The common belief that "the higher the precision, the better" is not always applicable, particularly when it comes to pressure transmitters. While certain industries demand exceptional precision for their applications, many others can operate effectively with standard models that meet basic measurement requirements.

Understanding the Precision of Pressure Transmitters

Pressure transmitters are among the most widely used sensors in industrial practice. They can serve as pressure measurement elements or sensitive elements for automatic control. For applications that require high precision, the impact of temperature on the semiconductor chip's accuracy must be considered, emphasizing the importance of the sensor's operating temperature range.

Static Accuracy and Full Temperature Range Accuracy

1. Static Accuracy: This refers to the precision that should be achieved at a specific temperature and can be categorized into four levels:

• Ultra-high precision: 0.01-0.1%FS

• High precision: 0.1-1%FS

• Standard precision: 1-2%FS

• Low precision: 2-10%FS

2. Full Temperature Range Accuracy: This is the precision that a pressure sensor should maintain throughout its entire operating temperature range, also divided into four levels:

• 0.01-0.1%FS

• 0.1-1%FS

• 1-2%FS

• 2-10%FS

For instance, a sensor with a static accuracy of 0.1-1%FS might only achieve a full temperature range accuracy of 1-2%FS or even 2-10%FS.

Balancing Precision and Cost

Users often prefer pressure transmitters with the highest possible precision. However, achieving high precision involves additional manufacturing processes, calibration procedures, and compensation techniques, which increase costs and, consequently, the selling price. Therefore, it's essential to set reasonable precision requirements and corresponding temperature ranges based on the actual application and requirements of the pressure transmitter.

Precision as an Indicator of Measurement Reliability

The precision of a pressure transmitter, like all measuring and displaying instruments, is an indicator of the credibility of the measured values. Instruments have a maximum allowable error (deviation), and there is a probability of over 98% that the measurement results from infinite repeated measurements of the same value will not exceed this range.

Accuracy=Maximum Allowable Error/Measurement Range×100%

For a pressure transmitter with a precision of 0.1%:

Output Allowable Error=Output Range×Instrument Precision%=16×0.001=0.016 mA

This means the maximum possible error in measurement for this device is ±0.016 mA.

When selecting a pressure transmitter, it's crucial to consider the application's specific needs rather than blindly pursuing the highest precision. By understanding the differences between static and full temperature range accuracy, you can make an informed decision that balances performance, reliability, and cost-effectiveness.