Calibration is the process of verifying a device’s accuracy. This is done by a professional comparison of the data logger’s temperature readings against a reference thermometer, which is traceable to national standards.
Device calibration must be done annually (or every other year when the manufacturer recommends calibration done in a period that is longer than two years). Data loggers should be calibrated by a laboratory with accreditation from an International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA) Signatory Body. Laboratories that have attained accreditation from an ILAC/MRA signatory body meet the requirements for traceability.
An accredited laboratory can issue a certificate of traceability and calibration testing (report of calibration). Such a certificate, issued for each device that a laboratory calibrates, is evidence of the standard of calibration testing performed by the laboratory.
No. A “NIST-certified data logger” does not meet current VFC requirements. Each refrigerator and freezer used for vaccine storage must have a device that has a current certificate of traceability and calibration (report of calibration) that is either from an ILAC/MRA accredited laboratory or from a laboratory that meets VFC requirements for alternative labs (See Certificate of Calibration Quick Guide.)
Laboratory calibration procedures must conform to the ISO/IEC 17025 calibration procedure standard. This is an international accreditation standard for testing and calibration laboratories.
No. The VFC Program recommends testing by an accredited laboratory or testing that meets the ISO/IEC 17025 standards specific to data logger calibration. Accreditation or compliance with ISO/IEC 17025 applies to laboratories that do calibration testing, not to individuals.
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The California Department of Public Health, Immunization Branch, VFC Program does not endorse a particular calibration laboratory. The minimum VFC Program requirements in choosing a calibration lab are that it be accredited by an ILAC/MRA signatory body and that the laboratory issues a certificate of traceability and calibration testing to accompany thermometers it calibrates.
We have a list of accredited calibration laboratories that includes a limited sample to guide your search for data logger calibration services. We recommend you contact a laboratory directly for current calibration price quotes and specific needs such as turnaround time, expedited services, availability of device loaner programs, related shipping and handling fees, and service payment methods.
The list of laboratories is subject to change without notice. It is not necessarily all-inclusive or reflects the endorsement of the California Department of Public Health, Immunization Branch, Vaccines for Children Program.
TIP: Use Key Words to find a Calibration Testing Laboratory
You can search the Internet using key words such as “accredited data logger calibration laboratories,” ”calibration companies,” or a combination of that with your specific requirements such as county or city where you are located. You are likely to end up with many listings so we’ve created a list to get you started.
- Ask to speak to someone about calibrating a data logger used in a vaccine storage unit.
- Provide the manufacturer name and device model number.
- Let them know the “working temperature ranges” at which refrigerator and/or freezer temperatures are acceptable to store vaccine. These are:
Storage Unit Type
Degrees in Fahrenheit
Degrees in Celsius
+35.0 to +46.0 degrees Fahrenheit
+2.0 to +8.0 degrees Celsius
-58.0 to +5.0 degrees Fahrenheit
-50.0 to -15.0 degrees Celsius
- Let them know the acceptable “tolerances” are +/-1.0 degree Fahrenheit (+/-0.5 degree Celsius). Tolerances refer to what we consider acceptable measures of error in a device’s temperature reading.
- Let them know you will need a certificate of traceability and calibration testing (report of calibration) for each device to be calibrated.
TIP: A Calibration Sticker Has Useful Information
Look for a calibration sticker on the device you currently have. You will find a:
- Model number
- Serial number
- Name of the laboratory that calibrated it in the past
- Due date for recalibration
2-point testing is sufficient to meet VFC Program requirements. “Calibration test points” refers to the number of points across the temperature spectrum at which the laboratory tests the accuracy of your device.
There is no national VFC standard for what must be contained on a certificate of calibration. At a minimum, in keeping with NIST (National Institute of Standards and Technology), the VFC Program recommends that:
- Calibration methods and procedures should be openly documented.
- Uncertainties of calibration should be clearly stated.
- Measurement results should be documented.
Traceability records should not be claimed to be private or proprietary knowledge.
As stated earlier, calibration should be conducted by an ILAC/MRA accredited laboratory.
If calibration is conducted by a non-accredited laboratory, calibration certificates must include:
- Name and address of laboratory conducting calibration testing
- Date of calibration
- Serial number
- Measurement results
- Statement of conformance with ISO/IEC 17025 calibration procedure standards
- Certificate report number
Note: Some laboratories offer online storage for a report of calibration. Though you may opt for that service, as a VFC provider, you are required to have current calibration certificates readily available upon request from VFC Program representatives.
A useful practice is to stagger the dates of data logger calibration so that there are always devices available on site that are calibrated. Some calibration laboratories have “loaner” devices. They may charge you a fee to loan you a calibrated data logger from their inventory while yours is being tested for calibration. You can ask the laboratory you call if they have a “loaner program.”
Turnaround time for a lab to calibrate a single device ordinarily ranges from two to seven business days. You’ll want to have a calibrated backup device while waiting for the return of the one you need to be calibrated. Some laboratories have loaner programs. Ask about that.
Calibration interval refers to the frequency at which a data logger should be calibrated. VFC providers should have their devices calibrated once per year, so the calibration interval is annual.
Some data logger manufacturers may recommend longer time intervals between calibrations. The VFC Program recommends that data loggers be calibrated every other year when a manufacturer’s recommendation is for a time interval that is longer than two years.
The price for calibration services can range widely from approximately $30 – $90 per device. Actual costs depend on the size and testing capability of the laboratory, the level of calibration testing, the number of test points desired, required turnaround time, costs associated with evaluation before calibration testing, and shipping and handling fees. Laboratories vary in their capability to offer calibration-related services.
Note: Some laboratories have online “Quote Request” forms on their web sites. Be prepared to indicate the number of data loggers to be calibrated by type. Have information on each device handy to complete the form. You will be asked to describe the device make and model number, calibration interval, and specific needs. You can also include additional details about your calibration needs.
Online forms may have a space on which to type questions you have about the process. Before preparing a quote, someone from the laboratory may contact you to answer your questions or for additional information e.g., temperature ranges for testing, verification of the type of calibration report you will need, calibration interval, etc.
Most calibration labs accept usual business payment methods such as cash, business checks, or company credit cards. Visit the laboratory website or call the laboratory for specific questions related to service payment.
Replace it. There are several thermometers on the market with features and functions that meet VFC Program requirements for use in vaccine storage units.