If your organisation uses high-accuracy weighing equipment, it is extremely important that it is carefully maintained and managed to ensure the best possible levels of precision.
Regular testing and calibration will extend the life of your scales, as well as reduce downtime caused by wear and tear ensuring that their scale accuracy is maintained.
However, it’s important to understand the impact of different factors on weighing scale accuracy to ensure that you can keep your instrumentation performing to excellent standards between calibrations.
So, what are the factors that most commonly affect the precision of weighing equipment? Below, the specialists at GNW Instrumentation explore some of the main offenders.
Load Cell Accuracy
Load cells are a key component of any scale. Their job is to convert the force to be measured by your scales into an electrical output that is then displayed – usually on a digital readout.
If the load cells in your equipment are inaccurate, they will provide an incorrect readout. Regular weighing scale calibration can serve to prevent this, but there is the potential for it to cause significant issues if it remains undetected.
Incorrect Zero Points
One of the most common – and easily rectifiable – reasons behind poor scale accuracy is an incorrect zero point. This means that the equipment’s preset state (before a load is placed on it) is either slightly above or below absolute zero, which will then have a knock-on effect on the eventual readout.
Interference
The signal that is sent to a scale’s digital readout has the potential to be affected by interference – in particular, Electromechanical or Electronic Interference (EMI) and Radio Frequency Interference (RFI). The “noise” that is created by interference of this kind can again lead to inaccuracies regarding the measurable output of your scales.
Environment
Numerous environmental factors have the potential to affect the scale accuracy of weighing equipment. For example, without a hermetic seal, moisture building up on the components of a scale can interfere with the electrical signals sent to the readout.
The temperature can also have an impact. The resistance of the wiring within your instrumentation, along with the voltage levels applied, have the potential to be erroneously altered as a result of surroundings that are too hot or too cold.
Vibration
Vibrations from surrounding equipment can throw off a high-accuracy scale, too. Readings taken from the instrumentation may be incorrect as a result. Any vibrations that can be detected – however minor they appear – should be remedied to achieve precise results.
Lack of Cleanliness
Dirt can add weight to a scale or may result in the load you are weighing being supported unevenly. It’s therefore very important to ensure that your equipment is perfectly clean before use.
Pressure Differentials
Your scales need to be calibrated to reflect the constant pressure (i.e. air pressure or similar) that it will experience in the location in which it is to be used. If this is not done, the differentials in that pressure between the location in which it is calibrated and the area in which it is utilised will result in inaccurate readouts.
Any existing airflow over your scales should also be considered.
Creep
If your scales are kept under pressure for an extended period – for example, if a load remains in place for too long – the digital readout is likely to change and become inaccurate. This is known as “creep”.
For this reason, it’s important to only keep items or loads on your scale for as long as you require to record the readout and no longer.
Shock Loading
If you drop or heavily place an item on your scales, you may cause the resulting pressure to exceed the equipment’s maximum capacity. This may cause damage that could lead to scale inaccuracy.
Response Time
It is important to allow a load to fully settle onto a scale before taking a reading, and, likewise, to fully reset before a new load is put in place. This may equate to a matter of seconds or less, but many workplaces expect extremely fast readouts from their equipment – some of which are not designed to work at such a pace. Doing this may result in a range of inaccuracies.
The Effect of Gravity
Exceptionally precise instrumentation can even be affected by the earth’s gravitational pull. Because the strength of gravity is actually minutely different in different locations, careful calibration must be undertaken to ensure this does not result in inaccurate readouts.
The Importance of Regular Calibration
The above factors are just a few of the issues that may affect scales and other weighing equipment over time. Arranging for the regular calibration of instrumentation of this kind, either on-site or off-site, will ensure that equipment is frequently tested and maintained to ensure sustained levels of absolute scale accuracy.
Failure to have your scales regularly calibrated will result in incorrect readouts, which may, in turn, cause poor quantity control, inaccuracies in stock-taking and other problems.
For further advice on the calibration of your industrial weighing equipment, simply get in touch with the specialists at GNW Instrumentation today.
FAQs:
How often do I have to calibrate my scale, and what are the risks of not calibrating?
The team at GNW recommends that you get your scale professionally calibrated at least once annually. However, if the equipment relies on exceptionally high levels of scale accuracy, or if it is very regularly used, it could be worth doing so more regularly.
Depending on the industry in which your company operates, neglecting to calibrate industrial weighing scales could lead to a reduction in product quality, uneven dosages of medication being measured out, incorrect recording of stock levels, a significant reduction in customer trust or failure to comply with industry standards.
What is the difference between calibration and adjustment?
Simply put, calibration is the process of measuring errors in accuracy using expert techniques to compare the current readout of a piece of equipment against a measure that offers the highest possible levels of precision.
Adjustment, on the other hand, is the act of carefully changing and manipulating the equipment being calibrated so that its performance reflects and replicates that of the accurate measure as closely as possible.
Is routine calibration important between calibration intervals?
The GNW team highly recommends arranging calibrations on a routine basis to prevent wear and tear and to reduce the likelihood of your equipment becoming inaccurate.