GB 31975: Evolution and historical versions
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Respiratory protection - Technical requirements for compressed air of breathing apparatus
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GB 31975-2025
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Technical Requirements of Compressed Air for Respiratory Protection
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Basic data | Standard ID | GB 31975-2025 (GB31975-2025) | | Description (Translated English) | Respiratory protection - Technical requirements for compressed air of breathing apparatus | | Sector / Industry | National Standard | | Date of Implementation | 2026-09-01 | | Older Standard (superseded by this standard) | GB/T 31975-2015 | GB/T 31975-2015: Technical Requirements of Compressed Air for Respiratory Protection---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Technical requirements of compressed air for respiratory protection
ICS 13.340.30
C73
National Standards of People's Republic of China
Technical requirements for compressed air for respiratory protection
2015-09-11 release
2016-10-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Published by China National Standardization Administration
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the State Administration of Work Safety.
This standard is under the jurisdiction of the National Technical Committee for Personal Protection Standardization (SAC/TC112).
This standard was drafted. China Academy of Safety Science and Technology, Chemical Research Institute of General Equipment Department, Quartermaster Equipment Institute of General Logistics Department, Mei Si
(China) Safety Equipment Co., Ltd., Dräger Safety Equipment (China) Co., Ltd.
The main drafters of this standard. Zhang Mingming, Ding Songtao, Fu Yahui, Dong Huijun, Yao Haifeng, Chang Hong, Yang Xiaobing, Zhang Huijun, Zhu Hua.
Technical requirements for compressed air for respiratory protection
1 Scope
This standard specifies the quality indicators and test methods for compressed air for respiratory protection.
This standard applies to self-contained open-circuit compressed air respirators and compressed air respirators for occupational protection and escape.
This standard does not apply 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 for the application of this document. For dated references, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 3863-2008 industrial oxygen
GB/T 5832.2 Determination of trace moisture in gases. Part 2. Dew point method
GB/T 8984 Determination of carbon monoxide, carbon dioxide and hydrocarbons in gas
GB/T 18204.2-2014 Hygienic inspection methods for public places Part 2. Chemical pollutants
3 terms and definitions
The following terms and definitions apply to this document.
3.1
Dewpoint
At constant pressure, the temperature at which the moisture in the gas reaches saturation and condenses into dew or frost (ice).
3.2
Dewpoint method
A method of measuring the moisture content of compressed air by measuring the dew point of the gas.
3.3
Atmosphericdewpoint
Dew point of compressed air measured at atmospheric pressure.
4 Technical requirements
The quality of compressed air for respiratory protection should meet the requirements of various indicators in Table 1.
Table 1 Compressed air quality indicators for respiratory protection
Requirements for quality indicatorsa
Oxygen (O2) 19.5% (volume fraction) ~ 23.5% (volume fraction)
Carbon monoxide (CO) ≤10mL/m3
Carbon dioxide (CO2) ≤1000mL/m3
Table 1 (continued)
Requirements for quality indicatorsa
Dew point ≤ -45.6 ℃
Oil mist and particles≤5.0mg/m3
No obvious odor
a The requirements of each index are the values under standard conditions (20 ° C, 101.3kPa).
5 Test method
5.1 Determination of oxygen
5.1.1 The determination of oxygen content in compressed air should adopt the copper ammonia solution absorption method, and it should be implemented according to 4.2 in GB/T 3863-2008;
5.1.2 The oxygen content in compressed air can also be measured by instrumental analysis methods such as paramagnetic analyzers and electrochemical analyzers.
The accuracy is at least ± 0.2% oxygen (absolute value).
5.2 Determination of carbon monoxide
5.2.1 The determination of carbon monoxide content can be carried out by catalytic methanation gas chromatography in accordance with the provisions of GB/T 8984;
5.2.2 The carbon monoxide content can also be measured by non-spectroscopy infrared gas analysis method according to 3.1 in GB/T 18204.2-2014
carried out.
5.3 Determination of carbon dioxide
5.3.1 The determination of carbon dioxide content can be carried out by catalytic methanation gas chromatography in accordance with the provisions of GB/T 8984;
5.3.2 The determination of carbon dioxide content can also use non-spectroscopy infrared gas analysis method, according to 4.1 in GB/T 18204.2-2014
carried out.
