
[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2001]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR7]

[Page 46-58]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 7--TESTING BY APPLICANT OR THIRD PARTY--Table of Contents
 
Subpart F--Diesel Power Packages Intended for Use in Areas of Underground Coal 
Mines Where Permissible Electric Equipment is Required

    Source: 61 FR 55518, Oct. 25, 1996, unless otherwise noted.

Sec. 7.95  Purpose and effective date.

    Part 7, subpart A general provisions apply to subpart F. Subpart F 
establishes the specific requirements for MSHA approval of diesel power 
packages intended for use in approved equipment in areas of underground 
coal mines where electric equipment is required to be permissible. It is 
effective November 25, 1996.

Sec. 7.96  Definitions.

    In addition to the definitions in subparts A and E of this part, the 
following definitions apply in this subpart.
    Cylindrical joint. A joint comprised of two contiguous, concentric, 
cylindrical surfaces.
    Diesel power package. A diesel engine with an intake system, exhaust 
system, and a safety shutdown system installed.

[[Page 47]]

    Dry exhaust conditioner. An exhaust conditioner that cools the 
exhaust gas without direct contact with water.
    Exhaust conditioner. An enclosure, containing a cooling system, 
through which the exhaust gases pass.
    Exhaust system. A system connected to the outlet of the diesel 
engine which includes, but is not limited to, the exhaust manifold, the 
exhaust pipe, the exhaust conditioner, the exhaust flame arrester, and 
any adapters between the exhaust manifold and exhaust flame arrester.
    Fastening. A bolt, screw, or stud used to secure adjoining parts to 
prevent the escape of flame from the diesel power package.
    Flame arrester. A device so constructed that flame or sparks from 
the diesel engine cannot propagate an explosion of a flammable mixture 
through it.
    Flame arresting path (explosion-proof joint). Two or more adjoining 
or adjacent surfaces between which the escape of flame is prevented.
    Flammable mixture. A mixture of methane or natural gas with normal 
air, that will propagate flame or explode when ignited.
    Grade. The slope of an incline expressed as a percent.
    High idle speed. The maximum no load speed specified by the engine 
manufacturer.
    Intake system. A system connected to the inlet of the diesel engine 
which includes, but is not limited to, the intake manifold, the intake 
flame arrester, the emergency intake air shutoff device, the air 
cleaner, and all piping and adapters between the intake manifold and air 
cleaner.
    Plane joint. A joint comprised of two adjoining surfaces in parallel 
planes.
    Safety shutdown system. A system which, in response to signals from 
various safety sensors, recognizes the existence of a potential 
hazardous condition and automatically shuts off the fuel supply to the 
engine.
    Step (rabbet) joint. A joint comprised of two adjoining surfaces 
with a change or changes in direction between its inner and outer edges. 
A step joint may be composed of a cylindrical portion and a plane 
portion or of two or more plane portions.
    Threaded joint. A joint consisting of a male- and female-threaded 
member, both of which are the same type and gauge.
    Wet exhaust conditioner. An exhaust conditioner that cools the 
exhaust gas through direct contact with water, commonly called a water 
scrubber.

Sec. 7.97  Application requirements.

    (a) An application for approval of a diesel power package shall 
contain sufficient information to document compliance with the technical 
requirements of this subpart and include: drawings, specifications, and 
descriptions with dimensions (including tolerances) demonstrating 
compliance with the technical requirements of Sec. 7.98. The 
specifications and descriptions shall include the materials of 
construction and quantity. These shall include the following--
    (1) A general arrangement drawing showing the diesel power package 
and the location and identification of the intake system, exhaust 
system, safety shutdown system sensors, flame arresters, exhaust 
conditioner, emergency intake air shutoff device, automatic fuel shutoff 
device and the engine.
    (2) Diesel engine specifications including the MSHA approval number, 
the engine manufacturer, the engine model number, and the rated speed, 
rated horsepower, and fuel rate.
    (3) A drawing(s) which includes the fan blade material 
specifications, the location and identification of all water-cooled 
components, coolant lines, radiator, surge tank, temperature sensors, 
and orifices; arrows indicating proper flow direction; the height 
relationship of water-cooled components to the surge tank; and the 
proper procedure for filling the cooling system.
    (4) A drawing(s) showing the relative location, identification of 
components, and design of the safety shutdown system.
    (5) Specific component identification, or specific information 
including detail drawings that identify the characteristics of the 
cooling system and safety shutdown system that ensures compliance with 
the technical requirements.
    (6) Detail drawings of gaskets used to form flame-arresting paths.

