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How to Choose the Right Load Cell

Load cells are used to test and confirm the design of hardware, components, and fixtures used across industries and by consumers. From the structural integrity of an airplane to the sensitivity of a smartphone touchscreen, there’s a load cell available to measure force. In fact, here at Interface we have over tens of thousands of products used in force measurement, for all types of different applications.

How do engineers and product designers go about choosing the right load cell for a specific application or testing project?

Have no fear, Interface has put together a short guide on choosing the load cell that is right for you. This blog will cover the basic questions to answer when selecting a product, as well the most important factors affecting load cell choice.  Be sure to watch the online video, Load Cell Basics, that highlights key factors of consideration when choosing the right load cell for additional insights.

The basic questions you need to consider when selecting a load cell include:

  • What are the expected loads? What is the minimum and maximum load you’ll be measuring?
  • Is there any potential for higher peak loads than what you intend to measure? What are these expected peak forces?
  • Is it tension, compression, or both?
  • Will there be any off-axis loads? If so, what is their geometry? Do you want to measure them too?
  • Will it be a static, dynamic or fatigue measurement?
  • What is the environment in which you’ll be conducting your test? Will the load cell need to be sealed?
  • How accurate do your measurements need to be? Do they need to be at the highest accuracy of ±0.02-0.05% or within ±0.5-1%?
  • What additional features, accessories and instrumentation does your application require to complete a test?
  • Do you need standard electrical connectors or customized options? What about additional bridges or amplifiers?
  • How are you planning to collect and analyze the data output from the load cell?

Next, these are the most important factors affecting accuracy, which will have a heavy influence over the load cell you choose. It’s important to understand how your application and the load cell will be affected by each of the factors, which include:

  • Mechanical – Dimensions and Mounting
  • Electrical – Output and Excitation
  • Environmental – Temperature and Moisture

One of the most important factors in choosing the right load cell is understanding how it will be mounted for testing or as a component within a design. There are a wide variety of mounting types including threaded connections, inline, through hole or even adhesive. Understanding the mounting type that suits your application is critical to getting the correct data because a poorly mounted load cell will distort the results and can damage the load cell.

The mounting process also requires you to understand which direction the load is coming from, in addition to any extraneous loads that may be present. The load cell mating surface is also an important factor. For example, when using our LowProfile® load cells without a pre-installed base, the best practice is to ensure that the mating surface is clean and flat to within a 0.0002-inch total indicator reading and is of suitable material, thickness, and hardness (Rc 30 or higher). Also make sure that bolts are torqued to the recommended level.

If you’re conducting a fatigue measurement, it’s also important to address the frequency and magnitude of load cycles with your load cell provider. Factors to address include single mode versus reverse cycles, deflection versus output resolution, and material types. Interface offers a wide variety of fatigue-rated load cells that are perfect for these types of applications.

Another consideration in choosing the right load cell is the electrical signal. Load cells work by converting force into an electrical signal. Therefore, it’s important to understand the electrical output type necessary for your application, which could include millivolt, voltage, current or digital output. You can find the excitation voltage data on our website for each of our load cells. Additional considerations include noise immunity, cable length and proper grounding.

The environment is also a critical factor in ensuring accurate performance of your load cell. Interface provides load cells in a variety of material types including aluminum, steel, and stainless steel. Each material has a variety of properties that make them more suitable for different environments. For a more in-depth perspective on the different strengths and weaknesses of materials, please read our blog titled, Considerations for Steel, Stainless Steel and Aluminum Load Cells. For applications where load cells need to be submerged in liquid or enter an explosive environment, we also have a variety of harsh environment and IP rated load cells, in addition to load cells suitable for high humidity or splash resistance. Learn more about our intrinsically safe load cells here.

Learn more about choosing the right load cell in these online resources:

WATCH: Load Cell Basics with Keith Skidmore

WATCH: How to Choose a Load Cell with Design Engineer Carlos Salamanca

READ: Load Cell Field Guide

VISIT: Interface Technical Library

To learn more about choosing the right load cell for any application, connect with our applications engineers about the force measurement needs for your next project at 480-948-5555.

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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