1. Description

ZC25A catalytic combustion gas sensor works according to the principle of catalytic combustion effect. It is composed of a detection element and a compensation element paired to form an arm of the bridge. When encountering combustible gas, the resistance of the detection element increases, and the output voltage of the bridge changes. The voltage change increases in direct proportion to the increase in gas concentration. The compensation element plays a reference and temperature and humidity compensation role.

2. Technical specifications

3. Appearance and dimension

4. Basic test circuit

5.Sensitivity, response recovery characteristics

6.Output signal changes with ambient temperature

7.Output signal changes with ambient humidity

8.Output signal changes with operating voltage

9.Precautions for use

1. Situations that must be avoided

1.1 Exposure to volatile silicon compound vapor

If the surface of the sensor adsorbs volatile silicon compound vapor, the sensitive material of the sensor will be wrapped by the silicon compound, inhibiting the sensitivity of the sensor and making it irreversible. The sensor should avoid being exposed to places where silicone adhesives, hair spray, silicone rubber, putty or other silicone-containing plastic additives may exist.

1.2 Highly corrosive environment

Sensors exposed to high concentrations of corrosive gases (such as H2S, SOX, Cl2, HCl, etc.) will not only cause corrosion or damage to the sensor leads, but also cause irreversible changes in the performance of sensitive materials.

1.3 Alkali, alkali metal salts, halogen pollution

After the sensor is contaminated by alkali metals, especially salt water spray, if it is exposed to halogens such as Freon, it will also cause performance deterioration.

1.4 Contact with water

Splashing or immersion in water will cause a decrease in sensitive characteristics.

1.5 Freezing

Water freezing on the surface of the sensitive element will cause the sensitive material to break and lose its sensitive characteristics.

1.6 Excessive voltage applied

If the voltage applied to the sensor is higher than the specified value, even if the sensor is not physically damaged or destroyed, it will cause damage to the lead and cause the sensor's sensitivity to decrease.

2. Situations to avoid as much as possible

2.1 Condensation

Under indoor conditions, slight condensation will have a slight effect on the sensor's performance. However, if water condenses on the surface of the sensitive material and remains for a period of time, the sensor's characteristics will decrease.

2.2 In high-concentration gas

Regardless of whether the sensor is powered on or not, long-term placement in high-concentration gas will affect the sensor's characteristics. For example, using lighter gas to spray directly at the sensor will cause great damage to the sensor.

2.3 Long-term storage

If the sensor is stored for a long time without power, its sensitive material will undergo reversible changes, which are related to the storage environment.

The sensor should be stored in a sealed bag with clean air and without silica gel. Sensors that have been stored without power for a long time need to be powered on for a longer time to stabilize before use. If the storage time without power exceeds half a year, it is recommended to age it for one day before use.

2.4 Long-term exposure to extreme environments

Regardless of whether the sensor is powered on or not, long-term exposure to extreme conditions such as high humidity, high temperature or high pollution will seriously affect the performance of the sensor.

2.5 Vibration

Frequent and excessive vibration can cause the sensor leads to resonate and break. This vibration can be generated by using pneumatic screwdrivers/ultrasonic welders during transportation and on the assembly line.

2.6 Impact

If the sensor is subjected to strong impact or falls, its leads will break.

3. Usage suggestions

3.1 Connection circuit

When the sensor is connected to the circuit, one pin of the detection element and the compensation element are connected together as the signal output end, the other pin of the detection element is connected to the negative pole, and the other pin of the compensation element is connected to the positive pole; the sensor with "D" marked on the bottom of the tube socket is the detection element, and the sensor with "C" marked on the bottom of the tube socket is the compensation element.

3.2 Soldering

Manual soldering is the most ideal soldering method for sensors. The recommended soldering conditions are as follows:

 Flux: Rosin flux with the least chlorine

 Constant temperature soldering iron

 Temperature: no more than 350℃

 Time: no more than 5 seconds

Violation of the above conditions will degrade the sensor characteristics.