The load cells on a scale are an isolated circuit. When moisture enters the load cell or junction boxes, the circuit is no longer isolated and may cause drifting. Before opening any box on your scale ensure that the indicator is off and that you are not opening anything other than the scales junction box. Check the box for moisture and if moisture is found, dry out the box with paper towels or a hair dryer. Make sure not to melt any of the wires in the box as this can cause other problems. If the boxes are dry then check for a damaged cable in between the indicator-J-box-load cell. Old splices in load cell cables are common areas that can also cause problems. Note: Removing the cable from the load cell will damage it beyond repair.
This problem is normally caused in the colder months. It has to do with debris (ice, dirt, etc.) under the scale and interfering with the transfer of load directly to the load cells. Areas that should be checked are the gaps between approaches and scale and where sections meet. If the debris is frozen you can try chipping or melting it away. Melting with heat can cause other problems, melting cables or load cells. Steam is very effective at removing debris but be careful not to directly spray the load cells or junction boxes.
This too is a common problem in the colder months. There are two types of zeroing on a scale. One that is done during calibration, this is called setting the dead load. The other done by the operator after calibration, a key pad zero or push to zero. A dead load creates an internal zero whereas a push to zero sets a temporary one. The push to zero has a limit of 2% of capacity, so if your scale has a capacity of 100,000 kg your allowed to push to zero 2000 kg above and below internal zero. What happens over the course of winter is snow and ice build up on your scale and even though you’re zeroing it off, you’re not changing the internal zero. So when you have reached 2%, your push to zero stops working. The solution is to remove the ice or snow from the deck to get down closer to your internal zero. Sometimes this is easier said than done. If you find problems with clearing the deck, give us a call and there are sometimes other ways to to get your zero button working again.
Testing of your scale ensures it is working properly and not costing or losing money. Scales are normally tested before their busy season starts. There might also be other factors that play into the frequency of testing your scale ie. weather, volume of traffic or a company’s quality system. What ever schedule you decide to use there are key things that need to be done to make sure your scale works properly on the day of testing and for many days following. Build up under the scale should be removed, no testing should be done on a dirty scale. The debris under the scale could cause measurement errors. It is suggested that you or your service provider clean the scale thoroughly in the Fall. Having debris under the scale in the colder months will only cause you more issues and cost more money to fix. If you have any questions regarding the frequency of testing your scale, please call or email us.