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GB/T 31975-2015 (GB/T31975-2015)

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GB/T 31975-2015: PDF in English (GBT 31975-2015)
GB/T 31975-2015
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 13.340.30
C 73
Technical Requirements of Compressed Air for
Respiratory Protection
ISSUED ON: SEPTEMBER 11, 2015
IMPLEMENTED ON: OCTOBER 01, 2016
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Technical Requirements ... 5
5 Test Methods ... 5
6 Collecting Requirements for Gaseous Samples ... 6
Appendix A (Normative) Test Methods of Oil Mist and Particulate Matter in the
Compressed Air ... 7
Bibliography ... 10
Foreword
This Standard was drafted as per the rules specified in GB/T 1.1-2009.
This Standard was proposed by State Administration of Work Safety.
This Standard shall be under the jurisdiction of National Technical Committee for
Standardization of Personal Protection (SAC/TC 112).
Drafting organizations of this Standard: China Academy of Safety Science and
Technology; Research Institute of Chemical Defense, General Armaments Department;
Quartermaster Equipment Research Institute of the General Logistic Department; MSA
(China) Safety Equipment Co., Ltd.; and Draeger Safety Equipment (China) Co., Ltd.
Chief drafting staffs of this Standard: Zhang Mingming, Ding Songtao, Fu Yahui, Dong
Huijun, Yao Haifeng, Chang Hong, Yang Xiaobing, Zhang Huijun, and Zhu Hua.
Technical Requirements of Compressed Air for
Respiratory Protection
1 Scope
This Standard specifies the quality indicators and test methods of compressed air for
respiratory protection.
This Standard is applicable to self-contained open-circuit compressed air breathing
apparatus and compressed air line breathing apparatus for occupational protection
and escape.
This Standard is not applicable to compressed air for medical use, breathing
equipment for diving and compressed air for aviation breathing equipment
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) are applicable to this document.
GB/T 3863-2008 Industrial Oxygen
GB/T 5832.2 Determination of Moisture in Gases - Part 2: Dew Point Method
GB/T 8984 Determination of Carbon Monoxide Carbon Dioxide and Hydrocarbon
in Gases - Gas Chromatographic Method
GB/T 18204.2-2014 Examination Methods for Public Places - Part 2: Chemical
Pollutants
3 Terms and Definitions
For the purpose of this document, the following terms and definitions apply.
3.1 Dew point
At constant pressure, the temperature at which the moisture in the gas reaches
saturation and condenses into dew or frost (ice).
3.2 Dew point method
A method of measuring the dew point of the gas to reflect the moisture content of
compressed air.
3.3 Atmospheric dew point
Dew point of compressed air measured at atmospheric pressure.
4 Technical Requirements
The quality of compressed air for respiratory protection shall meet the requirements of
various indicators in Table 1.
Table 1 -- Quality Indicators of Compressed Air for Respiratory Protection
Table 1 – Continued
5 Test Methods
5.1 Determination of oxygen
5.1.1 The determination of the oxygen content in compressed air should adopt the
copper ammonia solution absorption method, and implement according to the
provisions of 4.2 in GB/T 3863-2008;
5.1.2 The oxygen content in the compressed air may also be measured by
paramagnetic analyzers, electrochemical analyzers and other instrumental analysis
methods. The accuracy of the instrument is at least ±0.2% oxygen (absolute value).
5.2 Determination of carbon monoxide
Quality indicators Indicator requirements a
Oxygen
Carbon monoxide
Carbon dioxide
19.5% (volume fraction) ~ 23.5% (volume fraction)
Quality indicators Indicator requirements a
Dew point
Oil mist and particulate matter
Peculiar smell No obvious peculiar smell
a The requirements for each indicator is the value under the standard state (20°C, 101.3 kPa).
5.2.1 The determination of carbon monoxide content may adopt the catalytic
methanation gas chromatography, and implement in accordance with the provisions of
GB/T 8984;
5.2.2 The determination of carbon monoxide content may also use non-spectroscopy
infrared gas analysis method, and implement according to 3.1 in GB/T 18204.2-2014.
5.3 Determination of carbon dioxide
5.3.1 The determination of carbon dioxide content may adopt the catalytic methanation
gas chromatography, and implement in accordance with the provisions of GB/T 8984;
5.3.2 The determination of carbon dioxide content may also use non-spectroscopy
infrared gas analysis method, and implement according to 4.1 in GB/T 18204.2-2014.
5.4 Determination of oil mist and particulate matter
The sample collection and determination of oil mist and particulate matter content shall
filter adopt the filter weighing method, and implement in accordance with the method
specified in Appendix A.
