This standard specifies the basic principles of parameter test methods for military metal oxide semiconductor gas sensors (hereinafter referred to as components or products). It does not specify the technical details of these methods in actual use. When testing, they can be carried out according to the provisions of the corresponding detailed specifications. This standard applies to the test of gas and electrical parameters of military metal oxide semiconductor gas sensors. Other gas sensors can also refer to it. SJ 20026-1992 Test methods for metal oxide semiconductor gas sensors SJ20026-1992 standard download decompression password: www.bzxz.net
This standard specifies the basic principles of parameter test methods for military metal oxide semiconductor gas sensors (hereinafter referred to as components or products). It does not specify the technical details of these methods in actual use. When testing, they can be carried out according to the provisions of the corresponding detailed specifications. This standard applies to the test of gas and electrical parameters of military metal oxide semiconductor gas sensors. Other gas sensors can also refer to it.

GB 3095-1982 Atmospheric environment quality standards
GB 4475-1984 Terminology of sensitive components

Military Standard of the Electronic Industry of the People's Republic of China FL5911
SJ20026—92
Metal Oxide Semiconductor Gas Sensors
Test Methods
Measuring Methods for Gas Sensors of Metal-Oxide Semiconductor
Published on February 1, 1992
China Electronics Industry Corporation
Implementation on May 1, 1992
1 Scope
Military Standard of the Electronic Industry of the People's Republic of China Measuring Methods for Gas Sensors of Metal Oxide Semiconductor1.1 Subject Content
SJ20026—92
This standard specifies the basic principles of parameter test methods for military metal oxide semiconductor gas sensors (hereinafter referred to as components or products), but does not specify the technical details of these methods in actual use. The tests can be carried out in accordance with the provisions of the corresponding detailed specifications.
1.2 Scope of application
This standard applies to the test of gas-electric parameters of military metal oxide semiconductor gas sensors, and other gas sensors can also be used for reference.
2 Reference documents
GB3095-82 Atmospheric environment quality standard
GB4475-84
3 Definitions
3.1 Symbols and codes
Terms of sensitive components
Parameter symbols of this standard shall comply with the provisions of Appendix B. 4 General requirements
4.1 Test box
The box material of the test box should be selected from materials that do not react with the detection gas; the box volume should ensure that each product in the test product has a volume of not less than 1 liter; the box should be equipped with a liquid vaporization device, a temperature and humidity display device and a gas stirring device. 4.2 Test atmosphere
The requirements for clean air should meet the secondary ambient air standards specified in GB3095. When using calibration gas for detection, the concentration tolerance shall comply with the provisions of Table 1. China Electronics Industry Corporation Published on February 1, 1992 Implementation on May 1, 1992
Concentration range
ppb level
100~1000
4.3 Power supply
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Tolerance
The DC power supply for testing shall maintain a certain polarity, and the ripple of the AC power supply shall not affect the required test accuracy. The error of the regulated power supply voltage within the given value range shall not exceed 2%. 4.4 Test instrument
The error of the indicating voltmeter and ammeter (including range extension) shall not exceed 1%. A digital voltmeter with high input impedance shall be used to measure the output voltage on the load resistor. 4.5 Test environmental conditions
Unless special conditions are specified, the measurement of various parameters of the components shall be carried out under normal environmental conditions. a. Normal environmental conditions
Environmental temperature: 15~35℃;
Relative humidity: 20%~80%;
Atmospheric pressure: 86~106kPa
b. Arbitration environmental conditions
Environmental temperature: 25±1℃;
Relative humidity: 48%~52%;
Atmospheric pressure: 86～106kPa.
4.6 Test condition tolerance
Temperature: The temperature of any reference point in the working area is maintained at ±2℃, Relative humidity: The relative humidity of the control test environment should be within ±5% of the measured value: Air pressure: The test error is controlled within ±5% of the measured pressure value. 4.7
General precautions
All parameter measurements should be carried out under the specified working conditions; for continuous testing of a certain number of products, the test time requirements must be specified; before testing, the length of time the product should be kept under the test conditions should be specified; if the time between the time when the component is powered on and the test is doubled, and the measured reading changes within the specified error, the product is considered to have reached the initial steady state; e., the time between the time when the component is placed in a certain working state and the test is doubled, and the measured reading changes within the specified error, the product is considered to have reached the steady state. 5. Detailed requirements
5.1 Method 1001 Measurement of resistance Ra in clean air 5.1.1 Definition
SJ20026—92
The steady-state resistance of the component in clean air under specified working conditions. 5.1.2 Test system schematic
The test system schematic is shown in Figure 1.
