Guide to Selecting Load Cells

A load cell is a core component that converts mass signals into measurable electrical signals, widely used in industrial metrology, electronic scales, automated production lines, logistics and warehousing, and other scenarios. The core of selection is to match actual requirements—avoiding cost waste from overpursuing high parameters while preventing insufficient parameters from affecting measurement accuracy and stability. Below is a systematic, actionable selection process, combining key parameters, scenario adaptation, and practical suggestions to help achieve precise selection.

Step 1: Clarify Core Requirements and Application Scenarios (Foundation of Selection)

Before selection, it is necessary to define "what to measure, under what environment to measure, and how to install," which is the premise for subsequent parameter selection:

1. Core Measurement Requirements

• Measured object: Solid (block/granular), liquid, or gas? Is it corrosive or viscous (e.g., liquid adhering to the sensor)?
• Measurement range (capacity): Specify the maximum weighing value (including the measured object + container/bracket and other auxiliary weights), and reserve a 1.2~1.5 times safety factor (to avoid sensor damage caused by impact load or overload). Example: If the actual maximum weighing is 50kg, a sensor with a range of 60~75kg should be selected; for dynamic weighing (e.g., materials on an assembly line), it is recommended to reserve a 1.5~2 times safety factor (to cope with impact).
• Measurement accuracy requirement: Is it for trade settlement (requiring legal metrological certification), process monitoring (allowing a certain error), or high-precision laboratory measurement? Example: Electronic pricing scales need to meet OIML Class III accuracy (error ≤ ±0.1%), industrial batching systems usually have an accuracy requirement of ±0.05%~±0.1%, and ordinary warehousing weighing can have an error of ≤ ±0.5%.
• Dynamic/static requirement: Is it static weighing (e.g., platform scales, tank weighing) or dynamic weighing (e.g., belt scales, high-speed sorting lines)? Dynamic scenarios require emphasizing "response speed."

2. Installation and Space Conditions

• Loading method: Tension (e.g., suspended weighing), compression (e.g., platform scale bearing), or shear force (e.g., cantilever beam installation)?
• Installation space: Are the sensor's external dimensions (length, diameter, mounting hole spacing) compatible with the equipment structure? Example: Thin sensors are suitable for narrow spaces (e.g., small electronic scales), and column/bridge sensors are required for large tank weighing (strong load-bearing capacity and small space occupation).
• Number of installations: Single-point weighing (e.g., small platform scales, 1 sensor) or multi-point weighing (e.g., large silos, platform scales, 3~4 sensors in parallel)? Multi-point weighing requires selecting "bridgeable" sensors to ensure uniform force distribution.

3. Environmental Conditions (Key Factor Affecting Sensor Stability)

• Temperature: Operating environment temperature range (-40℃~85℃ is conventional; high-temperature scenarios such as near kilns require high-temperature resistant types, and low-temperature scenarios such as cold storage require low-temperature compensated types). Note: Temperature drift will affect accuracy, so select sensors with "temperature compensation" function (the compensation range must cover the actual ambient temperature).
• Humidity/protection: Is it used in humid (e.g., workshop washing, outdoor rain), dusty, or corrosive environments (e.g., chemical workshops, acid-base liquids)? Define with IP protection level: ≥IP67 (dustproof, protection against short-term immersion) for outdoor/humid environments, ≥IP68 (dustproof, protection against long-term immersion) for corrosive environments, and select corrosion-resistant materials (e.g., stainless steel 316L).
• Interference factors: Are there vibrations (e.g., on production lines, near machine tools) or electromagnetic interference (e.g., near frequency converters, motors)? For vibration scenarios, select sensors with "anti-vibration" design; for electromagnetic interference scenarios, select sensors with shielded wires and EMC certification.

Step 2: Select Sensor Type (Match Scenarios by Principle/Structure)

The type of load cell is determined by the core principle and structure. Different types have significant differences in adaptive scenarios, so selection must be based on "loading method, accuracy, and environment":

Key Selection Suggestions:

• For most industrial scenarios (static weighing, accuracy requirement ±0.01%~±0.5%), prioritize strain gauge type (highest cost-effectiveness and adaptability);
• For dynamic weighing (response speed < 10ms), select piezoelectric type or high-speed strain gauge type;
• For laboratory high-precision measurement, select electromagnetic force balance type;
• For high-temperature/strong vibration/strong corrosion environments, select strain gauge type with special materials (e.g., 316L stainless steel, ceramic elastic body) or capacitive type.

Step 3: Confirm Core Technical Parameters (Precisely Match Requirements)

After determining the type, refine the technical parameters to avoid "parameter surplus" or "parameter insufficiency":

1. Accuracy-Related Parameters (Core Indicators Determining Measurement Accuracy)

• Combined error (nonlinearity + hysteresis + repeatability): During selection, it is necessary to meet "combined error ≤ actual required error." Example: If the required error ≤ ±0.1%, the sensor's combined error must be ≤ ±0.05% (reserve redundancy).
• Sensitivity: Output signal corresponding to unit weight (e.g., 2mV/V), indicating the sensor's "sensing capability." Recommendation: Good sensitivity consistency (sensitivity deviation of sensors in the same batch ≤ ±0.1%) to facilitate signal matching in multi-point weighing; the output signal must match the input range of subsequent amplifiers and data collectors (e.g., amplifier input range 0~10V, sensor sensitivity 2mV/V, power supply 10V, maximum output 20mV, so the amplifier needs to have signal amplification function).
• Zero drift: Change in output signal of the sensor over time/temperature without load (e.g., ±0.01%FS/℃). The smaller the drift, the better the long-term stability.

