An atmosphere containing less than 21 per cent oxygen by volume.


Related Terms

OXYGEN-KEROSINE BURNER

Liquid-fuel device using a mixture of oxygen and vaporized or ozonizer See ozone generator.

OXYGEN CUTTING

Any of several types of cutting processes in which metal is removed with or without a flux by a chemical reaction of the base metal with oxygen at high temperatures.

OZONE GENERATOR

Apparatus that converts oxygen, O2, into ozone, O3, by subjecting the oxygen to an electric-brush discharge. Also known as ozonizer.

OXYACETYLENE TORCH

A torch that mixes acetylene and oxygen to produce a hot flame for the welding or cutting of metal. Also known as atomized kerosine for combustion.

LUNG-GOVERNED BREATHING APPARATUS

Abreathing apparatus in which the oxygen that issupplied to the wearer is governed by the wear-er's demand.

LOW-PRESSURE TORCH

A type of torch inwhich acetylene enters a mixing chamber, whereit meets a jet of high-pressure oxygen; theamount of acetylene drawn into the flame is con-trolled by the velocity of this oxygen jet. Also known as injector torch.

HYPERBARIC CHAMBER

A specially equipped pressure vessel used in medicine and physiological research to administer oxygen at elevated pressures.

HIGH-PRESSURE TORCH

A type of torch in which both acetylene and oxygen are delivered to the mixing chamber under pressure.

IGS

Inert Gas System - a system that introduces a blanket of non-explosive or inert gas on top of cargo in a tank usually consisting of burned stack gases which are low in oxygen.
With an inert gas system, a tank is protected from exploding by introducing inert gas into it to keep the oxygen content low and to reduce to safe proportions the hydrocarbon gas concentration of its atmosphere.

Ship's IGS installation usually consists of:

  • Burner and combustion chamber
  • Oxygen Analyzer
  • Main and Aux. Blower (It is necessary to deliver the gas through the deck water seal, the non-return valve and the deck isolating valve to the cargo tanks)
  • Scrubber (It is necessary to cool and cleaning the exhaust gas from AB)
  • Deck Water Seal and Non-return valves (Are necessary for prevents backflow of cargo gases from the cargo tanks to the machinery spaces)
  • P/V Breaker (It prevents the damage of cargo tanks from high or vacuum pressure in cargo tanks)
  • pipes and valves and P/V valves
  • gas pressure regulating valve is fitted downstream of the blowers to regulate the flow of gases to the cargo tank
  • Mast Riser (It is necessary for quick relief of inert gas the pressure in cargo tanks)

ANAEROBIC

A condition in which 'free' or dissolved oxygen is not present in the water.

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