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GB/T 31911-2015 PDF in English

GB/T 31911-2015 (GB/T31911-2015, GBT 31911-2015, GBT31911-2015)
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GB/T 31911-2015: PDF in English (GBT 31911-2015)

GB/T 31911-2015
ICS 91.140
P 45
Methods for determination of emissions from appliances
burning gaseous fuels
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Measuring systems, analyzers, auxiliary equipment, accessories ... 4
5 System check ... 10
6 Sampling ... 10
7 Test operation ... 11
8 Calculation methods ... 12
Appendix A (Informative) Test gas and its characteristics ... 15
Appendix B (Informative) Example of uncertainty assessment of NOx measurement
results in gas combustion emissions ... 17
Appendix C (Informative) Concentration unit conversion and result correction ... 25
Methods for determination of emissions from appliances
burning gaseous fuels
1 Scope
This standard specifies the terms and definitions, measurement systems, analyzers,
auxiliary equipment and accessories, system inspection, sampling, test operations,
calculation methods for the determination of NOx, CO, CO2, O2 in emissions from
appliances burning gaseous fuels.
This standard applies to the determination of emissions during type inspection and other
inspections of appliances burning gaseous fuels.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB 16410 Domestic gas cooking appliances
GB 25034 Gas-fired heating and hot water combi-boilers
CJ/T 28 Chinese cooking gas appliances
JJF 1059.1 Evaluation and expression of uncertainty in measurement
JJF 1001 General terms in metrology and their definitions
3 Terms and definitions
The terms and definitions, as defined in JJF 1001, apply to this document.
4 Measuring systems, analyzers, auxiliary equipment,
4.1 Measurement system
4.2 Analyzer
4.2.1 Category
This standard applies to analyzers with the following measurement principles:
a) An analyzer, that uses the principle of chemiluminescence to measure NOx
b) When the NOx concentration is greater than 100×10-6 m3/m3, an analyzer uses the
infrared or ultraviolet absorption principle to measure the NOx concentration;
c) Analyzers that measure CO and CO2 concentrations, using the principle of infrared
or ultraviolet absorption;
d) Analyzer that uses the paramagnetic principle to measure O2 concentration.
4.2.2 Indication error
The indication error of the analyzer shall not exceed ±5%.
4.2.3 Repeatability
Analyzer repeatability shall not be greater than 2%.
4.2.4 Response time
The response time -- from adding standard gas to displaying 90% of the indicated
concentration -- shall not be greater than 20 s.
4.2.5 Stability
The change in the indication value within 1 hour shall not be greater than 5%.
4.2.6 Interference
Analyzer measurements shall consider interference from CO2, O2, H2O. Interferences
can be corrected, using correction data provided by the manufacturer or a standard gas
of the same concentration.
4.3 Auxiliary equipment
4.3.1 Sampler General requirements
The sampler shall be made of materials, that do not chemically react with the sample to
be tested, have no or weak adsorption, ensure the homogeneity of specimen.
Household gas stove samplers and their sampling locations shall comply with the
requirements in GB 16410. Commercial gas stoves
Commercial gas stove samplers and their sampling locations shall comply with the
requirements in CJ/T 28.
4.3.2 Condenser or permeation dryer
The condenser material in contact with the specimen shall be made of glass,
polytetrafluoroethylene or stainless steel; its capacity shall match the sampling gas flow
rate and water vapor concentration. The dew point temperature of the flue gas, at the
outlet of the condenser or permeation dryer, shall be below the ambient temperature;
the cooling temperature should be between 2 °C and 5 °C; the condensate shall be able
to be quickly recovered to reduce contact with the specimen. Desiccant shall not be
When the penetration drying method is used, one-half of the dryer tube shall be heated
to at least 15 K above the gas dew point and shall comply with the manufacturer's air
purging requirements.
