A Guide to Reducing the Risks of Working in Confined Spaces

Confined spaces present some of the most challenging and hazardous conditions for industrial professionals. From oxygen-deficient environments to the presence of flammable vapours and toxic gases, the dangers are real, and too often, fatal.

According to the UK Health and Safety Executive (HSE), a number of people are killed or seriously injured in confined spaces every year. The HSE’s own confined space working guide makes it clear that these environments carry significant and immediate dangers. In many of these cases, not only confined space workers but would-be rescuers lose their lives due to lack of planning, training, or proper equipment.

That’s why understanding confined space hazards, ensuring proper ventilation, and using certified equipment like portable industrial ventilation fans is essential. This guide brings together key information and expert advice to help you create safer work environments – especially in hazardous area classifications where explosion risks are present.

What is a Confined Space?

The HSE defines a confined space as “any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions (e.g. lack of oxygen)”. In practical terms, a confined space typically meets three key criteria:

  1. Limited entry and exit points
  2. Poor or restricted natural ventilation
  3. Not intended for continuous occupancy by workers

These spaces can include:

  • Storage tanks
  • Boilers
  • Silos
  • Enclosed drains and sewers
  • Void spaces on ships or cargo holds
  • Ductwork
  • Poorly ventilated rooms

What’s especially dangerous is that confined spaces often don’t appear hazardous at first glance. But without the right ventilation strategy, these environments can turn deadly in moments

Why are Confined Spaces Dangerous?

A lack of oxygen in a confined space can have immediate and severe consequences.

This deficiency can occur in ways that aren’t always obvious. Certain soils, for instance, can react with atmospheric oxygen. In ships’ holds or transport vehicles, oxygen may be displaced by cargo that reacts chemically inside the space. Rust forming in steel tanks and vessels can also consume oxygen over time, gradually creating a hazardous atmosphere.

Beyond low oxygen, confined spaces can contain:

  • Poisonous gases, fumes, or vapours: which may build up in connected systems (like pipes or pits), seep in from contaminated ground, or be released from residue left in tanks.
  • High levels of dust or extreme heat: both of which can severely impair working conditions and safety.

Serious Risks Identified by the HSE

The HSE highlights several potentially life-threatening hazards in confined spaces, including:

  • Oxygen deficiency – from soil-air reactions, groundwater interacting with limestone, or rusting metal in enclosed areas.
  • Toxic gases, fumes, or vapours – accumulating in sewers, manholes, and pits, or entering via connecting pipes from contaminated land.
  • Liquids and solids – that may unexpectedly flood the space or release harmful gases. Solids like grain can form unstable blockages in silos.
  • Fire and explosion – due to flammable vapours, excess oxygen, or ignition sources.
    Residues – remaining on tank or vessel surfaces that emit hazardous vapours.
  • Dust – especially in high concentrations, such as in flour or sugar silos.
  • Excessive heat – which can raise body temperatures to dangerous levels, particularly in enclosed areas with limited airflow.

A UK HSE case study from 2023 illustrates the dangers of not properly addressing these risks. In one incident, two employees suffered burns while removing paint in a confined space aboard a yacht. It was found that flammable solvent fumes were ignited by an electric sander. There had been no confined space risk assessment conducted for entry into the confined space, and inadequate equipment selection highlighted the specific dangers of working in such an environment.

Reducing the Risks of Confined Space Work

Airflow plays a critical role in minimising the risks associated with confined space operations. Ensuring that air is effectively moved in and out of these spaces can help prevent exposure to hazardous atmospheres, improve working conditions, and ultimately save lives. 

Efficient ventilation in confined spaces serves three essential purposes:

1. Sufficient Airflow

To ensure safety, a ventilator should be capable of circulating air at a rate 20 times the volume of the confined space per hour. Before entry, it’s recommended to ventilate the space at 7.5 times its volume to purge hazardous atmospheres.

Tip: The higher the airflow capacity of the ventilator, the less time is required to make the space safe for entry.

2. Reaching the Entire Space

Pushing fresh air into a confined space is generally more effective than extracting air. Pushed air travels up to 30 times farther than exhausted air. This creates a strong, continuous airstream throughout the space, helping to displace contaminants more effectively. In contrast, extraction may leave stagnant pockets of polluted air, especially in corners or irregular spaces.

3. Avoiding Polluted Air

It’s crucial that the air being introduced is clean. To avoid circulating contaminated air back into the workspace, position the ventilator at a safe distance from the confined space and avoid placing it near exhaust points or pollution sources.

What to Look for in Confined Space Ventilation Equipment

To ensure safe and effective use, ventilation equipment for confined space operations should meet the following five key criteria:

  1. Enhances Safety: The system should provide consistent, effective ventilation and extract hazardous vapours or fumes safely.
  2. Prevents Ignition Risks: Look for units with ATEX, UKEX, and IECEx certifications to guarantee the equipment won’t act as an ignition source in explosive atmospheres.
  3. Quick to Deploy and Easy to Use: Time spent in a hazardous space should be kept to a minimum. Equipment should offer fast setup, intuitive controls, and a lightweight design.
  4. Built for Tough Environments: The unit must be durable enough to withstand harsh industrial conditions, with rugged construction as standard.
  5. Reliability You Can Trust: When working in potentially life-threatening environments, reliability is non-negotiable. Equipment should be proven, consistent, and trustworthy.

It’s important to note that not all ventilation equipment performs the same. Several factors influence a fan or air mover’s effectiveness, including:

  • Ducting configuration (how ducting is attached e.g. inlet, outlet, or both)
  • Ducting length
  • Bends or corners in the ducting
  • Fan size and performance

To support correct equipment selection,  SA Equip offers a quick-reference air flow performance guide, detailing essential configurations and fan performance charts.

Equipment for Safer Confined Space Working

At SA Equip, we’re more than just an equipment supplier — we’re a trusted partner in delivering safe, high-performance solutions for hazardous environments. We specialise in portable EX-certified equipment for confined spaces, including ventilation, heat, lighting, and power distribution systems.

From ready-to-deploy systems to bespoke solutions developed by our in-house R&D team, we tailor every recommendation to meet your project’s exact requirements. A flexible hire option is also available for short-term or one-off confined space work.

If you need help selecting the right solution for your confined space working project? Simply contact us or speak to a member of the SA Equip team on 0333 240 6111.

Please Note: This article is for information purposes only and does not constitute formal safety advice. Always ensure your project complies with current legislation, standards, and confined space entry procedures.