How to Choose the Right Load Cell for Your Application

Selecting the appropriate load cell for your application is crucial to ensuring accurate and reliable measurements. This guide will walk you through the considerations, factors affecting load cell performance, and how to match load cell specifications to your application requirements.

Considerations for Load Cell Selection:

Measurement Range: Determine the full range of loads you need to measure, including both minimum and maximum expected loads. Ensure the load cell's capacity fully covers the maximum load to be measured, but also consider the minimum load requirement to avoid measurement inaccuracies at the lower end of the range.

Environmental Conditions: Evaluate the operating environment where the load cell will be installed. Consider factors such as temperature variations, humidity levels, exposure to corrosive substances, and potential vibration. Choose a load cell with suitable protection and robustness to withstand these conditions, especially if being used outdoors and exposed to the elements. To learn more on this visit this blog article here. 

Mounting and Installation: Assess the available space and mounting options in your application. Consider factors such as the physical dimensions of the load cell, mounting configurations and accessibility for installation and maintenance. Ensure compatibility between the load cell's mounting arrangement and the structure or equipment where it will be installed.

Accuracy and Precision: Determine the required level of accuracy and precision for your application. Also consider factors such as the tolerances allowed for your application and any regulatory requirements. Choose a load cell with appropriate accuracy specifications and resolution to meet your measurement objectives.

Output Signal: Decide on the type of output signal required. A mV/V output is generally supplied as standard, but if integration with your data acquisition or control system is required, other outputs are available. Common output signals include analogue (e.g., voltage or current) and digital (e.g., RS485, CAN bus). Consider compatibility with existing equipment, signal conditioning requirements, and communication protocols when selecting the load cell's output signal.

 

 

Factors Affecting Load Cell Performance:

Temperature Sensitivity: Understand how changes in temperature can affect load cell performance. Temperature variations can cause drift in output signals, leading to measurement inaccuracies. Choose a load cell with built-in temperature compensation or insulation to minimise the effects of temperature changes on measurement accuracy.

Creep and Hysteresis: Consider the load cell's ability to maintain accuracy over time and under repeated loading cycles. Creep refers to the gradual deformation of the load cell under constant load over time, while hysteresis refers to the difference in output readings for the same load applied sequentially in increasing and decreasing directions. Choose a load cell with low creep and hysteresis characteristics to ensure stable and repeatable measurements.

Overload Protection: Evaluate the load cell's ability to withstand loads beyond its rated capacity. Overloading can cause permanent damage to the load cell or affect its performance. Look for load cells with at least a 150% proof load (limit the load cell can be used without sustaining any damage) to prevent deformation and ensure safe operation under unexpected loading conditions.

Cross-talk and Interference: Minimise the risk of signal interference or cross-talk from external sources. In high-noise environments or applications with electromagnetic interference, choose load cells with proper shielding and isolation features to ensure signal integrity. Additionally, consider the layout of wiring and electrical connections to reduce the potential for interference. If using wireless load cells, make sure that other wireless systems nearby are not operating on the same frequency and that there is a clear line of sight between the wireless transmitter and the signal receiver.

Installation: Maximise the integrity of load readings by ensuring that load cells are properly installed and aligned during installation. The direction of the load should be constant and applied centrally, and side loads eliminated as far as possible. Typically load cells can be supplied with a variety of fixtures and fittings that aid installation and help achieve accurate readings post set up and during use.

Calibration Requirements: Take into account the frequency and ease of calibration needed to maintain accurate measurements. Calibration ensures that the load cell's output remains within specified tolerances over time. Annual calibration is recommended as the standard interval to ensure that measurements are always as accurate as possible, which is particularly important if being used for safety critical applications. However, more frequently than one year may be advisable if the load pin is being used in a particularly harsh environment or arduous operational conditions (high vibration levels, excessive cyclic loading).  
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Matching Load Cell Specifications to Application Requirements:

Load Capacity: Ensure that the load cell's rated capacity meets the maximum load expected in your application to avoid damaging the load cell. Consider factors such as peak loads, dynamic loading conditions, and safety factors when selecting the load cell's capacity.

Material and Construction: Choose load cells made from materials compatible with your application environment. Common materials include stainless steel for corrosion resistance, aluminium for lightweight applications, and alloy steel for high-strength requirements. Consider factors such as chemical exposure, abrasion resistance, and hygienic requirements when selecting the load cell's construction material.

Output Compatibility: Verify that the load cell's output signal is compatible with your data acquisition or control system. Consider factors such as voltage or current levels, signal conditioning requirements, and communication protocols when selecting the load cell's output signal. Ensure seamless integration with existing equipment and compatibility with software interfaces for data analysis and processing.

Accuracy and Resolution: Choose load cells with the appropriate accuracy and resolution to meet your measurement objectives. Consider factors such as the required measurement uncertainty, resolution of the measurement system, and calibration standards when selecting the load cell's accuracy specifications. Ensure that the load cell's performance meets or exceeds the desired level of accuracy for your application. There is more on this topic in this article. Click here. 

Certifications and Standards: Look for load cells that meet relevant industry standards and certifications, especially if the load cell is going to be used in a hazardous environment. Common certifications include ISO (International Organisation for Standardisation), ATEX (Atmospheres Explosibles) and IECEx (International Electrotechnical Commission Explosive). Certification ensures compliance with legislative, quality and performance standards, as well as traceability of measurement results to established reference standards.

 

By carefully considering these factors and matching load cell specifications to your application requirements, you can select the right load cell for your specific needs, ensuring accurate and reliable measurement results.