[[Page 48]]

    (7) An assembly drawing showing the location and identification of 
all intake system components from the air cleaner to the engine head.
    (8) An assembly drawing showing the location and identification of 
all exhaust system components from the engine head to the exhaust 
outlet.
    (9) Detail drawings of those intake and exhaust system components 
identified in paragraphs (a)(7) and (a)(8) of this section that ensure 
compliance with the technical requirements. An exhaust conditioner 
assembly drawing shall be provided showing the location, dimensions, and 
identification of all internal parts, exhaust inlet and outlet, sensors, 
and the exhaust gas path through the exhaust conditioner. If a wet 
exhaust conditioner is used, the exhaust conditioner assembly drawing 
must also show the location, dimensions, and identification of the fill 
port, drain port, low water check port; high or normal operating water 
level; minimum allowable low water level; and the maximum allowable 
grade that maintains explosion-proof operations.
    (10) A power package checklist which shall consist of a list of 
specific features that must be checked and tests that must be performed 
to determine if a previously approved diesel power package is in 
approved condition. Test procedures shall be specified in sufficient 
detail to allow the evaluation to be made without reference to other 
documents. Illustrations shall be used to fully identify the approved 
configuration of the diesel power package.
    (11) Information showing that the electrical systems and components 
meet the requirements of Sec. 7.98.
    (12) A drawing list consisting of a complete list of those drawings 
and specifications which show the details of the construction and design 
of the diesel power package.
    (b) Composite drawings specifying the required construction details 
may be submitted instead of the individual drawings in paragraph (a) of 
this section.
    (c) All documents shall be titled, dated, numbered, and include the 
latest revision.
    (d) When all testing has been completed, the following information 
shall be submitted and become part of the approval documentation:
    (1) The settings of any adjustable devices used to meet the 
performance requirements of this subpart.
    (2) The coolant temperature sensor setting and exhaust gas 
temperature sensor setting used to meet the performance requirements of 
this subpart.
    (3) The minimum allowable low water level and the low water sensor 
setting used to meet the performance requirements of this subpart for 
systems using a wet exhaust conditioner as the exhaust flame arrester.
    (4) The maximum grade on which the wet exhaust conditioner can be 
operated retaining the flame arresting characteristics.
    (5) A finalized version of the power package checklist.

Sec. 7.98  Technical requirements.

    (a) The diesel power package shall use a category A diesel engine 
approved under subpart E of this part with the following additional 
requirements:
    (1) A hydraulic, pneumatic, or other mechanically actuated starting 
mechanism. Other means of starting shall be evaluated in accordance with 
the provisions of Sec. 7.107.
    (2) If an air compressor is provided, the intake air line shall be 
connected to the engine intake system between the air cleaner and the 
flame arrester. If the air compressor's inlet air line is not connected 
to the engine's intake system, it shall have an integral air filter.
    (b) The temperature of any external surface of the diesel power 
package shall not exceed 302  deg.F (150  deg.C).
    (1) Diesel power package designs using water jacketing to meet this 
requirement shall be tested in accordance with Sec. 7.101.
    (2) Diesel power packages using other techniques will be evaluated 
under the provisions of Sec. 7.107.
    (3) When using water-jacketed components, provisions shall be made 
for positive circulation of coolant, venting of the system to prevent 
the accumulation of air pockets, and effective activation of the safety 
shutdown system before the temperature of the coolant

[[Page 49]]

in the jackets exceeds the manufacturer's specifications or 212  deg.F 
(100  deg.C), whichever is lower.
    (c) External rotating parts shall not be constructed of aluminum 
alloys containing more than 0.6 percent magnesium.
    (d) If nonmetallic rotating parts are used, they shall be provided 
with a means to prevent an accumulation of static electricity. Static 
conducting materials shall have a total resistance of 1 megohm or less, 
measured with an applied potential of 500 volts or more. Static 
conducting materials having a total resistance greater than 1 megohm 
will be evaluated under the provisions of Sec. 7.107.
    (e) All V-belts shall be static conducting and have a resistance not 
exceeding 6 megohms, when measured with a direct current potential of 
500 volts or more.
    (f) The engine crankcase breather shall not be connected to the air 
intake system of the engine. The discharge from the breather shall be 
directed away from hot surfaces of the engine and exhaust system.
    (g) Electrical components on diesel power packages shall be 
certified or approved by MSHA under parts 7, 18, 20, and 27 of this 
chapter.
    (h) Electrical systems on diesel power packages consisting of 
electrical components, interconnecting wiring, and mechanical and 
electrical protection shall meet the requirements of parts 7, 18, and 27 
of this chapter, as applicable.
    (i) The diesel power package shall be equipped with a safety 
shutdown system which will automatically shut off the fuel supply and 
stop the engine in response to signals from sensors indicating--
    (1) The coolant temperature limit specified in paragraph (b) of this 
section;
    (2) The exhaust gas temperature limit specified in paragraph (s)(4) 
of this section;
    (3) The minimum allowable low water level, for a wet exhaust 
conditioner, as established by tests in Sec. 7.100. Restarting of the 
engine shall be prevented until the water level in the wet exhaust 
conditioner has been replenished above the minimum allowable low water 
level; and
    (4) The presence of other safety hazards such as high methane 
concentration, actuation of the fire suppression system, etc., if such 
sensors are included in the safety shutdown system.
    (j) The safety shutdown system shall have the following features:
    (1) A means to automatically disable the starting circuit and 
prevent engagement of the starting mechanism while the engine is 
running, or a starting mechanism constructed of nonsparking materials.
    (2) If the design of the safety shutdown system requires that the 
lack of engine oil pressure must be overridden to start the engine, the 
override shall not be capable of overriding any of the safety shutdown 
sensors specified in paragraph (i) of this section.
    (k) The diesel power package shall be explosion-proof as determined 
by the tests set out in Sec. 7.100.
    (l) Engine joints that directly or indirectly connect the combustion 
chamber to the surrounding atmosphere shall be explosion-proof in 
accordance with paragraphs (m) through (q) of this section and 
Sec. 7.100. This paragraph does not apply to the following:
    (1) Pistons to piston rings;
    (2) Pistons to cylinder walls;
    (3) Piston rings to cylinder walls;
    (4) Cylinder head to cylinder block;
    (5) Valve stem to valve guide; or
    (6) Injector body to cylinder head.
    (m) Each segment of the intake system and exhaust system required to 
provide explosion-proof features shall be constructed of metal and 
designed to withstand a minimum internal pressure equal to four times 
the maximum pressure observed in that segment in tests under Sec. 7.100 
or a pressure of 150 psig, whichever is less. Castings shall be free 
from blowholes.
    (n) Welded joints forming the explosion-proof intake and exhaust 
systems shall be continuous and gas-tight. At a minimum, they shall be 
made in accordance with American Welding Society Standard D14.4-77 or 
meet the test requirements of Sec. 7.104 with the internal pressure 
equal to four times the maximum pressure observed in tests under 
Sec. 7.100 or a pressure of 150 psig, whichever is less.

