GB 31975-2025 Respiratory protection—Technical requirements for compressed air of breathing apparatus English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing thorugh draft translation, self-check, revision and varification) will be delivered upon being ordered.
ICS 13.340.30
CCS C 73
People's Republic of China National Standard
GB 31975-2025
Replaces GB/T 31975-2015
Respiratory protection—Technical requirements for compressed air of breathing apparatus
Issued on 2025-08-29 Implemented on 2026-09-01
Issued by State Administration for Market Regulation
Standardization Administration of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
5 Test methods
6 Sample collection and field testing
Appendix A (Normative) Detection methods for oil mist and particulate matter in compressed air
References
1 Scope
This document specifies the technical requirements for compressed air used in respiratory protective equipment, and describes test methods, sample collection, and field testing.
This document applies to compressed air for respiratory protective equipment.
This document does not apply to compressed air for medical use, diving breathing equipment, and aviation breathing equipment.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute essential requirements for this document. For dated references, only the editions cited apply. For undated references, the latest edition (including any amendments) applies.
GB/T 3863—2008 Industrial oxygen
GB/T 5832.2 Gas analysis—Determination of trace moisture—Part 2: Dew point method
GB/T 12903 Terminology for personal protective equipment
GB/T 18204.2—2025 Inspection methods for public places—Part 2: Chemical indicators
3 Terms and definitions
Terms and definitions established in GB/T 12903 and the following apply to this document.
3.1
Dew point
The temperature at which water vapor in a gas (water content) reaches saturation and condenses into dew or frost (ice) at constant pressure.
3.2
Dew point method
Method for indicating water content in compressed air by testing the dew point.
4 Technical requirements
4.1 Oxygen content
The oxygen (O₂) content in compressed air shall be 19.5% to 23.5% [volume fraction, standard state (20°C, 101.3 kPa)], tested according to 5.1.
4.2 Harmful substance content
The content of harmful substances in compressed air shall meet the technical requirements in Table 1 and be tested according to the corresponding test methods.
4.3 Dew point and water content
Tested according to 5.5, compressed air for respiratory protective equipment shall have sufficiently low dew points to prevent condensation and freezing. The pressure dew point of compressed air shall be at least 5°C lower than the minimum ambient temperature during use and storage of respiratory protective equipment. When the use and storage conditions of respiratory protective equipment are unknown, the dew point of compressed air shall not exceed -11°C.
The maximum water content requirements for compressed air supplied to respiratory protective equipment at different nominal maximum supply pressures shall comply with Table 2. For storage cylinders with filling pressures of 20MPa to 30MPa, the water content of compressed air shall not exceed 25 mg/m³; for storage cylinders with filling pressures above 30MPa, the water content of compressed air shall be less than 25 mg/m³.
4.4 Odor
Tested according to 5.6, compressed air shall have no obvious odor.
5 Test methods
5.1 Oxygen content
5.1.1 The determination of oxygen content in compressed air shall be carried out according to the copper ammonia solution absorption method specified in GB/T 3863—2008.
5.1.2 The oxygen content in compressed air may also be tested using instrumental analysis methods such as paramagnetic, electrochemical, or thermal conductivity methods. The instrument accuracy shall be at least ±0.25% oxygen content (volume fraction). During testing, operations and pre-calibration shall be performed according to the instrument manual. The compressed gas shall be adjusted to the pressure and flow range suitable for the test instrument. The final test results shall be corrected to standard state (20°C, 101.3 kPa). In case of disputes over test results, 5.1.1 shall be the arbitration method.
5.2 Carbon monoxide content
5.2.1 The determination of carbon monoxide content shall be carried out according to the gas chromatography method specified in section 4.2 of GB/T 18204.2—2025.
5.2.2 The determination of carbon monoxide content may also be carried out according to the non-dispersive infrared analysis method specified in section 4.1 of GB/T 18204.2—2025.
5.2.3 The determination of carbon monoxide content may also be performed using instrumental analysis methods such as electrochemical analyzers. The test precision shall be at least ±1 mL/m³. During testing, operations and pre-calibration shall be performed according to the instrument manual. The compressed gas shall be adjusted to the pressure and flow range suitable for the test instrument. The final test results shall be corrected to standard state (20°C, 101.3 kPa). In case of disputes over test results, 5.2.1 shall be the arbitration method.
5.3 Carbon dioxide content
5.3.1 The determination of carbon dioxide content shall be carried out according to the gas chromatography method specified in section 5.2 of GB/T 18204.2—2025.
5.3.2 The determination of carbon dioxide content may also be carried out according to the non-dispersive infrared analysis method specified in section 5.1 of GB/T 18204.2—2025.
5.3.3 The determination of carbon dioxide content may also be performed using instrumental analysis methods such as electrochemical analyzers. The test precision shall be at least ±5 mL/m³. During testing, operations and pre-calibration shall be performed according to the instrument manual. The compressed gas shall be adjusted to the pressure and flow range suitable for the test instrument. The final test results shall be corrected to
Standard
GB 31975-2025 Respiratory protection—Technical requirements for compressed air of breathing apparatus (English Version)
Standard No.
