Calibration is important for making sure your equipment is meeting a specified tolerance and ensuring the equipment is accurate. You should ask yourself these questions:
Is the reading I am getting what I expected?
Is it within the tolerance it is supposed to be?
For reference equipment, there is a certain tolerance allowed via the National Institute of Standards in Technology (NIST) which dictates what the real answer should be when recording temperature, humidity, or other reading you are trying to get. Calibration is a way to make sure that what you observe is really correct, both scientifically and according to NIST standards.
Calibration just means that a device has been checked by a more calibrated device to read a certain reading. This is determined by whomever is performing the calibration, and anyone can perform a calibration as long as they have the right software and equipment. Although, it should be noted that in order to perform a calibration correctly, they should have all of the metrology equipment necessary for the type of measurement they are calibrating for. For example, a humidity generator is required to generate humidity to a certain accuracy so the humidity in the chamber is a known value that can then be used to adjust the equipment being calibrated to read at the same value.
If you are performing your own calibration, you should automate the calibration and set it up ahead of time. Make sure to invest in mainstream equipment that is easy to communicate with by all pieces of software involved. Mesa offers metrology equipment including a reference thermometer and a calibration bath with silicon oil that can be used to perform calibrations at own facility with DT Pro. DT Pro has built-in tools to perform calibration and automate it with the equipment as well as others that the software can communicate with, such as Kaye dry well. Going this route, service and maintenance is another thing to consider. Will you be handling maintenance and repairs as well, or just the calibration?
There are uncertainties involved with calibration. More uncertainty means the equipment is believed to be less accurate, based on the tolerances set by the manufacturer up to the NIST standards. According to NIST, calibration equipment should be of high standard and able to maintain accuracy so there is less loss of accuracy in the calibrated device. It is important to have a reference (NIST traceable device) that has a certain accuracy and a calibration chamber (metrology equipment) that can create the environment necessary for calibrating. For example, this may be a fluke calibrator for pressure, a pressure generator, or a temperature bath. This requires a technician that has dedicated time to measure certain values with the device to be calibrated. The technician will measure the reference, performing the calibration within an environment that is generated by a generator or a bath, take those outcomes and calculate them back to the device that is being calibrated, determining whether the device needs to be adjusted or not.
Different labs perform calibrations as well, which may be a good option if you are looking for the full package: calibration, maintenance and repairs. As a note of caution, please keep in mind that some companies will not give a very complete certificate. Especially with data loggers, they may not have the ability to perform for all of the calibration points. More calibration points included means more accurate it is at certain points. It is possible for a sensor to be linear, so only one calibration point is necessary. However, you may be dealing with a non-liner sensor in which several points will improve accuracy and ability to read over the measurement range. Ask for an example certificate before you consider sending your device to someone. Does it have all of the information that you need on it? It might not. You may not be able to use it if it is not comprehensive enough.
You will want to look for ISO 17025 accredited laboratories. ISO 17025 dictates how a calibration lab should be run, how records should be kept, and institutes regulation on the facility performing the calibration. It regulates calibration itself by regulating the standards that are used and how accurate they need to be. Some accreditation labs are more stringent than others, but they all use the same certificate. Look for a lab that has ISO 17025 accreditation and look at the uncertainties and how much people charge per data point to be calibrated. For example, Mesa provides 17pt for the same price as any other calibration, no extra charge per data point. Take a look at how many data points they are charging for and whether it is all inclusive.
For further information or guidance on selecting which calibration services are best for your facility, contact our consultants today.Contact Us