Planning for extreme conditions with robust force measurement solutions

When tests need to be conducted under extreme conditions – be it 150 meters underwater, in a high-temperature chamber, or at a hazardous industrial site – standard force sensors reach their limits. Unless, of course, you plan from the outset with robust solutions designed to maintain their accuracy even under environmental stressors that would damage conventional equipment.

What defines a robust sensor?

A robust force measurement solution is more than just a standard sensor in a durable housing or bending body. A sensor's robustness begins with the design and manufacturing of the load cell or instrumentation, ensuring it operates within accuracy specifications while withstanding one or more extreme conditions. Robust sensors require three fundamental considerations:

#1 Advanced material selection

How does the material behave in an extreme environment? For example, switching from alloy steel to 17-4 PH stainless steel and using high-temperature strain gauges that can withstand intense heat can affect performance. As in Webinar on robust test and measurement solutions During the discussion, the interface experts noted that "approximately 260°C (500°F) represents a kind of limit" and that at these extremes "some performance losses are to be expected – so there are compromises at such high temperatures."

#2 Environmental insulation

This includes hermetic sealing to protect against moisture or vented designs for immersion sensors. The sealing of a load cell must be defined in the early stages of sensor manufacturing. For some applications, interface engineers use a specialized approach to insulation. As described in the webinar: “We took the reverse approach and fully vented the load cell… this essentially allowed us to immerse the load cell” in a highly dielectric mineral oil bath, resulting in excellent performance. Read more: Interface Submersible Load Cells.

#3 Performance Management

Robustness is about Temperature compensationThis can include, for example, the use of a 6-wire system to monitor the supply voltage at the bridge in order to compensate for thermal effects and voltage drops that occur over long cable lengths in harsh climates. The use of so-called "sense wiring" ensures that the instrumentation monitors the supply voltage directly at the load cell bridge and compensates for any drops along the cable length.

Best practices for robust solutions

The dose

• Do you know your exact specifications? Describe each exposure in detail, including media type (salt water, oil, etc.), temperature range, and immersion duration.
• Schedule maintenance. Understand that equipment in harsh environments requires more frequent calibration and special cleaning to ensure its longevity.
• Check the certifications. Always evaluate ATEX or North American safety certifications to ensure they meet the specific safety protocols of your site.

The Don'ts

• Accept nothing. Standard products rarely withstand harsh conditions unless they have been explicitly designed and approved for that purpose.
• Make no compromises. Never use instrumentation under conditions for which it was not designed. The risk of data loss or security protocol failure is too high.

Frequently asked questions about robust test and measurement solutions

Are all the robust products custom-made? That depends on the product line. Load bolt are almost always custom-made to fit a specific joint or form factor. However, Interface also offers standard, robust solutions, such as ours Coil Tubing Load Cells, fatigue-tested sensors and different Stainless steel products.

What are the maximum temperature limits? We generally consider 260°C (500°F) to be the limit. Beyond this, the choice of strain gauges becomes the limiting factor. At these extremes, some performance degradation is to be expected. We often recommend active cooling of the load chain or thermal insulation to protect the integrity of the sensor. Learn more: High temperature load cells 101

How are the calibration requirements for submersible sensors changing? For a standard product, we generally recommend annual calibration. However, the interval should be shortened if the sensor is used in a high-risk environment with less controlled exposure. Conversely, a controlled laboratory environment with very specific exposure may allow for a longer interval.

How far can I transfer data in the field?

• Wired: Theoretically, as far as necessary. However, for long distances, we always recommend 6-wire (sense wiring). This allows the instrumentation to monitor the supply voltage at the load cell bridge and compensate for voltage drops across the cable. Read our Guide to force measuring cables and connectors.
• Wireless: Our Telemetry-Technology can achieve a range of 600 to 800 meters with a clear line of sight, depending on local WLAN activity and the required level of data synchronization.

What is the difference between intrinsically safe and ATEX? These are regional certification standards. ATEX is the primary standard. We can meet most certification requirements, but an application-specific discussion is always necessary. Learn more: Hazardous areas ATEX 101

Are load pins and load shackles always custom-made? While 98% of load pins are custom-made to fit a customer's joint, we also offer standardized versions designed for standard Crosby™ shackles. Load shackles themselves are much more standardized, with form factors developed around industry-standard force ranges. For more information, please visit [website address]. Load bolt 101.

Watch the in-depth discussion with Ken Bishop and Elliot Speidell, experts in force measurement solutions with a deep understanding of robustness.

Webinar on robust test and measurement solutions