[[Page 50]]

    (o) Flexible connections shall be permitted in segments of the 
intake and exhaust systems required to provide explosion-proof features, 
provided that failure of the connection activates the safety shutdown 
system before the explosion-proof characteristics are lost.
    (p) Flame-arresting paths in the intake and exhaust systems shall be 
formed either by--
    (1) Flanged metal to metal joints meeting the requirements of 
paragraph (q) of this section; or
    (2) Metal flanges fitted with metal gaskets and meeting the 
following requirements:
    (i) Flat surfaces between bolt holes that form any part of a flame-
arresting path shall be planed to within a maximum deviation of one-half 
the maximum clearance specified in paragraph (q)(7) of this section. All 
metal surfaces forming a flame-arresting path shall be finished during 
the manufacturing process to not more than 250 microinches.
    (ii) A means shall be provided to ensure that fastenings maintain 
the tightness of joints. The means provided shall not lose its 
effectiveness through repeated assembly and disassembly.
    (iii) Fastenings shall be as uniform in size as practicable to 
preclude improper assembly.
    (iv) Holes for fastenings shall not penetrate to the interior of an 
intake or exhaust system and shall be threaded to ensure that all 
specified bolts or screws will not bottom even if the washers are 
omitted.
    (v) Fastenings used for joints of flame-arresting paths on intake or 
exhaust systems shall be used only for attaching parts that are 
essential in maintaining the explosion-proof integrity. They shall not 
be used for attaching brackets or other parts.
    (vi) The minimum thickness of material for flanges shall be \1/2\-
inch, except that a final thickness of \7/16\-inch is allowed after 
machining rolled plate.
    (vii) The maximum fastening spacing shall be 6 inches.
    (viii) The minimum diameter of fastenings shall be \3/8\-inch, 
except smaller diameter fastenings may be used if the joint first meets 
the requirements of the static pressure test in Sec. 7.104, and the 
explosion test in Sec. 7.100.
    (ix) The minimum thread engagement of fastenings shall be equal to 
or greater than the nominal diameter of the fastenings specified, or the 
intake or exhaust system must meet the test requirements of the 
explosion tests in Sec. 7.100 and the static pressure test in 
Sec. 7.104.
    (x) The minimum contact surface of gaskets forming flame-arresting 
paths shall be \3/8\-inch, and the thickness of the gaskets shall be no 
greater than \1/16\-inch. The minimum distance from the interior edge of 
a gasket to the edge of a fastening hole shall be \3/8\-inch. The 
gaskets shall be positively positioned, and a means shall be provided to 
preclude improper installation. When the joint is completely assembled, 
it shall be impossible to insert a 0.0015-inch thickness gauge to a 
depth exceeding \1/8\-inch between the gasket and mating flanges. Other 
gasket designs shall be evaluated in accordance with Sec. 7.107.
    (q) The following construction requirements shall apply to flame-
arresting paths formed without gaskets:
    (1) Flat surfaces between fastening holes that form any part of a 
flame-arresting path shall be planed to within a maximum deviation of 
one-half the maximum clearance specified in paragraph (q)(7) of this 
section. All metal surfaces forming a flame-arresting path shall be 
finished during the manufacturing process to not more than 250 
microinches. A thin film of nonhardening preparation to inhibit rusting 
may be applied to these finished metal surfaces, as long as the final 
surface can be readily wiped free of any foreign materials.
    (2) A means shall be provided to ensure that fastenings maintain the 
tightness of joints. The means provided shall not lose its effectiveness 
through repeated assembly and disassembly.
    (3) Fastenings shall be as uniform in size as practicable to 
preclude improper assembly.
    (4) Holes for fastenings shall not penetrate to the interior of an 
intake or exhaust system and shall be threaded to ensure that all 
specified bolts or screws will not bottom even if the washers are 
omitted.

