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QC/T 664-2019 (QC/T664-2019)

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QC/T 664-2019: PDF in English (QCT 664-2019)

QC/T 664-2019
AUTOMOBILE INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 43.040.60
T 26
Replacing QC/T 664-2000
Automotive air-conditioning refrigerant hose
ISSUED ON: DECEMBER 24, 2019
IMPLEMENTED ON: JULY 01, 2020
Issued by: Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 5 
1 Scope ... 7 
2 Normative references ... 7 
3 Terms and definitions... 7 
4 Categories ... 8 
5 Technical requirements ... 9 
6 Test methods ... 12 
7 Signs ... 23 
8 Inspection, packaging, transportation, storage ... 23 
Automotive air-conditioning refrigerant hose
1 Scope
This standard specifies the classification, dimensions, technical requirements, test
methods, marking, inspection and packaging, transportation, storage of hoses for
conveying refrigerants in automotive air-conditioning systems.
This standard is applicable to rubber or thermoplastic hoses, for conveying liquid or
gaseous HFC-134a/HFO-1234yf refrigerants in automotive air-conditioning systems.
2 Normative references
The following documents are essential for the application of this document. For dated
references, only the dated version applies to this document. For undated references, the
latest edition (including all amendments) applies to this document.
GB/T 1690 Rubber, vulcanized or thermoplastic - Determination of the effect of
liquids
GB/T 2941 Rubber - General procedures for preparing and conditioning test pieces
for physical test methods
GB/T 30512 Requirements for prohibited substances on automobiles
3 Terms and definitions
The following terms and definitions apply to this standard.
3.1
High pressure hose
A hose, which has a working pressure of not less than 3.5 MPa (marked as HP).
3.2
Low pressure hose
A hose, which has a working pressure not higher than 1.5 MPa (marked as LP).
Carry out the test, according to the test method specified in 6.8. The collapse of the
outer diameter of the hose, during the test, shall not be less than 20% of the initial outer
diameter of the hose.
5.8 Length change rate
Carry out the test, according to the test method specified in 6.9. During the test, under
the action of the specified pressure, the length change rate of the hose shall be -4% ~
2%.
5.9 Burst pressure
Carry out the test, according to the test method specified in 6.10. The minimum burst
pressure of the hose, which has a nominal inner diameter not greater than 13.0 mm,
shall be 14.7 MPa. The minimum burst pressure of the hose, which has a nominal inner
diameter greater than 13.0 mm, shall be 12.0 MPa.
5.10 Pressure resistance
Carry out the test, according to the test method specified in 6.11. During the test, the
hose shall be tested, according to the specified pressure and time. The abnormal
phenomena, such as leakage, crack, sudden twisting of the hose, are not allowed.
5.11 Extractables content
Carry out the test, according to the test method specified in 6.12. After the test, the
content of extractables, on the inner surface of the hose, shall not exceed 118 g/m2.
5.12 Volume change rate of inner layer material
Carry out the test, according to the test method specified in 6.13. After the test, the
volume change rate of the rubber material shall be -5% ~ 35%; the volume change rate
of the thermoplastic material shall be -5% ~ 5%.
5.13 Ozone resistance
Carry out the test, according to the test method specified in 6.14. After the test, the outer
rubber layer of the hose shall have no visible cracks, under an eight-fold magnifying
glass.
5.14 Internal surface cleanliness
Carry out the test, according to the test method specified in 6.15. After the test, the
impurity content shall not exceed 270 mg/m2; the size of the gas particles shall not
exceed 0.5 mm x 1.0 mm.
5.15 Pulse fatigue resistance
conditions specified in GB/T 2941.
6.2 Test medium
The test medium used in the test shall be a mixture of HFC-134a, which has a mass
fraction of 90% or HFO-1234yf refrigerant and 10% refrigerating machine oil.
6.3 Dimensional measurement
6.3.1 Inner and outer diameters of hoses
The inner diameter of the hose shall be measured by a special measuring tool, such as
a tapered plug gauge, expanding ball type or retractable meter, etc. The diameter is
measured 3 times; the results are averaged.
6.3.2 Deviation of hose's wall thickness
The deviation of wall thickness of the hose shall be measured by a special meter, such
as a caliper with a probe that can touch the inner wall of the hose. Measure the wall
thickness of the cross section of the hose, at four points; take the difference between the
maximum value and the minimum value measured. Make 3 measurements. Take the
average of the results.
6.4 Permeation
Take 3 hoses. Fill the hoses with the specified test medium, according to the method in
6.5.3.1. Weigh the hoses and accessories. Then place the samples at a temperature of
100 °C ± 2 °C, for 24 hours. After taking out, weigh the mass of the hose and accessories
again. Calculate the mass loss.