4.3.3 Filters
The filter shall be installed between the condenser and distributor. The material in
contact with the specimen shall be made of stainless steel or glass. Filter size shall be
determined, based on the sample gas flow rate and the flow rate per unit area data
provided by the manufacturer. The filter diameter shall not be larger than 1 μm;
contaminants on the filter shall be prevented from reacting with the gas.
4.3.4 Distributor
The material of the distributor shall be stainless steel or polytetrafluoroethylene. The
volume shall be as small as possible; the upper flow limit shall ensure the specimen
flow required by each analyzer. Each analyzer shall be able to be connected
independently and shall have a discharge system leading to the outdoors.
4.3.5 Flowmeter
The flowmeter material shall be made of corrosion-resistant materials; the measurement
range shall be selected, according to the sample flow rate, which is required by each
4.3.6 Sampling pump
The materials of the sampling pump, which is in contact with gas, shall be made of
polytetrafluoroethylene, stainless steel and other materials, that do not react with the
specimen. The pump flow rate shall be at least 1.1 times the sum of the flow rates,
which are required by all analyzers in the system.
4.4 Accessories
Auxiliary equipment and devices in contact with the specimen, such as regulators,
valves, pipelines, joints, etc., shall be made of stainless steel, polytetrafluoroethylene,
glass and other materials, that do not adsorb and do not react chemically with them.
When the specimen temperature is higher than 250 °C and the NOx component needs
to be measured, stainless steel materials shall not be used in the parts in contact with it.
The diameter of the pipeline shall be determined according to the specimen flow rate,
which should be 4 mm ~ 8 mm; however, it shall not be less than 4 mm.
5 System check
5.1 Air tightness inspection
Under normal pressure conditions, after inputting the normal pressure standard gas at
point 1 in Figure 1, introduce the standard gas at calibration point 7. The difference
between the measured values at the two points shall not exceed ±5% of the indication
value. The air tightness of the sampling pipeline, at the front end of the analyzer, shall
be inspected at least once a month.
5.2 Linearity inspection
The linearity inspection shall control four measuring points of 0%, 20%, 50%, 80% of
the analyzer range. For the nonlinear calibration curve, at least 10 measuring points of
the analyzer range shall be controlled; the deviation of each point shall not exceed ±5%.
Linearity inspection shall be performed annually or after equipment maintenance.
6 Sampling
6.1 Conditions
Burning appliances shall use the test gas, which is required by the current relevant
national standards, operate under the heat flow rate corresponding to the gas supply
pressure. Conduct the test when a thermal equilibrium state is reached.
6.2 Methods
The following methods can be used for sampling:
- Dry (elimination of water vapor) sampling method;
- Wet sampling method.
6.3 Dry sampling and configuration
The temperature of the upstream pipeline of the condenser or dryer shall be controlled
and maintained, at least 15 K above the water dew point temperature and the acid dew
point temperature of the specimen gas.
6.4 Wet sampling and configuration
In addition to dry sampling requirements, wet sampling shall also comply with the
following requirements:
a) There shall be no cooler or dryer on the sampling pipeline;
b) The temperature of the sampling pipeline upstream of the analyzer shall be
maintained, at least 15 K above the water dew point and the acid dew point of the
specimen gas;
c) The analyzer is specially designed;
d) The water vapor in the specimen shall be corrected.
7 Test operation
7.1 Instrument warm-up
Before measurement, the instrument shall be set up and reach a stable state, in
accordance with the instructions provided by the manufacturer.
7.2 Adjustment
If necessary, the test system shall be adjusted; the standard gas shall be introduced
directly into the analyzer through the pipeline (Figure 1, calibration point 7; Figure 2,
calibration point 6). The flow rate, temperature, pressure shall be adjusted and
consistent with those measured, meanwhile they shall be within the normal range
specified by the manufacturer.
Follow these steps to adjust the analyzer:
a) Introduce the zero point gas into the analyzer; adjust it to zero;
b) Then introduce a standard gas with a known concentration of approximately 80%
of the full scale; adjust the reading;
c) Introduce the zero point gas again; check whether the reading is zero. If not, repeat
the above operation.
7.3 Test
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.