[[Page 51]]

    (5) Fastenings used for joints of flame-arresting paths on intake or 
exhaust systems shall be used only for attaching parts that are 
essential in maintaining the explosion-proof integrity. They shall not 
be used for attaching brackets or other parts.
    (6) The flame-arresting path of threaded joints shall conform to the 
requirements of paragraph (q)(7) of this section.
    (7) Intake and exhaust systems joints shall meet the specifications 
set out in Table F-1.

   Table F-1--Dimensional Requirements for Explosion-Proof Intake and
                          Exhaust System Joints
------------------------------------------------------------------------

------------------------------------------------------------------------
Minimum thickness of material for flanges........  \1/2\"<SUP>thnsp</SUP><gr-th
n-
                                                    eq><SUP>1</SUP>
Minimum width of joint; all in one plane.........  1"
Maximum clearance; joint all in one plane........  0.004"
Minimum width of joint, portions of which are      \3/4\" <SUP>2</SUP>
 different planes; cylinders or equivalent.
Maximum clearances; joint in two or more planes,
 cylinders or equivalent:
    Portion perpendicular to plane...............  0.008" <SUP>3</SUP>
    Plane portion................................  0.006"
Maximum fastening <SUP>4</SUP> spacing; joints all in one     6"
 plane \5\.
Maximum fastening spacing; joints, portions of     8"
 which are in different planes.
Minimum diameter of fastening (without regard to   \3/8\"
 type of joint) \6\.
Minimum thread engagement of fastening \7\.......  \3/8\"
Maximum diametrical clearance between fastening    \1/16\"
 body and unthreaded holes through which it
 passes \8\ \9\ \10\.
Minimum distance from interior of the intake or
 exhaust system to the edge of a fastening hole:
 \11\
    Joint-minimum width 1".......................  \7/16\"\8\ \12\
Shafts centered by ball or roller bearings:
    Minimum length of flame-arresting path.......  1"
    Maximum diametrical clearance................  0.030"
Other cylindrical joints:
    Minimum length of flame-arresting path.......  1"
    Maximum diametrical clearance................  0.010"
------------------------------------------------------------------------
\1\ \1/16\-inch less is allowable for machining rolled plate.
\2\ If only two planes are involved, neither portion of a joint shall be
  less than \1/8\-inch wide, unless the wider portion conforms to the
  same requirements as those for a joint that is all in one plane. If
  more than two planes are involved (as in labyrinths or tongue-in-
  groove joints), the combined lengths of those portions having
  prescribed clearances are considered.
\3\ The allowable diametrical clearance is 0.008-inch when the portion
  perpendicular to the plane portion is \1/4\-inch or greater in length.
  If the perpendicular portion is more than \1/8\-inch but less than \1/
  4\-inch wide, the diametrical clearance shall not exceed 0.006-inch.
\4\ Studs, when provided, shall bottom in blind holes, be completely
  welded in place, or have the bottom of the hole closed with a plug
  secured by weld or braze. Fastenings shall be provided at all corners.

\5\ The requirements as to diametrical clearance around the fastening
  and minimum distance from the fastening hole to the inside of the
  intake or exhaust system apply to steel dowel pins. In addition, when
  such pins are used, the spacing between centers of the fastenings on
  either side of the pin shall not exceed 5 inches.
\6\ Fastening diameters smaller than specified may be used if the joint
  or assembly meets the test requirements of Sec.  7.104.
\7\ Minimum thread engagement shall be equal to or greater than the
  nominal diameter of the fastening specified, or the intake or exhaust
  system must meet the test requirements of Sec.  7.104.
\8\ The requirements as to diametrical clearance around the fastening
  and minimum distance from the fastening hole to the inside of the
  intake or exhaust system apply to steel dowel pins. In addition, when
  such pins are used, the spacing between centers of the fastenings on
  either side of the pin shall not exceed 5 inches.
\9\ This maximum clearance only applies when the fastening is located
  within the flame-arresting path.
\10\ Threaded holes for fastenings shall be machined to remove burrs or
  projections that affect planarity of a surface forming a flame-
  arresting path.
\11\ Edge of the fastening hole shall include any edge of any machining
  done to the fastening hole, such as chamfering.
\12\ If the diametrical clearance for fastenings does not exceed \1/32\-
  inch, then the minimum distance shall be \1/4\-inch.

