GB 20800.3-2008 PDF in English
GB 20800.3-2008 (GB20800.3-2008) PDF English
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General rules of explosion-protect techniques of reciprocating internal combustion engines for explosive atmospheres -- Part 3: Group I engines for use in underground workings susceptible to firedamp and/or combustible dust
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GB 20800.3-2008: PDF in English GB 20800.3-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.060.20
K 35
General rules of explosion-protect techniques of
reciprocating internal combustion engines for
explosive atmospheres - Part 3: Group I engines for
use in underground workings susceptible to firedamp
and/or combustible dust
ISSUED ON: MAY 20, 2008
IMPLEMENTED ON: APRIL 01, 2009
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 7
4 Safety requirements and safety measures ... 9
5 Inspection of safety requirements and safety measures ... 19
6 Data provided by the manufacturer to the user ... 29
7 Marking and nameplate ... 30
Appendix A (Informative) List of various hazards ... 32
Appendix B (Normative) Operating conditions and ignition sources of internal
combustion engines ... 33
Appendix C (Informative) Comparison of clause numbers between this part and
EN 1834-2:2000 ... 36
Appendix D (Informative) Technical differences between this part and EN 1834-
2:2000 and their reasons ... 39
General rules of explosion-protect techniques of
reciprocating internal combustion engines for
explosive atmospheres - Part 3: Group I engines for
use in underground workings susceptible to firedamp
and/or combustible dust
1 Scope
This part of GB 20800 specifies the safety requirements and (or) safety
measures for Group I category M2 reciprocating compression ignition engines
for use in underground workings with methane and/or combustible dust
(hereinafter referred to as internal combustion engines), which are used to
eliminate or limit various dangers and hazards that may occur on internal
combustion engines.
This part applies to the explosion-proof structure design, manufacture and
inspection of internal combustion engines 1).
This part does not apply to Group I category M1 internal combustion engines
that require special conditions.
This part does not apply to internal combustion engines used in places where
explosives are processed, manufactured, stored.
This part does not apply to ignition type internal combustion engines.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this Standard;
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
1 EN 1834-2:2000 has no specific requirements for inspection procedure. For the specific requirements
of the inspection procedure, see Appendix A of GB 38336.1-2000.
GB/T 15706.2-1995 Safety of machinery - Basic concepts, general principles
for design - Part 2: Technical principles and specifications (eqv ISO/TR
12100-2:1992, eqv EN 292-2:1991)
GB/T 16856-1997 Safety of machinery - Principles for risk assessment
GB 20800.1-2008 General rules of explosion-protect techniques of
reciprocating internal combustion engines for explosive atmospheres - Part
1: Group II engines for use in flammable gas and vapor atmospheres (MOD
EN 1834-1:2000)
JB 8890-1999 Reciprocating internal combustion engines - Safety
requirement
3 Terms and definitions
This part adopts the terms and definitions as proposed in GB/T 1883.1-2005,
GB 6809.1-1986, GB 6809.2-1988, GB 6809.3-1989, GB 6809.4-1989 as well
as the following terms and definitions.
3.1
Explosive atmosphere
Under atmospheric conditions, the atmosphere wherein the mixture of
combustible substances in the form of methane and/or combustible dust with
air whose, after being ignited, combustion can spread to the entire unburned
mixture.
3.2
Potentially explosive atmospheres
An explosive atmosphere that cause explosion due to the influence of site
conditions and operating conditions.
3.3 Category
3.3.1
Engines of category M1 of group 1
The internal combustion engines for use in underground workings and mine
above-ground operation areas where methane and/or combustible dust
exist.
The explosion-proof measures of this kind of internal combustion engine can
When the internal combustion engine needs to install an intake air booster
device, it shall select a booster device whose internal temperature and pressure
cannot produce ignition conditions (see 4.4 and 4.9), meanwhile be equipped
with air filter, to prevent foreign objects from entering the booster device.
Alternatively, the intake air booster device shall be part of the flameproof
enclosure and be tested in accordance with the requirements of 5.3.
4.7.5 Reverse
Except for the internal combustion engine that can be reversed, the internal
combustion engine shall be designed so that it cannot be reversed.
4.7.6 Fuel system
4.7.6.1 For the installation requirements of the fuel system, see 6.5.
4.7.6.2 The fuel tank shall be of metal structure, protected from corrosion,
installed in a place free from mechanical damage.
The fuel tank shall pass a seal test with a pressure of at least 20 kPa.
