Scrap yards are among the most challenging and harshest environments with regard to the application of handheld alloy analyzers. Drops, shocks, rain, vibration, sharp objects, and dust pose daily risks. With a bit of common sense, some precautions, and proper training, several incidents can be averted—albeit accidents still happen.
Contemporary handheld instruments are designed to be used outdoors in harsh environments and endure heavy treatment, to a certain extent.
Mikko Järvikivi, Product Manager at Hitachi High-Tech, analyzes the inputs needed to convert high-precision laboratory instruments into rugged handheld tools and where exactly the limits of the current technology lie.
Analyzer nose—the Achilles’ Heel
Virtually anyone operating handheld X-ray fluorescence (XRF) instruments for a considerable period of time becomes painfully aware of the sensitivity of the nose of the instrument, and more specifically, the susceptible x-ray detector. Detector punctures are expensive accidents that have to be prevented whenever possible.
To guarantee the best achievable performance and detection of even the lightest elements such as aluminum, magnesium, silicon, phosphorous, and sulfur, the detector should be positioned very close to the measurement window. It is also necessary to manufacture the window from the thinnest material possible to make sure that the signal reaches the detector with no attenuation. This combination renders the nose of the XRF analyzer very sensitive, and detector punctures are the most common causes of inadvertent damage to the instrument.
In the last two years, the industry has devised ways to avoid detector punctures. Solutions are essentially different types of shields that safeguard the detector itself or protect the measurement window. Although the shields offer an extra layer of security for field operation, they also have a disadvantage that needs to be considered.
If anything is placed in the path between the to-be-measured sample and the detector, it always affects the analytical performance to a certain extent. This is the constraint set by fundamental XRF physics. Generally, using a shield relates to higher detection limits for light elements and somewhat longer measurement times. For instance, for sorting close aluminum grades based on magnesium and silicon or for monitoring phosphorous content in stainless steels or content, a shield cannot usually be used, and this point has to be considered while selecting an instrument.
Handheld laser-induced breakdown spectroscopy (LIBS) analyzers operate based on a totally different technique and hence are not sensitive to sharp items such as turnings. One of the toughest materials known today, sapphire glass, is used to protect the measurement optics in LIBS analyzers. Some measurement windows are even buried, in a way that the glass itself does not come into contact with the sample. The users need to bear in mind to keep the measurement window clean to guarantee the maximum possible performance.
Dropping the Instrument—Always a Bad Idea
Dropping an expensive precision instrument has to be avoided at all costs. While several instruments today are marketed with MIL-STD-810G compliance, what does that actually mean and what kind of protection does it provide against heavy treatment of the instrument and accidental drops?
The MIL standard was published by the United States military and includes a sequence of tests that simulate ruggedness in the laboratory instead of carrying out the tests in real-field conditions. The MIL-STD-810G standard includes a range of sub-tests from drop tests to the growth of fungus on the surface of the instrument being tested. A closer look at the instruments’ technical specifications reveals that typical tests performed for handheld analyzers are related to transport, vibration, shock, and drop. It is also worthwhile to check whether the tests are performed according to the specifications or whether there are exceptions such as when the instrument is dropped from a lower height than specified.
In order to pass the MIL-STD-810G drop test, the instrument is dropped 26 times at different angles from four feet (122 cm) on a two-inch (5 cm) plywood platform. Nearly five different units can be used to pass this test so a single unit does not have to pass all 26 drops. The most recent advancements to the design of handheld analyzers have rendered it possible to pass this test without breaking the electronics or key components inside.
It is most significant to understand that mere passing of the military standard test is generally not a warranty statement. This means that the user must drop the instrument and still expect it to be covered by warranty. Instruments usually include shock sensors that reveal during a service whether the instrument has been dropped. Moreover, dropping the unit on a hard surface such as concrete or asphalt is an entirely different scenario when compared to the simulated drop on plywood. Therefore, although prevalent instruments are considerably more robust than earlier instruments, the wrist straps or lanyards have to be always kept attached.
Water and Dust—Less of an Issue
Cutting fluids, oils, dust, and water are invariably present in scrap yards. Fortunately, these conditions are now well tolerated by the instruments. Since most of the instruments are NEMA 3 (US) or IP54 (Europe) classified, they are resistant to dust and splash. While higher classifications for water ingress are also available, these tend to limit the instrument’s analytical performance by removing the light elements from the equation as thicker film has to be used to shield the instrument’s nose.
Therefore, in dusty and light rain environments, most of the handheld analyzers work fine, provided they are cleaned regularly and that the cleanliness of the measurement window is tracked frequently. It is not recommended to use instruments in heavy rain, and none of the analyzer parts should be immersed in water.
The surface of the sample surface poses a bigger challenge in wet and dusty environments, as particles and water will invariably affect the analytical performance to a certain extent. As a result, it is always recommended to dry and clean the surface before performing a measurement. This is extremely important, particularly when operating LIBS analyzers that are more prone to sample surface conditions than XRF analyzers.
Thanks to latest advances in the design of handheld analyzers, the instruments can now be operated safely in even the harshest environments. Yet, the laws of physics have set certain limitations that cannot be resolved, and constructing an indestructible instrument still continues to be a challenge.
The best way to ensure a long and trouble-free operation is to use the instrument carefully and in accordance with the instructions provided. Yet, in case of inevitable accidents, today’s instruments have a considerably higher chance of survival without warranting a visit to the service depot.
Hitachi Gets Users Covered
However, if one needs to visit a service depot following an unavoidable accident, Hitachi High-Tech provides service packages to keep customers up and running to assure minimal downtime. Alternatively, customers can select the company’s extended warranty that gives them complete peace of mind while allowing them to increase their machine up-time, performance, productivity, and profitability.
This information has been sourced, reviewed and adapted from materials provided by Hitachi High-Tech Analytical Science.
For more information on this source, please visit Hitachi High-Tech Analytical Science.