    (r) Intake system. (1) The intake system shall include a device 
between the air cleaner and intake flame arrester, operable from the 
equipment operator's compartment, to shut off the air supply to the 
engine for emergency purposes. Upon activation, the device must operate 
immediately and the engine shall stop within 15 seconds.
    (2) The intake system shall include a flame arrester that will 
prevent an explosion within the system from propagating to a surrounding 
flammable mixture when tested in accordance with the explosion tests in 
Sec. 7.100. The flame arrester shall be located between the air cleaner 
and the intake manifold and shall be attached so that it can be removed 
for inspection or cleaning.

[[Page 52]]

The flame arrester shall be constructed of corrosion-resistant metal and 
meet the following requirements:
    (i) Two intake flame arrester designs, the spaced-plate type and the 
crimped ribbon type, will be tested in accordance with the requirements 
of Sec. 7.100. Variations to these designs or other intake flame 
arrester designs will be evaluated under the provisions of Sec. 7.107.
    (ii) In flame arresters of the spaced-plate type, the thickness of 
the plates shall be at least 0.125-inch; spacing between the plates 
shall not exceed 0.018-inch; and the flame-arresting path formed by the 
plates shall be at least 1 inch wide. The unsupported length of the 
plates shall be short enough that permanent deformation resulting from 
explosion tests shall not exceed 0.002-inch. The plates and flame 
arrester housing shall be an integral unit which cannot be disassembled.
    (iii) In flame arresters of the crimped ribbon type, the dimensions 
of the core openings shall be such that a plug gauge 0.018-inch in 
diameter shall not pass through, and the flame-arresting path core 
thickness shall be at least 1 inch. The core and flame arrester housing 
shall be an integral unit which cannot be disassembled.
    (3) The intake system shall be designed so that improper 
installation of the flame arrester is impossible.
    (4) The intake system shall include an air cleaner service 
indicator. The air cleaner shall be installed so that only filtered air 
will enter the flame arrester. The air cleaner shall be sized and the 
service indicator set in accordance with the engine manufacturer's 
recommendations. Unless the service indicator is explosion-proof, it 
shall be located between the air cleaner and flame arrester, and the 
service indicator setting shall be reduced to account for the additional 
restriction imposed by the flame arrester.
    (5) The intake system shall include a connection between the intake 
flame arrester and the engine head for temporary attachment of a device 
to indicate the total vacuum in the system. This opening shall be closed 
by a plug or other suitable device that is sealed or locked in place 
except when in use.
    (s) Exhaust system. (1) The exhaust system shall include a flame 
arrester that will prevent propagation of flame or discharge of glowing 
particles to a surrounding flammable mixture. The flame arrester shall 
be constructed of corrosion-resistant metal.
    (i) If a mechanical flame arrester is used, it shall be positioned 
so that only cooled exhaust gas at a maximum temperature of 302  deg.F 
(150  deg.C) will be discharged through it.
    (ii) If a mechanical flame arrester of the spaced-plate type is 
used, it must meet the requirements of paragraph (r)(2)(ii) of this 
section and the test requirements of Sec. 7.100. Variations to the 
spaced-plate flame arrester design and other mechanical flame arrester 
designs shall be evaluated under the provisions of Sec. 7.107. The flame 
arrester shall be designed and attached so that it can be removed for 
inspection and cleaning.
    (2) The exhaust system shall allow a wet exhaust conditioner to be 
used as the exhaust flame arrester provided that the explosion tests of 
Sec. 7.100 demonstrate that the wet exhaust conditioner will arrest 
flame. When used as a flame arrester, the wet exhaust conditioner shall 
be equipped with a sensor to automatically activate the safety shutdown 
system at or above the minimum allowable low water level established by 
Sec. 7.100. Restarting of the engine shall be prevented until the water 
supply in the wet exhaust conditioner has been replenished above the 
minimum allowable low water level. All parts of the wet exhaust 
conditioner and associated components that come in contact with 
contaminated exhaust conditioner water shall be constructed of 
corrosion-resistant material. The wet exhaust conditioner shall include 
a means for verifying that the safety shutdown system operates at the 
proper water level. A means shall be provided for draining and cleaning 
the wet exhaust conditioner. The final exhaust gas temperature at 
discharge from the wet exhaust conditioner shall not exceed 170  deg.F 
(76  deg.C) under test conditions specified in Sec. 7.102. A sensor 
shall be provided that activates the safety shutdown system before the 
exhaust gas temperature at discharge from the wet exhaust conditioner 
exceeds 185  deg.F

[[Page 53]]

