
What is a Calibration Weight?
Accurate weighing is essential in many industries, and the only way to keep your scales and balances accurate is by calibrating them regularly with calibration weights. What is a calibration weight, and how do you know the best one for your scale or balance? Let’s discuss.
What is a Calibration Weight?
A calibration weight, also known as a test weight, is a carefully crafted block of metal that has been certified by the Intergovernmental Treaty Organization (OIML) for representing an exact weight value. Depending on the type of metal used to create the weight and the weight’s designated OIML class, some are crafted within a finer tolerance than others.
What is a Calibration Weight For?
Over time, even the most precise and accurate scale or balance may begin to provide results that drift (can’t stabilise) or don’t match when the same item is weighed twice. Luckily, this is completely avoidable by letting a qualified individual, such as yourself, regularly calibrate your scale or balance with calibration weights. Calibration weights are only necessary for scales and balances that offer external calibration – internal calibration doesn’t require them.
Calibration weights work by essentially ‘reminding’ the scale or balance what a specific weight value feels like on the pan. For example, when entering calibration mode, your scale may request that you place a 20g test weight on the pan. Once it’s recalibrated to that weight, it may ask for a 50g test weight next, and so on. This allows it to recompute these reference points across its entire capacity. Once the scale has recalibrated its expectations, it’s once again able to provide highly accurate results.
Types of Calibration Weights
Calibration weights come in different classifications, materials, and shapes.
Classifications
The EU’s regulating organization for calibration weights, OIML, separates them into classes. On Inscale, we offer classes E1, E2, F1, F2, and M1.
E1 and E2 class weights are ideal for use with highly precise semi-micro and analytical balances that have four-place readabilities or finer. F1 is great for analytical and precision balances with three to two place readabilities, and F2 for precision balances with 0.01 readabilities. You’re likely to find these classes of calibration weights in laboratories. Meanwhile, M1 class test weights are the most common because they’re sufficiently accurate for bench, floor, and platform scales with higher readabilities of 0.1g or more, so you can use them for industries beyond the lab.
Materials
Stainless steel, cast iron, aluminium, German silver, and brass are common materials for calibration weights. You’ll find that on Inscale, all our E1, E2, and F2 calibration weights are stainless steel. Our F1 weights are stainless steel for any with a value of 1g or above, while the milligram weights are German silver. Our M1 category contains a variety of materials, they’re very versatile.
Your environment may impact which one you choose. For example, if you work in a humid climate, stainless steel is resistant to corrosion and rust, while brass is more susceptible.
Shapes
Calibration weights can be cylindrical, slotted, block, hooked, or, when it comes to milligram weights, tiny sheets or wires. Cylindrical is most common on our site, but we offer many heavy cast-iron block weights for platform scales, and hooked weights to calibrate your scale’s below-balance weighing. Choose a shape that fits the scale’s weighing platform and your application.
Sets
You can purchase individual calibration weights should you know what your scale requires during the calibration process. If you own multiple scales or balances that have similar capacities and readabilities, you may be better off purchasing a set of weights. This way, you know you have enough weights all in one box to calibrate multiple different scales or balances.
How to Use Calibration Weights
Prep the Scale and the Weight
Before calibrating, ensure that both your scale and your weight are as clean as possible. For advice on how to clean and take care of your calibration weights, you can read our blog here. To help keep them clean in the first place, avoid touching them with bare hands, which can transfer oils and impact the weight over time. Use clean cotton gloves or tweezers!
The Process
Turn on your scale and let it warm up – both temperature wise and mechanically. You may overlook this, but it's important. Both your balance and the weight should be as close to the same temperature as possible. Make sure your scale is on a flat, level, and stable surface.
Follow your scale’s instructions, typically found in the manufacturer’s manual, on how to enter calibration mode. It may have a dedicated button or require a sequence of steps to reach.
There shouldn’t be any guessing as to which calibration weights are necessary, your scale will request them. Place the weight in the middle of the pan and step back to allow recalibration. Once notified of completion, confirm the weight result on the display matches the weight value you placed on the pan. If so, you’re good to go! Continue until your scale clarifies that calibration is complete.
When Should I Calibrate My Scale or Balance?
The more precise the balance, the more often you should perform calibration. You should calibrate semi-micro, analytical, and precision balances at least every few months, if not weeks. Should you begin a project that needs extremely precise results, calibrating beforehand is a good idea, to lend credibility and peace of mind to your operation. Larger scales such as bench, floor, or platform scales can get by with calibration only once or twice a year.
If you notice that your results never seem to stabilise or an item was reweighed and you received two different results, this is an indication calibration is overdue. You should try your best never to get to that point. This is because all weighing results in the immediate past before noticing these discrepancies may be called into question – that’s a headache you don’t want to deal with.
So, what is a calibration weight? They’re crucial tools for any weighing scale user. To learn more about which is best for your scale or balance, contact the Inscale team.
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