2. Environmental Adaptation Parameters

• Temperature compensation range: Must cover the actual operating temperature (e.g., -10℃~60℃), otherwise accuracy will drop significantly.
• Protection level (IP): Select according to the environment (mentioned earlier).
• Note: IP67 can prevent short-term immersion (1m water depth for 30 minutes), IP68 can prevent long-term immersion, and IP69K can prevent high-pressure spray (e.g., cleaning in food workshops).
• Anti-interference ability: For electromagnetic interference scenarios, select sensors with shielded wires (e.g., twisted-pair shielded wires) and CE/EMC certification; for vibration scenarios, select sensors with "anti-vibration level" ≥ actual vibration frequency (e.g., vibration frequency ≤50Hz, sensor anti-vibration level ≥100Hz).

3. Output Signal and Power Supply

• Output signal type: Must be compatible with subsequent equipment (amplifiers, PLCs, displays):
  • Analog signals (mainstream): Voltage signals (e.g., 0~5V, 0~10V), current signals (4~20mA, suitable for long-distance transmission, strong anti-interference), differential signals (e.g., 2mV/V, requiring amplifier conversion);
  • Digital signals (RS485, CAN bus, Modbus protocol): Strong anti-interference, can be directly connected to PLCs/computers without amplifiers, suitable for multi-point weighing (e.g., 4 sensors in parallel networking).
• Power supply voltage: Conventional is 5V, 10V, 24V DC. Ensure stable power supply (fluctuation ≤ ±5%) to avoid unstable output signals caused by voltage fluctuations.

4. Structure and Installation Parameters

• External structure: Select according to loading method and space:
  • Cantilever beam type: Suitable for platform scales, electronic bench scales (single-point/two-point support, easy installation, range 1kg~5t);
  • Bridge/column type: Suitable for large tanks, truck scales (strong load-bearing capacity, range 10t~1000t, good anti-eccentric load ability);
  • S-type tension type: Suitable for suspended weighing (e.g., cranes, hopper suspended weighing, range 10kg~50t, bidirectional measurement of tension/compression);
  • Thin/micro type: Suitable for narrow spaces (e.g., small electronic scales, medical equipment, range 1g~10kg).
• Installation interface: The sensor's mounting hole type (threaded hole, through hole) and spacing must match the equipment bracket to avoid "eccentric load error" caused by installation deviation (uneven force affecting accuracy).

Step 4: Avoid Selection Mistakes and Pay Attention to Practical Details

1. Common Selection Mistakes

• Mistake 1: Pursuing "the higher the accuracy, the better"—high-precision sensors have higher costs and stricter requirements for the environment and installation (e.g., laboratory sensors may lose accuracy due to vibration in industrial workshops);
• Mistake 2: Range exactly matching requirements—no safety factor, easy to damage the sensor due to impact or overload (e.g., instantaneous overload caused by material falling);
• Mistake 3: Ignoring the impact of eccentric load—for multi-point weighing (e.g., a platform supported by 4 sensors), failing to select "anti-eccentric load" sensors leads to inconsistent weighing results at different positions of the platform;
• Mistake 4: Neglecting signal compatibility—the sensor's output signal is incompatible with the amplifier/PLC, requiring additional conversion modules, increasing costs and fault points.

2. Practical Notes

• Multi-point weighing requires "bridge compatibility": When multiple sensors are connected in parallel, select sensors with consistent sensitivity and output impedance (deviation ≤ ±0.1%), and use a dedicated junction box (to balance signals);
• Material adaptation to the environment: Select stainless steel 304 for ordinary scenarios, 316L or ceramic for corrosive environments, and Inconel alloy for high-temperature environments;
• Calibration and maintenance: For trade settlement scenarios, select sensors that are "calibratable" and have passed legal certifications such as OIML and NTEP; for industrial scenarios, consider the calibration cycle (e.g., once a year) and select sensors with simple calibration processes;
• Supplier qualifications: Prioritize suppliers with industry experience and technical support (e.g., installation guidance, signal debugging) to avoid low-cost and low-quality sensors (usable in the short term but with large long-term drift and short service life).

Typical Scenario Selection Examples (Quick Reference)

Summary: Core Logic of Selection

The essence of load cell selection is the layer-by-layer matching of "requirements → type → parameters → details": first clarify "what to measure, where to measure, and how to install," then select the appropriate sensor type, and finally accurately implement it with core parameters (range, accuracy, protection, signal), while avoiding mistakes and paying attention to practical details (e.g., installation, calibration, compatibility).

If you are unsure about specific parameters, you can provide the following information to consult the supplier:

① Maximum weighing value (including auxiliary weight);

② Accuracy requirement;

③ Operating temperature/humidity/corrosion status;

④ Installation method (tension/compression/space size);

⑤ Subsequent connected equipment (e.g., PLC model, amplifier type), and the supplier can provide targeted recommendations.