A Guide to Dry-Well Calibrators

A Guide to Dry-Well Calibrators

Dry-Well Calibrators

Dry-well calibrators have become the most practical tools in industrial temperature calibration.  They now build units that fit into the palm of your hand that is accurate enough to lab standards.  Each unit is unique in its ability to satisfy the requirements of specific calibration applications.  Which is why it is important when choosing one to find the option that best fits your needs.  Here is a guide to finding a good match for your application.

What is a Dry-Well Calibrator?

A dry-block calibrator also known as a dry-well calibrator is used inaccurate, liquid-free calibrations of temperature devices.  A dry block or dry-well features a heated block which contained a temperature-controlling sensor.

If you are series about portable temperature calibration tools, then you understand that a good dry-well calibrator is more than just a stable heat source.

Things to Consider When Choosing a Dry-Well

When choosing a dry well calibrator, there are key factors to consider.

  • Temperature Range – The temperature limits of the dry-well must meet your minimum test requirements for the sensors being calibrated. The ideal calibration spans the entire usable range of the test sensor.
  • Accuracy and Stability – The two most critical aspects of a dry-well are accuracy and stability. Accuracy is how close the dry-well is to the program point.  Stability is the temperature fluctuation of the instrument around the desired set point over time.  If the dry-well does not meet these, your probe could be reading a much different temperature than your display indicates.
  • Well Flexibility – When purchasing a dry-well, make certain that the probes you need to test will fit the unit’s heated block. The best accuracy comes from the holes that drill directly into the block.  Because the contact between the sensor and the heated block is better.
  • Portability – Size, weight and “carry-ability” are important factors to consider with many industrial applications. A dry-well design should be for easy transport to the test site.
  • Sensor Immersion – Immersion can be the single largest contributor to an error in dry-well calibrations.
  • Throughput – If you are trying to calibrate as many sensors as possible in a short time, then get a dry-well calibrator that allows you to insert more than one probe at a time. Another consideration for increased output is automation.  It can save you an enormous amount of time.


Traditionally, an internal control sensor has a wide accuracy, which largely contributes to its long-term drift.  This is why using an external reference probe as your standard is the best way to perform a temperature calibration.  However, it is not always necessary or convenient depending upon the application, which is why an internal sensor would be preferred.

Using a dry-well calibrator with a built-in self-calibration feature allows you to run an automated calibration of the internal control sensor using your external reference.  The calibration can run automatically giving you a fresh, traceable calibration of the control sensor which will improve its accuracy as you will not have to account for its long-term drift when used as a reference.

Successful Calibration with a Dry-Well Calibrator

Select the dry-well that best fits your application, and you will have years of successful calibrating.  The Additel 875 Series Dry-Well Calibrators offer three models so that you can choose the perfect one for your needs.  If you have specific application concerns, contact SRP Control Systems, they have 40 years of experience in working with leading manufacturers to help their clients get the best calibration products in the market.