Whether a pressure sensor needs calibration can be determined from the following aspects:
Time factor
Fixed period calibration
Generally, even under normal use and stable environmental conditions, pressure sensors will drift over time, leading to a decrease in measurement accuracy. Pressure sensors should typically be calibrated every six months to a year to ensure their measurement accuracy.
After being idle for a long time
If a pressure sensor has been idle for an extended period, it needs to be calibrated before being used again. This is because during periods of inactivity, the sensor's internal electronic and elastic components may be affected by environmental factors such as humidity and temperature changes, causing their performance to alter. Therefore, calibration is necessary before reuse to ensure measurement reliability.
Environmental factors
Large temperature variation
When the ambient temperature of a pressure sensor varies significantly, its measurement accuracy is easily affected. For example, in some outdoor industrial sites, the temperature difference between day and night can reach tens of degrees Celsius. Under such circumstances, for every 10°C change in temperature, the zero point and sensitivity of the pressure sensor may drift. Generally, for every 10°C change, the zero point drift can reach ±0.1% of the measurement range, and the sensitivity change can reach ±0.2%. Therefore, when the temperature change exceeds the specified range, such as exceeding ±5°C of the sensor's specified operating temperature range, the sensor needs to be calibrated.
abnormal humidity
High humidity environments can cause moisture to accumulate inside pressure sensors, damaging electronic components or affecting their insulation performance, thus impacting measurement accuracy. If the ambient humidity consistently exceeds 85% RH, sensor calibration should be considered, along with moisture-proof measures such as using desiccants or sealed protective enclosures.
Corrosive gases or liquids are present.
In industries such as chemical engineering and electroplating, pressure sensors are frequently exposed to various corrosive media, such as gases or solutions like hydrochloric acid and sulfuric acid. These corrosive substances can erode the sensor's housing, diaphragm, and other components, leading to a decline in sensor performance. If a sensor operates continuously in such an environment for more than a month, it needs to be calibrated promptly, its degree of corrosion checked, and replaced if necessary.
Use conditions and factors
Frequent use or overload
If a pressure sensor performs frequent measurements in a short period, such as more than 10 measurements per minute, its internal mechanical and electronic components are prone to fatigue and wear, affecting measurement accuracy. Furthermore, when the sensor is subjected to a pressure overload exceeding its measurement range, even a short overload period can cause permanent damage, leading to inaccurate measurements. Therefore, sensor calibration is necessary after frequent use or overload conditions.
Installation location change
The installation location of a pressure sensor has a significant impact on measurement results. Changes in the installation location, such as from horizontal to vertical, modifications to the piping system, or changes in vibration conditions, can alter the pressure distribution and stress state of the sensor, thus affecting measurement accuracy. In such cases, recalibration is necessary.
Performance factors
The measured values showed significant deviations.
During normal measurements, if a significant deviation is found between the pressure sensor's measured value and the actual value, and this deviation exceeds the allowable error range, generally speaking, when the deviation exceeds ±2% of the measurement range, it indicates that the sensor may need calibration. The deviation may appear gradually or suddenly, and both require attention.
Poor repeatability
When measuring the same pressure multiple times, if the repeatability of the measurement results is poor, that is, the values obtained from each measurement fluctuate greatly and exceed the repeatability index specified by the sensor, such as the repeatability error exceeding ±0.5% of the range, it is very likely that the performance of the sensor has changed and it needs to be calibrated to restore its stability and accuracy.
