Pressure sensors are important measuring devices used in many applications to measure the pressure of gases or liquids. The accuracy of pressure sensors is crucial as they are typically used to monitor processes or control systems. In this context, zero point error, span error, and non-linearity play an important role and can affect the accuracy of pressure sensors. The following sections explain these types of errors and their impacts in more detail.
Zero Point Error
Zero point error occurs when the sensor shows a deviating zero point at a specific pressure. This means that the sensor displays a value other than zero in the absence of pressure. Zero point error is also known as zero offset or offset error.
Causes of Zero Point Error
There are several causes of zero point error. A common cause is the use of low-quality materials or poor manufacturing quality during the production of the pressure sensor. Another reason can be inaccurate mounting of the sensor, leading to deformation or twisting of the sensor housing. Environmental factors such as temperature changes or vibrations can also affect the zero point error.
Effects of Zero Point Error
Zero point error can lead to measurement inaccuracies as the sensor displays an incorrect value at a specific pressure. If the zero point error is too large, the sensor may show a significant value in the absence of pressure, which can be mistaken for an actual measurement. However, if the pressure measurement is relative, i.e., if only the change in pressure matters, the zero point error can be neglected.
Span Error
Span error occurs when the sensor displays different values at various pressures. Unlike zero point error, span error varies with the pressure level and increases or decreases with rising pressure.
Causes of Span Error
One cause of span error can be the use of low-quality materials in the sensor's production. Another reason can be incorrect calibration of the sensor, where the sensor's sensitivity is improperly set. Environmental factors such as temperature changes or vibrations can also affect span error.
Effects of Span Error
Span error can lead to significant measurement inaccuracies as the sensor displays different values at various pressures. If the span error is too large, the sensor may show a significant value at higher pressures, which can be mistaken for an actual measurement. To avoid this, pressure sensors must be carefully calibrated.
Non-Linearity
Non-linearity is an error that occurs when the sensor does not respond linearly to pressure changes. In other words, the change in output voltage or current is not proportional to the change in pressure. This can lead to inaccurate measurements, especially over large pressure ranges.
Causes of Non-Linearity
Non-linearity can have various causes, including inaccurate sensor manufacturing, asymmetrical design, or uneven distribution of voltage or current across the sensor. Environmental factors such as temperature or vibrations can also influence non-linearity.
Effects of Non-Linearity
Non-linearity can lead to inaccurate measurements as the output voltage or current is not proportional to the pressure increase. This can cause the sensor to display incorrect values at high pressures or result in overall inaccurate measurements.
Error Compensation
To minimize the effects of zero point errors, span errors, and non-linearity, pressure sensors must be carefully calibrated. One way to correct zero point error is to use a zero offset. In this process, the sensor is calibrated in the absence of pressure to ensure it displays zero at zero pressure. One way to correct span error is to use a span adjustment. In this process, the sensor is calibrated at various pressures to ensure accurate performance at different pressures. Non-linearity can be corrected through appropriate mathematical adjustments based on the sensor's calibration curve.
Conclusion
Zero point errors, span errors, and non-linearity can affect the accuracy of pressure sensors. Careful calibration of the sensor is necessary to minimize these errors. If these errors are not corrected, they can lead to inaccurate measurements that can cause errors in process monitoring or system control. It is important to ensure that pressure sensors are properly calibrated to guarantee the reliability and accuracy of measurements.