How do Handheld XRF Guns Work?

How do handheld XRF guns work?

If you have clicked on this article then you’re probably wondering: “How does handheld XRF guns work?”

You have come to the right place.

Handheld XRF works by using a battery to turn on an X-Ray tube that you can think of like a light bulb. When “on” the X-Ray tube generates about as much X-Ray radiation as you receive when you visit the dentist. The tube is powered by pressing and holding the trigger and then stops producing X-Ray when the trigger is released. This is called a “dead man’s trigger” as if you are not constantly pressing the trigger, the X-Rays will stop. Some analyzers also allow you to turn this feature off and instead set a timed test for each press of the trigger. A timed test can help reduce variation in some applications.

Once the X-Rays are generated the X-Rays fly out the nose of the XRF gun similar to how light exits a flashlight—you just cannot see X-Rays with the naked eye!

The X-Rays bombard the sample surface and interact in a unique way with each element. Each element will then scatter back a very small amount of X-Ray into the nose of the XRF gun—which has a special detector to capture the X-Rays coming back.

Each element emits a different flavor of X-Ray scattering back into the detector. For example, iron atoms will emit a unique emission when compared to other elements such as nickel or copper. This is how the analyzer can tell which elements are present in the sample.

Next, the detector counts the characteristic X-Rays for each element. The result is now a close chemical analysis of the sample. Keep in mind there is a detection limit for which elements can be seen at all in the sample. This means very small amounts of elements often cannot be seen.

The computer system of the XRF then performs a “Grade Match” which is when the on-board computer matches the generated chemistry within the known bounds of a pre-loaded database of grades or alloys within your device.

What do you see?

In a fraction of a second the computer has done all of these measurements for us. It gives us the best Grade Match as compared to its database. While each manufacturer of handheld XRF generates chemistries like this the same way all cars have wheels, the grade match algorithm is proprietary to each OEM but all of the current OEMs do a fantastic job with this.

How do I know we have a good result?

Handheld XRF devices will rate each match with a “Match Number” that tells you how close to the result you are. This is typically a number 0-100% or 0-1.00. If your grade match is 90% or more, you likely have a good match!

Can the grade match be wrong?

Yes! There are no perfect handheld metal analyzers out there and there never will be. A trained user can tell when the analyzer has a good match and when the match needs some human input.

This article was written by Nate Newbury, Founder of Alloy Geek LLC

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