At Central Carolina Scale in addition to selling and installing truck scales; we also check, test, adjust, and calibrate truck scales just about every working day of the year. We have factory trained technicians who can troubleshoot even the smallest problem areas like a load cell that might be creeping. We also have certified test weights and a weight cart which allows us to provide the highest level of truck scale service available in North Carolina. When we’re finished doing our scale check, we supply the customer with documentation that shows before and after readings and how much weight we tested the scale with, etc…
However, in quite a few cases, where money changes hands based on scale weight, the state of North Carolina will also check the customer’s truck scale to make sure it is weighing correctly and performing within legal for trade tolerances. The blog post linked below is a field trip that describes a state test in more detail.
The Standards Division checks any scales where “money changes hands.” This would include scales at grocery stores, livestock scales, buffets, agricultural-supply centers, highway patrol weigh stations and scrap metal facilities. Scales are checked on an annual basis or by complaint. The only exception is stockyards, which are checked twice a year.
When consumers bring unwanted appliances, metal debris or even old vehicles to a scrap metal facility the items are generally weighed on a truck scale. At some facilities, this scale can record up to 100,000 pounds of weight. The entire weight of the vehicle, trailer and scrap metal is recorded on the scale. After unloading inside the facility, the consumer then drives the emptied vehicle and trailer back over a scale at the exit and this weight is recorded. The consumer is paid for the difference of the two weights. Depending on the amount of scrap brought in, the amount could be a couple of hundred dollars.
To check a heavy truck scale, Inspector Glenn Farmer uses a six-wheeled, gas-powered, steel test cart. A hydraulic arm is used to fill the cart with certified 1,000-pound and 500-pound weights. For the test, he uses a known weight (the cart plus added weight) and test different quadrants of the scale. A five-section scale would have 18 different test points. There are two different types of truck scales, mechanical and load. To test a mechanical scale, Farmer must move his cart side to side to record weight. To check the accuracy of a load scale, he moves the cart down the center of the scale.
The Standards Division uses National Institute of Standards and Technology guidelines to determine tolerance levels on the scales. A tolerance level is the amount of weight a scale is allowed to vary. For a scale that can measure more than 25,000 pounds of weight, the tolerance level would be 60 pounds. A scale that does not pass inspection must be pulled out of service until the facility fixes the problem. “Many times the issue is debris buildup in the crevices of the scale,” Farmer said. “Pine straw, cans and other debris can cause the scale not to weigh correctly.
Our advice to the company is to power wash or use an air hose to clean the area around the scale.” If the scale is still recording incorrect weights after cleaning, the facility may call a scale calibration company to fix the problem. Some facilities will have a representative from their scale company go along with the standards inspector on the day of their inspection. This means that most problems can be fixed immediately, and the facility doesn’t have to endure a prolonged shutdown of a scale if problems are found.
This was a nice write up about testing scales and how important it is to keep your scales weighing accurately. It’s always a good idea to keep your scales clean and weighing as accurate as possible, year round. One easy way to do that is to contact us at (919) 776-7737 and set up a maintenance schedule for your scales. You’ll save money and you will have accurate scales with the regular scale checks.