5 Factors Affecting Your Weigh Scale Accuracy

At Active Scale Manufacturing Inc., we understand that your weigh scale is the heart of your business and that having an accurate and dependable weighing system is essential to the success of your operation. We work hard to ensure the scales we produce are accurate in a variety of industrial environments with exceptional scale accuracy.

Even with the highest quality scale systems, there are still factors you need to be aware of that greatly affect the accuracy of your weighing system. Taking advantage of our expertise can help you ‘weigh’ your options such as where and how the system will be installed and what factors can affect its operation.

What Factors Affect Truck Weigh Scale Accuracy?

1. Load Cell Accuracy

The load cell is the most important component of any digital weighing system.

Also called a transducer, a load cell converts a mechanical force into an electrical signal. In its simplest form, the load cell bends when weight is applied.

In a compression-mounted load cell, where the load cell is beneath the weighing vessel, like a truck scale, the load cell compresses when a load is applied. It then produces an analog output signal proportional to the applied weight or force that is transmitted to a controller that converts the signal into a digital weight measurement.

A malfunctioning load cell can result in inaccurate weight readings. You should be familiar with the following performance elements when looking to understand how load cells function in order to determine where a malfunction is coming from:

Response Time

This refers to the time it takes for a load cell to settle and provide an accurate reading. Response times can be a cause for errors if the load cell is being repeatedly used with little time between weighing sessions.

Nonlinearity

This refers to the maximum deviation of a load cell’s calibration curve from a straight line, charted between zero-weight and maximum rated capacity.

Creep

This refers to the change in the measured weight when a load is left stationary on the cell for a long period of time.

Hysteresis

This refers to the difference in scale output when the same load is measured twice – once increasing from a zero-weight, and a second measurement that is decreased from the load cell’s maximum weight rating.

Temperature

If the location of your load cell is exposed to significant temperature variations, its accuracy can be affected.

2. Scale Load Factors

An inaccurate rate may not be a result of the loading cell, but rather from the load on the scale itself and how it was applied and supported.

Here are just a few things to keep an eye out for when it comes to properly loading or unloading a scale:

• Ensure that the mounting structure located on the ground underneath the scale can fully support not just the scale, but its components and its load without flexing
• Ensure the load is properly aligned so as not to cause the load cell to interpret the force as weight, generating an inaccurate reading
• For vehicle scales, ensure drivers go slowly to prevent abrupt changes in weight
• Ensure the mounting hardware are properly functioning
• Use cross braces on systems that have flimsy support legs to reduce side loads when the support legs spread under strain

3. Environmental Factors

Environmental factors in the vicinity can also impact the accuracy of your weigh scale, such as:

Vibration

If there is equipment that is close by to the weigh scale, sensitive loads can misinterpret these vibrations resulting in incorrect weight readings.

Shock Loading

Suddenly dumping heavy materials on your weighing system can put more force than the maximum rated capacity and damage the system or the load cells.

Unclean Scales

Scales that are not regularly cleaned can build up weight due to dirt and other objects on the scale platform. The weight on the scale must be completely supported by the load cells, which is impossible if there is a significant amount of debris build-up underneath the scale itself.

Wind Loading

Whether your scale is indoors or outdoors, it can be affected by air movement, including air generated from air ducts, or air conditioning units.

Air Pressure Differences

If the air pressure in the calibration environment is different than the air pressure from the operating environment, this can lead to inaccurate measurements.

4. Usage

If your scale undergoes a lot of wear and tear and is constantly being spilled on or dirtied, your readings could become inaccurate. Much like any other type of scale, having debris between the mechanisms will create uncertainty and inaccurate weigh scale readings, and could even cause your weigh system to break down.

Ensuring that everyone who uses the scale understands how to use it safely and properly is also key – don’t let user error or incorrect scale usage cause you headaches and downtime.

5. Interference

Since load cells work by sending an electrical signal that is outputted onto the scale’s digital indicator, any kind of interference during that process can lead to inaccurate weight readings. Here are just a couple of the more common types of interference:

Moisture

From time to time condensation or moisture can build up on the load sensor, which can affect electrical outputs and cause interference in the signals being sent from the load cell to the display indicator.

Temperature

As temperatures increase, wire resistance also increases which causes the voltage to drop leading to the scale controller displaying results that are actually different from the load cell’s output.

At Active Scale, we’ve been providing our customers with highly accurate industrial scales that stand the test of time. Our quality equipment, commitment to service, and maintenance by our certified technicians can keep your business operational today, and in the future.

Contact us today, toll-free at 1-866-284-2223, if you have any questions about your weighing system.

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