Familiarizing Pressure Sensor Accuracy
According to the International Electrotechnical Commission (IEC), accuracy is defined as the maximum positive and negative deviation from the specified characteristic curve observed when testing a device under specified conditions and by a specified procedure. Defining accuracy for a pressure sensor can be even more complex, as it involves considering the quality, efficiency, and cost of the process the pressure sensor is measuring. When selecting a sensor, understanding the factors that determine accuracy and asking the right questions is essential.
IEC 61298-2 specifies that accuracy should include Hysteresis, Non-Repeatability, and Non-Linearity. Hysteresis refers to the maximum difference in sensor output at a specific pressure when approached with increasing pressure and then approached with decreasing pressure during a full span pressure cycle. Non-Repeatability, on the other hand, is the maximum difference in output when the same pressure is consecutively applied under the same conditions and from the same direction.
Non-Linearity can be differentiated using two methods: Best Fit Straight Line (BFLS) Non-Linearity and Terminal Point Non-Linearity. These factors are combined to determine the overall accuracy, which significantly impacts the total accuracy of the sensor. Some manufacturers use mathematical equations like Root of the Sum Squared or Root of the Mean Squared to combine Non-Linearity, Non-Repeatability, and Hysteresis into a total accuracy percentage.
Understanding the accuracy of a pressure sensor is crucial for several reasons:
- Cost Management: More accurate sensors tend to be more expensive, so understanding accuracy can help manage costs effectively.
- Avoiding Quality and Efficiency Issues: Using the wrong sensors with inaccurate readings can lead to costly quality or efficiency problems in the application.
- Informed Decision-Making: Knowledge of how accuracy is calculated and what parameters to consider empowers one to make more informed decisions when evaluating pressure sensors.
- Ensuring Appropriate Accuracy: It ensures that the selected sensor meets the required accuracy level for the application without unnecessary costs.
In summary, having a clear understanding of accuracy when selecting a pressure sensor enables making informed decisions that balance precision and cost-effectiveness for the specific application.
