5 Best Practices for Accurate Calibration Using Calibration Weights

Calibration weights are solid blocks of metal that are used to test the accuracy of scales and balances. They are carefully crafted to represent a specific weight anywhere from one milligram for the most sensitive analytical and microbalances to fifty kilograms for less sensitive platform scales. This blog will describe 5 best practices for obtaining accurate calibration using calibration weights.  

1. Choose the Correct Type of Calibration Weights

There are multiple distinct types of calibration weights, and you can’t choose which one to use willy-nilly. Calibration weights are organised by class. Inscale offers E1, E2, F1 and M1 Class test weights, which are constructed from a variety of materials including aluminium, stainless steel, brass and cast iron.

If you’re calibrating a scale that provides extremely precise weight measurements such as an analytical or microbalance, you’ll require E1 or E2 Class test weights. These weights are constructed from aluminium or stainless steel with the highest accuracy, and this makes them our most expensive options.

For a standard precision balance that requires accuracy but not absolute precision, F1 Class test weights are suitable. These stainless steel test weights have the added benefit of being more affordable than E1 and E2. For industrial or commercial scales that require less accuracy like platforms or floor scales, M1 class weights are ideal. M1 weights can reach up to 50+ kilograms in weight and can be constructed from brass, cast iron or steel.

Make sure you do your research and choose wisely. 

2. Use a Stable, Level Surface When Calibrating

When you’re preparing to calibrate, you want to guarantee that your scale or balance is on a stable, level surface and that your scale is level as well. Calibrating a three-footed analytical balance on a wobbly table will not result in a successful calibration (for any scale, really, not just an analytical balance).

Instead, consider calibrating your analytical balance on an anti-vibration table or a solid benchtop, depending on the amount of outside interference present. All four feet should be present and the bubble in the levelling tool should be resting nicely in the middle. For a large industrial scale, the floor will be the most ideal location for calibrating.

3. Follow the Manufacturer’s Instructions

While the calibration process for most scales or balances may be generally the same, it’s important never to assume you know what you’re doing, especially with a scale you’ve never calibrated before. Manuals are written for a reason; they’re meant to be read! You have a much higher chance of successfully calibrating your scale or balance if you follow the directions. If you’ve lost the directions, many websites, including Inscale, provide links to manuals within the product page.

4. Check Calibration Regularly

Unfortunately, calibration doesn’t last forever. Over time, your scales and balances may begin to drift or provide two different weight readings for the same item. These are signs that another calibration session is necessary. In the manual, you may see the manufacturer’s recommendation for how often to calibrate, in which case it’s best to mark your calendar accordingly.

If the manual doesn’t offer a recommendation, we suggest calibrating once a year at a minimum. Should your scale or balance be used with unusual frequency, for particularly rough, harsh tasks or moved to various locations, we advise calibrating more often, such as once a month.

5. Keep Calibration Weights Clean and Handled Properly

E1, E2 and F1 Class calibration weights are crafted to be incredibly precise, and improper care can easily jeopardise this. For example, these calibration weights should never be handled without either gloves or tweezers (you can get away without them with M1 Class weights). Your bare fingerprints produce oils that, almost unbelievably, add a minute amount of weight, and could even corrode the test weight over time. Dirt, dust, and lint are risks as well and should be avoided at all costs.

Should fingerprints, dirt, dust or lint mar the calibration weight despite your efforts, you can clean it with a soft brush, sans any cleaner or soap. Remember not to touch the brush with your bare hands, as those pesky finger oils can easily transfer. Scratches, however, will not be so easy to remove, so ensure that when you’re placing or removing the calibration weight from the weighing pan, you set it down and lift it without scraping or dragging it. For further information, see our blog The Care and Keeping of Calibration Weights.

We want you to have the most accurate scales and balances possible, which will be much more achievable when following these 5 best practices for calibrating using calibration weights. If you have any further questions, please Get In Touch.