Appendix D to Part 178 - Thermal Resistance Test
49:3.1.1.1.1.18.1.1.5 : Appendix D
Appendix D to Part 178 - Thermal Resistance Test
1. Scope. This test method evaluates the thermal
resistance capabilities of a compressed oxygen generator and the
outer packaging for a cylinder of compressed oxygen or other
oxidizing gas and an oxygen generator. When exposed to a
temperature of 205 °C (400 °F) for a period of not less than three
hours, the outer surface of the cylinder may not exceed a
temperature of 93 °C (199 °F) and the oxygen generator must not
actuate.
2. Apparatus.
2.1 Test Oven. The oven must be large enough in size to
fully house the test outer package without clearance problems. The
test oven must be capable of maintaining a minimum steady state
temperature of 205 °C (400 °F).
2.2 Thermocouples. At least three thermocouples must be
used to monitor the temperature inside the oven and an additional
three thermocouples must be used to monitor the temperature of the
cylinder. The thermocouples must be 1/16 inch, ceramic packed,
metal sheathed, type K (Chromel-Alumel), grounded junction with a
nominal 30 American wire gauge (AWG) size conductor. The
thermocouples measuring the temperature inside the oven must be
placed at varying heights to ensure even temperature and proper
heat-soak conditions. For the thermocouples measuring the
temperature of the cylinder: (1) Two of them must be placed on the
outer cylinder side wall at approximately 2 inches (5 cm) from the
top and bottom shoulders of the cylinder; and (2) one must be
placed on the cylinder valve body near the pressure relief device.
Alternatively, the thermocouples may be replaced with other devices
such as a remote temperature sensor, metal fuse on the valve, or
coated wax, provided the device is tested and the test report is
retained for verification. Under this alternative, it is
permissible to record the highest temperature to which the cylinder
is subjected instead of temperature measurements in intervals of
not more than five (5) minutes.
2.3 Instrumentation. A calibrated recording device or a
computerized data acquisition system with an appropriate range
should be provided to measure and record the outputs of the
thermocouples.
3. Test Specimen.
3.1 Specimen Configuration. Each outer package material
type and design must be tested, including any features such as
handles, latches, fastening systems, etc., that may compromise the
ability of the outer package to provide thermal protection.
3.2 Test Specimen Mounting. The tested outer package must
be supported at the four corners using fire brick or other suitable
means. The bottom surface of the outer package must be exposed to
allow exposure to heat.
4. Preparation for Testing.
4.1 It is recommended that the cylinder be closed at ambient
temperature and configured as when filled with a valve and pressure
relief device. The oxygen generator must be filled with an
oxidizing agent and may be tested with or without packaging.
4.2 Place the package or generator onto supporting bricks or a
stand inside the test oven in such a manner to ensure even
temperature flow.
5. Test Procedure.
5.1 Close oven door and check for proper reading on
thermocouples.
5.2 Raise the temperature of the oven to a minimum temperature
of 205 °C ±2 °C (400 °F ±5 °F). Maintain a minimum oven temperature
of 205 °C ±2 °C (400 °F ±5 °F) for at least three hours. Exposure
time begins when the oven steady state temperature reaches a
minimum of 205 °C ±2 °C (400 °F ±5 °F).
5.3 At the conclusion of the three-hour period, the outer
package may be removed from the oven and allowed to cool
naturally.
6. Recordkeeping.
6.1 Record a complete description of the material being tested,
including the manufacturer, size of cylinder, etc.
6.2 Record any observations regarding the behavior of the test
specimen during exposure, such as smoke production, delamination,
resin ignition, and time of occurrence of each event.
6.3 Record the temperature and time history of the cylinder
temperature during the entire test for each thermocouple location.
Temperature measurements must be recorded at intervals of not more
than five (5) minutes. Record the maximum temperatures achieved at
all three thermocouple locations and the corresponding time.
7. Requirements.
7.1 For a cylinder, the outer package must provide adequate
protection such that the outer surface of the cylinder and valve
does not exceed a temperature of 93 °C (199 °F) at any of the three
points where the thermocouples are located.
7.2 For an oxygen generator, the generator must not actuate.
[72 FR 4457, Jan. 31, 2008, as amended at 72 FR 55099, Sept. 28,
2007]