BS EN 12021:2014 pdf free.Respiratory equipment 一 Compressed gases for breathing apparatus.
2 Normative references
The following documents, in whole or in part. are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 132:1998. Respiratory protective devices – Definitions of terms and pictograms.
3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 132:1998 and the following apply.
hydrocarbon organic compound consisting of hydrogen and carbon
3.2 oil mixture of hydrocarbons and other organic compounds composed of six or more carbon atoms (C6+)
3.3 trimix gas comprising a specified mixture of oxygen, helium and nitrogen, capable of supporting human life under appropriate diving or hyperbaric conditions
Note 1 to entry: This includes manufactured gas mixtures made up from combinabons of pure oxygen, pure helium and pure nitrogen, with or without compressed air.
3.4 hellox gas comprising a specified mixture of oxygen and helium, capable of supporting human life under appropriate diving or hyperbaric conditions
3.5 oxygen and nitrogen gas mixture gas comprising a specified mixture of oxygen and nitrogen, capable of supporting human life under appropriate diving or hyperbaric conditions.
Note 1 to entry: Oxygen and nitrogen gas mixtures are also known as ‘nitrox’.
Note 2 to entry: This definition does not cover gas mixtures produced using oxygen compatible air or nitrogen depleted air.
5 Reference conditions
All data given in the tables or required in this European Standard are valid for normal atmospheric pressure (1 013 mbar absolute, 20。C). All percentage requirements are given in % by volume (dry gas).
All pressures in this European Standard are in bar absolute.
Typical composition of natural air is given in Annex A.
Maximum allowable concentrations of impurities for compressed gases are quoted as values calculated at normal atmospheric pressure.
Compressed gas for breathing shall not contain contaminants at a concentration which can cause toxic or harmful effects. In any event, all contaminants shall be kept to as low a level as possible and shall be less than one tenth of a national 8 h exposure limit. For breathing air only the limit shall be less than one sixth of a national 8 h exposure limit. For breathing at hyperbaric pressures greater than 10 bar or exposure times greater than 8 h the levels shall be revised to take into account the effects of pressure and exposure times.
In the absence of more stringent national regulations. the values in Table ito Table 10 shall be applied.
6.2 Breathing air
Typical composition of natural air is given in Annex A.
Compressed breathing air shall have a dew point sufficiently low to prevent condensation and freezing. Wher the apparatus is used and stored at a known temperature the pressure dew point shall be at least 5 °C below the likely lowest temperature.
Where the conditions of usage and storage of any compressed air supply is not known the pressure dew point shall not exceed -11 °C.
Where any of the gases specified in Table 4 to Table 10 are mixed to produce a breathing gas, the resultant gas mixture shall be tested for oxygen content. The oxygen content shall conform to the relevant value as given for the particular gas mixture, as applicable.
Where any of the gases specified in Table 8 to Table 9 are mixed to create a diving breathing gas, the resultant gas mixture shall also be tested for helium content. The helium content shall conform to the relevant value as given for the particular gas mixture in Table 8 to Table 9, as applicable.
As the purity and contaminant levels of the gases used for mixing are specified in Table 4 to Table 9 it is only the ratio of the mixing that needs to be confirmed. Therefore, post mixing, only the oxygen and, where applicable, the helium content need to be tested to confirm that the correct mixture has been achieved.
WARNING一Helium is specified in this standard as a gas for mixing with other gases to produce an appropriate breathing gas for diving or hyperbaric operations. Helium is an asphyxiant; it shall never be used alone as a breathing gas.
The gas shall be free from unsatisfactory odour or taste.
NOTE For guidance on measuring odour or taste detection thresholds, see Iso 13301. For determination of odour concentration, see EN 13725.
7 Sampling and testing
Any appropriate method may be employed.
—For measuring and assessing results the accuracy of the method shall be taken into consideration.
—The detection limit of the method employed shall be below the required limit value.
NOTE1 For standards on gas analysis see ISO 7504 (vocabulary), ISO/TS 14167 (use of calibration mixtures) and EN ISO 14912 (conversion of composition data).
NOTE 2 See also EN 482 and EN 689.
This European standard specifies requirements for the quality of compressed gas supplied for mixing or use in respiratory protective devices and hyper- and hypobaric operations. However, it does not specify the test methods to be used.
To ensure consistency in the application of this standard and in the analysis of the gases and any contaminants, this informative national annex has included the test methods previously specified in 85 8478:2011.
NA.2 Freedom from toxic components
For UK application, where the gas is to be used for breathing at ambient pressures greater than 10 bar and/or periods in excess of 8 h (subclause 6.1), the calculations given in EH 75/2 to take account of the increased pressure and/or duration should be applied.
NOTE At ambient pressures greater than 10 bar the level of contaminants needs to be less than lIlO” of the workplace exposure limit given in EH 40. Therefore the calculations given in EH 75/2 need to be applied.
NA.3 Test Methods
This Annex specifies the test methods to fulfil the requirements of clause 6 in BS EN 12021, as identified in Table NA. 1.
WARNING 1 Care should be taken to ensure that the gas stream issuing from an outlet port is vented safely to waste when tests are carried out on gases containing more than 21 % oxygen or less than 12 % oxygen as these could otherwise give rise to oxygen enrichment or oxygen depletion respectively.
WARNING 2 Gas samples should not be taken directly from a high pressure source as this could be hazardous. The pressure of the gas being sampled should always be reduced by means of a pressure regulator.
All gas analysis results should be corrected to 1.013 bar’ and 20 C.
Samples should be taken from a pressure receptacle (cylinder), or from the point of supply (charging connection).
Samples should be taken and analysed at least every three months or more frequently if there has been a change in, or concerns relating to, the production process.
NOTE Stored gases that have been shown to conform to this standard do not need to be retested. However, if the gases have been stored for an extended period of time It is recommended that the oxygen level is checked prior to use.BS EN 12021 pdf free download.Respiratory equipment