Archive for September, 2013

Positive Material Identification (PMI), is XRF or OES the right test method?

Positive material identification (PMI) is a critical aspect in the quality control process for many organizations and throughout many industries.  Defined as the analysis of a metallic alloy to establish composition by reading the quantities of its constituent elements by percentage, the common methods of PMI include x-ray fluorescence (XRF) and optical emission spectrometry (OES).  Required in settings such as petrochemical, power generation, steel/iron foundries, fabricators, and PMI inspection companies, choosing the right approach depends on a few aspects of an organizations metal identification needs.

A quick overview of the two methods of Alloy Analysis:

X-ray Fluorescence (XRF)
After exposing a sample to x-rays, the atoms of the sample absorb energy and become temporarily excited which results in emission of secondary x-rays.  Each element emits x-rays at a unique energy and by measuring the intensity of those x-rays, an XRF analyzer can provide a qualitative and quantitative analysis. (Read the answer to “What is XRF?”)

Optical Emission Spectroscopy (OES)
Atoms are also excited in the OES method but the excitation energy comes from a spark formed between sample and electrode.  The sparks energy causes the electrons in the sample to emit light, which is converted into a spectral pattern.  An OES analyzer provides qualitative and quantitative analysis by measuring the intensity of the peaks in this spectrum.

The OES method will be the right fit when an organization requires carbon analysis.  However, without that requirement, X-ray Fluorescence will be the more common method chosen for positive material identification.  Below is a comparison of the two methods and the chart highlights the benefits of XRF, including faster measurement times, ease of use, portability, and providing a non-destructive approach to PMI testing.

Good quality Handheld XRF analyzers have been a proven solution for positive material identification since they were first introduced.  Several options are available but the question is what to look for in an XRF?  Organizations that choose Oxford Instruments X-Met 7000 series, available through Eastern Applied Research, see the benefits of both performance and features.  The performance of this series offers a high degree of precision, repeatability, and accuracy when quantification of metal alloys is the goal.  Features like the largest screen for navigation, longest battery life, and fastest start-up time…along with seamless data storage and report generation…make the X-Met 7000 series and the X-Met8000 the top options in Handheld XRF.

The evolution of optical emission spectrometry has made portable OES  systems more popular.  The benefit of taking the technology anywhere a measurement is required is becoming easier as systems like the PMI-Master Smart can be transported by hand, by back-pack, or by cart – without giving up on the precision that a user requires.

Day-in and day-out, the X-Met 7000 series, X-Met8000, and a full line of optical emission spectrometers are proving Oxford Instruments as a leader in metal analysis applications.  Eastern Applied Research can discuss the benefits of each for your organization and schedule a complimentary demonstration of the technology.  Contact Eastern Applied Research to start a conversation.