Introduction & Main Types Of Respirators

Breathing air which contains toxic substances or an atmosphere which has insufficient oxygen to support human life is a very real and common hazard in industry. Hazards include harmful dusts, fogs, fumes, mists, gases, smokes, sprays, common vapours and lack of oxygen.

The aim is to work in air that is clean and safe. Prevention or control of exposure must always be investigated before using respiratory protection. There are four ways this can be done:

  • Avoiding the use of toxic or irritant substances.
  • Totally enclosing the process.
  • Partially enclosing the process and using local exhaust ventilation.
  • Installing adequate ventilation systems and engineering controls.

In emergencies or general situations where these principles cannot be applied, a respirator must be worn. Some substances irritate the eyes and skin, others can be absorbed through the skin. Anyone entering an atmosphere containing materials with these properties requires whole body protection.

Main Types of Respirators

Air Purifying Respirators

These respirators draw inhaled air through a purifying filter.
They range from simple disposable cup masks and low-
maintenance half mask facepieces with cartridges and/or
filters, to the more complex powered air-purifying respirators
with full facepiece and hoods.

There are two main types:

  • A particulate respirator uses a filter to capture dusts, mists and fumes. Filters do not protect against gases or vapours and generally become less effective as particles accumulate on the filter and plug spaces between the fibres.
  • A gas and vapour respirator employs chemical cartridges or canisters to remove hazardous gases or vapours from the air. They do not protect against airborne particles. Made to protect against specific gases or vapours, they provide protection only as long as the cartridge's absorbing capacity is not depleted.

There are combinations of both types available. These respirators do not give protection against a lack of oxygen and should only be used when the type and concentration of the contaminant is known.

Supplied Air or Airline Respirators

Supplied air respirators deliver a supply of clean air from a source outside the contaminated area. Clean air can be supplied either at normal atmospheric pressure or from a higher pressure source, e.g. compressed air supply line or independent supply.

Self-contained Breathing Apparatus

This type of respirator uses a supply of clean air from a source that is carried by the wearer, e.g. compressed air bottle. It is used to give protection against dangerous breathing hazards such as lack of oxygen, very poisonous contaminants or when the type of hazard is unknown.