Industrial scales are available in many shapes and sizes. Laboratory scales weigh items as light as fractions of a milligram. Their platforms may be as small as 2 inches in diameter, which is sufficient for the items being weighed. Somewhat heavier items are weighed on bench scales, with capacities ranging from about 2 pounds up to more than 100 pounds. The sensitivity of a bench scale is generally proportional to its capacity. Platform sizes can range from about 5‰ x 7‰ up to 12‰ x 16‰ for the higher capacity bench scales. Next in size are platform scales which may range up to about 1000 pounds in capacity. A common platform size is 20‰ x 27‰, which is ideal for 55 gallon drums. Other available sizes range from 22‰ x 44‰, often used for livestock, up to 30‰ x 30‰ and 36‰ x 36‰, which can be used for larger packages. Standard pallets and totes require electronic scales with larger platforms and higher capacities. A very typical pallet has a dimension of 40‰ x 48‰, and can be quite heavy. Large floor scales are used to weigh these types of items. The corresponding scale for the pallet described will have platform dimensions of 48‰ x 48‰. The most common capacity is 5000 lb. But some pallets can be much heavier, so other capacities for this size platform include 10,000 lb and 20,000 lb. Floor scales include one load cell mounted in each of its four corners. These cells are accurate instruments that produce a low level millivolt electrical output that is proportional to the weight on that cell. The output signals from the four load cells are added together in order to determine the total weight applied to the scale platform. This system will only be accurate if there are identical output characteristics from each of the four load cells. Some floor scales employ a resistor matching summation board to accomplish this. The values of resistance are adjusted to achieve excellent matching. A preferred method, used by Arlyn Scales, selects load cells with exactly the same output signal values. This avoids the additional components needed for the summation board, and also avoids the possibility of scale failure caused by any problem with that board. Pallets may be placed on a scale using a forklift. Another method is to use a pallet jack. In this case, the loaded pallet jack is pushed up a ramp and onto the floor scale. For this reason, it is advantageous to design the industrial scale with as low a platform height as possible. This allows the slope of the ramp to be very low. Usually, the load cells are bolted to the bottom frame of the scale frame. A preferable design, offered by Arlyn Scales, machines a pocket into the scale frame and attached the load cell inside this pocket. Not only does this reduce the height by approximately 2 inches, but it also protects the load cell from any mechanical damage. Floor scales are used in a wide variety of industrial environments. Because they are usually constructed from steel, they should be protected from moisture and other corrosive chemicals. A spray enamel paint or a powder coat is often used for this protection. But this type of coating will quickly be scratched by a forklift or palletjack. Rust will quickly form in these scratches, and eventually migrate underneath the paint. Arlyn Scales uses a three part, zinc rich epoxy coating on the scale. Even thought it is more resistant to scratches than regular paint, it will still eventually become scratched. But the zinc rich coating will offer preferential oxidation and protect the steel. For particularly harsh environments, the scales are also offered with full stainless steel construction. This makes the floor scales suitable for use in a wide variety of chemical manufacturing environments. For extremely difficult situations, a glass filled epoxy coating offers even more protection. Garnet particles are suspended in the coating for good abrasion protection. It is also possible to order these scales with full aluminum construction. Generally, this is chosen if it is important for the scale to be very portable. When not in use, the scale can be stored on its side, providing the minimal usage of floor space. It can also be easily carried to different locations within a manufacturing facility.
Copyright © 2007-2022 Circuits & Systems Inc. Arlyn Scales. All Rights Reserved.
