I’ve lost count of how many sites I’ve stood on with a multimeter in one hand and a datasheet in the other, trying to work out why a “precision” sensor is telling us a load is 4% higher than the calibrated reference says it should be. Almost every time, the sensor itself is fine. The problem is somewhere else in the system: a poor mounting surface, an under-spec cable run, a calibration interval nobody tracked, or a signal conditioner configured for the wrong bridge configuration.
That’s really what this post is about. Precision sensors get the marketing attention, but precision measurement systems are what actually get the result right. After 30-plus years supplying and calibrating instrumentation for Australian manufacturing, mining, rail, automotive and structural testing clients, here’s what I’d want an engineer to know before they spec their next sensor.
Every datasheet says “precision.” Very few explain what that means in practice. In our world, it comes down to three separate properties, and mixing them up is the single most common spec mistake I see.
Accuracy is how close a reading is to the true value. Precision (often expressed as repeatability) is how consistent readings are with each other under the same conditions. A sensor can be extremely precise and still be consistently wrong, in fact, which is arguably more dangerous than a noisy signal, because it looks trustworthy on a chart.
A genuine precision measurement system needs both: tight repeatability and a traceable link back to a known reference. One without the other is a false sense of security.
Traceability means every reading can be linked, through an unbroken chain of calibrations, back to a national or international measurement standard. This is the entire point of NATA (National Association of Testing Authorities) accreditation in Australia. A NATA certificate isn’t a formality for the compliance folder; it’s the evidence that the number on your report would hold up if someone else measured the same thing with a different, independently calibrated system.
We run our own NATA-accredited laboratory for tension and compression forces up to 22kN, alongside in-house calibration for pressure, linear displacement, tilt and GPS instruments. If you want the detail on scope and process, our team has written up the full breakdown of NATA calibration services and lab scope on our site.
Case studies in this industry rarely make headlines; nobody writes a press release about a load cell that worked correctly for eight years. But two projects, in particular, reshaped how our team scopes new work.
A structural fabrication client came to us after a batch of imported, low-cost weldable strain gauges started showing drift after only a few months in a corrosive coastal environment. On paper, the gauges met spec. In the field, the adhesive and gauge backing weren’t rated for the moisture and temperature cycling the structure actually experienced.
We re-specified the installation using Hitec weldable strain gauges with the correct environmental rating, alongside a proper waterproofing and cable-strain-relief protocol at the weld point the kind of detail that never appears on a sensor datasheet but decides whether a $40 gauge survives a five-year monitoring program. Total re-instrumentation cost was a fraction of what the client had already spent chasing phantom “load spikes” that were actually gauge drift.
A manufacturing client wanted continuous load monitoring on ageing machinery that had no existing cable runs and no appetite for a shutdown to install them. This is a very common brief, and it’s exactly why wireless strain gauge and load cell acquisition modules exist.
We deployed a wireless sensing setup similar to our Wireless Strain Gauge / Load Cell Acquisition (T24-SA) module, configured and linearised over multiple calibration points using free toolkit software rather than a factory recalibration cycle. No new cable trays, no production stoppage, and the client had trend data within a day of the sensors going live.
None of these are exotic failures. They’re the same handful of decisions that quietly undermine an otherwise good sensor choice.
This is roughly the order we walk clients through when scoping a new instrumentation project.
Not the tolerance that sounds impressive, but the tolerance the downstream decision actually requires. Over-specifying precision adds cost and calibration burden for no operational benefit.
Two identical applications in different environments (a coastal structure vs. an indoor test rig) can need completely different sensor construction, ingress protection, and cabling.
Decide the calibration interval, who performs it, and whether it needs to be NATA-traceable before the sensor is ever installed, not after an audit asks for the certificate.
Signal conditioning, cabling, data acquisition hardware and software all introduce their own error budgets. A precision sensor feeding a poorly configured data acquisition system will still produce imprecise results.
These are the questions that come up most often on calls, in site visits, and in the searches that bring engineers to this page. I’ve kept the answers as direct as I’d give them in a phone call.
A precision sensor is built and calibrated to hold a tighter, more repeatable tolerance across its operating range, and typically comes with (or requires) a traceable calibration certificate. A standard sensor may be accurate enough for indication purposes but isn’t built or verified to the same repeatability standard.
It depends on the sensor type, criticality and environment, but most force, pressure and displacement transducers used in safety- or quality-critical roles are recalibrated annually, with more frequent checks in harsh or high-cycle environments. Your calibration provider’s accreditation scope will usually specify a recommended interval.
It guarantees that the calibration was performed under an assessed quality system, by demonstrably competent staff, with traceability back to national measurement standards recognised internationally through mutual recognition arrangements. It’s a statement about the calibration process, not a claim about the sensor’s brand.
Accuracy is closeness to the true value; precision is consistency between repeated readings. You can have one without the other, which is why both need to be checked, not assumed, during commissioning.
A strain gauge measures the tiny deformation (strain) a material undergoes under load, which is then converted into force, pressure, torque, or weight readings depending on how it’s mounted and wired. They’re the sensing element inside most load cells and torque transducers.
Wired systems generally offer the highest sample rates and the fewest variables for very high-precision lab or structural testing. Wireless systems win when retrofitting monitoring onto existing machinery, when cable runs are impractical, or when the site needs sensors spread across a wide area without trenching or conduit.
Drift is a slow, unwanted change in a sensor’s output over time, independent of any real change in the measured quantity. It’s usually only caught through scheduled recalibration against a known reference, which is exactly why calibration intervals matter more than sensor brand.
Yes, but only if they’re specified for it. Look for appropriate IP ingress ratings, temperature range, corrosion-resistant materials and, for wireless units, a radio range and battery life suited to the site, not just the accuracy figure on the front page of the datasheet.
Well-specified, correctly installed load cellsa and transducers routinely run for ten years or more between failures, provided they’re calibrated on schedule and protected from overload events. Environment and duty cycle affect this far more than the sensor’s price point.
Most standard measurement problems force, pressure, displacement, acceleration are well served by proven off-the-shelf sensors. Custom design earns its cost when the geometry, environment, or mounting constraint genuinely doesn’t fit any standard product, which is more the exception than the rule.
If there’s one opinion I’ll defend without hesitation, it’s this: the sensor you choose matters less than the system you build around it. A mediocre sensor in a well-designed, well-calibrated system will usually outperform an excellent sensor bolted onto a poorly conditioned, poorly maintained one.
If you’re scoping a new instrumentation project, it’s worth starting with the questions above rather than the product catalogue; the right sensor becomes obvious once the measurand, environment and calibration plan are actually nailed down.
Explore our full range of sensors and instrumentation products, learn more about our high-speed strain data acquisition systems, or visit appliedmeasurement.com.au to talk to our team about your next precision measurement project.
Contact Applied Measurement: Phone: (03) 98745777 Email: sales@appliedmeasurement.com.au Location: 24a/49 Corporate Blvd, Bayswater VIC 3153 Hours: Monday to Thursday 09:00 – 17:00 Friday 09:00 – 16:00
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