Solid State Electrochemical VOC Sensor Instructions for Use Ⅱ

Precautions When Detecting Different Gases

In the context of the All Gas sensor's standard response state, the sensor reacts to ethanol (alcohol) gas by initiating a chemical reaction on the SE (sensing electrode) upon the gas's entry. The CE (counter electrode) and RE (reference electrode) do not come into contact with the ethanol gas. When an appropriate amount of ethanol gas enters, it is fully reacted on the SE working electrode, resulting in the sensor operating at its optimal measurement state. The reaction of ethanol on this sensor is positive, generating a positive output signal.In the case of high-concentration ethanol or when pressurized gas is directed towards the inlet, a significant amount of ethanol gas may enter the sensor. The SE working electrode may not be able to react to all of it within a short period, or due to pressure, the gas may enter the RE reference electrode, causing the signal to switch from positive to negative. If the concentration exceeds 1500 ppm and continuous exposure lasts for 2 hours, a recovery period of at least 10 hours is required before the sensor can resume normal measurement.

Calibration Method for Ethanol

For ethanol (alcohol) measurements only, a special alcohol sensor is recommended. However, if a comprehensive measurement is still required for occasional detection of alcohol, please calibrate the sensor promptly using a concentration of ethanol gas of less than 100 ppm, with a flow rate of 300 ml/min, and for a maximum of 3 minutes of continuous venting. During calibration, avoid directing the flow of gas towards the air inlet. Use a side air inlet positioned at a 90-degree angle to the air inlet, ensuring the sensor operates in a diffuse measurement state, thereby avoiding flow shocks. For special applications, please consult us separately.When standard ethanol gas is not available for testing/calibration of the sensor, and liquid alcohol is used instead, please note that when cloth or other material is soaked in liquid alcohol and placed in a plastic or glass sealing bag or box, the concentration in the confined space can instantly volatilize to up to 600,000 ppm at a room temperature of 25°C, and even higher when the temperature exceeds 25°C. Consequently, the concentration in the confined space will be even higher. Therefore, it is not recommended to test the sensor by placing a cloth or other material soaked in liquid alcohol directly on the sensor. If this method is the only option for performing relative calibration/testing, you should dilute the gas before measuring. This can be achieved by preparing a syringe, a Ziploc bag/sealed case, calculating the volumes of the Ziploc bag and the sealed case, and determining a dilution ratio based on a target concentration of 100 ppm or less. Then, use the syringe to extract the calculated volume of gas from the 600,000 ppm volatile bag and inject it into another sealed bag/box for dilution. It is best to place the test sensor into the dilution bag/box in advance. Please refer to the specific gravity of ethanol gas to air for placement.

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