Confined Space Entry & Compliance

Confined space entry always presents a potential hazard and unnecessary accidents can be avoided by having a robust procedure in place. It is imperative to ensure that workers are fully trained and properly equipped
to work in these types of environments and an essential component of the safety equipment is a portable gas detector.

Recognise the hazards
A confined space is defined by three factors. The space must be large enough for a worker to enter. Secondly, the space cannot be designed for continuous worker occupancy. Thirdly, a confined space has limited
openings for entry and exit.

Some confined spaces may require a permit to enter, owing to the likelihood of hazards that the operator may face. For example, environments with inwardly sloping walls or sloping floors will allow gases to build up more quickly. Areas containing materials that present the potential for engulfment are also very dangerous. Regardless of whether the area is permit required or not, all confined spaces should be treated with caution.

Confined spaces may contain various gas hazards that can only be detected through testing. Oxygen (O) deficiency, Hydrogen Sulphide (H2S), Carbon Monoxide (CO) or Methane (CH4) are common hazards that can
be monitored with a portable gas detector.

An Oxygen deficient atmosphere can be the result of Oxygen displacement by a toxic or inert gas. Microbial action, oxidation caused by rusting metal, combustion and absorption can also create an Oxygen deficient environment (when the Oxygen in the atmosphere has fallen below 19.5%). At this concentration, an operator will feel drowsy, whilst less than 17% Oxygen will result in severely compromise cognitive processes and coordination and then lead to death.

The possibility of the presence of H2S gas is another confined space hazard. H2S is produced as a byproduct of rotting vegetation or matter. Although H2S smells of rotten eggs, you cannot rely on your sense of smell to alert you to this hazard; at concentrations higher than 30ppm, H2S paralyses the sense of smell. At concentrations of 500 to 700 ppm, death will occur within 30 mins to 1 hour.

It is important to be aware of the vapour density of the gas hazards that are likely to be encountered; for example, H2S is slightly heavier than air and can collect in confined spaces where there is little air movement.
Varying vapour densities means that it is essential to test at various levels in a confined space.

A confined space gas detector kit makes stratified testing easy and generally includes a multi-gas monitor with pump, 10 foot sampling hose for pre-testing (longer lengths available), spare batteries (rechargeable or
alkaline), quad-gas cylinder for bump testing and calibration with gas regulator, all conveniently contained in a rugged carrying case.

Besides H2S, the decomposition of organic waste materials can also produceMethane (CH4). Leaks in gas pipelines can be another source of CH4 in confined spaces. Although CH4 is the most commonly encountered combustible gas hazard, it is important to monitor for additional combustible gases. A combustible sensor that reads in the %LEL range is suitable formeasurement of CH4, Propane, and other common combustible gases. It is important to remember that a gas like Propane, which is heavier than air, can displace Oxygen in sumps and basements. Catalytic bead sensors require Oxygen to work, so in some instances IR sensors may be preferable.

The internal combustion engine exhaust from vehicles, pumps and compressors running in the vicinity of a confined space can also create a build-up of Carbon Monoxide (CO). A concentration of only 1,600 ppm of CO can be fatal within hours.

When working in confined spaces it is important to consider all hazards that could potentially be encountered. Taking into consideration the impact that process equipment and machinery can have is also essential. For example, an Oxygen enriched environment can be created when an Oxy-acetylene torch’s supply perishes, producing Oxygen. Oxygen enrichment is very dangerous as materials may spontaneously combust. So when working in confined space always ensure that all factors have been taken into account.