6.5 Refrigerant permeability
6.5.1 Test device
6.5.1.1 Accessories and fixtures
Accessories and clamps shall be sealed and leak-free, when subjected to the pressure in
the hose.
6.5.1.2 Leak detector
The sensitivity of the leak detector shall be higher than 2 g/year (under the same volume
and temperature conditions, the refrigerant's equivalent ratio HFC-134a:HFO-1234yf =
1:0.92).
6.5.1.3 Constant temperature chamber
The control accuracy of the constant temperature chamber shall be ±2 °C.
6.5.1.4 Balances
The measurement accuracy of the balance shall be 0.01 g.
6.5.2 Test conditions
For use of hoses at higher working pressures, the test temperature shall be 90 °C ± 2 °C
or 100 °C ± 2 °C (high-pressure hose). For use of hoses at lower working pressures, the
test temperature shall be 80 °C ± 2 °C (low-pressure hose).
6.5.3 Test method
6.5.3.1 Preparation before the test
Take 4 hoses, which have an exposed length of 1m, and accessories. Use seals to seal
them at both ends. Three of them are used to measure the loss of refrigerant; the fourth
one is connected with a joint, which is used as a comparison hose, to detect the change
of the mass torsion of the hose itself. In the standard state, measure the exposed length
of the hose (L1, L2), the accuracy is required to be ±1 mm. Weigh the mass of each hose
and accessories (including joints), which is required to be accurate to ± 0.1 g. The hose
assembly is filled with 0.6 mg of test medium per millimeter volume; the filling volume
is accurate to ±5 g. The number of filled hoses is 3. Use a leak detector, to check that
each hose is leaking.
Filling of refrigerant
Method 1:
Before filling the hoses and accessories, they must be kept in a low temperature
chamber of -30 °C or lower, for 4 hours. Use the density of the test medium, at this
temperature, to calculate the mass of the test medium to be filled. Keep the test medium
and the hose at this temperature Use an electronic balance, to weigh the test medium.
Then fill the test medium into the hose. The filled hose and accessories are sealed at
this temperature.
Method 2:
The hose and accessories are filled with the test medium, under a certain pressure, at
ambient temperature. The device, to keep the test medium flowing, has a storage
compressed air system, a piston pump, a device for controlling and measuring the flow.
6.5.3.2 Test procedure
First, place 3 test hoses, which are filled with refrigerant, AND 1 comparison hose, in
a constant temperature chamber. Dry them for 30 minutes at the test temperature, to
remove the moisture on the surface of the hose and accessories. Then use a leak detector
to check for leaks. Weigh it.
out the specimen. Cool it to room temperature. Then loose the hose. Carefully check
the external surface of hose, for the defects, such as cracks, which are visible to naked
eyes. Then maintain the hose, under the hydrostatic pressure of 2.4 MPa (low-pressure
hose) OR 3.5 MPa (high-pressure hose), for 5 minutes. Check the hose.
6.7 Low-temperature resistance
Take 3 hoses and accessories, which have exposed length of 300 mm ~ 1000 mm. At
room temperature, fill the sample with test medium to 70% of the volume of the hose,
at room temperature. OR cool the hose, accessories and test medium to below -30 °C,
for filling.
Place the filled hose and accessories, in a constant temperature chamber, at 70 °C ±2 °C.
Keep it for 48 hours. Take it out and let it cool to room temperature. Put the hose in
straight line state AND the mandrel which has a diameter 8 times the outer diameter of
hose together, in a low temperature chamber, at -40 °C ± 2 °C, for 24 hours. Then bend
the hoses and accessories, around the mandrel, at a uniform speed by 180°, within 4 s
~ 8 s, in the low temperature chamber. After removal, restore the specimen to room
temperature. Carefully inspect the outer surface for defects, such as cracks visible to
the naked eye. Then pour the test medium, which is filled in each hose and accessories,
back into a suitable recovery container. Maintain the hose at hydrostatic pressure of 2.4
MPa (low-pressure hose) OR 3.5 MPa (high-pressure hose), for 5 minutes. Check the
hose.
6.8 Vacuum resistance
Take hoses and accessories, which have a length of 600 mm ~ 1000 mm. Bend the hose
into a U shape. The inner diameter of the U shape is 5 times the nominal outer diameter
of the hose (the U-shaped inner diameter of hose, which has an inner diameter of more
than 19 mm, is 6 times the nominal outer diameter of the hose). Measure the minimum
outer diameter, on any plane, at the bottom of the U-shape, as the initial outer diameter
(D0). Vacuum the hose to an absolute pressure of 81 kPa ± 3 kPa. Hold the pressure for
2 min. When the hose is still in a vacuum state, after the pressure holding, measure the
minimum outer diameter (D1), on any plane, at the bottom of the U-shape again. Then
calculate the collapse of the outer diameter of the hose, as follows:
Collapse of the outer diameter = D0 - D1 ………………….. (2)
Where:
D0 - The outside diameter of hose, before test, mm;
D1 - The outside diameter of hose, after test, mm.
