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BIS STANDARD CLOSED CIRCUIT BREATHING APPARATUS

CLOSED CIRCUIT BREATHING APPARATUS ( COMPRESSED OXYGEN CYLINDER ) AS PER BIS STANDARD

Terminology
Working Duration: The maximum period of time for which the apparatus should be used.
Effective Duration: working time duration + reserve time period.
Inhaled Air: The atmosphere breathed in by the wearer.
Exhaled Air: The atmosphere breathed out by the wearer.
Method of Operation
In closed-circuit breathing apparatus exhaled air passes from a face piece (mouthpiece) through a breathing tube into a purifier containing chemicals.
The chemical absorbs the exhaled carbon dioxide.
Oxygen is fed into the breathing circuit from a cylinder of compressed oxygen.
The oxygen and purified gas mix and are fed to the wearer who inhales from a breathing bag.
The excess gas is released through a relief valve.
Construction
Materials
All materials used should have adequate mechanical strength, durability and heat resistance, fire resistance, etc.
Exposed parts of the apparatus, excluding cylinders,  shall not be made of such materials which give rise to frictional sparks  capable of igniting flammable gas mixtures.

Materials that may come into contact with the skin shall be non-staining, soft, pliable and shall not contain known dermatitic substances.
Strength and Resistance in Water
The apparams shall be sufficiently robust to withstand the rough usage.
It will not be rendered defective if temporarily submerged in water.
Separation of Parts
The design and construction of the apparatus shall permit its component parts to be readily separated for cleaning, examination and testing.
The couplings required to achieve this shall be readily connected and secured, where possible by hand.
Any means for sealing used shall be retained in position when the joints and couplings are disconnected during normal maintenance.
Adjustable Parts
All parts requiring manipulation by the wearer shall be readily accessible and easily distinguishable from one another by touch.
All adjustable pans and controls shall be so constructed that their adjustment is not liable to accidental alteration during use.
 
Mass
The mass of the breathing apparatus, fully charged and ready for use shall not exceed 16.0 kg, (including breathing fittings).
Leak Tightness
The apparatus shall be so designed and constructed as to prevent ingress of the eternal atmosphere within the limits set out in this standard.
Cleaning and Decontamination
  The design of the apparatus shall be such as to facilitate cleaning.
Facepiece
Facepieces are not suitable for persons with beards. Unless special fabrications are made.
They will also not be suitable for wearers with spectacles, having side arms. In such situations, a mouthpiece with nose clips should be preferred.
Where face pieces are used, they shall be designed to meet the following requirements.
The component parts, 1:1 best edition replica watches including breathing tubes, shall withstand a test under water at an air pressure or 1.7 KN/m and shall be proved from leakage.
Face piece shall cover the eyes, nose, mouth and chin and shall provide adequate sealing on the face of the wearer of the breathing apparatus against the outside gas.
 

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