QC/T 1164-2022Natural gas filters for automobiles (English PDF)

3.3 Initial differential pressure

The pressure difference -- between the inlet and outlet of an unused filter, under specified conditions.

3.4 Water dew point

The temperature, at which natural gas precipitates the first drop of water, under a certain pressure.

3.5 High-pressure natural gas filter

A natural gas filter, which is located between the CNG gas supply system's gas cylinder and the pressure reducer, under a pressure equal to the output pressure of the CNG gas cylinder greater than 3.5 MPa.

3.6 Low-pressure natural gas filter

A natural gas filter, which is located at the back end of the pressure reducer of the CNG gas supply system, OR installed in the LNG gas supply system, under a working pressure generally not more than 3.5 MPa.

3.7 Equivalent flow velocity

For a filter, whose rated pressure is different from the test pressure of 0.7 MPa, the test flow velocity shall be such that the flow velocity under the test condition is equal to the flow velocity achieved under the rated pressure and flow velocity, THEN, the flow velocity under the test condition is called the equivalent flow velocity.

[Source: GB/T 30475.1-2013, 3.6]

5.6.3 Test procedure

5.6.3.1 Prepare dry test ash with constant weight (drying temperature 120 °C ± 5 °C, time 1 h) and electronic balance.

5.6.3.2 Use the electronic balance, which has the accuracy required by the standard, to weigh the filter elements of the filter under test and the backup filter. Record their masses as m1 and m1', respectively.

5.6.3.3 Install the weighed filter element into the filter under test and the backup filter, respectively.

5.6.3.4 Confirm that valves 2 and 5 are closed. Slowly open valve 1. Adjust the pressure reduction valve 3, to make pressure gauge 7 reach the test pressure. Adjust the flow control valve 12, to make the reading of flow meter 11 reach the test value. Record the initial pressure drop value, after stabilization.

5.6.3.5 Add the weighed ash into the ash-adding container 6. Then fully open the valves 2 and 5, in sequence. Then close the valves 5 and 2 in sequence after a few seconds. Record the reading, after the reading of the differential pressure gauge 9 is stable.

5.6.3.6 Repeat step 5.6.3.5, until the reading of differential pressure gauge 9 reaches or exceeds the net differential pressure. Add up the total amount of ash added at this time. Record it as m.

5.6.3.7 Slowly close the valve 1. After the pressure gauge's reading drops to close to 0, carefully take out the filter elements of the filter under test and the backup filter. Weigh their masses. Record them as m2 and m2', respectively.

5.6.3.8 Use the abscissa as the amount of ash added, the pressure difference as the ordinate, to draw the differential pressure characteristic curve of the tested filter element, as shown in Figure 2.

5.6.3.9 Draw a straight line, using the cut-off pressure difference on the ordinate; the product -- of the corresponding value on the abscissa corresponding to the intersection point of the curve and (m2 - m1)/m -- is the dust holding capacity of the filter element.

5.6.3.10 Repeat the test of the filter element of the same specification. Take the average value of 3 valid test results. Record it as the dirt holding capacity of the filter.

5.6.4 Judgment of test validity

5.6.4.1 The ratio -- of the mass change of the tested filter element TO the total amount of ash added (m2 - m1)/m -- shall be within the range of 90% ~ 105%.

5.6.4.2 The ratio -- of the mass change of the backup filter element to the total ash addition -- (m2' - m1')/m, shall meet the requirement of not more than 1%.

5.9 Overpressure strength test

5.9.1 Test medium

Use water or hydraulic oil.

5.9.2 Test procedure

5.9.2.1 The test sample is connected to the pressure source. The pressure relief valve and pressure gauge shall be installed, in the pressure supply pipe, which is not less than 1.5 times and not more than 2 times the working pressure.

5.9.2.2 Open the pressure relief valve to exhaust. Close the pressure relief valve, after the test liquid appears at the gas outlet.

5.9.2.3 Turn on the pressure pump to increase the pressure. The pressure increase rate shall be in accordance with the requirements in Table 9.

7.2 Packaging

7.2.1 When the filter product leaves the factory, a special packing box shall be used. The marks on the packing box and the outside to prevent rain, moisture, pressure, bumps shall comply with the provisions of GB/T 191 and GB/T 6388. On the packing box, at least the following shall be marked:

a) Manufacturer's name, trademark, address;

b) Product model, name, quantity;

c) Production date and mass.

7.2.2 The following documents shall be attached into the packing box:

a) Product testing report, material report, performance report, etc.;

b) The qualification certificate signed or stamped by the inspector;

c) Product instruction manual.

7.3 Transportation

During the transportation of the product, it is necessary to prevent bumps, pressure, rain, moisture; the gas inlet and outlet must be protected with dust caps.

7.4 Storage

The product shall be stored in a ventilated, dry and non-corrosive gas warehouse; it shall not be squeezed by heavy objects.