4.7.6.3 The fuel filling port of the fuel tank shall be easily accessible; the
structure and configuration shall be able to prevent fuel spillage or leakage. The
metal cap of the fuel filler opening shall not be loose when it is covered and
shall not be lost when it is opened.
4.7.6.4 The fuel tank shall be provided with vents, to keep the fuel tank under
atmospheric pressure and not allow foreign objects to enter it.
4.7.6.5 The fuel tank shall be provided with an easy-to-control shut-off valve.
4.7.6.6 The fuel system shall be designed so that fuel will not flow out of the
fuel tank in the event of failure of any fuel pipeline on the pumping side of the
fuel pump.
4.7.6.7 The fuel pipeline shall:
a) Designed as a metal pipe or hose with a metal mesh braid;
b) Prevent internal and external chemical, thermal and mechanical damages;
c) Lay in a place that can prevent mechanical damage;
d) Be accessible.
4.7.6.8 The connection of the fuel pipeline shall be as short as possible; it shall
minimize leakage during operation.
starting auxiliary devices uses the cylinder block of the internal combustion
engine as the ground circuit during the operation of the starting auxiliary circuit,
this is an exception; when starting auxiliary devices are not used, both the
positive and negative connections shall be insulated from the cylinder block of
the internal combustion engine.
For mobile internal combustion engines, if the power source is not together with
the internal combustion engine and is installed in a place where the starter is
only used in non-hazardous areas, the electric starter can also be of ordinary
type.
4.12 Static electricity
4.12.1 Plastic materials
If there is no possibility of electrostatic discharge ignition, plastic materials can
only be applied to external parts.
If any of the following measures are taken, it can prevent electrostatic discharge
from ignition:
- The surface resistance shall not exceed 109 Ω when measured in
accordance with the provisions of 23.4.7.8 in GB 3836.1-2000;
- The electrostatic discharge surface area is limited to 100 cm2;
- The thickness of the non-conductive material on the conductive layer or the
metal mesh shall not exceed 2 mm; when the metal mesh is used as the
conductive layer, the mesh width shall not exceed 100 mm.
4.12.2 Potential balance
All externally accessible components shall be connected to the cylinder block
of the internal combustion engine using conductors, to achieve potential
balance. If these components are firmly installed and maintain metallic contact
with the cylinder block, separate conductors are not necessary for connection.
4.13 Drive belt
The drive belt shall meet the requirements for resistance in GB 10715-1989.
4.14 Compressed air system
It is recommended not to install a compressor on the internal combustion engine.
If the internal combustion engine is equipped with a compressor under special
circumstances, the following safety precautions shall be considered.
If air enters from a hazardous area, the internal temperature and pressure of
It shall not be possible to restart the internal combustion engine before the
shutdown device is manually reset.
4.15.3 Internal combustion engine's shutdown system
The normal shutdown device and emergency automatic shutdown device of the
internal combustion engine shall be located next to the fuel shutoff device of
the fuel injection pump or directly close to the fuel injection pump.
All internal combustion engines shall be equipped with intake shutoff valves.
When the overspeed protection device is activated, it shall automatically cut off
the fuel supply and close the intake shutoff valve.
The intake shut-off valve shall be capable of manual operation. For an
unattended internal combustion engine, control shall be performed at the
operator's position. For an unattended internal combustion engine, control shall
be performed at an obvious and accessible location outside the engine
enclosure.
For large internal combustion engines, manual control shall be possible in
several positions.
In the case of emergency shutdown, the inert gas can be injected into the intake
pipe while operating the air shut-off valve. No other types of fire extinguishing
liquids are allowed in the intake pipe.
5 Inspection of safety requirements and safety
measures
5.1 Documentation
The manufacturer shall prepare some technical documents to stipulate all the
technical requirements for explosionproof of internal combustion engines
(including accessories and auxiliary devices), so as to show that the internal
combustion engine has implemented the requirements of this part when
designing.
5.2 Test requirements
The internal combustion engine and its accessories and auxiliary devices
(including flame arresters, spark extinguishers and pipelines) shall be type
tested in accordance with the requirements of 5.3, 5.4, 5.5.
5.3 Type test of flameproof enclosure
The following devices are required for the test:
1) Simulate the cylinder block. It replaces the cylinder block and is used
to install accessories. The simulated cylinder block shall be equipped
with a simulated combustion chamber with a volume not greater than
the cylinder volume.
If it is confirmed that the cylinder head has no effect on the test results,
the corresponding volume can be used instead.
