QC/T 674-2007Compressed natural gas solenoid valves for automobiles (English PDF)

5.2.1 Minimum start voltage

When the rated voltage of the solenoid valve is 12V (DC), its minimum start voltage shall be 8V (DC). When its rated voltage is 24V (DC), the minimum start voltage shall be 18V (DC).

When the test is done according to the test method of 6.3, the solenoid valve shall be able to work normally and no abnormal sound.

5.2.2 Over-voltage test

When the test is done according to the test method of 6.4, the solenoid valve shall be able to work normally and no abnormal sound.

5.2.3 Insulation resistance

When the test is done according to the test method of 6.5, the insulation resistance between the coupling end of the solenoid valve coil and the shell shall not be less than

10Mohm.

5.2.4 Hydro-static pressure

When the test is done according to the test method of 6.6, there shall be no fracture or permanent deformation of the solenoid valve.

5.2.5 Leakage test

5.2.5.1 Normal temperature leakage test. When the normal temperature leakage test is done according to the test method regulated in 6.7.1, the displayed value of the pressure gauge shall not decline within one minute, or its leak rate shall not be more than

15*10

-6

N.m

3

/h.

5.2.5.2 High temperature leakage test. When the high temperature leakage test is done according to the test method regulated in 6.7.2, the displayed value of the pressure gauge shall not decline within one minute, or its leak rate shall not be more than 15*10

-6

N.m

3

/h.

5.2.5.3 Low temperature leakage test. When the low temperature leakage test is done according to the test method regulated in 6.7.3, the displayed value of the pressure gauge shall not decline within one minute, or its leak rate shall not be more than 15*10

-6

N.m

3

/h.

5.2.6 High temperature test

After the high temperature test is done according to the test method regulated in 6.8, when the high temperature leakage test is done according to the test method regulated in

6.7.2, the result shall meet requirements of low-temperature air tightness regulated in

5.2.5.2.

a) After the test is done according to the test method regulated in 6.15, the fasteners shall not be found loosened; the solenoid valves shall be able to be opened and closed normally.

b) After the test is done according to the test method regulated in 6.7.1, the vibration strength shall meet requirements of 5.2.5.1;

c) After the test is done according to the test method regulated in 6.14, the vibration strength shall meet requirements of 5.2.12.

5.2.14 Durability

a) After 50000 durability tests are done according to the test method regulated in 6.16, the samples shall have no breakage or deformation;

b) After the test is done according to the test method regulated in 6.7.1, the durability shall meet requirements of 5.2.5.1;

c) After the test is done according to the test method regulated in 6.14, the durability shall meet requirements of 5.2.12.

5.2.15 Torque test

a) After the test is done according to the test method regulated in 6.17, the samples shall have no breakage or deformation;

b) After the test is done according to the test method regulated in 6.7.1, the torsion moment shall meet requirements of 5.2.5.1;

c) After the test is done according to the test method regulated in 6.14, the torsion moment shall meet requirements of 5.2.12.

5.2.16 Bending moment test

a) After the test is done according to the test method regulated in 6.18, the samples shall have no breakage or deformation;

b) After the test is done according to the test method regulated in 6.7.1, the bending moment shall meet requirements of 5.2.5.1;

c) After the test is done according to the test method regulated in 6.14, the bending moment shall meet requirements of 5.2.12.

6.1 Test conditions and meter accuracy

6.1.1 Test conditions

Unless otherwise specified, the test conditions and test medium shall meet the following regulations:

a) Temperature: 15°C~35°C;

b) The relative humidity shall not be more than 85%;

c) The barometric pressure shall be between 86kPa and 106 kPa;

d) Test medium shall be the clean air or nitrogen.

6.1.2 Accuracy and measuring range of all instruments for tests

Unless otherwise specified, the accuracy and measuring range of all instruments shall meet the following regulations:

a) Electric instruments: The accuracy degree shall not be lower than Level 1.0; the measuring range shall be 1.5 ~ 3 times of the measured value;

b) Pressure instrument: The accuracy degree shall not be lower than Level 1.0; the measuring range shall be 1.5 ~ 3 times of the measured value;

c) Flow instrument: The accuracy degree shall not be lower than Level 1.0; the measuring range shall be 1.5 ~ 3 times of the measured value;

d) Temperature instrument: The accuracy degree shall be ±0.5°C; the minimum resolution shall not be greater than 2 times of the measured value (that is, 1°C).

