What Functions Should You Look for in Digital Thermocouple Calibrators?
GENEVA, OH, December 20, 2019
There are several brands and manufacturers of thermocouple calibrators in the marketplace today. Like most instruments and devices, not all temperature calibrators are created equal. TEGAM provides information here based on our 940A and 945A thermocouple calibrators as well as our white paper, How Digital Thermocouple Calibrators Work. Below are functions that an operator should expect to be able to use with the thermocouple calibrator that is purchased.
Support for multiple types of thermocouples – choose a model compatible with the thermocouple types that you use. Thermocouple calibrators are generally available in a basic model which will support Types J, Type K, Type T and Type E thermocouple probes - which are the four most popular thermocouple types - and a higher priced model that will support 14 (or more) thermocouple types. If you are a heat treater or measuring high temperatures, you will need the model with more TC types in order to get the Tungsten and Platinum thermocouple types typically used in high-temperature measurements.
Precision Sourcing – simulating a thermocouple output. The thermocouple calibrator should easily and accurately supply (SOURCE) a small, stable voltage that simulates a thermocouple signal. “Easily” is the key word here as this is what you as the user will have to setup and adjust every time you use the thermocouple calibrator. “One hand” operation is important for the sourcing function as you are often holding something in you other hand or recording a reading when preforming this operation.
Cold Junction Compensation (CJC) – is a key component of any thermocouple measurement. Remember, a thermocouple is a differential device - creating a voltage that is equal to the difference in the temperature between its two ends: one end being your measurement point and the other end being the temperature at the connection to the temperature calibrator. The CJC is also a key component in the overall accuracy of the calibrator. Be sure to note that the calibrator’s accuracy specification includes the CJC. Some manufacturers claim high accuracy but use an external $5000 ice point reference as the CJC for their specifications……yielding unrealistic accuracy specifications that you will never achieve using the unit.
Dual Displays – being able to see what the unit is SOURCING and what a system thermocouple is outputting to the calibrator (READ) at the same time is a must-have feature. Otherwise you will have to switch between the SOURCE and READ functions (and wait for the reading to settle) to get both temperatures and you can never be sure the output is where you set it at the exact time to compare the two.
Precision Thermometer – a thermocouple calibrator should also be a precision thermometer. The TEGAM 940A and 945A thermocouple calibrator models now have 0.01° resolution so you can easily see the direction of drift or when the system has reached stability.
AVG, STD (Deviation), TREND direction, MAX and MIN can be invaluable tools for understanding your readings.
The AVG function does a mathematical average of the temperature over the time between resets. This function helps interpret real world situations where the temperature will vary slightly due to heating/cooling systems or day/night temperatures and you need to balance the overall effect vs the temperature.
STD is the standard deviation over a period of time. This helps you understand how large the temperature swings of a system are and helps in tuning or dialing-in a control system.
Trend arrows are a feature that can tell you at a glance whether your system is increasing or decreasing in temperature. (Rather than watching the display bounce between 0.1 degree increments…)
The MAX function will capture and hold the maximum reading the unit reads once you start the function. This can be used to check for long-term stability of a system or to assure that nothing went wrong over an unobserved time period of a test (overnight).
The MIN function works in conjunction with the MAX function so you can immediately know the MAX and MIN temperatures that a system produced over a time period.
For more information on the functions you should expect and look-for in your next thermocouple calibrator, please see our white paper - How Digital Thermocouple Calibrators Work. Please contact TEGAM with any questions or comments you may have on our durable temperature calibrators for multiple industries. The 940A and 945A temperature calibrators can be purchased securely on their individual product pages.