5.5 Determination of dew point
The determination of the dew point is performed in accordance with the provisions of
GB/T 5832.2.
6 Collecting Requirements for Gaseous Samples
When on-site testing is not convenient, gaseous samples shall be collected in
accordance with the following requirements:
a) The collected gaseous samples shall be representative of the compressed air
supplied by normal production;
b) Sample containers shall be filled at the same time and in the same filling position
in the same way;
c) The gas shall be collected from the same gas supply container into the sample
container through an appropriate connection; and the regulator shall not be
connected between the gas supply container and the sample container (allowing
the use of a control valve);
d) The sample container shall be directly connected to the analysis equipment after
appropriate pressure adjustments. At the same time, the analysis equipment
shall not be subjected to excessive pressure.
Appendix A
(Normative)
Test Methods of Oil Mist and Particulate Matter in the Compressed
Air
A.1 Principle
The oil mist and particulate matter in the gas sample shall be collected with a filter
membrane of known quality. The content of the oil mist and particulate matter in the
compressed air shall be calculated from the weight gain of the filter membrane and the
volume of the collected gas after sampling.
A.2 Instruments and materials
The instruments and materials required for the method include:
a) Filter membrane: perchloroethylene microporous filter membrane or other dust
measurement filter membrane, diameter 37mm or 40mm, and pore diameter no
greater than 1μm;
b) Sampling clip or sampling box: the size is consistent with the filter membrane,
which is used to hold the microporous filter membrane;
c) gas needle valve and rubber-plastic tube for connection;
d) flow meter with accuracy of 2%;
e) Analytical balance: accurate to 0.1 mg.
A.3 Preparation before sampling
The following preparations shall be made before sampling:
a) Wash and dry the sampling clamp and sampling box;
b) Dewater the filter membrane in a desiccator for at least 4h; weigh the mass, m1,
(accurate to 0.1mg); and put it into the numbered filter box. The weighed filter
membrane shall not be contaminated or adsorb oil or dust;
c) Connect the needle valve, sampling clamp and rotor flowmeter with plastic pipes
in order.
A.4 Sample collection
A.4.1 Adjust the outlet pressure of the compressed air cylinder or air supply equipment
to 0.1MPa ~ 0.12MPa (absolute pressure); and then connect the inlet of the needle
valve to the outlet of the compressed air equipment. With the needle valve closed,
insert the filter box into the filter box holder. Open the needle valve and adjust the flow
meter to allow the gas to pass through the filter membrane at a flow rate, V, of 10L/min
~ 20L/min to stabilize the gas flow and record the start time of sampling.
A.4.2 When the cumulative flow rate exceeds 1m3, close the needle valve and record
the end time of sampling. Take out the filter membrane, fold the dust-receiving side of
the filter membrane inward twice and place it in a clean container for transportation
and storage. During the transportation and storage process, prevent the dust falling off
or pollution.
A.4.3 When sampling from a pressure vessel, the pressure vessel shall be placed
upside down (valve facing down) for 5min before sampling. Gas cylinders and
components shall be kept above 0°C.
A.4.4 When sampling the compressor system, the compressed gas outlet or the filter
drying pipe connected to it shall keep hanging. When measuring the oil content, the
sample air shall be passed through a sufficient filter membrane medium; and then the
weight gain of the filter membrane shall be measured, or the decolorization of the filter
membrane shall be observed.
A.5 Sample weighing and result processing
A.5.1 Before weighing, place the sampled filter membrane in a desiccator to dewater
for more than 4 hours. After removing static electricity, weigh accurately on the
analytical balance and record the mass, m2, of the filter membrane and dust. The
difference between the relative humidity of the balance chamber before and after the
sampling of the membrane filter is no more than 10%.
A.5.2 The content of oil mist and particulate matter in the gas is calculated according
to Formula (A.1):
Where:
x - oil mist and particulate matter content, in mg/m3;
m2 - the mass of the filter membrane after sampling, in mg;
m1 --- the mass of the filter membrane before sampling, in mg;
V - sampling volume (converted to under standard state of 20°C and 101.3kPa), in m3.
A.5.3 The number of parallel samples collected at the same sampling point shall be no
less than 2. The same batch of samples shall contain at least one blank sample. The
test results of each sample shall be deducted from the blank value. The final result is
the average value of each parallel sample.
Bibliography
__________ END __________
......
 
(Above excerpt was released on 2020-03-31, modified on 2021-06-07, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT31975-2015