Note: The test has shown that the cylinder volume has no effect on the
test results.
2) Low-energy ignition source. They are installed on the floor in the
simulated combustion chamber. The design of the floor shall enable the
ignition source to be installed at each entrance and exit of the simulated
combustion chamber.
3) Inlet valve. It is installed on the floor in the simulated combustion
chamber.
4) Pressure sensor and pressure recording system. There are at least
three pressure sensors, installed on the floor close to the ignition source
or far from the ignition source, inside or near the flame arrestor. The
measurement system shall use a frequency limit of 5 kHz ± 10%, in
order to obtain a smooth measurement pressure.
5) A device that supplies the corresponding test gas mixture.
6) Test container. It consists of the following units:
(1) The airtight test cover used to contain the flameproof enclosure
[intake system and/or exhaust system], such as a transparent
plastic bag or a steel container, or a combination of the two; or,
(2) A separate transparent plastic bag, which is used to close the end
of the system away from the pipe and each joint surface.
No part of the test container shall be within 300 mm from any vent or joint
surface on the flameproof enclosure.
b) Two-stroke internal combustion engine - Exhaust system
The test device shall meet the requirements of 5.3.3.2a).
c) Two-stroke internal combustion engine - Intake system
The following devices are required for the test:
component next to the flame arrestor. The relevant valve shall be in the
open position.
b) Install and seal an airtight test cover or a transparent plastic bag as a test
container containing the flameproof enclosure and gas under test.
c) Flush the test system with a test gas mixture of at least 6 times the volume
of the test system and determine the state of the test gas mixture:
- Ambient temperature (0 ~ 40 °C);
- Atmospheric pressure.
d) After flushing, use a low-energy ignition source to ignite and detonate;
record the resulting explosion pressure.
e) Refill the test gas mixture that meets the requirements, to confirm that the
system is connected correctly and detonate again.
Use each ignition source located at the inlet and outlet positions to carry out
multiple tests on the inlet and outlet, respectively. Perform at least 5 tests at the
inlet and outlet where the maximum pressure is formed.
Record the maximum pressure displayed during each test as the maximum
explosion pressure.
When testing water-based flame arresters, the liquid level before the test shall
be the maximum level as specified by the manufacturer, meanwhile the
explosion shall be carried out under static conditions (no air flow).
Note: There is danger of explosion, so it shall take preventive and protective measures.
5.3.4 Overpressure test
5.3.4.1 Overview
The purpose of this test is to apply a control pressure to the flameproof
enclosure that is greater than the maximum explosion pressure that has ever
occurred under the most severe explosion conditions, to show that the
flameproof enclosure can maintain its integrity under such conditions.
5.3.4.2 Static pressure test device
The following devices are required for the test:
a) Simulate the cylinder block. It replaces the cylinder block and seals the
opening to the surrounding environment.
- The liquid level of the flame arrestor before the test shall be the minimum
value specified by the manufacturer;
- The lateral and longitudinal inclination angles of the flame arrestor shall be
the maximum value as specified by the manufacturer;
- During the test, the test gas mixture shall be filled into the system with a
flow rate equal to the maximum flow rate of the exhaust gas. Maximum flow
shall be specified by the manufacturer.
5.3.5.5 Qualification judgement criteria
If the test gas mixture outside the flameproof enclosure is not ignited during
each test, the system test is considered qualified.
5.3.6 Type test of the complete set of internal combustion engine and
accessories
5.3.6.1 Overview
The purpose of these tests is to verify that the safety requirements listed in this
part are correct. The test can be carried out either on the test bench or on-site.
5.3.6.2 Operation of internal combustion engine
The internal combustion engine shall be operated at its maximum surface
temperature, or according to the specific working cycle of the internal
combustion engine and its use. If the installation of the enclosure and the
ventilation device can accurately represent the actual state of use, the load can
be applied by connecting ordinary driving equipment, dynamometer or taking
other appropriate measures.
5.3.6.3 Measuring instrument
The test equipment and instruments shall meet the accuracy requirements
specified in GB/T 6072.1-2000. The test shall be carried out in accordance with
the manufacturer's instructions; the internal combustion engine runs at the
specified speed and working conditions for a long enough time until the
temperature stabilizes before reading the data.
5.3.6.4 Test data
When the internal combustion engine is running and inhaling ambient gas,
measure and record the following data:
a) Ambient air temperature.
b) Maximum surface temperature. Measure the temperature at the possible
- A filter that captures particles passing through the spark extinguisher;
- A measuring device for measuring the gas flow through the spark
extinguisher.
