Common Questions and Answers About Sensors

1. How often does the sensor need to be recalibrated?

The interval between initial calibration and recalibration depends on multiple factors, including the sensor’s operating temperature, humidity, pressure conditions, the types of gases it is exposed to, and the duration of exposure.

2. How significant is the difference in cross-interference?

The degree of cross-interference variation can be quite substantial. This is evaluated based on tests of a limited number of sensors, which measure the sensors’ responses to non-target gases rather than the target gases themselves. It is important to note that when environmental conditions change, the sensor’s performance may differ, and cross-interference values may vary by up to 50% between different batches of sensors. Therefore, in practical applications, these variables should be fully considered for the sensor’s accuracy and reliability.

3. Will using a pump in front of the sensor accelerate the reaction?

Using a pump does not speed up the sensor’s own reaction rate, but it can rapidly and efficiently draw gas samples through the sensor from inaccessible locations. This allows the pump to influence the overall response time of the device.

4. Can a film or filter be added in front of the sensor?

A film or filter can be placed in front of the sensor for protection, but it must ensure that no "dead space" is created, which could prolong the sensor’s response time.

5. What factors should be considered when designing a suitable sample system?

When designing a sample system, it is critical to use materials that prevent gas adsorption on the system’s surfaces. The best materials include polymers, PTFE, TFE, and FEP. Gas concentration may cause moisture condensation, which can block the sensor or lead to overflow, so appropriate dehydrators should be used—such as Nafion tubing to remove moisture at the condensation stage. For high-temperature gases, the sample gas should be cooled to meet the sensor’s temperature requirements, and appropriate filters should be used to remove particulate matter. Additionally, axial chemical filters can be installed in the sample system to eliminate cross-interference from gases.