Mo-component under test, B-gas test box, V-voltmeter: A-ammeter RL-load resistor; V, output voltage on the load resistor: V-test circuit voltage: V-heating voltage: I-heating current 5.1.3
Test steps
Adjust the heating voltage V (or current I) so that the reading of the voltmeter (or ammeter) is the specified value: adjust the test circuit voltage V. Make the reading of the voltmeter the specified value; select the load resistance RL as the specified value
Let clean air pass into the test box:
Read the steady-state value of the output voltage V on the load resistance in the clean air on the digital voltmeter5.1.4Calculate
The steady-state resistance R of the component in the clean air is: R-VXR-R
Wherein, R, the steady-state resistance of the component in the clean air, ka; V
-test circuit voltage, V;
The steady-state value of the output voltage on the load resistance in the clean air, V; load resistance, ko.
Specified conditions
Heating voltage (or heating current):
Test circuit voltage;
Load resistance;
Preheating time.
5.2 Method 1002 Measurement of resistance R& in detection gas 5.2.1 Definition
Under specified working conditions, the steady-state resistance value of the component in the detection gas of specified concentration. 5.2.2 Schematic diagram of test system
See Figure 1 for the schematic diagram of the test system.
5.2.3 Test steps
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a. Carry out according to the provisions of 5.1.3 a, b, c; b. Prepare the detection gas of specified concentration according to the gas distribution method of volume ratio mixing method in Appendix A; c. Read the steady-state value Vd of the output voltage on the load resistor in the detection gas on the digital voltmeter 5.2.4 Calculation
The steady-state resistance R& of the component in the detection gas is: V.×R-RL
Wherein, R. Steady-state resistance of the component in the detection gas, kQ;V. - Test loop voltage, V
Ve - Output steady-state voltage on the load resistor in the test gas, V, Rt
- Load resistance, ka.
5.2.5 Specified conditions
a. Same as the provisions of Article 5.1.5;
b. Type and concentration of the test gas.
Note: When measuring the resistance in the interfering gas, change Article 5.2.3 b to the interfering gas and change the relevant parameter angle dg to g. 5.3 Method 1003 Measurement of heating power P.
5.3.1 Definition
The product of the heating voltage and heating current that should be provided when the component is in normal working state. 5.3.2 Test system schematic diagram
The test system schematic diagram is shown in Figure 1.
5.3.3 Test steps
a. Carry out according to the provisions of Article 5.1.3 a;
b. Read the heating current I value (or heating voltage V. value) on the heating ammeter (or voltmeter). 5.3.4 Calculate the heating power P as follows: Where: P.--heating power, mW Vh--heating voltage, V I heating current, mA. 5.3.5 Specified conditions a Heating voltage (or heating current). 5.4 Method 1004 Measurement of sensitivity S (2) 5.4.1 Definition The ratio of the steady-state resistance of an element in clean air to the steady-state resistance in a test gas of a specified concentration under specified working conditions. 5.4.2 Schematic diagram of the test system See Figure 1 for the schematic diagram of the test system.
5.4.3 Test steps
Measure V according to the provisions of Article 5.1.3;
Measure V according to the provisions of Article 5.2.3.
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Calculate R and Rdg according to formula (1) in Article 5.1.4 and formula (2) in Article 5.2.4 respectively. c.
5.4.4 Calculate the sensitivity S as follows:
Where S-sensitivity;
R.—Steady-state resistance in clean air, ka;
Ra—Steady-state resistance in test gas, kn. R.
Note: When measuring P-type components or detecting oxidizing gases, the inverse form of formula (4) can be used. 5.4.5 Specified conditions
Same as the provisions of 5.2.5.
5.5 Method 1005 Measurement of gas resolution D (4)
5.5.1 Definition
Under specified working conditions, the ratio of the steady-state resistance of the component in the specified concentration of detection gas and interference gas to the change in the steady-state resistance in clean air.
5.5.2 Schematic diagram of the test system
The schematic diagram of the test system is shown in Figure 1.
5.5.3 Test steps
Measure V. in accordance with the provisions of 5.1.3;
b. Measure V in accordance with the provisions of 5.2.3;
Measure V. in accordance with the provisions of 5.2.3.
d. Calculate R., R& and Rig according to formula (1) in 5.1.4 and formula (2) in 5.2.4 respectively. 5.5.4 Calculate the resolution D as follows:
Where: D--gas resolution
R.--stable resistance in clean air, ka
R.--stable resistance in interference gas, ka
R--stable resistance in detection gas, ka.
