On Solid Ground

The basics behind establishing an effective calibration program

by Jay L. Bucher

If they don’t have an in-house metrology or calibration department, then most biopharmaceutical and medical-device organizations assign calibration responsibilities to the lowest-ranking member of either their quality assurance or facility services departments.

That’s how it used to be done, but this is the 21st century, and I hope times have changed for the better.

A quality calibration program, regardless of whether the calibration and repair of that test equipment is outsourced or performed in-house, must include a training program, which is a requirement of standards from the International Organization for Standardization (ISO) and regulations from the U.S. Food and Drug Administration.

There are a few fundamentals every calibration or metrology department should know to get moving in the right direction. The basic parts of a training program might include the following topics:

  • What the standards and regulations actually say.
  • The real meaning of calibration and traceability.
  • The five steps of a quality calibration program.
  • How to survive an audit or inspection.

Two of a kind

Let’s start by looking at what the standards say about calibration requirements. ISO 9001:2008 and ISO 13485:2003 are basically identical when it comes to their requirements:

  • Measuring equipment will be calibrated at specified intervals against measurement standards traceable to international or national measurement standards (the International System of Units).
  • Measuring equipment will have identification that makes it easy to determine its calibration status (calibration labels or stickers).
  • Adjustments cannot be made to the equipment after calibration has been performed (labels indicate that calibration is void if seal is broken).
  • There will be an assessment and records kept for the validity of the previous measuring results when the equipment is found to be out of tolerance (an out-of-tolerance program).
  • Appropriate action will be taken if the equipment is found to be out of tolerance, as well as any subsequent equipment that is also affected.
  • Calibration records will be maintained.1, 2

The regulations state the same thing but in more detail and are not voluntary when it comes to compliance. The requirements from part 820.72 of the Code of Federal Regulations Title 21 cover the requirements in the greatest detail by stating the following:

  • Each manufacturer shall establish and maintain procedures to ensure equipment is routinely calibrated, inspected, checked and maintained. The procedures shall include provisions for handling, preservation and storage of equipment so its accuracy and fitness for use are maintained. These activities shall be documented.
  • Calibration procedures shall include specific directions and limits for accuracy and precision. When accuracy and precision limits are not met, there shall be provisions for remedial action to reestablish the limits and to evaluate whether there was any adverse effect on the device’s quality. These activities shall be documented.
  • Calibration standards used for inspection, measuring and test equipment shall be traceable to national or international standards.
  • Regarding calibration records—including labels and stickers—the equipment identification, calibration dates, the individual performing each calibration and the next calibration date shall be documented. These records shall be displayed on or near each piece of equipment or shall be readily available to the personnel using such equipment and to the individuals responsible for calibrating the equipment.3

Standard definition

The next task is defining calibration and traceability. These are probably the most misunderstood words in the calibration and metrology community, as well as with auditors and inspectors.

In simplest terms, calibration is the comparison of two measurement devices or systems—one of known uncertainty (your standard) and one of unknown uncertainty (your test equipment).

Traceability is the property of the result of a measurement or the value of a standard that can be related to stated references, usually national or international standards, through a documented unbroken chain of calibrations—the paper trail—all having stated uncertainties, and each contributing to the measurement uncertainty.

Both require the documentation or display of uncertainties. Without that data, there can be no calibration or traceability. Examples of myths concerning these two definitions include:

You cannot calibrate a glass thermometer because it cannot be adjusted.

This is false because calibration is a comparison; it has nothing to do with adjustment or alignment.

If the test instrument’s "as found" readings are within tolerance, calibration is not required.

This is false. Every time a calibration is performed, the equipment’s "as found" readings, as well as those of the standard it was compared against, must be recorded.

Calibrations must be traceable to the National Institute of Standards and Technology (NIST) in the United States.

This is false because traceability should be to a national or international standard through NIST, a national metrology institute or a primary standards laboratory. Your test equipment does not need to be traceable to an institution, but rather to the standards used by that institution.

Calibration can only be performed in a controlled environment, such as a third-party calibration laboratory.

This is incorrect. A controlled environment is required only when metrics such as temperature or humidity will have an effect on the calibration results—usually highly accurate test equipment used as reference standards.

The vast majority of test equipment used within biopharmaceutical or medical organizations can be calibrated on site for traceability using standards that fall under the four-to-one rule: The uncertainty of the standard is four times more accurate than the tolerance of the item being calibrated.

Gimme five

It’s also important to know the five steps of a quality calibration program:

1. Say what you do. Have written procedures in place for all calibrations that need to be performed at your organization. It’s usually acceptable to include alignment, adjustment and repair procedures in your calibration procedures if they are segregated from the actual calibration portion of the procedure.

Keep in mind that a full calibration must be performed and all readings recorded before performing any alignment, adjustment or repair on the test instrument being calibrated.

Also, if a preventive maintenance inspection (PMI) is going to be performed during this timeframe, you must properly document your calibration readings, perform the PMI and then calibrate to ensure the unit is still within its specified tolerances.

2. Do what you say. Use those procedures every time a calibration is performed. It’s not enough to just have them in place; they need to be available and in use by your calibration staff, not just sitting on the shelf looking pretty.

3. Record what you did. You must record what your standards are, as well as what the item being calibrated read, before and after any adjustment or alignment is made. That record must be kept for a predetermined amount of time and made available during audits or inspections.

This is one of the many reasons to have a paperless record system for your calibration department; it’s much easier to be able to access the appropriate calibration record on a computer than to travel to a specific location, search through filing cabinets to find the record the inspector has required, and then hunt through another filing cabinet to locate the calibration records for the standards used for that calibration.

4. Check the results. Did the item being calibrated pass or fail?

5. Act on the difference. If the item failed to meet the specified tolerances, what happened? Was an assessment performed on the test equipment or product affected by the failed item? Was all of this documented according to the written procedures you must have in place?

Brass tacks

This is an extremely high-level view of the five steps of a quality calibration program. I’ve written entire books on this concept, going into great detail on each step and how they cover the specific requirements of ISO standards and FDA regulations.

The bottom line is this: Do you have a program in place that covers these topics to the satisfaction of your auditors or inspectors for the standards or regulations that govern your organization?

It makes no difference whether you use the same terminology I do. But if the quality of the product going to customers is positively affected by a quality calibration program, you can call it anything you desire. If your program has a negative impact on product quality, you should reassess your calibration program.

The final topic you should cover in your training program is surviving an audit or inspection. For tips on that, take a look at my last Measure for Measure column.4


  1. International Organization for Standardization, ISO 9001:2008—Quality management system—Requirements.
  2. International Organization for Standardization, ISO 13485:2003—Medical devices—Quality management systems—Requirements for regulatory purposes.
  3. U.S. Food and Drug Administration, "Code of Federal Regulations Title 21," www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?cfrpart=820.
  4. Jay L. Bucher, "Under the Microscope," Quality Progress, September 2011, pp. 54-56.

Jay L. Bucher is president of Bucherview Metrology Services LLC in DeForest, WI. He is the author of The Quality Calibration Handbook and A Paperless Calibration Department That Meets Biotech, Pharmaceutical and Medical Device Requirements. Bucher is a senior member of ASQ, the secretary of the Measurement Quality Division and a certified calibration technician.

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