When the spark extinguisher is tested on an internal combustion engine, the
exhaust gas from the internal combustion engine shall be used instead of the
blower. At this time, there is no need to measure the exhaust gas flow rate.
In order to determine the capture efficiency, the test particles shall be sprayed
into the air blown by the blower or the air flow from the internal combustion
engine. The trapping efficiency is the ratio of the mass of particles trapped in
the filter to the mass of particles injected.
The test particles shall be non-flammable; the apparent density shall be less
than 0.9 g/cm3. The specification grades of the test particles are 0.1 mm, 0.2
mm, 0.5 mm. The test shall be performed with the middle value representing
the range of the exhaust gas flow rate designed for the spark extinguisher.
When the spark extinguisher is tested on an internal combustion engine, it shall
be tested at least at no load and idle speed, 50% of the rated power and rated
speed, 100% of the rated power and rated speed.
At each flow rate and each particle specification grade, at least one
measurement is made to determine the capture efficiency of the spark arrestor.
The mass ratio of particles to air or particles to exhaust gas shall be about 1/100.
The test particles shall be sprayed into the air blown by the blower or the air
flow from the internal combustion engine at a uniform rate; the spray time is
about 1 min (the error is ±5%).
Note: When performing this test on an internal combustion engine, care shall be taken
to adjust the water, burned and unburned particles.
5.4.3 Visual inspection
The spark extinguisher can be installed on the tested internal combustion
engine for type testing; or installed on an internal combustion engine with similar
exhaust flow for type testing. During the type test, the spark extinguisher shall
be installed as close as possible to the exhaust pipe of the internal combustion
engine.
The test shall use freshly ground carbon which has a particle size between 0.5
mm and 1 mm.
The internal combustion engine shall reach a stable operating temperature with
the air filter and air intake flame arrestor removed.
6 Data provided by the manufacturer to the user
6.1 General rules
The data provided by the manufacturer to the user shall meet the following
requirements in addition to the technical requirements specified in Chapter 5 of
GB/T 15706.2-1995.
6.2 Accompanying files
The manufacturer shall provide some accompanying documents, detailing all
the maintenance requirements of the internal combustion engine included in
this part, specifying the conditions for the restricted use of the internal
combustion engine.
Due to different conditions of use, subsequent hazards may occur, which may
require some additional safety measures. The internal combustion engine's
installation designer shall consider these conditions.
In particular, the accompanying documents shall point out that the temperature
of the hot surface and hot gas as specified in 4.2 shall not exceed the ignition
temperature of the explosive environment, meanwhile the externally accessible
parts that have the risk of collision or friction shall comply with the requirements
of 8.1 in GB 3836.1-2000.
6.3 Inspection items
The accompanying documents shall stipulate the inspection period of the
following items according to the usage and working system of the internal
combustion engine:
a) General maintenance and external cleaning of internal combustion
engines;
b) The cleanliness, size and working condition of the flame arrester, as well
as the corrosion damage degree of the air inlet flame arrester;
c) Exhaust system with spark extinguisher: carbon deposit, corrosion
damage degree;
d) Rotating mechanical parts: Robustness, no contact with stationary parts;
e) Fan belt: Working condition and tightness;
f) Electrical equipment: Degree of damage and aging;
g) Shutdown system sensor: Functional status of the set limit;
Appendix A
(Informative)
List of various hazards
This part lists the various hazards of internal combustion engines for use in
potentially explosive environments according to the provisions of GB/T 16856-
1997 as follows.
- The hazards arising from the materials processed, used, discharged or
ejected by machinery, including fire and explosion (see 4.4, 4.10, 4.11);
- Various hazards caused by failure or malfunction of the control system (see
4.15);
- Various hazards caused by incorrect positions or missing of protective
devices or safety devices (including starting devices and shutdown devices,
as well as safety signals and safety signs, warning devices or information)
(see 4.5, 4.6, 4.7, 4.8, 4.9).
The main sources of ignition are:
- Hot surface;
- Flame (sparks) and hot gas;
- Mechanical sparks;
- Electrical equipment and systems;
- Static electricity.
The potential sources of ignition that may ignite the surrounding explosive
environment are listed in Appendix B.2.
The design and technical conditions of internal combustion engines shall
reduce the possibility of ignition as much as possible according to the operating
environment of the internal combustion engine, and stipulate:
- Temperature group;
- Existence of combustible dust;
- Existence of other combustible gases besides methane.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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