GB 31975-2025
Status
to be valid
Language
English
File Format
PDF
Word Count
8000 words
Price(USD)
240.0
Implemented on
2026-9-1
Delivery
via email in 1~3 business day
Detail of GB 31975-2025
Standard No.
GB 31975-2025
English Name
Respiratory protection—Technical requirements for compressed air of breathing apparatus
GB 31975-2025 Respiratory protection—Technical requirements for compressed air of breathing apparatus English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing thorugh draft translation, self-check, revision and varification) will be delivered upon being ordered.
ICS 13.340.30
CCS C 73
People's Republic of China National Standard
GB 31975-2025
Replaces GB/T 31975-2015
Respiratory protection—Technical requirements for compressed air of breathing apparatus
Issued on 2025-08-29 Implemented on 2026-09-01
Issued by State Administration for Market Regulation
Standardization Administration of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
5 Test methods
6 Sample collection and field testing
Appendix A (Normative) Detection methods for oil mist and particulate matter in compressed air
References
1 Scope
This document specifies the technical requirements for compressed air used in respiratory protective equipment, and describes test methods, sample collection, and field testing.
This document applies to compressed air for respiratory protective equipment.
This document does not apply to compressed air for medical use, diving breathing equipment, and aviation breathing equipment.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute essential requirements for this document. For dated references, only the editions cited apply. For undated references, the latest edition (including any amendments) applies.
GB/T 3863—2008 Industrial oxygen
GB/T 5832.2 Gas analysis—Determination of trace moisture—Part 2: Dew point method
GB/T 12903 Terminology for personal protective equipment
GB/T 18204.2—2025 Inspection methods for public places—Part 2: Chemical indicators
3 Terms and definitions
Terms and definitions established in GB/T 12903 and the following apply to this document.
3.1
Dew point
The temperature at which water vapor in a gas (water content) reaches saturation and condenses into dew or frost (ice) at constant pressure.
3.2
Dew point method
Method for indicating water content in compressed air by testing the dew point.
4 Technical requirements
4.1 Oxygen content
The oxygen (O₂) content in compressed air shall be 19.5% to 23.5% [volume fraction, standard state (20°C, 101.3 kPa)], tested according to 5.1.
4.2 Harmful substance content
The content of harmful substances in compressed air shall meet the technical requirements in Table 1 and be tested according to the corresponding test methods.
4.3 Dew point and water content
Tested according to 5.5, compressed air for respiratory protective equipment shall have sufficiently low dew points to prevent condensation and freezing. The pressure dew point of compressed air shall be at least 5°C lower than the minimum ambient temperature during use and storage of respiratory protective equipment. When the use and storage conditions of respiratory protective equipment are unknown, the dew point of compressed air shall not exceed -11°C.
The maximum water content requirements for compressed air supplied to respiratory protective equipment at different nominal maximum supply pressures shall comply with Table 2. For storage cylinders with filling pressures of 20MPa to 30MPa, the water content of compressed air shall not exceed 25 mg/m³; for storage cylinders with filling pressures above 30MPa, the water content of compressed air shall be less than 25 mg/m³.
4.4 Odor
Tested according to 5.6, compressed air shall have no obvious odor.
5 Test methods
5.1 Oxygen content
5.1.1 The determination of oxygen content in compressed air shall be carried out according to the copper ammonia solution absorption method specified in GB/T 3863—2008.
5.1.2 The oxygen content in compressed air may also be tested using instrumental analysis methods such as paramagnetic, electrochemical, or thermal conductivity methods. The instrument accuracy shall be at least ±0.25% oxygen content (volume fraction). During testing, operations and pre-calibration shall be performed according to the instrument manual. The compressed gas shall be adjusted to the pressure and flow range suitable for the test instrument. The final test results shall be corrected to standard state (20°C, 101.3 kPa). In case of disputes over test results, 5.1.1 shall be the arbitration method.
5.2 Carbon monoxide content
5.2.1 The determination of carbon monoxide content shall be carried out according to the gas chromatography method specified in section 4.2 of GB/T 18204.2—2025.
5.2.2 The determination of carbon monoxide content may also be carried out according to the non-dispersive infrared analysis method specified in section 4.1 of GB/T 18204.2—2025.
5.2.3 The determination of carbon monoxide content may also be performed using instrumental analysis methods such as electrochemical analyzers. The test precision shall be at least ±1 mL/m³. During testing, operations and pre-calibration shall be performed according to the instrument manual. The compressed gas shall be adjusted to the pressure and flow range suitable for the test instrument. The final test results shall be corrected to standard state (20°C, 101.3 kPa). In case of disputes over test results, 5.2.1 shall be the arbitration method.
5.3 Carbon dioxide content
5.3.1 The determination of carbon dioxide content shall be carried out according to the gas chromatography method specified in section 5.2 of GB/T 18204.2—2025.
5.3.2 The determination of carbon dioxide content may also be carried out according to the non-dispersive infrared analysis method specified in section 5.1 of GB/T 18204.2—2025.
5.3.3 The determination of carbon dioxide content may also be performed using instrumental analysis methods such as electrochemical analyzers. The test precision shall be at least ±5 mL/m³. During testing, operations and pre-calibration shall be performed according to the instrument manual. The compressed gas shall be adjusted to the pressure and flow range suitable for the test instrument. The final test results shall be corrected to
