Explosion tests.
(a) Test procedures. (1) Prepare to test the diesel power package
as follows:
(i) Perform a detailed check of parts against the drawings and
specifications submitted under § 7.97 to determine that the parts
and drawings agree.
(ii) Remove all parts that do not contribute to the operation or
ensure the explosion-proof integrity of the diesel power package such
as the air cleaner and exhaust gas dilution system.
(iii) Fill coolant system fluid and engine oil to the engine
manufacturer's recommended levels.
(iv) Interrupt fuel supply to the injector pump.
(v) Establish a preliminary low water level for systems using the
wet exhaust conditioner as a flame arrester.
(2) Perform static and dynamic tests of the intake system as
follows:
(i) Install the diesel power package in an explosion test chamber
which is large enough to contain the complete diesel power package. The
chamber must be sufficiently darkened and provide viewing capabilities
of the flame-arresting paths to allow observation during testing of any
discharge of flame or ignition of the flammable mixture surrounding the
diesel power package. Couple the diesel power package to an auxiliary
drive mechanism. Attach a pressure measuring device, a temperature
measuring device, and an ignition source to the intake system. The
pressure measuring device shall be capable of indicating the peak
pressure accurate to + 1 pound-per-square inch gauge (psig)
at 100 psig static pressure and shall have a frequency response of 40
Hertz or greater. The ignition source shall be an electric spark with a
minimum energy of 100 millijoules. The ignition source shall be located
immediately adjacent to the intake manifold and the pressure and
temperature devices shall be located immediately adjacent to the flame
arrester.
(ii) For systems using the wet exhaust conditioner as an exhaust
flame arrester, fill the exhaust conditioner to the specified high or
normal operating water level.
(iii) Fill the test chamber with a mixture of natural gas and air
or methane and air. If natural gas is used, the content of combustible
hydrocarbons shall total at least 98.0 percent, by volume, with the
remainder being inert. At least 80.0 percent, by volume, of the gas
shall be methane. For all tests, the methane or natural gas
concentration shall be 8.5 + 1.8 percent, by volume, and the
oxygen concentration shall be no less than 18 percent, by volume.
(iv) Using the auxiliary drive mechanism, motor the engine to fill
the intake and exhaust systems with the flammable mixture. The intake
system, exhaust system, and test chamber gas concentration shall not
differ by more than + 0.3 percent, by volume, at the time of
ignition.
(v) For static tests, stop the engine, actuate the ignition source,
and observe the peak pressure. The peak pressure shall not exceed 110
psig. If the peak pressure exceeds 110 psig, construction changes shall
be made that result in a reduction of pressure to 110 psig or less, or
the system shall be tested in accordance with the static pressure test
of § 7.104 with the pressure parameter replaced with a static
pressure of twice the highest value recorded.
(vi) If the peak pressure does not exceed 110 psig or if the system
meets the static pressure test requirements of this section and there
is no discharge of visible flames or glowing particles or ignition of
the flammable mixture in the chamber, a total of 20 tests shall be
conducted in accordance with the explosion test specified above.
(vii) For dynamic tests, follow the same procedures for static
tests, except actuate the ignition source while motoring the engine.
Forty dynamic tests shall be conducted at two speeds, twenty at
1800 + 200 RPM and twenty at 1000 + 200 RPM.Under some circumstances, during dynamic testing the flammable mixture may
continue to burn within the diesel power package after ignition. This
condition can be recognized by the presence of a rumbling noise and a
rapid increase in temperature. This can cause the flame-arrester to
reach temperatures which can ignite the surrounding flammable mixture.
Ignition of the flammable mixture in the test chamber under these
circumstances does not constitute failure of the flame arrester.
However; if this condition is observed, the test operator should
immediately stop the engine and allow components to cool to prevent
damage to the components.
(3) Perform static and dynamic tests of the exhaust system as
follows:
(i) Prepare the diesel power package for explosion tests according
to § 7.100(a)(2)(i) as follows:
(A) Install the ignition source immediately adjacent to the exhaust
manifold.
(B) Install pressure measuring devices in each segment as follows:
immediately adjacent to the exhaust conditioner inlet; in the exhaust
conditioner; and immediately adjacent to the flame arrester, if
applicable.
(C) Install a temperature device immediately adjacent to the
exhaust conditioner inlet.
(ii) If the exhaust system is provided with a spaced-plate flame
arrester in addition to an exhaust conditioner, explosion tests of the
exhaust system shall be performed as described for the intake system in
accordance with this section. Water shall not be present in a wet
exhaust conditioner for the tests.
(iii) If the wet exhaust conditioner is used as the exhaust flame
arrester, explosion testing of this type of system shall be performed
as described for the intake system in accordance with this section with
the following modifications:
(A) Twenty static tests, twenty dynamic tests at 1800 +
200 RPM, and twenty dynamic tests at 1000 + 200 RPM shall be
conducted at 2 inches below the minimum allowable low water level. All
entrances in the wet exhaust conditioner which do not form explosion-
proof joints shall be opened. These openings may include lines which
connect the reserve water supply to the wet exhaust conditioner, insert
flanges, float flanges, and cover plates. These entrances are opened
during this test to verify that they are not flame paths.
(B) Twenty static tests, twenty dynamic tests at 1800 +
200 RPM, and twenty dynamic tests at 1000 + 200
RPM shall be conducted at 2 inches below the minimum allowable low
water level. All entrances in the wet exhaust conditioner (except the
exhaust conditioner outlet) which do not form explosion-proof joints
shall be closed. These openings are closed to simulate normal
operation.
(C) Twenty static tests, twenty dynamic tests at
1800 + 200 RPM, and twenty dynamic tests at
1000 + 200 RPM shall be conducted at the specified high or
normal operating water level. All entrances in the wet exhaust
conditioner which do not form explosion-proof joints shall be opened.
(D) Twenty static tests, twenty dynamic tests at
1800 + 200 RPM, and twenty dynamic tests at
1000 + 200 RPM shall be conducted at the specified high or
normal operating water level. All entrances in the wet exhaust
conditioner (except the exhaust conditioner outlet) which do not form
explosion-proof joints shall be closed.
(iv) After successful completion of the explosion tests of the
exhaust system, the minimum allowable low water level, for a wet
exhaust conditioner used as the exhaust flame arrester, shall be
determined by adding two inches to the lowest water level that passed
the explosion tests.
(v) A determination shall be made of the maximum grade on which the
wet exhaust conditioner can be operated retaining the flame-arresting characteristics.
(b) Acceptable performance. The explosion tests shall not result in
any of the following--
(1) Discharge of flame or glowing particles.
(2) Visible discharge of gas through gasketed joints.
(3) Ignition of the flammable mixture in the test chamber.
(4) Rupture of any part that affects the explosion-proof integrity.
(5) Clearances, in excess of those specified in this subpart, along
accessible flame-arresting paths, following any necessary retightening
of fastenings.
(6) Pressure exceeding 110 psig, unless the intake system or
exhaust system has withstood a static pressure of twice the highest
value recorded in the explosion tests of this section following the
static pressure test procedures of § 7.104.
(7) Permanent distortion of any planar surface of the diesel power
package exceeding 0.04-inches/linear foot.
(8) Permanent deformation exceeding 0.002-inch between the plates
of spaced-plate flame arrester designs.