(85  deg.C) under test conditions specified in Sec. 7.103(a)(4).
    (3) The exhaust system shall be designed so that improper 
installation of the flame arrester is impossible.
    (4) The exhaust system shall provide a means to cool the exhaust gas 
and prevent discharge of glowing particles.
    (i) When a wet exhaust conditioner is used to cool the exhaust gas 
and prevent the discharge of glowing particles, the temperature of the 
exhaust gas at the discharge from the exhaust conditioner shall not 
exceed 170  deg.F (76  deg.C) when tested in accordance with the exhaust 
gas cooling efficiency test in Sec. 7.102. A sensor shall be provided 
that activates the safety shutdown system before the exhaust gas 
temperature at discharge from the wet exhaust conditioner exceeds 185 
deg.F (85  deg.C) when tested in accordance with the safety system 
controls test in Sec. 7.103. All parts of the wet exhaust conditioner 
and associated components that come in contact with contaminated exhaust 
conditioner water shall be constructed of corrosion-resistant material.
    (ii) When a dry exhaust conditioner is used to cool the exhaust gas, 
the temperature of the exhaust gas at discharge from the diesel power 
package shall not exceed 302  deg.F (150  deg.C) when tested in 
accordance with the exhaust gas cooling efficiency test of Sec. 7.102. A 
sensor shall be provided that activates the safety shutdown system 
before the exhaust gas exceeds 302  deg.F (150  deg.C) when tested in 
accordance with the safety system control test in Sec. 7.103. A means 
shall be provided to prevent the discharge of glowing particles, and it 
shall be evaluated under the provisions of Sec. 7.107.
    (5) Other means for cooling the exhaust gas and preventing the 
propagation of flame or discharge of glowing particles shall be 
evaluated under the provisions of Sec. 7.107.
    (6) There shall be a connection in the exhaust system for temporary 
attachment of a device to indicate the total backpressure in the system 
and collection of exhaust gas samples. This opening shall be closed by a 
plug or other suitable device that is sealed or locked in place except 
when in use.

[61 FR 55518, Oct. 25, 1996, 62 FR 34640, 34641, June 27, 1997]

Sec. 7.99  Critical characteristics.

    The following critical characteristics shall be inspected or tested 
on each diesel power package to which an approval marking is affixed:
    (a) Finish, width, planarity, and clearances of surfaces that form 
any part of a flame-arresting path.
    (b) Thickness of walls and flanges that are essential in maintaining 
the explosion-proof integrity of the diesel power package.
    (c) Size, spacing, and tightness of fastenings.
    (d) The means provided to maintain tightness of fastenings.
    (e) Length of thread engagement on fastenings and threaded parts 
that ensure the explosion-proof integrity of the diesel power package.
    (f) Diesel engine approval marking.
    (g) Fuel rate setting to ensure that it is appropriate for the 
intended application, or a warning tag shall be affixed to the fuel 
system notifying the purchaser of the need to make proper adjustments.
    (h) Material and dimensions of gaskets that are essential in 
maintaining the explosion-proof integrity of the diesel power package.
    (i) Dimensions and assembly of flame arresters.
    (j) Materials of construction to ensure that the intake system, 
exhaust system, cooling fans, and belts have been fabricated from the 
required material.
    (k) Proper interconnection of the coolant system components and use 
of specified components.
    (l) Proper interconnection of the safety shutdown system components 
and use of specified components.
    (m) All plugs and covers to ensure that they are tightly installed.
    (n) The inspections and tests described in the diesel power package 
checklist shall be performed and all requirements shall be met.

Sec. 7.100  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 Sec. 7.97 to determine that the parts and 
drawings agree.

[[Page 54]]

    (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 <plus-minus>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<plus-minus>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 <plus-minus>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 Sec. 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<plus-minus>200 RPM and twenty at 1000<plus-minus>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:

[[Page 55]]

    (i) Prepare the diesel power package for explosion tests according 
to Sec. 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 <plus-minus> 
200 RPM, and twenty dynamic tests at 1000<plus-minus>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<plus-minus> 
200 RPM, and twenty dynamic tests at 1000<plus-minus>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<plus-minus>200 
RPM, and twenty dynamic tests at 1000<plus-minus>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<plus-minus>200 
RPM, and twenty dynamic tests at 1000<plus-minus>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 Sec. 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.

[61 FR 55518, Oct. 25, 1996; 62 FR 34641, June 27, 1997]

[[Page 56]]

Sec. 7.101  Surface temperature tests.

