Innovation Electronic Co.,Ltd
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How to choose one load cell compared to another?
To meet the manifold needs of a weighing system, what specifications do we have to take into consideration, and in relation to what variables?
To define the most suitable load cell it is necessary to assess several factors, both external ones and ones inherent to the very application for which the weighing system is intended.
In particular, it is necessary to pay attention:
The environment affects the performance of load cells, so it is fundamental to analyze the conditions in which they are going to work in order to select the most appropriate characteristics.
We will have to carefully consider the degree of severity of the environment that is going to accommodate the weighing system, both as regards the natural and special weather conditions and as regards the conditions more closely related to the type of plant and industry of the application.
Specifically, we will have to ask some helpful questions:
Will the load cell be installed indoors or outdoors where it is not protected from the weather?
Is the application environment dusty? Damp?
Will the load cell be subjected to immersion? If so, to what depth? Will they be temporary or continual immersions?
❖ It will first of all be necessary to consider the required IP protection rating, that is the level of resistance against the ingress of dust and/or water into the sensor.
❖ All these conditions also affect the choice of the construction material of the load cell.
For example, if the application is in a dusty environment, but indoors, aluminium or a non-stainless steel can be sufficient.
Whereas, if it is outdoors or exposed to liquids or aggressive agents such as chemicals, it will be necessary to consider stainless steel 420 as a basic requirement, to then reach stainless steel 17- 4 PH that is the one most resistant to corrosion.
What are the minimum and maximum temperatures at which the load cell will be working?
All materials undergo changes according to the temperature, expanding in response to heat and contracting in response to cold.
This then also applies to load cells and their strain gauges.
Environments with out-of-standard temperatures (very hot or very cold) can condition the deformation of metal and entail alterations in the electrical resistance of the conductor.
The same happens in the case of considerable thermal excursions.
❖ For load cells to correctly measure the weight regardless of the ambient temperature, during production each load cell undergoes a thermal compensation treatment.
This allows them to work within the temperature range specified on the data sheet observing the reported temperature errors (effect of the temperature on zero and effect of the temperature on full scale).
❖ Another element of the data sheet to bear in mind is the working temperature range, that is the operating temperature range within which the load cell can in any case work without breaking, but it does not guarantee its methodological characteristics.
Will the load cell be used in an area with potentially explosive atmosphere?
❖ If we have to install the load cell in an area classified as a place with a risk of explosion due to the presence of mixtures of gas, vapors or flammable mists or combustible powders, targeted certification will be essential.
The most suitable certification will depend both on the classification of the hazardous area and on the market where the application is installed.
The load cell will then have to be certified on the basis of the regulations in effect in the country of reference, for example:
Is the installation area classified as seismic? Or is it an especially windy area?
❖ All conditions that can generate extraordinary vibrations or forces must be considered for questions of both safety and accuracy and precision of the weighing.
In these cases it is necessary, already at the time of purchasing the load cells, to make provision for accessories, mounting kits and adequate constraints that can ensure proper installation able to protect it from any potentially damaging stresses.
Sometimes the standard mounting kits might not be sufficient for the purpose; in these cases it will be the job and responsibility of the plant designer to make provision for, calculate and install specific anti-tilt constraints supporting the weighing system.
Contact Person: Miss. TINA LIU
Tel: +8618758163948
Fax: 86-571-8838-5175