How to Calibrate a Scale

How to Calibrate a ScaleA scale must be perfectly calibrated to ensure that they meet industry standards. The process of calibration is different for every kind of scale and the industry in which the scale is used. Some fields require accuracy extending to several decimal points. Other fields that center around smaller products are suited by less meticulous calibration.

Floor Scales

To calibrate a large floor scale without the aid of a professional, one must know the maximum amount of weight that the scale can accurately measure. A large scale can be easily calibrated if its owner has an object on hand that weighs 80% of the scale’s maximum measurable weight. The display on the scale should be adjusted to accurately display the precise weight of the object. The scale is properly calibrated if the display returns to zero when the object is removed.

If the scale is technically calibrated but the corners are still registering different weights for the same object, the corners must be individually leveled. A weight amounting to 25% of the scale’s capacity should be placed on each corner in succession and the read-outs recorded. The weight should be placed on the corner that yielded the lowest reading while the display is adjusted until the number matches the corner with the highest reading. This process should be repeated until all four corners measure weight equally.

Crane Scales

Crane scales are incredibly difficult to calibrate. Getting an accurate reading from such a scale is difficult in itself. Tilted loads yield inaccurate readings, and the display fluctuates in response to sudden movements. Accuracy in low weight ranges does not guarantee accuracy when weighing incredibly large items. The difficulty of calibrating crane scales at weights over several tons means that the scales may never be accurate in the upper ranges.

The most common means of calibrating a crane scale is to measure a very large item on a flat scale that has already been calibrated. The item is then placed on the crane scale while the display is fixed. This manner of calibration is flawed because it transfers any inaccuracy involved in the first weighing to the calibration of the crane, which is then subjected to a second round of human error. Calibrating a crane scale this way only guarantees accuracy at the exact weight of the object being used, necessitating multiple weighings of disparate objects to ensure full reliability.

Platform Scales

Large platform scales can only be calibrated when the atmospheric conditions are ideal. The temperature must be comfortably warm, and the level of humidity cannot be too high. No cellphones, vibrating machinery or magnets can be present in the same room as the scale or the reading will be affected. The temperamental nature of platform scales usually does not allow owners to easily calibrate their scales by themselves if the test readings are not accurate.

If the readings on the scale do not correspond to the known weights of the test objects, a representative from BrightScale may have to calibrate the scale himself according to the manufacturing standards. The scale owner should be in the habit of recording the dates and times of his scale’s calibrations. He should be very careful about keeping track of the true weights of the test weights and their corresponding readings on the scale. He should also note the temperatures and humidity levels on the days he performed the tests.

All of this information will help the professional calibrator make the necessary adjustments to the scale. Platform scales can be so temperamental that they display different weights for identical objects if the other conditions of the initial weighing are not replicated exactly. Old test weights may weigh less than they are supposed to weigh due to damage or general wear, so they may be the sources of the inaccurate readings. Sometimes a scale must be taken completely apart and adjusted internally before it can produce accurate results again.

Livestock Scales

Livestock Scales may be subject to local regulations that only allow for minor deviations over and under an animal’s true weight. Old scales will naturally be less accurate than new ones, and this is taken into account when calibrating them. There are complicated mathematical formulas that allow technicians to determine if the scale is within the acceptable range of error. This allowable margin of error also applies when the animal is removed and the display is supposed to return to zero.

Due to the variable natures of livestock scales, it is best not to test the accuracy on one’s own but to have any recalibration performed by a BrightScale professional. Different models of livestock scales demand different methods of calibration. It is especially important to have this procedure performed by a skilled technician if the scale is subject to official inspections. The scale’s owner should be able to perform corner and regional weighing tests on his own, as long as he keeps clear records of the results.

Bench Scales

Digital bench scales are fairly easy to calibrate without professional help. They usually have built-in mechanisms that reset the scale at zero when a button is pushed while nothing is being weighed. The scale must be clean and free of any residue before it is reset to zero. The ease and speed of calibrating a bench scale can lead to problems if one is not careful. The scale could accidentally be reset to zero while something is on top of it, distorting the read-outs of all subsequent weighings.

If none of these calibration and testing methods are producing the desired results, scale owners should consult BrightScale immediately for assistance. An uncalibrated scale can lead to a great deal of lost revenue, so a professional calibration is a good business investment. Scale owners should not attempt to calibrate their scales by themselves if they are unsure of how to do so, but it is always a good idea to run frequent weight tests and write down the results. BrightScale is the premier retailer of new scales and home to technicians who can quickly and expertly repair old scales.