    The test for determination of exhaust gas cooling efficiency 
described in Sec. 7.102 may be done simultaneously with this test.
    (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 to MSHA under compliance with Sec. 7.97 to 
determine that the parts and drawings agree.
    (ii) Fill the coolant system with a mixture of equal parts of 
antifreeze and water, following the procedures specified in the 
application, Sec. 7.97(a)(3).
    (iii) If a wet exhaust conditioner is used to cool the exhaust gas, 
fill the exhaust conditioner to the high or normal operating water level 
and have a reserve water supply available, if applicable.
    (2) Tests shall be conducted as follows:
    (i) The engine shall be set to the rated horsepower specified in 
Sec. 7.97(a)(2).
    (ii) Install sufficient temperature measuring devices to determine 
the location of the highest coolant temperature. The temperature 
measuring devices shall be accurate to <plus-minus>4  deg.F 
(<plus-minus>2  deg.C).
    (iii) Operate the engine at rated horsepower and with 
0.5<plus-minus>0.1 percent, by volume, of methane in the intake air 
mixture until all parts of the engine, exhaust coolant system, and other 
components reach their respective equilibrium temperatures. The liquid 
fuel temperature into the engine shall be maintained at 100  deg.F (38 
deg.C) <plus-minus>10  deg.F (6  deg.C) and the intake air temperature 
shall be maintained at 70  deg.F (21  deg.C) <plus-minus>5  deg.F (3 
deg.C).
    (iv) Increase the coolant system temperatures until the highest 
coolant temperature is 205  deg.F to 212  deg.F (96  deg.C to 100 
deg.C), or to the maximum temperature specified by the applicant, if 
lower.
    (v) After all coolant system temperatures stabilize, operate the 
engine for 1 hour.
    (vi) The ambient temperature shall be between 50  deg.F (10  deg.C) 
and 104  deg.F (40  deg.C) throughout the tests.
    (b) Acceptable performance. The surface temperature of any external 
surface of the diesel power package shall not exceed 302  deg.F (150 
deg.C) during the test.

Sec. 7.102  Exhaust gas cooling efficiency test.

    (a) Test procedures. (1) Follow the procedures specified in 
Sec. 7.101(a).
    (2) Install a temperature measuring device to measure the exhaust 
gas temperature at discharge from the exhaust conditioner. The 
temperature measuring device shall be accurate to <plus-minus>4  deg.F 
(<plus-minus>2  deg.C).
    (3) Determine the exhaust gas temperature at discharge from the 
exhaust conditioner before the exhaust gas is diluted with air.
    (b) Acceptable performance. (1) The exhaust gas temperature at 
discharge from a wet exhaust conditioner before the exhaust gas is 
diluted with air shall not exceed 170  deg.F (76  deg.C).
    (2) The exhaust gas temperature at discharge from a dry exhaust 
conditioner before the gas is diluted with air shall not exceed 302 
deg.F (150  deg.C).

Sec. 7.103  Safety system control test.

    (a) Test procedures. (1) Prior to testing, perform the tasks 
specified in Sec. 7.101(a)(1) and install sufficient temperature 
measuring devices to measure the highest coolant temperature and exhaust 
gas temperature at discharge from the exhaust conditioner. The 
temperature measuring devices shall be accurate to <plus-minus>4  deg.F 
(<plus-minus>2  deg.C).
    (2) Determine the effectiveness of the coolant system temperature 
shutdown sensors which will automatically activate the safety shutdown 
system and stop the engine before the coolant temperature in the cooling 
jackets exceeds manufacturer's specifications or 212  deg.F (100 
deg.C), whichever is lower, by operating the engine and causing the 
coolant in the cooling jackets to exceed the specified temperature.
    (3) For systems using a dry exhaust gas conditioner, determine the 
effectiveness of the temperature sensor in the exhaust gas stream which 
will automatically activate the safety shutdown system and stop the 
engine before the cooled exhaust gas temperature exceeds 302  deg.F (150 
 deg.C), by operating the engine and causing the cooled exhaust gas to 
exceed the specified temperature.

[[Page 57]]

