Glossary - Confined Space Safety

This glossary defines terms likely be encountered in material safety data sheets (MSDS).

  • Acute: The effect caused by a single short term exposure to a high amount of concentration of a substance.
  • Asphyxiation: A condition whereby oxygen in the is replaced by an inert gas such as nitrogen, carbon dioxide, ethane, hydrogen or helium to a level where it cannot sustain life. Normal air contains 21 percent of oxygen. If this concentration falls below about 17 percent, the human body tissue will be deprived of supply of oxygen, causing dizziness, nausea and loss of coordination. This type of situation may occur in confined work places.
  • Auto-ignition temperature: The minimum temperature at which a material ignites without application or a flame.
  • Chronic (health) effect: An adverse effect on a human body with symptoms development slowly over a long period of time.
  • Chronic toxicity: A chronic effect resulting from repeated doses of or exposure to a substance over a relatively prolonged period of time.
  • Confined space: Any area that has limited opening for entry or exit that would make escape difficult in an emergency, has a lack of ventilation, contains known and potential hazard, and is not normally intended or designed for continuous human occupancy (e.g. A storage tank, manhole of collection conveyances systems in effluent treatment plants.)
  • Explosion proof-equipment: Apparatus or device enclosed in a case capable of withstanding an explosion of specified gas of vapor and preventing the ignition of specified gas or vapour surrounding the enclosure by spark, flash or explosion and operating at an external temperature so that surrounding flammable atmosphere will not be ignited.
  • Flammable: A flammable liquid is defined as a liquid with a flash point between 21 and 55 degrees Celsius. It may catch fire on contact with a source of ignition.
  • Flammable/explosion limits: Flammable / explosion limits produce a minimum and a maximum concentration of gases/vapours/fumes in air that will support combustion. The lowest concentration is known as the lower flammable/explosion limit (LEL), the highest concentration is know as upper flammable/explosion limit (UFL).
  • Hazard: A potential to cause danger to life, health, property or the environment.
  • Local exhaust: A system or device for capturing and exhausting contaminants from the air the point where the contaminants are produced (e.g. Dust in shaving and buffing).
  • Poisoning: Normally the human body is able to cope with a variety of substances within certain limits. Poisoning occurs when these limits are exceeded and the body is unable to deal with a substance (by digestion, absorption or excretion).
  • Risk: The measured probability of an event to cause danger to life, health, property or the environment.
  • Toxicity: The inherent potential of a chemical substance to cause poisoning.


Locations of visitors to this page