5.5.5 Specified conditions
Same as those in 5.2.5.
5.6 Method 1006 Measurement of characteristic concentration resistance ratio r 5.6.1 Definition
Under specified working conditions, the ratio of the steady-state resistance of the element to the same type of detection gas at two different characteristic concentrations. (5)
5.6.2 Schematic diagram of the test system
The schematic diagram of the test system is shown in Figure 1.
5.6.3 Test steps
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Measure V(C) at concentration C, and V&(Cz) at concentration C, respectively according to the provisions of 5.2.3. a.
b. Calculate the resistance Rd(C,) and Ra(C2) respectively according to formula (2) of 5.2.4. 5.6.4 Calculate the characteristic concentration resistance ratio as follows:
Rag(C,)
Ra(C2)
Where: \— Characteristic concentration resistance ratio:
R(C)- Steady-state resistance at concentration C, kQ; Ra(C)- Steady-state resistance at concentration C, kn. 5.6.5 Specified conditions
Same as the provisions of 5.2.5.
5.7 Method 1007 Response Time Measurement
5.7.1 Definition
Under specified working conditions, the time required for the output voltage of the element to change to 70% of the steady-state value after it is exposed to the specified concentration of the detection gas.
5.7.2 Test System Schematic Diagram
The test system schematic diagram is shown in Figure 1.
5.7.3 Test Steps
Perform in accordance with the provisions of 5.2.3 a and b:
The stopwatch records the output voltage Vre on the load resistor when the specified value of the response time is reached; b.
Continue to record the voltage V when the output voltage on the load resistor changes to the steady-state value; compare the voltages Vr and Vdg, which should satisfy V≤70%V. d.
5.7.4 Specified Conditions
Same as the provisions of 5.2.5.
5.8 Method 1008 Measurement of recovery time
5.8.1 Definition
The time required for the output voltage of the element to change to 30% of the steady-state value after it is separated from the detection gas under specified working conditions.
5.8.2 Schematic diagram of the test system
The schematic diagram of the test system is shown in Figure 1.
5.8.3 Test steps
Separate the element from the detection gas and place it in clean air; a.
Stopwatch records the output voltage Vre on the load resistor when the specified value of the recovery time is reached; b.
Compare the voltages Vr and Va, which should meet V≤30%Vdg5.8.4 Specified conditions
Same as the provisions of 5.1.5 a, b, c.
5.9 Method 1009 Measurement of temperature coefficient
5.9.1 DefinitionbzxZ.net
SJ20026—92
The average value of the logarithm of the ratio of the steady-state resistance of the element in the test gas of specified concentration, with the relative humidity of 50% and the ambient temperature in the range of T~T, for every 1°C change in temperature. 5.9.2 Schematic diagram of the test system
The schematic diagram of the test system is shown in Figure 1.
5.9.3 Test steps
a. Measure the voltage V (T,) at temperature T, and the voltage Va (T,) at temperature T, respectively according to the provisions of 5.2.3; b. Calculate the resistance Rd (T,) and Ra (T,) respectively according to formula (2) in 5.2.4. 5.9.4 Calculate
Ra,(T)
log RT
Where: r—temperature coefficient:
β T,- T,
Rd (T)—stable resistance at temperature T, kQ; Rd (T)-stable resistance at temperature T, kQ: T—end point temperature, T=-10±2℃;
T,—end point temperature, T,-+40±2℃. 5.9.5 Specified conditions
Same as specified in 5.2.5.
5.10 Method 1010 Determination of humidity coefficient β 5.10.1 Definition
(7)
The ratio of the resistance of the element when it is in the test gas of specified concentration, the ambient temperature is 40℃, the relative humidity is H, and H,. 5.10.2 Test system schematic diagram
The test system schematic diagram is shown in Figure 1.
5.10.3 Test steps
a. Measure the voltage V (H) under H humidity and the voltage V (Hz) under H humidity respectively according to the provisions of Article 5.2.3; b. Calculate the resistance R (H,) and Ra (H,) respectively according to formula (2) in Article 5.2.4. 5.10.4 Calculate the humidity coefficient βH as follows:
Wherein — humidity coefficient;
Ra (H,)
R (H) steady-state resistance under H humidity, kQ; R (H,) steady-state resistance under H humidity, k2; H,——end point humidity, H=35%±3%;
—end point humidity, H,=90%±5%.
