Confined space entry

Air quality is an important environmental concern for all people. It is also a safety concern for many underground workers such as miners and anybody who has a reason to be working in a sewer. Chemicals plant and refinery workers must also enter confined spaces such as storage tanks and reactor vessels for cleaning or other maintenance activities. On board ships such as LNG transporters or crude oil tankers, there are also reasons to enter storage tanks in the hold of the ship.

All of these confined spaces may present a safety risk through the presence of toxic gases. In some cases, such as the presence of hydrogen sulphide in sewers, our noses will warn us of danger. In other cases, such as the presence of nitrogen purge gas in a reactor tank, our senses have no means of detecting the lack of oxygen and the danger can be immediate.

The two main defences against these hazards are:

1. To use gas sensors to detect flammable gases, toxic gases and oxygen deficiency. These may be either portable and carried by the operator or fixed in the location of risk. These safety gas detectors require various test and calibration gas mixtures to ensure that they are functioning as they should be.
2. To use breathing apparatus so that the operator has a supply of clean fresh air to breathe. Air may be piped to the operator from a large storage bank if they will be close to a single point for a prolonged period of time. Alternatively, the operator can carry an air cylinder on their back, like a diver.