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Understanding Load Cell Temperature Compensation

The performance and accuracy of a load cell is affected by many different factors. When considering what load cell will work best for your force measurement requirements, it is important to understand how the impact of the environment, in particular the temperature impact on output.

An important consideration when selecting a load cell is to understand the potential temperature effect on output. This is defined as the change in output due to a change in ambient temperature. Output is defined as the algebraic difference between the load cell signal at applied load and the load cell signal at no load. You can find more detailed information in our Technical Library.

Temperature affects both zero balance and signal output. Errors can be either positive or negative. To compensate for this, we use certain materials that are better suited for hot or cold environments. For instance, aluminum is a very popular load cell material for higher temperatures because it has the highest thermal conductivity.

In addition to selecting the right material, Interface also develops its own proprietary strain gages, which allows us to cancel out signal output errors created by high or low temperatures.

In strain gage-based load cells, the effect is primarily due to the temperature coefficient of modules of elasticity of the force bearing metal. It is common in the industry to compensate for this effect by adding temperature sensitive resistors external to the strain gage bridge which drop the excitation voltage reaching the bridge. This has the disadvantages of adding thermal time constants to the transducer characteristic and of decreasing the output by 10%.

Our load cells are temperature compensated for zero balance. By compensating for zero balance, we can flatten the curve in the relationship between temperature and zero balance. An uncompensated load cell has a much more severe curve, which ultimately affects accuracy and performance.

Interface offers thousands of load cell designs, standard use and for hazardous environments. For instance, rocket engine tests subject our load cells to extremely high temperatures. For use in various maritime industry projects, they can be used in very cold coastlines and even submerged in cold water. No matter where you are, environment influences the load cells performance.

If you are concerned about temperature, Interface provides specifications for every load cell we manufacture. The Interface specification datasheet, as see referenced here, is available for download by product. It always includes all the necessary data required to understand the load cell’s ability to perform at the highest-level including compensation range, operating range, effect on zero balance and effect on span.

One thing that is also unique about our products is that while most competitors only compensate for hot temperatures (60 to 160 degrees Fahrenheit), Interface covers both hot and cold thermal compensation from 15 to 115 degrees Fahrenheit, including adjust and verify cycles.

Be sure to tune into Load Cell Basics, where Keith Skidmore discusses temperature compensation.  He notes during this informative presentation that if the temperature is changing during a test that can affect the zero and the output of the load cell. How much effect depends how much temperature is changing and how well the load cell is compensated against the errors, which can be either positive or negative. Good news is they are repeatable from test to test so if you have large temperature swings you can characterize the system and then subtract out the shift if you know the temperature effect on zero.

Interface Application Engineers are available to answer questions regarding the effect of temperature on force measurement data, or the different ways we can help design a solution to compensate for your environment.

Load Shackles 101

A load shackle is a u-shaped, load-bearing connecting device designed to be used with a removable pin. Load shackles can be used in a number of different rigging and load securement applications to provide sensor technologies in the connection of different types of lifting slings, chains or ropes to an object or to each other.  A load shackle is essentially the installation of a load monitoring pin into the shackle body allowing you to replace existing rigging hardware with a load cell for force measurement and weighing data.

Load shackles are rugged in design and are used to provide accurate and reliable measurement of tensile loads, as well as support applications for harsh and challenging environments. The industries that most regularly take advantage of our load shackles include industrial, aerospace and defense, agriculture, and construction. Applications for lifting, moving and weighing objects can be monitored as well as optimized for performance using load shackles. They are often designed into engineered structures or for use with cranes, winches or other robust lifting mechanisms.

Interface offers a wide variety of load shackle designs for different environments and force measurement needs, ranging from 2.2K to 2205K lbf. Our load shackles come in both cabled and wireless, as well as environmental resistance options including flameproof and IP67. Visit our overview here.

Load shackles come in many standard shapes and sizes, including customization options to meet a specific design or use requirement. Some of our shackles are exclusively designed to meet the needs of applications in hazardous environments like the oil and gas industry, or marine industry where they’ll be submerged in water during testing and for continuous use, or in areas with high heat and flames. Some of our most popular load shackles are listed below:

WTSSHK-B Wireless Crosby™ Bow Load Shackle  – Suitable for use in a wide range of industrial and marine weighing applications, these load shackles are robust, reliable and easy to install. The unique telemetry housing is manufactured from tough high-performance polyamide resin making it strong yet light, resulting in a better-balanced load shackle when compared to others available on the market.

