In our blog series "Technical issues in the world of force measurement" we write blogs to help our customers and visitors.
Earlier we wrote a blog ‘How to make a load cell selection?’, now we want to inform you about the next step, the installation.
Once you have selected the correct load cell for your application it is very important to install the load cell correctly. By doing this, the maximum accuracy and working life of the load cell can be achieved. In this blog we will elaborate more about the accessories available at Zemic Europe, their advised applications of use and proper installation. If you have any further questions, please don’t hesitate to contact us. We are happy to help.
Available accessoires at Zemic Europe
Before making a choice of accessory, it is important to know in what kind of application the load cell is going to be installed and what kind of forces and force introduction can be expected. If the wrong accessory is chosen, this could result in inaccuracy of the application or breakage of the accessory or load cell.
At Zemic Europe we have the right accessories for all kinds of applications. A small selection of our accessory program and their uses will be discussed in this blog.
Elastomers
Elastomers are accessories which combine the stiffness of metal with the vibration absorption capabilities of layers of rubber. They are moulded together by a vulcanization process. This gives the advantage that, when either shock load or vibration can be expected during the use of the application, this will not affect the load cell. The elastomer is also capable of absorbing high amounts of side force. The elastomer is generally assembled by two fastening nuts which will clamp the load cell in between. The elastomers are able to horizontally deflect over 10mm and due to their self-restoring force, coming from the vulcanized rubber, will be able return back to their original shape when the side force has been lifted.
Because elastomers experience a lot of deformation from nominal load, the accuracy of load cells with elastomer accessories will be less than it would be when mounted with a stiff accessory. Vibration and side load will affect the load cell greatly when a stiff accessory is chosen. An example of an application for which elastomers are used are dosing systems.
Tension accessories
Tension accessories are used in combination with S-type load cells. With this combination you are able to make applications which work with the tension force principle. For example filling bags applications. The tension accessories usually come in the form of a ring, hook or rod end. These accessories make sure the force introduction into the load cell is always straight through the centre and no misalignments can occur.
Most sideward forces and bending motion which could damage the load cell or give inaccurate measurements will be absorbed by the accessories. The accessories will also make sure that the assembly is self-centering. It is very important to make sure the assembly is not able to rotate because this could cause the thread, which connects the accessory to the load cell, to come loose.
Feet
Feet accessories are widely used in applications where a load cell is resting on the ground or another fixed world. The feet can be screwed into the loading hole or can be mounted inside a T-end loading hole of a load cell and fixed with a split-pin or cotter-pin. Zemic Europe have many different feet available, therefore it is important to take the dimensions of the threaded hole or T-end hole into consideration when selecting the right feet. It is important to check if the surface on which the feet will rest is flat and does not exceed the maximum slope of <0.5° or 10 mm/m. Some of the feet available at Zemic Europe have an integrated ball and cup. This gives the possibility to move along with the deformation of the application while loaded or deformation induced by temperature change. In this way, inaccurate readings can be prevented.
Height adjustable feet are also available for our load cells. In this way, the height of the application can be adjusted and the application can be levelled. Another big advantage of feet accessories is that no other accessories are necessary to install the load cell into an application this results in a very flat and easy installation. Feet are used, for example, for platform weighing.
Mounts
Zemic Europe also have complete mounting sets available. These are multi-component accessories which will provide an optimal load introduction into the load cell for the most accurate results. Mounts are available for even the highest capacity load cells and suitable for the most harsh environments. Zemic Europe mounts are designed in such a way they provide quick and easy installation. We have mounting kits available with different installation heights and with specialised designs.
This includes lift-off protection which prohibits an application to lift-off and tumble over, like silos which experience a lot of side wind. Another specialised design is mounting kits with self-aligning capabilities. This design makes sure the mounting kit and therefore the load introduction is always entering the load cell in a correct way, even when side loads are present.
Another available addition to the mounting kits are stay rods. A stay rod will absorb a side load into a specified direction. This is exceptionally useful when a side load usually occurs. An example of this is a vessel tank with build-in agitator. Due to the stirring, it will always induce some side load which will be absorbed by the stay rods. Mounts are often used for e.g. silos and weighbridges.
After selecting the right accessories for your application, it is important the load cell and accessories are installed correctly. This is of course depending on the kind of application and what forces are to be expected. However, some general guidelines can be followed.
General guidelines:
- Always make sure the accessories are installed in the same horizontal plane and are levelled (within <0.5° of each other).
- Make sure the load cells and accessories are never loaded with forces which are exceeding the maximum capacity.
- When more than one load cell with accessories is used in an application, it is advised to have an equal load distribution. If this is not possible, the difference should never exceed 20%.
- Check if the load introduction is in the right position and in the right direction. On most Zemic Europe load cells, there is an arrow indicating the direction of the force. Load should always be introduced on the loading area of the load cell. When using a Zemic Europe accessory, this is always guaranteed.
You can find our weighing accessories here: https://www.zemiceurope.com/en/categories/weighing-accessories.html
If you need help choosing the right accessory or advice on installing the load cell with an accessory in your application, please feel free to contact us. Our experts are ready to help.
