Confined space entry is one of the most dangerous activities on any worksite. Tanks, silos, pits, vaults, pipes and trenches can harbour invisible atmospheric hazards that incapacitate or kill within seconds. Every year in Australia, workers die in confined spaces because the entry was rushed, the atmosphere was not tested or rescue planning was treated as an afterthought.
This guide walks through the full confined space entry procedure, from risk assessment and permit completion through to atmospheric testing, ventilation, rescue arrangements and closeout. It applies to all confined space work, whether you are cleaning a tank, inspecting a sewer main or performing maintenance inside a vessel.
Before you start
Gather a confined space entry permit, a calibrated multi-gas detector (checking O2, LEL, H2S and CO at a minimum), mechanical ventilation equipment, rescue equipment and all required PPE. Confirm the gas detector has been calibrated within the manufacturer-specified interval, typically every 6 months or as shown on the gas detector calibration log.
Before any entry, the first question should always be: can the work be done from outside the space? Many confined space fatalities occur during tasks that could have been performed remotely using cameras, long-reach tools or robotic systems. If entry is unavoidable, a competent person must complete a risk assessment and authorise the entry permit.
Step-by-step entry procedure
1. Identify the confined space and assess the risks
Confirm the area meets the regulatory definition of a confined space: it is enclosed or partially enclosed, not designed for continuous human occupancy, has restricted means of entry or exit, and presents a risk of hazardous atmosphere, engulfment or other serious hazard. Complete a confined space risk assessment covering atmospheric hazards, engulfment, mechanical and electrical hazards, biological risks, thermal extremes and the physical constraints of the space.
2. Isolate and lock out all energy sources
Isolate all pipework, electrical supply, mechanical drives and process feeds connected to the space. Apply lockout/tagout procedures to every energy source. Blank or disconnect piping to prevent introduction of gases, liquids or solids during the entry. Verify isolation by attempting to operate each isolated system.
3. Complete the entry permit
The permit must capture the space location, date, permitted time window, names of all entrants, the standby person, atmospheric readings, isolation register references, the rescue plan reference and emergency contact numbers. The permit must be authorised by a competent person before any entry occurs. Under no circumstances should entry proceed without a signed, current permit.
4. Test the atmosphere
Using a calibrated multi-gas detector, test at multiple levels within the space (top, middle and bottom) because gases stratify by density. Safe entry limits are typically: oxygen 19.5% to 23.5%, LEL below 5%, H2S below 10 ppm and CO below 30 ppm. Record all readings on the permit. Do not enter if any reading falls outside safe limits.
| Gas / parameter | Safe entry limit | Action if exceeded |
|---|---|---|
| Oxygen (O2) | 19.5% to 23.5% | Do not enter; ventilate and re-test |
| Flammable gas (LEL) | Below 5% | Do not enter; identify source and ventilate |
| Hydrogen sulphide (H2S) | Below 10 ppm | Do not enter; ventilate and re-test |
| Carbon monoxide (CO) | Below 30 ppm | Do not enter; ventilate and re-test |
5. Establish ventilation
Set up mechanical ventilation to supply fresh air into the space and dilute or displace contaminants. Position the fan and ducting to create effective airflow throughout the entire space, not just near the entry point. Allow sufficient purge time before entry. Continuous ventilation must run for the entire duration of the entry. Never rely on natural ventilation alone.
6. Set up rescue arrangements
Position rescue equipment at the entry point before anyone enters. This includes a rescue tripod or davit arm, full body harness with retrieval line, self-contained breathing apparatus (SCBA), a stretcher suitable for the space geometry and a first aid kit. Check the rescue equipment checklist to confirm everything is serviceable. The rescue team must be briefed, competent and immediately available for the entire entry duration.
7. Brief the team and enter
Conduct a pre-entry toolbox talk covering the specific hazards, permit conditions, communication protocols, emergency procedures and abort criteria. Confirm each entrant understands their role. The standby person must remain at the entry point for the entire duration, maintain a log of who is inside and never enter the space to attempt rescue.
8. Monitor continuously and close out
Entrants wear personal gas monitors that alarm if conditions deteriorate. The standby person maintains visual or voice communication at all times. If atmospheric conditions change, ventilation is interrupted or any other hazard is identified, all entrants must exit immediately. Once work is complete, confirm all entrants have exited, retrieve tools and equipment, and formally close out the permit with the completion time and any issues encountered.
Atmospheric hazards explained
Atmospheric hazards are the leading cause of confined space fatalities. They are particularly dangerous because they are often invisible and odourless. The three primary atmospheric risks are:
- Oxygen deficiency - caused by displacement by other gases, consumption by rusting metal, microbial activity or absorption by the stored product. Oxygen levels below 16% cause impaired judgement; below 10% cause unconsciousness within seconds.
- Toxic gases - hydrogen sulphide (common in sewers and tanks), carbon monoxide (from engines or combustion), and other process-specific gases can incapacitate or kill at low concentrations.
- Flammable atmospheres - vapours from fuels, solvents or decomposition can reach explosive concentrations inside an enclosed space, creating an ignition risk from any spark source.
Roles and responsibilities
| Role | Responsibility |
|---|---|
| Entry supervisor / issuer | Authorises the permit, verifies controls, cancels the permit if conditions change |
| Entrant | Wears PPE, monitors personal gas detector, exits immediately if alarm triggers or conditions change |
| Standby person (attendant) | Stays at entry point, tracks entrants, maintains communication, initiates rescue if needed, never enters the space |
| Rescue team | Trained in confined space rescue, immediately available with SCBA, tripod and retrieval equipment |
Regulatory requirements
In Australia, the WHS Regulations (Part 4.3, Division 3) set detailed requirements for confined space work, including risk assessments, entry permits, atmospheric testing, signage, training and emergency procedures. AS 2865 provides the code of practice for safe working in a confined space. Each state and territory adopts these through their own WHS legislation.
In the US, OSHA 29 CFR 1910.146 (general industry) and 29 CFR 1926 Subpart AA (construction) regulate permit-required confined space entry. Requirements include written programs, atmospheric testing, attendants, rescue provisions and entry permits. Employers must evaluate the workplace to identify all permit-required confined spaces.
In the UK, the Confined Spaces Regulations 1997 require employers to avoid confined space entry where reasonably practicable, follow a safe system of work when entry is necessary, and have emergency rescue arrangements in place. The HSE Approved Code of Practice (L101) provides detailed guidance.
Going digital with MapTrack
Paper-based confined space permits introduce risk. They get lost, damaged by weather or left incomplete. With MapTrack, teams complete digital confined space entry permits on a phone or tablet with mandatory fields, timestamped atmospheric readings and photo evidence. No field can be skipped, and the permit is stored centrally the moment it is submitted.
Atmospheric readings are logged digitally with the time and location, creating a continuous record that auditors and regulators can review. When a permit expires or conditions change, MapTrack triggers automated alerts so the entry supervisor is notified immediately. All permits link back to your compliance records, giving you a complete audit trail for every confined space entry on every site.