ISHK-B Bow Type Crosby™ Cabled Load Shackle – The Interface range of ISHK-B load shackles are designed for lifting and weighing in rugged or harsh environments, including submersible applications. The shackle pins are forged from high tensile stainless steel to 6.5 MT (14.3K lbf) and high tensile carbon steel from 9.5 MT (20.9K lbf), and are machined to an exacting specification. The basic shackle uses the Crosby G2130 (1 to 25 MT / 2.2K to 55.1K lbf), G2140 (40 to 120 MT / 88.2K to 265K lbf) and GN Rope H10 (150 to 1K MT / 331K to 2205K lbf).

Flame Proof Bow Type Crosby™ Cabled Load Shackle – The Interface range of flameproof load shackles is designed for lifting and weighing in rugged or harsh environments, and also meet the requirements for operation in Zone 1 and 2 hazardous areas. The shackle pins are forged from high tensile stainless steel and are machined to an exacting specification. The basic shackle uses the Crosby G2130 (1 to 25MT or 2.2K to 55.1K lbf) and G2140 (40 to 400MT or 88.2K to 882K lbf) series.

Load Shackle Application:

Load shackles are commonly used in the construction industry to measure heavy machinery. For cranes outfitted with a lifting attachment such as a claw, a tension sensing load shackle is used on the pulley mechanism to measure the weight lifted by the crane. The tension sensor can provide real-time data to the construction crew to help monitor the lifting process and provide the operator with the information necessary to refrain from lifting weights that are too heavy for the crane to handle. If the claw arm lifts more than the crane is able to withstand, the attachment could break off, or worse, the crane could topple over.

In a recent example, Interface’s customer used a WTSSHK-B Wireless Load Shackle connected to load-bearing strings and a WTS-BS-1-HA Wireless Handheld Indicator to gather data. The customer was able to successfully lift and read the weight (wirelessly) on a handheld display while the material was being relocated.

Learn more in this product video

To learn more about our wide variety of load shackles and their many applications, please contact our application specialists today.  You can see all of Interface’s Load Pins, Load Shackles and Tension Links here.

This post is part of our Interface 101 series where we provide a basic overview of the wide variety of product lines we offer here at Interface. In this series, we explain our force measurement product line and its benefits and then provide a few examples of our product’s in real-world situations. Here are some of our other popular 101 posts.

 

Hazardous Environment Solutions from Interface

There are hundreds of thousands of engineers and manufacturers that spend their days working in hazardous environments. Whether its operating inside of facilities with large machines with intricate moving parts, working hundreds of feet in the air repairing a bridge, or deep within a mine shaft, these professionals put themselves in danger every day by the nature of their work. As engineers and manufacturers, many of us are also tasked to solve for safety challenges and keep these professionals protected in any environment.

At Interface, one of the ways we contribute to industrial safety is with the development of our Interface Ex Rated Load Cells, also known as Interface Intrinsically Safe Products. These specialized load cells and force measurement solutions are designed and manufactured so that the materials and electronic components are safe for use in hazardous gas and dust environments when installed per applicable installation instructions. These components play an integral role in the safety of the men and women working in dangerous environments in particular industries like oil and gas, mining, aerospace, automotive and more.

These hazardous environments are categorized by the amount of explosive risk that is present in the environment. These levels include:

  • Zone Zero – explosive presence is always there
  • Zone One – explosive presence is close and is sometimes there
  • Zone Two – explosive presence is nearby, but is rarely present other than in some type of leak or other catastrophes

In order for force measurement products to operate safely in these environments, companies must design the devices in accordance with a regulatory body. These products must also be inspected for approval and then it is marked with the certification code that displays the zone and temperatures it’s safe to operate in. In addition, the manufacturing process needs to be highly controlled. Manufacturers must keep documentation for each product, which includes how the product was made and where it went. And they are required to keep that documentation for 10 years in case of a product recall.

There are a number of different regulatory bodies focused on product safety throughout the world, and each has different specifications for explosiveness that need to be met based on the area in which the product is sold. Locations in which Interface can sell its Ex Rated products include countries in North America, Europe, Asia, and Brazil in South America.

The regulatory bodies that develop the specifications and approve products include:

  • International Electrotechnical Commission Explosive Atmospheres (IECEx) is given after a manufacturer proves compliance through a quality assessment report (QAR).
  • ATmospheres EXplosible or ATEX is a European Union(EU) examination certification. In order to receive ATEX certification, the manufacturer must obtain a quality assurance notification (QAN) to sell products in certain EU areas.

Interface develops a host of Ex Rated force measurement products that are certified by both IECEx and ATEX. These products have been used in a wide variety of applications within the energy and automotive industries. Included below are a few examples of the products we sell and the applications using our Ex products

ATEX 3400 Series Load Cells

The 3400 series of load cells are rated for Zone 1 and include the 3416 and 3430 Coil Tubing Intrinsically Safe Load Cells, the 3420 Coil Tubing Intrinsically Safe Load Cell and the 3410 Intrinsically Safe LowProfile® Load Cell. These products are hermetically sealed and have been used in the oil and gas industry to measure the force of coil tubing as it goes down an oil well. The 3400 Series is used in the space industry to help develop hydrogen-powered vehicles because of the threat of explosion with hydrogen power. The 3400 Series Load Cells have also been used in a distillery for a custom whiskey-making application.