    (4) For systems using a wet exhaust conditioner, determine the 
effectiveness of the temperature sensor in the exhaust gas stream which 
will automatically activate the safety shutdown system and stop the 
engine before the cooled exhaust gas temperature exceeds 185  deg.F (85 
deg.C), with the engine operating at a high idle speed condition. 
Temporarily disable the reserve water supply, if applicable, and any 
safety shutdown system control that might interfere with the evaluation 
of the operation of the exhaust gas temperature sensor. Prior to 
testing, set the water level in the wet exhaust conditioner to a level 
just above the minimum allowable low water level. Run the engine until 
the exhaust gas temperature sensor activates the safety shutdown system 
and stops the engine.
    (5) For systems using a wet exhaust conditioner as an exhaust flame 
arrester, determine the effectiveness of the low water sensor which will 
automatically activate the safety shutdown system and stop the engine at 
or above the minimum allowable low water level established from results 
of the explosion tests in Sec. 7.100 with the engine operating at a high 
idle speed condition. Temporarily disable the reserve water supply, if 
applicable, and any safety shutdown system control that might interfere 
with the evaluation of the operation of the low water sensor. Prior to 
testing, set the water level in the wet exhaust conditioner to a level 
just above the minimum allowable low water level. Run the engine until 
the low water sensor activates the safety shutdown system and stops the 
engine. Measure the low water level. Attempt to restart the engine.
    (6) Determine the effectiveness of the device in the intake system 
which is designed to shut off the air supply and stop the engine for 
emergency purposes with the engine operating at both a high idle speed 
condition and a low idle speed condition. Run the engine and activate 
the emergency intake air shutoff device.
    (7) Determine the total air inlet restriction of the complete intake 
system, including the air cleaner, as measured between the intake flame 
arrester and the engine head with the engine operating at maximum air 
flow.
    (8) Determine the total exhaust backpressure with the engine 
operating at rated horsepower as specified in Sec. 7.103(a)(7). If a wet 
exhaust conditioner is used, it must be filled to the high or normal 
operating water level during this test.
    (9) The starting mechanism shall be tested to ensure that engagement 
is not possible while the engine is running. Operate the engine and 
attempt to engage the starting mechanism.
    (10) Where the lack of engine oil pressure must be overridden in 
order to start the engine, test the override to ensure that it does not 
override any of the safety shutdown sensors specified in Sec. 7.98(i). 
After each safety shutdown sensor test specified in paragraphs (a)(2) 
through (a)(5) of this section, immediately override the engine oil 
pressure and attempt to restart the engine.
    (b) Acceptable performance. Tests of the safety system controls 
shall result in the following:
    (1) The coolant system temperature shutdown sensor shall 
automatically activate the safety shutdown system and stop the engine 
before the water temperature in the cooling jackets exceeds 
manufacturer's specifications or 212  deg.F (100  deg.C), whichever is 
lower.
    (2) The temperature sensor in the exhaust gas stream of a system 
using a dry exhaust conditioner shall automatically activate the safety 
shutdown system and stop the engine before the cooled exhaust gas 
exceeds 302  deg.F (150  deg.C).
    (3) The temperature sensor in the exhaust gas stream of a system 
using a wet exhaust conditioner shall automatically activate the safety 
shutdown system and stop the engine before the cooled exhaust gas 
exceeds 185  deg.F (85  deg.C).
    (4) The low water sensor for systems using a wet exhaust conditioner 
shall automatically activate the safety shutdown system and stop the 
engine at or above the minimum allowable low water level and prevent 
restarting of the engine.
    (5) The emergency intake air shutoff device shall operate 
immediately when activated and stop the engine within 15 seconds.
    (6) The total intake air inlet restriction and the total exhaust

[[Page 58]]

backpressure shall not exceed the engine manufacturer's specifications.
    (7) It shall not be possible to engage the starting mechanism while 
the engine is running, unless the starting mechanism is constructed of 
nonsparking material.
    (8) The engine oil pressure override shall not override any of the 
shutdown sensors.

Sec. 7.104  Internal static pressure test.

    (a) Test procedures. (1) Isolate and seal each segment of the intake 
system or exhaust system to allow pressurization.
    (2) Internally pressurize each segment of the intake system or 
exhaust system to four times the maximum pressure observed in each 
segment during the tests of Sec. 7.100, or 150 psig <plus-minus> 5 psig, 
whichever is less. Maintain the pressure for a minimum of 10 seconds.
    (3) Following the pressure hold, the pressure shall be removed and 
the pressurizing agent removed from the intake system or exhaust system.
    (b) Acceptable performance. (1) The intake system or exhaust system, 
during pressurization, shall not exhibit--
    (i) Leakage through welds and gasketed joints; or
    (ii) Leakage other than along joints meeting the explosion-proof 
requirements of Sec. 7.98(q).
    (2) Following removal of the pressurizing agent, the intake system 
or exhaust system shall not exhibit any--
    (i) Changes in fastening torque;
    (ii) Visible cracks in welds;
    (iii) Permanent deformation affecting the length or gap of any 
flame-arresting paths;
    (iv) Stretched or bent fastenings;
    (v) Damaged threads of parts affecting the explosion-proof integrity 
of the intake system or exhaust system; or
    (vi) Permanent distortion of any planar surface of the diesel power 
package exceeding 0.04-inches/linear foot.

Sec. 7.105  Approval marking.

    Each approved diesel power package shall be identified by a legible 
and permanent approval plate inscribed with the assigned MSHA approval 
number and securely attached to the diesel power package in a manner 
that does not impair any explosion-proof characteristics. The grade 
limitation of a wet exhaust conditioner used as an exhaust flame 
arrester shall be included on the approval marking.

Sec. 7.106  Post-approval product audit.

    Upon request by MSHA, but not more than once a year except for 
cause, the approval-holder shall make an approved diesel power package 
available for audit at no cost to MSHA.

Sec. 7.107  New technology.

    MSHA may approve a diesel power package that incorporates technology 
for which the requirements of this subpart are not applicable if MSHA 
determines that the diesel power package is as safe as those which meet 
the requirements of this subpart.

Sec. 7.108  Power package checklist.

    Each diesel power package bearing an MSHA approval plate shall be 
accompanied by a power package checklist. The power package checklist 
shall consist of a list of specific features that must be checked and 
tests that must be performed to determine if a previously approved 
diesel power package is in approved condition. Test procedures shall be 
specified in sufficient detail to allow evaluation to be made without 
reference to other documents. Illustrations shall be used to fully 
identify the approved configuration of the diesel power package.