5.4 Determination of oil mist and particulate matter
The oil mist and particulate matter samples were collected and measured using the filter membrane weighing method, according to 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 Gathering requirements for gaseous samples
When on-site testing is not convenient, gaseous samples should be collected in accordance with the following requirements.
a) The gaseous samples collected should be representative of the compressed air supplied by normal production;
b) sample containers should be filled at the same time and in the same filling position in the same way;
c) The gas should be collected from the same gas supply container into the sample container through an appropriate connection.
A regulator should be connected (allowing the use of a control valve);
d) The sample container should be directly connected to the analysis equipment after appropriate pressure adjustments. At the same time, the analysis equipment should not be overloaded.
Appendix A
(Normative appendix)
Method for detecting oil mist and particulate matter in compressed air
A.1 Principle
The oil mist and particulate matter in the gas sample are collected with a filter membrane of known quality, and the compressed air is calculated from the weight gain of the filter membrane and the volume of the collected gas after sampling.
The content of oil mist and particles in the gas.
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 not 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 plastic tube for connection;
d) flow meter, accuracy is 2%;
e) Analytical balance. accurate to 0.1 mg.
A.3 Preparation before sampling
The following preparations should be made before sampling.
a) Wash and dry the sampling clamp and sampling box;
b) Dewater the filter in a desiccator for at least 4h, weigh the mass m1 (accurate to 0.1mg), put it into the numbered filter box, and weigh
The subsequent filter membrane should not be contaminated and adsorb oil and 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 adjust the pressure of the needle valve.
The air inlet is connected to the outlet of the compressed air equipment. With the needle valve closed, insert the filter cartridge into the filter cartridge holder. Open needle valve
And adjust the flow meter to let the gas pass through the filter at a flow rate V of 10L/min ~ 20L/min to stabilize the gas flow rate and record the start of sampling
time.
A.4.2 When the cumulative flow rate exceeds 1m3, close the needle valve and record the end time of sampling. Remove the filter and place the dust-receiving surface of the filter
Fold in two inwards, transport and store in a clean container. During the transportation and storage process, dust should be prevented from falling off or being polluted.
A.4.3 When sampling from a pressure vessel, the pressure vessel should be placed upside down (valve facing down) for 5 minutes before sampling. Cylinders and components should be kept at
Above 0 ° C.
A.4.4 When sampling the compressor system, the compressed gas outlet or the filter drying pipe connected to it should keep hanging. Oil measurement
In this case, the sample air should be passed through a sufficient filter medium, and then the weight gain of the filter should be measured, or the decolorization of the filter should be observed.
A.5 Sample weighing and result processing
A.5.1 Before weighing, place the sampled filter membrane in a desiccator for more than 4 hours.After removing static electricity, weigh accurately on the analytical balance
The quality of the membrane and dust m2. The difference between the relative humidity of the balance chamber before and after the sampling of the membrane filter is not more than 10%.
A.5.2 The content of oil mist and particulate matter in the gas is calculated according to formula (A.1).
x =
m2-m1
(A.1)
Where.
x --- oil mist and particulate matter content in milligrams per cubic meter (mg/m3);
m2 --- the mass of the filter membrane after sampling, the unit is milligram (mg);
m1 --- the mass of the filter membrane before sampling, the unit is milligram (mg);
V --- Sampling volume (converted to 20 ℃ and 101.3kPa under standard conditions), the unit is cubic meter (m3).
A.5.3 The number of samples collected in parallel at the same sampling point should be not less than 2.The same batch of samples should contain at least one blank sample.
The test result should be deducted from the blank value, and the final result is the average of each parallel sample.
references
[1] ISO 8573-1Compressedair-Part 1. Contaminantsandpurityclasses
[2] ISO 8573-2Compressedair-Part 2. Testmethodsforaerosoloilcontent
[3] ISO 8573-3Compressedair-Part 3. Testmethodsformeasurementofhumidity
[4] ISO 8573-4Compressedair-Part 4. Testmethodsforsolidparticlecontent
[5] ISO 8573-5Compressedair-Part 5. Detection ofoilvapourandorganicsolventcon-
tent
[6] ISO 8573-6Compressedair-Part 6. Determinationofcontentofgaseouscontaminantcon-
tent
[7] ANSI/CGAG-7.1..2004Communityspecificationforair
[8] EN12021..1998Respiratoryprotectivedevices-Compressedairforbreathingapparatus
[9] NFPA1989-2008 Standardonbreathingairqualityforemergencyservicesrespiratorypro-
tection
[10] 29CFRPart 1910.134RespiratoryProtection
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