ATEX, IECEx, ETL, Inmetro 1923 Series

The 1923 Series Load Cell is used in the oil and gas industry. These load cells include designs rated for both Zone 0 and Zone 2 applications. This load cell measures the force in which the pump jack is operating to avoid allowing the pump to go too fast and interrupt the capillary flow of oil. We also recently developed and released the 1923 Wireless Series load cell. Our 1923 Wireless Series innovation provides the same accurate, real-time data readings with little to no fuss over wires, which can create more hazards for the user.

ATEX SSMH Sealed Hazardous Environment Intrinsically Safe S-Type Load Cell

Our Zone 1 rated SSMH S-Type Load Cell is our only load cell that is certified for dust, so it is most often used in mining operations. This product is a tension and compression load cell that is environmentally sealed at an IP65 rating. It also has a high-temperature rating of up to 290° F for dust environments.

ATEX IECEx Bow Type Crosby™ Cabled Load Shackle

The Interface range of ATEX IECEx load shackles is designed for lifting and weighing in rugged or harsh environments, and also meet the requirements for operation in Zone 1 and 2 hazardous areas. The shackle pins are forged from high tensile stainless steel and are machined to an exacting specification. This range of load shackles is proof loaded to 150% of the normal rated load and is available in a range from 3.25 to 400 MT (7.17K to 882K lbf). The product is internally gaged and the whole instrumented area is sealed to IP67 to protect it in service.

When operating in explosive environments, our customers need to know that their products are safe and reliable. Here at Interface, we stand by the quality of our work and the safety of our Ex Rated products. For more information on Interface’s Intrinsically Safe and Ex Rated products, please visit /product-category/intrinsically-safe/.

Contributor:  Ken Vining, Chief Engineer at Interface

Interface Most Promising Energy Tech Solution Provider

Interface is proud to be recognized as one of the ‘20 Most Promising Energy Tech Solution Providers” of 2020 by CIO Review Magazine.

As a pioneer of load cell technology, Interface has long been recognized around the world for providing the most accurate and reliable force measurement solutions on the market. Accuracy matters for safety and reliability in test and measurement projects, engineering and product design and in the original equipment manufacturing of products that require precision sensor technology capabilities.

“The key ingredient to our product’s quality is our more than 50 years of experience and the fact that we have vertically integrated the entire manufacturing process from design to production. Because of this, we have a deep understanding of the materials and product capabilities necessary to suit every industry, application and customer need.” Brian Peters, Director US Sales, Interface

One of the industries where our knowledge of force measurement is vertically integrated processes is in the energy industry. The conditions energy professionals work in can be harsh. They’re often in dangerous environments extracting oil and natural gas, wind, or coal to fuel our nation’s need for power. The equipment our energy sector customers use must be ruggedized and provide the most accurate results possible. If the equipment fails, our customers risk steep financial losses and their staff is more exposed to safety hazards.

Interface has a special line of intrinsically safe solutions for harsh environments. These low profile load cells with loop-powered intrinsically safe amplified output are designed for use in the oil field and other hazardous locations. These load cells are specifically designed from Interface models by adding high resistance strain gages for low-current loop power and shielded internal amplifier for extra low emissions and minimal EMI susceptibility. Interface’s S-type load cell provides a suitable force measurement sensor for applications in coal mining and transfer and other heavy industries where explosive dust and environment conditions are potentially explosion-hazard rated.

Often times, our energy customers come to us needing a custom force measurement solution to deal with these unique challenges for all energy types including thermal, radiant, chemical energy, nuclear, electrical, motion, sound, elastic, and gravitational energy. Innovation in the energy is also heavily dependent upon accuracy in performance, whether it is advancing in the capabilities in the extraction of oil or measuring forces in solar and geothermal. Interface is relied upon by the energy industry leaders and OEM solution providers for their vast ranges of standard and customized load cells, torque transducers, digital instrumentation products and expanding wireless technologies. Read more here about our innovative solutions for the energy industry.

Upon selection for this recognition, Interface application expert Brian Peters contributed to an article for CIO Review Magazine detailing our work developing a custom downhole rig solution for an oil and gas customer. He also explains how Interface has evolved to meet the rising challenges of an industry that is addressing the need for more sustainable energy sources. Click this link to be redirected to Brian’s article online to share.  If you would like to speak with Brian or an application engineer about your test and measurement project or requirements for sensor technology, contact us here.

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