A2LA: Important Definitions You Should Know

A2LA Definitions

FDA Auditor: “Have your units been calibrated?”

You: “Why yes sir, they have.”

FDA Auditor: “I need to see the certificate of calibration”.

You: “No Problem, it’s right here.”

(You hand the FDA Auditor your certificate of calibration . . . )

FDA Auditor: “The laboratory that calibrated this instrument was not A2LA certified.

You: “So . . .”

FDA Auditor: “So you’re in trouble.”

You: “Gulp.”

You don’t want to gulp.

Getting your units calibrated and re-calibrated can be a confusing process. Which is why we've pulled a list of the most important terms from our own A2LA Certificate of Accreditation, to define, for you. Next time re-calibration rolls around, you will be equipped with some essential knowledge on who to have calibrate your units, and what kind of calibration you may need.

1. A2LA

A2LA stands for the American Association for Laboratory Accreditation.

What does that mean?

To start, unless you work in a lab, testing, measuring, and calibrating, you probably won’t ever deal directly with these people. However, you need to know who and what they do, because if you own any instrument used to measure, well, anything, there’s a good chance the A2LA had a hand in it’s creation, and accuracy.

The American Association for Laboratory Accreditation is a nonprofit membership society, that accredits testing and calibration labs. Just as you may have to comply to the FDA, or TJC, the people who make your monitoring instruments may decide to become accredited by the A2LA.

So why do you need to make sure their name is on a certificate for your monitoring and measuring device? Because when they accredit an organization, that organization is said to have reached certain standards for measurement capability. The A2LA uses particular competence standards (explained below!) to evaluate just how “good” a testing or calibration laboratory is. If the laboratory shows competence, quality, and an ability to measure any number of variables accurately, they receive accreditation.

2. Accreditation

It’s a term found in A2LA’s name, appears many times on an A2LA certification, and yet it is commonly misunderstood. The goal of any calibration laboratory is to pass specific tests, or prove competency in key areas to a regulatory organization. When those tests are passed, and the calibration lab proves it’s ability to maintain a certain standard, the regulatory body (like the A2LA) gives them their “formal” approval (usually through documentation). This approval is called accreditation.

3. ISO/IEC 17025:2005

A lot of weird numbers and letters. Here’s what they mean:

  • ISO: International Organization for Standardization
  • IEC: International Electrotechnical Commision
  • 17025: Standard for requirements of competence in testing and calibration laboratories
  • 2005: The year, 2005.

Combine all 4, and you get a standard, published by the International Organization for Standardization (with the help of the International Electrotechnical Commission), in 2005, on requirements of competence in testing and calibration laboratories.

4. ANSI/NCSL Z540-1-1994

ANSI/NCSL Z540-1-1994 is the second national standard for calibration laboratories in the United States, and has been a standard since 1994. While the ISO standard pertains to both calibration and testing laboratories, ANSI is only applicable for calibration laboratories.  Just like ISO, ANSI has requirements that a calibration lab must meet, in order to become accredited by an accreditation body. Specifically, ANSI is concerned with the trace-ability of measurements to national standards, and stresses the authenticity and verification of test and measurement equipment.

5. Calibration

One of the most important, yet possibly most misunderstood words in all of temperature monitoring. Be on the lookout for a blog post, catalog feature, .pdf, and overall big commitment on the topic from us soon, but in the meantime, we've come to define it like this:

How do you know an inch is an inch? Who decided what an inch was? An organization on standards, like the International Standards Organization (ISO! Call back to early info alert!) holds standards of measurement, that we all use. Standards make our lives easier.

So, let’s say I own a ruler that is 13 inches long, but is supposed to equal a foot. I have a hunch that it is not completely accurate, and all of my measurements seem a little off. How can I figure out if it is 1 inch too long? One way, is to compare it to a standard. That standard would be accurate to 12 inches, or a foot, and I could make a comparison between my ruler, and this correct standard. I would see that the ruler was one inch too long, and I could correct it by sawing off an inch, making my ruler now accurate to a foot.

That's calibration.

It works the same way with temperature, humidity, and pressure monitoring instruments. Measuring those variables is a little more complicated than measuring distance with a ruler, but in the same fashion, units have to be compared to an accurate standard, and then adjusted so they accurately measure temperature, humidity, pressure, or a million other variables.

