Modern handheld instruments are designed to be used outdoors in tough environments and withstand heavy treatment – up to a certain point.
Hitachi High-Tech’s Product Manager, Mikko Järvikivi, looks at what does it take to convert high-precision laboratory instruments into rugged handheld tools and where are the limits of the technology today?
Analyser nose – the Achilles’ heel
Almost anyone who’s been operating handheld X-ray fluorescence (XRF) instruments for a significant period of time has become painfully aware of the sensitivity of the instrument’s nose and more specifically, the vulnerable x-ray detector. Detector punctures are costly accidents that everyone would like to avoid whenever possible.
To ensure the best possible performance and detection of even the lightest elements such as magnesium, aluminium, silicon, sulphur and phosphorous, the detector must be placed very close to the measurement window. The window must also be manufactured from the thinnest material possible to ensure that the signal reaches the detector without any attenuation. This combination makes the XRF analyser’s nose very sensitive and detector punctures are among the most common reasons for accidental damage to the instrument.
Over the past couple of years, the industry has developed ways to prevent detector punctures. Solutions are typically different kind of shields that protect the measurement window or the detector itself. The shields provide an additional layer of security for field operation, but have a downside that needs to be taken into account.
When anything is put in the path between the detector and sample being measured, it always compromises the analytical performance to some extent. This is the limitation set by basic XRF physics. Typically using a shield means slightly longer measurement times and higher detection limits for light elements. For example, if you need to monitor phosphorous content in stainless steels or sort close aluminium grades based on magnesium and silicon content, then using a shield is often not possible and this needs to be taken into account when choosing an instrument.
Handheld Laser Induced Breakdown Spectroscopy (LIBS) analysers work with a completely different technique and therefore aren’t sensitive to sharp items such as turnings. The measurement optics in LIBS analysers are protected by sapphire glass, one of the toughest materials known today. Some measurement windows are even recessed, meaning that the glass itself won’t come into contact with the sample. Only thing users need to remember is to keep the measurement window clean to ensure the best possible performance.
Dropping the instrument – always a bad idea
Dropping a precision instrument with a five digit price tag on it is always a bad idea. Many instruments these days are marketed with MIL-STD-810G compliance, but what does that actually mean and what kind of protection does it provide against accidental drops and heavy treatment of the instrument?
The MIL standard was created by the United States military and includes a series of tests that simulate ruggedness in the laboratory rather than performing the tests in real field conditions. The MIL-STD-810G standard includes several sub-tests from drop tests to the growth of fungus on the surface of the tested instrument. When taking a closer look at the instruments’ technical specifications, typical tests carried out for handheld analysers are related to drop, shock, vibration and transport. It’s also worth checking if the tests are carried out according to the specifications or if there are exceptions such as dropping the instrument from a lower height than specified.
To pass the MIL-STD-810G drop test, the instrument is dropped 26 times at different angles from 122 cm to a 5cm plywood platform. Up to five different units can be used to pass this test so a single unit does not need to pass all 26 drops. The latest developments in the design of handheld analysers have made it possible to pass this test without breaking key components or the electronics inside.
It’s important to understand that passing the military standard test is usually not a warranty statement. This means that the user can’t drop the instrument and expect it to be covered by warranty. Instruments are often equipped with shock sensors that will reveal during a service whether the instrument has been dropped. Also dropping the unit on hard surface such as asphalt or concrete is a completely different story to the simulated drop on plywood. So even though instruments today are significantly more robust than in the past, always keep those wrist straps or lanyards attached.
Water and dust – less of an issue
Water, dust, oils and cutting fluids are always present in scrap yards. Luckily the instruments can withstand these conditions well these days. Most of the instruments are IP54 (Europe) or NEMA 3 (US) classified and can tolerate splash water and dust. Even higher classifications for water ingress are available, but these limit the analytical performance of the instrument by taking the light elements out of the equation as thicker film needs to be used to protect the instrument’s nose.
So in light rain and dusty environments most handheld analysers are fine as long as they are cleaned on a regular basis and the cleanliness of the measurement window is monitored frequently. Instruments shouldn’t be used in heavy rain and no part of the analyser should be submerged in water.
In wet and dusty environments, the sample surface presents a bigger challenge as water and particles will always affect the analytical performance to some extent. Therefore the recommended practice is to always dry and clean the surface before taking a measurement. This is very important especially when operating LIBS analysers that are more sensitive to sample surface conditions than XRF analysers
Latest developments in the design of handheld analysers have made it possible to operate the instruments safely in even the harshest environments. However the laws of physics set certain limitations that are not possible to overcome and building an indestructible instrument is a challenge that still remains.
Using the instrument carefully and according to the instructions provided is still the best way to ensure a long and trouble-free operation. However in case of unavoidable accidents, the instruments nowadays have a significantly higher chance to survive without a visit to the service depot.
We’ve got you covered though
However, if you do need to visit a service depot because of an unavoidable accident, at Hitachi High-Tech, we offer service packages to keep you up and running to ensure minimal downtime. Or you could choose our extended warranty that gives you complete peace of mind whilst ensuring that you maximise machine up time, productivity, performance and profitability.
Mikko Järvikivi is a Product Manager at Hitachi High-Tech Analytical Science. Hitachi High-Tech Analytical Science has a rich 40 year heritage of providing high-tech analysis equipment and services, designed to meet the tough challenges of a rapidly evolving industrial sector.Click here for related articles about Handheld AnalysersSearch for Handheld Analyser manufacturers in our equipment guide
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