Since each option has its own unique advantages, the process of selecting a load cell is usually complicated. To be honest, different load cell applications have their own special requirements. Therefore, you should discuss the capacity requirements of the load cell with a knowledgeable supplier before choosing.
The decision you make based on the load cell selection criteria is only one step in the entire implementation process. In addition, you must also ensure that the correct load cell is installed and equipped with the correct load cell, otherwise you will not be able to obtain accurate measurement results. This load cell selection guide will help you make a more informed choice.
Know your application
In order to understand your load cell application, you must determine how to measure and how to apply the load. Many factors are involved in the measurement process, including:
The load cell measurement helps determine the weight of the tank and the performance of durability and breakpoint tests.
Define your capacity requirements
Pressure and load cell performance
Determine the maximum load capacity required for your application and the minimum necessary.
When determining the load cell capacity requirements for your application, you need to keep irrelevant factors in mind. To ensure that you have the best capacity, choose a capacity that exceeds the maximum operating load. In addition, you need to determine which engineering units are required for the process. The combined stresses caused by external loads and moments can affect the performance of the application.
Therefore, if you fail to choose a suitable load cell, you may seriously affect the accuracy of the application.
Most online load cells are not equipped to prevent the possibility of external loads. For more durable applications, choose the load cell with the best fatigue rating specified by the manufacturer.
Define your load cell needs
In order to choose the correct load cell, please determine your application requirements. The following questions can help you make a decision:
Is the load of your application dynamic or static?
Are you planning to use the load cell online?
Do you plan to use the load cell for side mounting?
Another factor is the design of related equipment. The capacity requirements of the load cell depend in part on the shape of the equipment used, which may include:
When choosing a load cell, make sure to consider these factors first to ensure that the product you buy meets the requirements of the application.
Define your size and specification requirements
Another key component of the selection criteria for load cells is the definition of size requirements. Most specifically, you must determine the requirements of the application according to the following measures:
Width and height
To ensure that you have sufficient load cell capacity, you also need to determine possible differences, such as:
Finally, you need to make a choice based in part on whether you will be using the application at high or low temperatures. Similarly, the capacity requirements of the load cell can be determined by whether the application is performed in an underwater environment or outside the water. When you determine your requirements, factors such as response frequency and special calibrations that may be required are also important.
Choose an instrument
While choosing a load cell, be prepared to choose any necessary instruments for the application you intend to perform. When you select all important components at the same time, you can better ensure that there are system-wide functions between each component in use.
You should also include system calibration in the order. This will ensure that you integrate the instrument and load cell into the same system. Calibration is an important part of all load cell applications.
Load cell application factors
Load cell application
Load cell options related to related settings or application requirements are preferable. When you learn how to choose the right load cell for a specific application, consider your first requirements. Generally speaking, the performance of the load cell will be related to the needs of the application, as shown below:
High endurance. In an industrial environment, strain gauge load cells are one of the best choices, because the accuracy is close to perfect in applications involving experimental stress.
Health and safety. In applications that require precise mechanical balance, pneumatic load cells are the preferred choice.
Remote applicability. When the application is performed in a remote setting, the best option is a hydraulic load cell, which can operate without a power connection.
The selection criteria for load cells-or the choice between strain gauges, pneumatic or hydraulic load cells-mainly depends on the aforementioned factors.
Load cell type
Strain gauge load cell
The most widely used load cell in the entire industry is the strain gauge type. People pay attention to the durability, stiffness and resonance value of strain gauge load cells. The strain gauge of the load cell is a planar resistor, which deforms with the movement of the load cell material. The resistance of the strain gauge changes at a level related to the strain.
Piezoelectric load cell
For piezoelectric load cells, the deformation is similar to that of strain gauge load cells. However, the piezoelectric substance generates voltage in response to the changing form of the load cell. Voltage is not used as a measurement of static values, but it is still important when strain changes. Through the adjustment of the charge amplifier, the piezoelectric load cell can measure a wide range particularly well.
Hydraulic load cell
The hydraulic load cell is used in combination with a cylinder and a piston with a diaphragm. Its working principle is like this-put oil into the load cell, and increase the pressure of the oil through the movement of the piston in response to the load. The hydraulic pressure is measured by the pressure transmission of the hose. Due to the lack of electrical components, hydraulic load cells can be safely used in hazardous environments.
Pneumatic weighing load cell
The pneumatic load cell is used to control the pressure balance. One side of the diaphragm is exposed to air pressure, and the air passes through the lower nozzle of the load cell. An additional meter measures the pressure in the load cell.
Load cell shape
S-beam load cell
You can identify the S-beam load cell (also known as the Z-beam load cell) by a shape similar to the letter of the same name. S-Beam load cells are mainly used in applications involving tension and provide accuracy when the weighing system is suspended or suspended.
In addition to high accuracy, S-Beam load cells are largely popular due to their reasonable price and easy setup. However, S-Beam load cells are specially manufactured for online applications and often fail to operate accurately when subjected to external loads.
Beam type load cell
You can use beam load cells named after rectangles, from static weighing and dynamic weighing to hopper weighing, silo weighing and tank weighing. As a broad category, beam load cells can be subdivided as follows:
Curved beam. Designed for bench-scale applications, bending beams need to be set up very carefully, otherwise side loads may occur. The bending beam is made of aluminum alloy and is ideal for low-volume operations from 1 to 500 kg.
Shear the beam. Designed with internal shears-to protect the unit from side loads-the shear beams are available in single and double ends. Medium-capacity applications usually use a single machine, while applications that require higher capacity use dual machines. The shear beam is made of carbon steel alloy nickel plated and is corrosion resistant, making it the best choice for heavy-duty applications.
In general, bending beam and shear beam load cells are low-cost options for a range of industrial applications.
Tank type load cell
The tank load cell is named after its tank-like shape, and its history can be traced back to the very beginning of the strain gauge load cell. In contemporary use, tank load cells have become a common choice for compression applications with a capacity requirement of 100,000 pounds. or more.
Pancake weighing load cell
Applications involving high precision use pancake load cells, also known as low profile load cells. The pancake type load cell has one of two designs-one with a curved beam and one with a shear strut. Most pancake load cells have a mounting device and a female center thread, which makes them suitable for compression and tension applications.
Button load cell
As one of the smaller load cell designs, the button load cell gets its name from its raised center button. Due to its compactness, button load cells are one of the most ideal choices for applications in narrow and restricted environments. Button load cells are especially popular in the medical field because the operating space in the medical field is very precious. Applications in the automation industry also benefit from the small design of the button-type load cell.
Through hole load cell
The through-hole load cell is called a doughnut load cell because of its Lifesaver-like shape, and is ideal for applications involving the use of clamping force or bolt force measurement. Designed for high rigidity, the through-hole load cell provides the highest accuracy in pressure loading and eccentric applications.
Adverse loading conditions
When dealing with unfavorable load conditions, consider the following:
Overload capacity. This must be determined first in order to understand at which level the load cell must be verified for loading, otherwise the risk factor may be too high.
Dynamic load. The load cell rating must consider the durability, speed and pressure of the dynamic load, otherwise you may not be able to determine the overload capacity and make the load cell vulnerable under high dynamic conditions.
Fatigue load. You must determine the load level of each cycle and information about the frequency and total number of cycles throughout the life of the load cell. Otherwise, the continuous cycles experienced by the load cell may cause fatigue loading.
Off-axis loading. Off-axis loads may affect the accuracy and health of the load cell, which may occur in applications where the load does not conform to the designed shaft. You can solve this problem by using bearings and load buttons, and some load cells can completely solve this problem.