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The Niton XLt Reloaded

I recently saw a demonstration of the Niton XLt 797 and had the opportunity to use it. As a result, I decided to write an update to my original article on Niton's portable XRF analyzer.

The Niton XLt 797 is a hand-held, portable XRF analyzer configured to work effectively as a RoHS compliance screening tool. It is a rugged, integrated design that does the screening job quickly and thoroughly. And it still looks as cool as it did when I first saw a photo of it.

XRF, or X-Ray Fluorescence spectrometry, is a powerful tool for analyzing the elemental composition of unknown materials. Miniature X-Ray tubes and PIN diode detectors have enabled this lab technology to leave the lab in the form of portable analyzers. Niton, recently acquired by Thermo Electron, is the industry leader in portable XRF.

All portable XRF analyzers do the same basic task. They emit low-level X-Rays focused on a sample of interest, and examine the spectra of even softer X-Rays emitted by the sample atoms. Using an onboard library of spectral patterns for elements, the analyzers identify the element by the energy, and measure the quantity by the intensity. The XLt 797 does this job superbly and does it with style.

XLt 797

Niton's XLt is shaped like a futuristic gun. It has a nice balance. The lithium battery pack connects to the bottom of the grip and is generally good for 8 to 12 hours of use. A second battery pack is included with the package so you can always have one charged up. The onboard computer and touch-screen display are integrated into the unit and are powered off of the same battery as the analyzer. The entire unit is sealed and usable in wet or harsh environments. Included is a bench top stand, and a holster for field measurements. The unit is designed to sit stably, upside-down, on a flat surface.

And how well does it work? Great. It is fast and accurate. Measurement times are always conditional with XRF. If you are looking for Pb and the sample contains a lot of it, a 200 second measurement will give you very little additional information over a 15 second scan. But for most unknowns, a one minute scan is usually the best starting place.

I brought along some samples to test during the demo. I am happy to report that 80's vintage Raingo gutters, though made of PVC, contain no Pb. More importantly, I learned yet another reason to be wary of plastics after analyzing a sample of wire.

What I brought in was a three inch piece of stranded, tinned, copper wire, 14 AWG, with nylon insulation. I stripped one inch of the insulation off of one end and kept it for a separate scan. Then I scanned the insulated end of the wire, the uninsulated end, and the insulation minus any wire. The results surprised me.

Sample Scan Time Composition
Nylon insulated, tinned, 14AWG Cu wire 25 sec. Sb, Sn, Pb, Br, Cu
Uninsulated, tinned, 14AWG Cu wire 25 sec. Sn, Bi, Pb, Se, Hg, Cu, Fe
Nylon insulation 20 sec. Pb, Sb, Br

Using 20 to 25 second scans it was clear the wire would not be RoHS compliant. The insulated wire contained plenty of Pb which was still there when I scanned the bare wire. What surprised me was the Pb in the insulation.

PVC commonly contains Pb, usually as a carbonate, added for temperature stability. Typical PVC lead concentrations range from 2% to 6%. However, I had naively considered nylon to be a clean plastic, like polyethylene. The XLt proved me wrong. The insulation alone contained 1.8% Pb. The Sb and Br are probably part of flame retardants. This is a perfect example of how XRF screening can save your business by detecting RoHS non-compliance. Even if the wire had been pure copper, the insulation would still make it non-compliant.

If you have read any of my previous articles on XRF, you already know most of the technical details (if not, check out The RoHSwell View or the RoHSwell archives). The other part of a large instrument purchase is the company behind the hardware.

Niton is a 15 year old company. They started out making Pb paint analyzers, the first ones. About 7 years ago, they expanded into metal alloy analysis. Around 4 years ago they tackled RoHS with a miniature X-Ray tube unit.

A major strength of the company is their scientific and technical expertise. The sales reps and marketing staff are very knowledgeable about XRF and its application. The company is a prolific source of papers on XRF. The demo I attended emphasized radiation safety, XRF capabilities and limitations.

They were also up front about X-Ray regulation requirements. Colorado is one of two states that require all X-Ray devices, including portable XRF units, to be inspected upon purchase and annually thereafter. I had been told by another source that portable XRF analyzers had no regulatory restrictions. Clearly, Niton is on top of all the regulatory requirements and careful to inform their prospective customers.

Recently, Thermo Electron Corporation acquired Niton to add portable XRF to their line of elemental analysis products. Thermo Electron is a large and successful company with many years of experience with XRF, Atomic Absorption Spectrometry, Mass Spectrometry, and other techniques. With the resources of Thermo Electron behind them, I expect Niton's offerings to just keep getting better.

(Continued Below ...)

Related articles:
RoHS Screening With Niton XLt
Electronic Parts: Material Content Analysis With XRF
Material Screening With The Innov-X XRF Analyzer
XRF Analyzer Directory

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