6.9 Length change rate
Take two hoses, which have an exposed length of 600 mm, and accessories. Make 3
6.12 Extractables content
Take the hose which have an exposed length of 450 mm ~ 1000 mm and its accessories.
Use isooctane solvent, to thoroughly clean the inner surface of the hose. Fill the hose
to 70% of the hose capacity, by the liquid refrigerant, at room temperature. For
convenience, the hose and refrigerant can be cooled to below -30 °C, so that the
refrigerant is in a liquid state for easy filling. Put the hose and accessories in a constant
temperature chamber, at 70 °C ± 2 °C, for 24 h. After aging, cool the hose to below -
30 °C. Pour the refrigerant into a dried beaker, which was weighed as G0, to let it
evaporate at room temperature. After evaporation, put the beaker in a 70 °C constant
temperature chamber, for 1 hour. Take it out and cool it to room temperature. Weigh the
beaker again, as G1. Calculate the extractables content of the hose, according to the
following formula. Calculate the inner surface area of the hose, using the nominal inner
diameter of the hose as the standard.
Extractables content = (G1 - G0)/S ………………….. (4)
Where:
G0 - Beaker mass before test, g;
G1 - Beaker mass after test, g;
S - Inner surface area of hose, m2.
6.13 Volume change rate of inner layer material
Carry out test, according to GB/T 1690. Take the material of the inner rubber layer of
the hose as a specimen. Place it in a pressure container, that can withstand at least 10
MPa pressure. Cool it to below -30 °C. Make the specimen be completely immersed in
the test medium. Seal the container. Place it in a constant temperature chamber, at
100 °C ± 2 °C for 70 h. After placing it, cool it to below -30 °C. Then take the specimen
out of the test medium. Measure the volume change rate of the specimen, according to
GB/T 1690.
6.14 Ozone resistance
Types A, C, D hoses must be tested. After bending the hose around a mandrel, which
has a diameter of 8 times the nominal outer diameter of the hose, put it into an ozone
test chamber, which has a test temperature of 40 °C ± 2 °C AND an ozone partial
pressure of 50 MPa ± 5 MPa; the test time is 70 h ± 2 h. After the test, take out the hose.
Observe whether the outer rubber layer of the hose has cracks or fractures, under an 8X
magnifying glass.
6.15 Internal surface cleanliness
Take the hose, which has an exposed length of more than 300 mm. The inner wall of
the hose shall be dry. Bend the hose into a U shape; the lengths of both sides of the U
shape are the same. Make the two ends of the hose stand upright. Use isooctane solvent
to fill the hose. Then open the hose. Use the 0.8 μm filter paper, which was dried and
weighed as G0, to filter the solvent into the filter device, which has the filter paper
installed. Dry the filter paper at 70 °C ± 2 °C, for 30 min. Weigh the filter paper, after
cooling to G1. Calculate the inner surface cleanliness of the hose, as follows:
Inner surface cleanliness = (G1 - G0)/S …………………… (5)
Where:
G0 - Filter paper mass before test, mg;
G1 - Filter paper mass after test, mg;
S - Inner surface area of hose, m2.
6.16 Pulse fatigue resistance
Install at least two hoses and accessories on the hose pulse fatigue test device. For hoses,
which have a nominal diameter less than or equal to 22 mm, bend it for 180°; the
exposed length of hose = π (r + d/2) + 2d (see Figure 5). For hoses, which have a
nominal inner diameter greater than 22 mm, bend it for 90°; the exposed length of the
hose = π (r + d/2)/2 + 2d (see Figure 6). The minimum bending radius is 5 times the
nominal outer diameter of the hose. Then according to the provisions in Figure 7, apply
pulse pressure of (0.5 ± 0.5) MPa ~ (3.5 ± 0.175) MPa to high-pressure hose and
accessories; apply pulse pressure of (0.5 ± 0.5) MPa ~ (2.6 ± 0.13) MPa to low-pressure
hose and accessories; the frequency is 30 ~ 40 cycles per minute. The test liquid is
refrigerating machine oil; the oil temperature is 40 °C ± 2 °C; the test is carried out, at
an ambient temperature of 125 °C ± 2 °C. After a total of 150000 cycles, carefully
observe the hose and accessories, for leaks and damage.
......
 
(Above excerpt was released on 2022-04-20, modified on 2022-04-20, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/QCT664-2019