GB/T 31975-2015Technical Requirements of Compressed Air for Respiratory Protection (English PDF)

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.

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

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

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