MACS Monthly Newsletter - 2021 - AUG5

cluded in the bulk hose standard SAE J3062. The working
group who developed the bulk hose standard SAE
J3062 included the coupling integrity test to be certain
that the quality of bulk air-conditioning hose in the market
was able to pass the coupling test. This would ensure
that bulk hose materials, when subjected to heat, cold,
aging and material compression during crimping of the
fittings, were of a high enough quality level to pass the
assembly test.
Each SAE standard has its specific test and procedure.
The test assembly is similar to Figure 3 but requires exposed
hose lengths which are shorter than the permeation
test. There is an elaborate test procedure described
in the SAE standards which allows for two different test
options. Option one includes low to high temperature
cycling (-30 to 125 °C) and constant temperature exposure
at 125 °C ± 2 °C for four exposure intervals. Option
two includes low to high temperature cycling (-30 to 121
°C) and constant temperature exposure at 121 °C ± 2 °C
for six exposure intervals. Figure 5 is an example of a
thermal chamber which can be programmed for thermal
cycling and constant temperature exposure testing.
Acceptance criteria for passing this test is described in
each SAE standard.
Proof Test
Both SAE J3062 and SAE J2064 require a Proof Test.
The Proof Test is a hydrostatic pressure test to ensure
that the hose or hose assembly will withstand a minimum
of 50% of the required burst strength as specified
in the standard for each hose type or hose assembly application.
TESTING
UNIQUE TO SAE J3062
The following tests are performed in SAE J3062 only:
Aging Test: It is important that hose materials show
no cracks or other disintegration over time. SAE J3062
includes an Aging Test procedure that air-conditioning
hoses must pass to ensure hose quality over the life of
the vehicle.
Cold Test: SAE J3062 includes a Cold Test. Prior to
performing the Cold Test, the hose samples are charged
with refrigerant and heat aged. The hose is then subjected
to cold temperature (-30 °C for 24 hours) and shall
show no evidence of cracking or breaking after testing to
the procedure described in the standard.
Vacuum Flattening: Automotive and mobile airconditioning
systems need to be evacuated to remove
air and moisture prior to charging the system with the
specified refrigerant. Hoses used on these systems must
not show collapse or " flattening " which would interfere
with system evacuation and could ultimately restrict fluid
flow. The standard includes a detailed test procedure
and acceptance criteria.
Burst Strength: A very important feature of automotive
and mobile air-conditioning hose is its Burst Strength.
All of the hose types included in SAE J3062 provide a
reinforcement layer to give the hose adequate strength
to withstand the pressures of the refrigerant system. FigAugust
2021
5
ure 6 illustrates a typical burst chamber which is used
to pressurize the hose using the procedure described in
the standard.
Figure 6: Burst Test Chamber.
Extraction Test: Another test unique to SAE J3062
is the Extraction Test. Hose materials, when exposed to
refrigerant and compressor oils may extract substances
from the interior surface of the hose into the system. SAE
J3062 has a requirement that any material which is potentially
extracted from the hose material be minimized
and be of a nature which is not detrimental to the system.
It is important that any substance contained in the
system does not harm or interfere with any component
or the operation of the system.
The standard has a specific test procedure and acceptance
criteria for this test.
Ozone Test: Similar to the Aging Test is an additional
exposure test to ensure that when the hose is exposed
to an ozone air atmosphere, that the outer cover of the
hose shows no signs of cracking when tested to the procedure
described in the standard.
Moisture Ingression: Another important function of
automotive and mobile air-conditioning hose is to minimize
the amount of moisture which is contained in the
system. Hose materials by design can " ingress " moisture
contained in the environment surrounding the hose
into the system through the hose layers. The Moisture
Ingression Test in SAE J3062 tests the hose when it is
subjected to a humid environment with a vacuum being
drawn on the ID of the hose.
Hose test samples are placed into a temperature and
humidity-controlled chamber which will allow moisture
to ingress into the hose samples. The moisture is collected
into tubes which are placed in a cold trap as part
of the test set-up. Figure 5 illustrates a typical cold trap
set-up used in the Moisture Ingression Test.
The acceptance criteria list two different moisture level
classes as follows:
*
Class I - Moisture Resistant = not greater than
MACS Service Reports
Gene Dianetti
MACS Monthly Newsletter - 2021

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