Lesson 1, Topic 1
In Progress



The diving bottle is a cylindrical, metallic reservoir capable of storing respiratory mixtures at very high pressures (200 or 300bar). The tap is screwed and sealed with a toric gasket, in order to retain the air inside the bottle (this piece will be said later).


The bottle is usually made of steel or aluminum alloy , with steel bottles being the most used in Portugal.

The most common bottle volumes are 10, 12 and 15 liters .

Usually the bottle has a plastic or rubber base, which is used so that the bottle can be placed standing when it is being loaded.


The technical characteristics of the bottle are inscribed on the upper edge of the bottle, next to the neck. In these inscriptions we can see the following elements:

  • Date of manufacture of the bottle.
  • Date of the last hydraulic test.
  • Service pressure (maximum pressure to which the bottle can be loaded).
  • Test pressure (bottle test pressure in hydraulic test).
  • Ability.
  • Weight.
  • EU (European Union) approval.


For a dive service provider to be able to carry bottles you must present a licensing of “Filling Station and Supply of Respiratory Mixtures” , which must be visible affixed.

The filling of diving bottles is always carried out by specially manufactured compressors, with purification systems that make the air suitable to be breathed in the practice of recreational diving. Compressor maintenance should be carried out on a regular basis and upon the manufacturer’s instructions.

In the event that the safety conditions of this process are met, no bottle must be filled if the date of hydraulic proof is outside the time required by law. In addition, the service pressure should never be exceeded to avoid permanent deformation of the material.

Only technicians with compressor operator certification can fill the bottles. The CMAS One Star Diver will be able to purchase the CMAS Compressor Operator diving specialty certification .


Although the bottle is the most robust element of the scaffolding, care should be taken when handling it, especially because of the fragility of the faucet which, given its protruding position, is always subject to blows that can damage it.

These are the precautions that the diver should follow:

  1. The bottle should always be lying down so as not to fall accidentally, which can wreak havoc and hurt anyone nearby.
  2. During transport (car, boat), in addition to lying down, the bottle must be jamming so as not to roll, preventing the faucet from getting bumped.
  3. The painting of the bottle should be kept in good condition, since the skinning and cuts are entrance doors for oxidation of the material. The use of nets or canvases involving the body of the bottle are adequate protections, although they have some drawbacks.
  4. The tap should be avoided too much and the air to come out quickly to prevent condensation from being left inside the bottle due to the sudden cooling that occurs when the air expands.
  5. It is advisable that every year a visual inspection of the inside of the bottle is carried out to assess the internal condition (absence or absence of rust or corrosion), an inspection which must be carried out by a qualified technician.
  6. The bottle should always be stored with some compressed air around 50bar.