Planning for Extremes with Ruggedized Force Measurement Solutions

When testing requires you to test the extremes, whether that is 500 feet underwater, in a high-temperature chamber, or at a hazardous industrial site, standard force measurement sensors will have limits. That is, unless you plan for a ruggedized test plan with solutions engineered to maintain accuracy while withstanding extreme and environmental stressors that would normally damage standard equipment.

What Defines a Ruggedized Sensor? A ruggedized force measurement solution is more than just a standard sensor in a heavy-duty enclosure or flexure model. Ruggedizing a sensor starts with the design and manufacturing of the load cell or instrumentation to operate within accuracy specifications while withstanding one or more extreme factors. Ruggedized sensors require three fundamental considerations:

#1 Advanced Material Selection

How will the material perform in an extreme environment? For example, switching from alloy steel to 17-4 PH stainless steel and using high-temperature strain gages that can withstand intense heat are ways material will impact performance. As discussed in our Ruggedized Test and Measurement Solutions Webinar, Interface experts noted “approaching 500 degrees is kind of a line,” noting that at these extremes, “there’s going to be some performance degradation, so there are trade-offs going to that high.”

#2 Environmental Isolation

This includes hermetic sealing to keep moisture out, or vented designs for submersibles. Sealing a load cell must be defined during the early stages of sensor fabrication. For some applications, Interface Engineers use a specialized approach to isolation. As described in the webinar, “we took the opposite approach and actually vented the load cell entirely… that essentially allowed us to submerge the load cell” within a high-dielectric mineral oil bath, resulting in excellent performance. Read: Interface Submersible Load Cells.

#3 Performance Management

Ruggedization is about temperature compensation. For example, this can include using a 6-wire system to monitor excitation voltage at the bridge and compensate for thermal effects and voltage drops that occur over long cable runs in harsh climates. Using what is termed “sense wiring” ensures that the instrumentation monitors the excitation voltage at the load cell bridge directly, compensating for any drop across the cable length.

Ruggedized Best Practices

The Do’s

• Do you know your exact specifications? Detail each exposure, including media type (saltwater, oil, etc.), temperature range, and submersion duration.
• Do plan for maintenance. Understand that devices in harsh environments require more frequent calibration and specialized cleaning to ensure longevity.
• Do verify certifications. Always evaluate ATEX or North American safety certifications to ensure they meet your site’s specific safety protocols.

The Don’ts

• Don’t assume. Standard products rarely withstand harsh conditions unless explicitly designed and rated for them.
• Don’t “make do.” Never use instrumentation in conditions for which it wasn’t designed. The risk of data loss or safety protocol failure is too high.

Ruggedized Test & Measurement Frequently Asked Questions

Are all ruggedized products custom-made? It depends on the product line. Load pins are almost always engineered-to-order to fit a specific joint or form factor. However, Interface does offer standard ruggedized solutions, such as our Coil Tubing load cells, fatigue-rated sensors, and various stainless-steel products.

What are the maximum temperature limits? We generally see 500°F as the limit. Beyond this, strain gage selection becomes the limiting factor. At these extremes, some performance degradation is expected. We often recommend active cooling of the load string or thermal isolation to protect the sensor’s integrity. Review: High Temperature Load Cells 101

How do calibration requirements change for submersible sensors? If it’s a standard product, we typically recommend annual calibration. However, the interval should be shortened if the sensor is in a high-risk environment with less controlled loading. Conversely, a controlled lab environment with very specific loading may allow for a longer interval.

How far can I transmit data in the field?

• Cabled: Theoretically, as long as you need. However, for long runs, we always recommend 6-wire (sense wiring). This allows the instrumentation to monitor the excitation voltage at the load cell bridge and compensate for voltage drops across the cable. Review our Force Measurement Cables and Connectors Guide.
• Wireless: Our telemetry technology can reach 600 to 800 meters with a clear line of sight, depending on local Wi-Fi activity and the level of data synchronization required.

What is the difference between Intrinsically Safe and ATEX? These are regional certification standards. ATEX is primarily the standard. We can accommodate most certification requirements, but it is always an application-specific conversation. Review Hazardous Locations ATEX 101

Are load pins and load shackles always engineered-to-order? While 98% of load pins are custom-made to fit into a customer’s joint, we do offer standardized versions designed to fit standard Crosby™ shackles. Load shackles themselves are much more standardized, with form factors designed around industry-standard force ranges. Get more information about Load Pins 101.

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

The Force Measurement Ruggedization Checklist

Before starting your next extreme-environment project, use this checklist to ensure you have the right specifications for your sensor provider:

1. Material Type: Will the sensor be in air, freshwater, saltwater, or a specific chemical/oil bath?
2. Thermal Profile: What is the maximum temperature? Is there a thermal gradient (uneven heat) across the sensor?
3. Submersion Depth: If underwater, what is the maximum depth and for how long?
4. Data Connectivity: Where are you sending the data? How close or far will the sensor be from the indicator or DAQ system? How synchronous does the data need to be?
5. Wireless or Cable: What type of connectors will you need? Are you connecting to a cabled system or wireless network? What instrumentation and accessories products will you use?
6. Safety Rating: Does the zone require ATEX or North American hazardous environment certifications?
7. Load Dynamics: Is the loading controlled (lab-like) or unpredictable (field-use)? This dictates your calibration schedule.

Designing for the extremes is not just about making a sensor “tougher”—it is about ensuring the integrity of your data when the environment is working against you. Whether you are managing the thermal gradients of a high-temperature chamber or the intense pressure of a subsea deployment, the success of your test plan depends on specifying the right isolation, materials, and performance management from day one.

To start, take a look at some of Interface’s most popular ruggedized products.

• 2400 Standard Stainless Steel High-Capacity Load Cell
• 3200 Precision Stainless Steel Load Cell
• 3410 Intrinsically Safe LowProfile® Load Cell
• 3420 Coil Tubing Intrinsically Safe Load Cell
• JB104SS 4-Channel Stainless Steel Junction Box
• LP Stainless Steel Load Pin
• ISHK-B Bow Type Crosby™ Cabled Load Shackle
• 2000 High Precision Canister Load Cell
• SSM-FDH Sealed High Temperature S-Type Load Cell
• WMC Sealed Stainless Steel Miniature Load Cell
• IPCD Pressure Compensated Downhole Load Cell

At Interface, we specialize in sensors that require high accuracy and operate in extreme environments. Our engineers are ready to help you navigate the trade-offs of extreme environments to ensure your results are as reliable as our sensors.

Watch the entire webinar here: Ruggedized Test and Measurement Solutions Webinar