5.10.5 Specified conditions
Same as the provisions of Article 5.2.5.
A1 Normal pressure method
A1.1 Principle
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Appendix A
Gas distribution method by volume ratio mixing method
(Supplement)
When a certain volume of clean air and a certain volume of test gas are mixed, the concentration of the mixed gas is constant. A1.2 Gas distribution steps
Take a test box of a certain volume, clean it three times with clean air and fill it with clean air to normal pressure; a.
Inject a certain volume of test gas into the test box; c
Fully stir the mixed gas in the test box, and after it is evenly mixed, the product measurement can be carried out. A1.3 Concentration calculation
The test gas concentration is:
Where: C--test gas concentration ppm;
C. Concentration of the standard sample gas of the test gas, ppm; V. Injection volume of the standard sample gas of the test gas, L; V.- volume of the test box, L.
A2 Non-normal pressure method
A2.1 Principle
Under known pressure, the concentration of the mixed gas can be determined according to the concentration and volume of the test gas mixed in the clean air, as well as the volume of the clean air. A2.2 Gas distribution steps
Take a test box of a certain volume, clean it three times with clean air, and fill it with clean air to make it close to atmospheric pressure; inject the required volume of test gas with a syringe; continue to fill the test box with clean air to make the pressure in the box reach a certain positive pressure: fully stir the mixed gas in the test box, and after it is mixed evenly, the product measurement can be carried out. A2.3 Concentration calculation
The concentration of the test gas is:
C=(P+P)XV× 10*
Where.C-concentration of the test gas, ppm:
P. --Atmospheric pressure, Pa;
PU-shaped tube mercury differential pressure gauge reading, Pa
aDetection gas sample gas volume, L;
·(A2)
6Detection gas sample gas purity, ppm;
V-test box volume, L.
A3Detection gas sample gas volume calculation method SJ20026--92
A3.1 When measuring gas, the volume of sample gas mixed in is calculated as follows: VxV×C×10-273+T
273+TB
Wherein: Vx is the volume of sample gas injected, ml; V is the volume of the test chamber, L;
C is the concentration of the sample gas used for testing, ppm; TR is the room temperature, ℃,
is the temperature inside the test chamber, ℃.
A3.2 When measuring liquid vapor, the volume of the liquid injected is calculated as follows: 510-273+T
22.4×d×P
273+TB
Wherein: Vx-
the volume of the liquid injected, ml;
-the volume of the test chamber, L;
C-the concentration of liquid vapor, ppm;
M--the molecular weight of the liquid, g;
the density of the liquid?g/m;
-the purity of the liquid, ppm.
.(A3)
.......(A4)
Note: The resistance value and voltage value refer to the steady-state value. 10
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Appendix B
Parameter symbol comparison table
(Supplement)
Parameter name
Component resistance in clean air
Output voltage in clean air
Component resistance in test gas
Output voltage in test gas
Component resistance in interference gas
Output voltage in interference gas
Heating power
Sensitivity
Gas resolution
Characteristics Concentration resistance ratio
Response time
Response time output voltage
Recovery time
Recovery time output voltage
Temperature coefficient
Humidity coefficient
C1 Working principle
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Appendix C
Resistance-voltage conversion method test method
(reference)
The gas sensor uses a resistance-voltage converter under the action of a constant current to measure the output voltage corresponding to the resistance to obtain the resistance.
C2 Several explanations on the application of the resistance-voltage conversion method C2.1 The resistance-voltage conversion test method is a recommended method for use by units. C2.2 The main differences in the preparation of the resistance-voltage conversion test method and the voltage method are: a. The test system schematic diagram has been modified and the circuit schematic diagram has been added. b. The definition of modified response time is: under specified working conditions, the time required for the element to contact the detection gas of specified concentration and its resistance to change to 30% of the difference between the resistance in clean air and the resistance in the detection gas. The definition of modified recovery time is: under specified working conditions, the time required for the element to be separated from the detection gas and its resistance to change to 70% of the difference between the resistance in clean air and the resistance in the detection gas. 3 The resistance-voltage conversion method is similar to the voltage method in terms of compilation: C2.3
Subject content and scope of application;
Reference standards;
General requirements;
Test environment conditions;
Test condition tolerance;
General precautions;
Parameter g of 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.9 and 5.10 in the detailed requirements.
Definition, calculation formula and specified conditions are the same, but the test steps are slightly different. The resistance-voltage conversion method directly measures the resistance value of the component.
C3 Circuit principle
See Figure C1.
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