibration is desired, and there are a number of ways to perform a calibration.
In some cases, people may conduct their own calibration tests. For example, a supermarket might check the accuracy of its scales every week with an object of a known weight. Market employees would zero out the scales, place the object on the scale, and take a reading before zeroing the scale out again and weighing a second time. For thoroughness, several different weights would be tried, to confirm that the scale can handle a range of weights. If inaccuracies were identified, the scales would need to be repaired, adjusted, or replaced. Calibration test kits are available for many common instruments and tools so that people can perform equipment calibration on their own.
In other instances, instrument calibration cannot take place on site and instruments may need to be sent out for calibration. Some types of calibration are very delicate, requiring specialized equipment and skills which are only available in a lab. Sending devices out for a calibration test can be tricky, as it is important to package and transport the devices safely so that they are not damaged on their way to or from a facility where calibration takes place.
Any device which is designed to weigh or measure can be subjected to calibration, from the equipment inside the pumps at a gas station which indicates how much fuel has been pumped to delicate scientific instruments used in meteorology. In all cases, the calibration test involves the use of an instrument known to be correct for comparison, or the use of an object of known specifications to determine whether or not a device is performing properly.
Calibration is so important that many nations have entire government agencies which are responsible for confirming that certain things are properly calibrated. For example, gas stations commonly have to submit themselves to periodic inspection by government officials who will check to see that their pumps are accurate. The scientific community also values calibration testing, as errors in calibration could invalidate or muddle results.
Some reasons to request a calibration test include: the need to test a new device, periodic testing recommended after set periods of time or amounts of usage, testing to check a device to confirm that it is accurate before being used in a sensitive task, testing to check a device which appears to be faulty, or testing after a device has suffered a shock or been repaired to confirm that it is still working properly.