In food and beverage production, weighing accuracy is absolutely crucial. It plays a vital role in ensuring product consistency, food safety, and minimal waste.

Most sites send their scales to an off-site service for calibration at least once a year, with internal verifications carried out on a more regular basis. The frequency of these tests will vary depending on the amount your scales are being used. However, the best-case scenario would see you verifying your scales at least once a day before use, as this will allow you to keep a close eye on the accuracy of your measurements – identifying any issues while there is still time to make the necessary adjustments. 

If you are wondering how to carry out these internal verifications or would like to enhance your site’s existing processes, this article contains everything you need to know. There is useful information in each section, but you can also use the links below to jump to the topic most relevant to your needs.

What method should I be using to check the accuracy of my scales?

When it comes to verifying a piece of equipment, the first step is to identify the method that you are going to use. If you are at all unsure of the best approach to take, it is often worth speaking to the supplier of your equipment or checking through its instruction manual. In this instance, the recommended method involves the use of calibrated reference weights. Helping you to ensure your weighing equipment is working accurately and in compliance with regulations, these weights should be accompanied by a calibration certificate that you will be able to share with auditors and customers if the need arises.  

What material should my reference weights be made from?

Reference weights are available in three key materials: cast iron, brass, and stainless steel.

Here at Klipspringer, we supply a cast iron reference weight in: 5kg, 10kg, and 20kg

We also supply a stainless steel reference weight in: 1g, 2g, 5g, 10g, 20g, 50g, 100g, 200g, 500g, 1kg, 2kg, 5kg, 10kg, and 20kg

We made the decision to supply such a large range of stainless steel reference weights because we believe this material is best suited to the task of verifying your scales and withstanding the daily demands of factory life.

Of course, the final decision is yours, so we have included a list of pros and cons to help you make your choice:  

Stainless Steel

  • Strong and durable
  • Resistant to corrosion
  • Long lifespan
  • Low maintenance
  • Easy to clean
  • Can be scratched or dented
  • Higher upfront cost

Brass

  • Strong and durable
  • Often have adjustment compartments
  • Higher cost
  • Some people are allergic
  • Slightly toxic
  • Loses strength and durability over time
  • Corrodes when exposed to moisture or acid
  • Adjustment compartments = food trap
  • If moisture penetrates the adjustment compartment it can change the weight's mass

Cast Iron

  • Strong and durable
  • Won't crack or dent
  • Lower upfront cost
  • Often have adjustment compartments
  • Prone to corrosion
  • Less accurate over time due to corrosion
  • Difficult to clean
  • Adjustment compartments = food trap
  • If moisture penetrates the adjustment compartment it can change the weight's mass

How many reference weights do I need? 

This tends to be decided by each individual factory and is usually a reflection of the range and number of measurements taking place.  

As a general rule, you will need to have a minimum of two reference weights per scale. Once you have these weights on site, you will be able to verify the following three readings: 

Lowest possible reading: The first step is to check the accuracy of your scale at 0kg. This test won’t require a reference weight. 

Most common reading: You will then need to find a reference weight that sits as close as possible to the most common reading carried out at your site. Say your operatives measure out 1.98kg of sugar on a regular basis, you will need a 2kg weight to verify this reading.  

Highest possible reading: You also need a reference weight that reflects the highest possible reading of your scale or sits as close to the top of its range as possible. If the top end of your scale doesn’t have a corresponding weight, you can always combine them to create the desired amount. For instance, a 7kg scale could be checked using 5kg and two 1kg weights. 

How do I use reference weights to check the accuracy of my scales? 

In this step-by-step guide, we’ll be using Klipspringer’s Stainless Steel IP68 Washdown Scales to demonstrate how to calibrate your scales. The exact instructions for this process will vary depending on the make and model of your scale, but the key steps in the process are nearly always the same.  

  1. Turn the scale on and wait for it to stabilise. 
  2. Press the relevant button to switch your scale to calibration mode. Usually this will be an easily identifiable button labelled ‘Cal’ 
  3. Press the function button, usually labelled ‘FUNC’ for the recommended length of time. Scroll through to the calibration function. 
  4. Use the arrow to input the weight of the reference weight you are using (e.g. 4kg), then press the 0 button again. 
  5. Once stabilised, place the weight on the scale. If the weight is out of spec, the scale will indicate a fail. Otherwise, the scale will indicate a pass. 
  6. Once complete, check the scale one final time using the reference weight. 
  7. Continue to check the different reference weights until they have all been confirmed twice.  

How should I record the results of each verification?

Whether you have recently purchased scales for your factory or your existing scales are being calibrated using an off-site service, such as the Klipspringer lab, it’s important that you are keeping a clear record of any certificates. With this in mind, we have developed an Equipment and Calibrations Portal. This free online resource offers an easy and independent way to manage your serial numbered products from Klipspringer, allowing you to download your important certificates in a matter of seconds.

As for your in-house verifications, now could be the perfect time to switch from paper records to a cloud-based quality management system like TRAKKD. A great opportunity for you to save your site time and money, improve accuracy, increase visibility, and ensure your business is scalable, TRAKKD allows you to safely store the results of your in-house verifications. You will then be able to access this data at the click of a button, something that is particularly useful when an audit is approaching. You can also use TRAKKD to set up acceptance criteria for your scales so that any results sitting outside of these parameters will be flagged automatically. What’s more, if you decide to alter the parameters across your site or wider group, you can simply update these changes via TRAKKD. 

So, there’s an overview of how you can use calibrated reference weights to check the accuracy of your scales. Hopefully you have come away with a more in depth understanding of how many weights you need, the right material for your site, the process you should be following, and the best approach to recording your results. If you would like any further guidance, you can contact the Klipspringer team on 01473 461800 or sales@klipspringer.com. You can also fill out the contact form below.   

If you would like further guidance relating to your calibrated reference weights, the Klipspringer team would be happy to help. Share your details below to arrange a free consultation.