Gas Sensor K903

◆Test Circuit  

◆Dimension

The sensitive part of the gas sensor is a miniature sphere with embedded heating wire and metal electrodes. 
This sensitive element is installed in the metal shell of double-layer 
100-mesh stainless steel mesh with explosion-proof function. (Figure 1)

Changes in the concentration of the alcohol gas to be measured will cause a change in 
the resistance of the sensitive material, which in turn will cause a change in the voltage 
across the load resistor. 

For the sensor to function optimally, the heating voltage, loop 
voltage and load resistance need to meet the standard operating conditions shown in the specifications. 

Before normal detection, it is necessary to apply a high voltage of 
2.2±0.2V to the sensor for 5-10 seconds, so that the sensor can stabilize and enter the
working state as soon as possible.

◆Features

1.Sensitivity Characteristics

2.Different Concentration Curves

3.Temperature And Humidity Change Curve

4.Response Recovery Curve

5.Long-Term Stability Curve

◆Precautions

1.Do not apply high voltage

If a voltage higher than the specified value is applied, it will cause damage to 
the sensor and cause a decrease in sensor sensitivity.

2.Prohibition of exposure to volatile silicon compound vapor

Avoid exposure to silicone adhesives, hairspray, silicone rubber, putty or other 
places where volatile silicon compounds exist.
If silicon compound vapor is adsorbed on the surface of the sensor, the sensitive
material of the sensor will be formed by the decomposition of silicon compound.  

The silicon dioxide coating suppresses the sensitivity of the sensor and is irreversible.

3.Prohibition of contact with highly corrosive environments

If the sensor is exposed to high concentrations of corrosive gases 
(such as H2S, SOX, Cl2, HCl, etc.), 
it will not only cause corrosion or damage to the heating
material and sensor leads, but also cause irreversible deterioration of the performance of sensitive materials change.

4.It is forbidden to be polluted by alkali, alkali metal salts and halogens

If it is polluted by alkali metals, especially salt water spray, or exposed to 
halogens such as Freon, it will also cause performance deterioration.

5.Prohibition of contact with water or gas liquid

Splashing or immersion in water can dislodge sensitive materials, causing changes in sensor performance or failure.

6.No icing

Freezing of water on the surface of the sensor's sensitive material will cause 
the sensitive layer to crack and lose its sensitive properties.

7.It is forbidden to apply voltage to the wrong pin

Add a heating voltage of 0.9V±0.1VDC between pins 1 and 3 of the sensor. 
If it is too high, it will damage the sensor or even burn the electrodes. 
Add a test voltage of 3.0V±0.1VDC between pins 2 and 1 or 3. 

8.Avoid condensation

Under indoor use conditions, slight condensation will have a slight impact on sensor performance.
However, if water condenses on the surface of the sensitive layer and remains 
for a period of time, the sensor characteristics will degrade.

9. Avoid exposure to high concentrations of gas

Regardless of whether the sensor is energized or not, 
long-term placement in high-concentration gas will affect the sensor characteristics.
If the lighter gas is sprayed directly on the sensor, 
it will cause great damage to the sensor.

10. Avoid long-term storage

If the sensor is stored without power for a long time, 
its resistance will have a reversible drift, 
which is related to the storage environment. Sensors should be 
stored in airtight bags free of volatile silicon compounds.

Sensors that have been stored for a long period of time need to be powered on
for a longer time to stabilize before use.
  
● Storage time and corresponding aging time suggestion

11.Avoid prolonged exposure to extreme environments

Whether the sensor is powered on or not, sensor performance will be 
severely affected by prolonged exposure to extreme conditions such as high 
humidity, high temperature, or high pollution.

12.Avoid Vibration Sensors

Frequent and excessive vibration will cause the internal leads of the sensor to resonate and break.
The use of pneumatic screwdrivers/ultrasonic welders in transit and on the assembly line can generate such vibrations.

13.Avoid shocks

If the sensor is subjected to a strong shock or dropped, its lead wires will break.

14.Conditions of use

Manual welding is the most ideal welding method, and the recommended 
welding conditions are as follows:

◆The following conditions should be met for wave soldering : 1 pass through the wave soldering machine

◆Violation of the above usage conditions will degrade the sensor characteristics!