6. Laboratory

We are not trying to insult your intelligence with this one. Laboratory’s are yes, where “science” tends to happen, and where evil giant man-monsters are made by Gene Wilder. That stated, in it’s R101 - General Requirements: Accreditation of ISO/IEC 17025 Laboratories, the A2LA outlines 8 different kinds of calibration laboratories that it accredits. They are listed below.

  • Main Laboratory
  • Permanent Laboratory
  • Branch Laboratory
  • Satellite Laboratory
  • Field
  • Field Testing/Calibration
  • Field Laboratory
  • Mobile Laboratory
  • Dexter’s Laboratory (just kidding)

7. Thermodynamics

Many science books and encyclopedias can give you a solid, concrete definition of thermodynamics. However, rarely do those definitions relate to A2LA Accreditation. Thermodynamics is simply a branch of physical science that deals with heat. So, when you are looking at a certificate of accreditation from the A2LA, and it has a section titled, “thermodynamics,” that laboratory manufactures or calibrates devices that measure the presence or absence of heat, energy, or work. In other words, temperature.

8. Resistance Thermometry

When deciding on an organization to buy, calibrate, or recalibrate temperature units from, the decision should begin with, “how do I want to measure temperature.” Once decided, you should search for an organization that is certified in your decision.

At Dickson, we're certified in Resistance Thermometry. On Dickson’s Certification of Calibration, Resistance Thermometry falls under Thermodynamics. What does this tell us? Well, it means that Resistance Thermometry is a way to measure temperature. Defining Resistance thermometry begins and ends with the RTD (Resistance Temperature Detector) which is one way (among many) to measure temperature. RTD’s measure temperature via predictable resistance of a metal to temperature. They are also very accurate at measuring temperature.

9. Thermocouple Temperature Simulation

Also found on Dickson’s certificate of calibration, thermocouple temperature simulation is another way to measure temperature, and another way in which the A2LA can certify you in measuring temperature. As you've probably guessed, the A2LA doesn't just stamp on the outside of a calibration lab “GOOD.” Their process of certification hinges on the various ways to measure a variable, and an organization thus attempts to be credited in those ways.

Thermocouple Temperature Simulation is an interesting topic, and one that we plan on giving a full description of in the coming months. As an appetizer and simple definition, we think of it like this:

Thermocouples measure temperature via two dissimilar metals who contact each other and produce a voltage. That voltage is predictable, and thus a temperature can be calculated from it. “Simulation” is used in the A2LA documentation because, as our engineers will repeatedly tell you, “You can’t really measure temperature, only something’s reaction to it.” Again, we’ll explain soon.

10. Calibration and Measurement Capability

We left this for the end because we felt it needed to be worked up to, and it is very important for an organization that monitors temperature to understand a calibration laboratory’s Calibration and Measurement Capability before deciding to calibrate with them.

When taking a measurement, you want to be sure that your measurement is accurate. This is why you calibrate. The problem, is that while we may wish it were as simple as “accurate” or “not accurate,” it isn't. Accuracy is a spectrum, and how accurate your measuring instrument is depends on the calibration labs ability to calibrate your instrument. An organizations Calibration and Measurement Capability then, is it’s ability to make your instruments accurate. Lower is better, as in the lower the degree, the less error your temperature measurement will have. When something is “more accurate,” it has a smaller uncertainty of measurement. That uncertainty of measurement is brought to you buy a calibration lab.

So please, ask what their Calibration Measurement Capability is before you calibrate with them!

11. Range

We thought we would end with an easy one. The definition of range is what you would expect. Found right next to Calibration Measurement Capability on an A2LA Certificate of Accreditation, range is the upper and lower limits that a particular tool can measure at. For our ruler, that means 1 inch to 12 inches. For some temperature monitoring devices, it can mean from almost absolute zero to really, really, really hot. If you know the temperature ranges you will be monitoring at, you can be better equipped to choose a calibration lab.

So that’s that. Some definitions of terms found on Dickson’s A2LA certification. Think we missed something? Post it in the comments below! As always, this was research done internally at Dickson, and does not reflect, or affect the A2LA’s recommendations in the least. We always recommend talking to your auditor first.