6.2 Appearance inspection

The appearance shall be inspected by visual observation.

6.3 Minimum start voltage

Input the air pressure of rated working pressure to the entrance of the solenoid valve; the outlet is opened; then, apply the minimum start voltage; close-open it for more than three times. Then, check whether the action is flexible and whether there are abnormal sounds.

6.4 Over-voltage test

Input the air pressure of rated working pressure to the entrance of the solenoid ; the outlet is opened; then, apply 1.5-times rated operational voltage for three minutes. The solenoid valve shall work normally with no damages.

6.5 Insulation resistance

Block the outlet of the test specimen; place it inside the high-temperature cabinet. Then, adjust its temperature to 120°C±2°C; add 20Mpa air pressure for 8 hours. Then, conduct the test according to the test method regulated in 6.7.2.

6.9 low-temperature test

Block the outlet of the test specimen; place it inside the low-temperature cabinet. Then, adjust its temperature to -40°C±2°C; add 20Mpa air pressure for 8 hours. Then, conduct the test according to the test method regulated in 6.7.3.

6.10 Drought-hot tolerance test

Expose the non-metallic parts of solenoid valve that contacts with the natural gas to the high temperature of 120°C±2°C for 168 hours; check the changes of their tensile strength and elongation rate according to the method regulated in GB/T 528.

6.11 Compatibility test

Dip in non-metallic parts of solenoid valve that contacts with the natural gas to the n-pentane or the n-hexane with the temperature of 23°C±2°C for 72 hours; check their volume change rate. Then, place them to the air with the temperature of 40°C±2°C;

maintain that for 48 hours. After that, check their mass change rate.

6.12 Ozone resistance test

Stretch 20% of non-metallic parts of solenoid valve that contacts with the natural gas according to regulations of GB/T 7762; place them to the ozone room with the ozone concentration of 50*10

-8

± 5*10

-8 and the temperature of 40°C±2°C for 120 hours. Then, use the two-times magnifying glass to observe surfaces of the sample pieces.

6.13 Corrosion resistance test

a) Seal the connecting hole of the solenoid valve; conduct the salt fog test for 144 hours according to neutral smog test method specified in GB/T 10125.

b) PLACE the brass components that is maintained with maximum working stress conditions (produced by mechanical assembly and rated working air pressure) and of which the surface greasy dirt is removed INTO a sealed container (the temperature is 35°C±2°C and the volume is 30L) that contains 0.6L of ammonia water with the density of 0.94g/cm

3

. The components shall be placed at 40mm above the surface of the ammonia water for 240 hours.

6.14 Rated flow

Install the flow-meter and the pressure gauge to the solenoid valve inlet; connect one end of the pipe of 600mm-long to the solenoid valve outlet. The other end of the pipe shall be open. The diameter of the pipe shall not be less than that of the solenoid valve. Then, according to regulations of Table 4.

7.3 Type inspection

Type inspection shall be done to solenoid valve products according to regulations of Table

4, if any one of the following items occurs. For newly-designed products, it shall conduct product design review according to requirements of 5.1.

a) There are major changes in design or design parameter, technology and materials;

b) If the production has been suspended for more than half a year, when the production is resumed again, the test shall be done.

c) If the production has been continuously run for one year.

7.4 Treatment of test specimens

If the inspection items can affect the performance or service life of the test specimens that pass the inspection, then the specimens can not be delivered out as qualified products.

8.1 Mark

8.1.1 Nameplate mark. Nameplates with clear lines and words shall be fixed to appropriate locations of the solenoid valve. In addition, the following items shall be marked:

a) Product name and model;

a) Rated voltage;

b) Nominal operating pressure;

c) Working medium;

d) Name of manufacturer;

e) Product serial number;

f) Manufacturing Date.

8.1.2 Valve body mark. Permanent arrows showing the flow direction of medium shall be marked on the solenoid valve body.

8.1.3 Coil mark. Types of voltage and rated voltage shall be marked on the appearance of the solenoid valve coil.