When discussing hazardous area compliance in regards to DSEAR, most people focus on obvious flammable substances—petrol, solvents, LPG. However, DSEAR applies much more broadly, and some of the most significant risks sit quietly in everyday systems that are often assumed to be “safe by default”.
Below are some commonly misunderstood areas.
- “Inert” Gases – Not Always Out of Scope
- Compressed gases such as carbon dioxide, nitrogen, and argon are routinely dismissed from DSEAR consideration because they are non-flammable.
However, DSEAR is not solely about flammability—it’s about dangerous substances and credible hazardous scenarios. These systems can still present risk through:
- Stored energy and pressure release
- Asphyxiation in enclosed spaces
- Process interactions (e.g. CO₂ enrichment in food or beverage environments)
In practice, this means compressed gas systems still warrant risk assessment, ventilation review, and procedural controls, even where zoning may not ultimately be required.
Utilities – Natural Gas Installations
A common question is why natural gas systems are included in DSEAR surveys. In short: any gas installation within the client’s control (typically downstream of the Emergency Control Valve) is assessed, regardless of whether it operates at low, intermediate, or medium pressure.
DSEAR requires this because natural gas:
- Is inherently flammable
- Can be released during normal (e.g. purging) and foreseeable fault conditions
- May create explosive atmospheres in plant rooms or enclosed spaces
So while the upstream network is managed by the transporter, on-site infrastructure—meters, regulators, pipework, and plant connections—must be assessed under DSEAR.
Dusts – More Than Just a Housekeeping Issue
Dust is often treated as a cleaning problem, not a DSEAR one. Even where materials like flour or wood dust are recognised risks, others—such as paper dust—are often overlooked because they appear too coarse or mixed in size to be hazardous.
In practice, dust on site is rarely uniform:
- Even “coarse” dust can contain fine, airborne fractions
- Settled dust can release finer particles when disturbed (e.g. cleaning or maintenance)
- Build-up often occurs in hidden areas, not just obvious surfaces
The issue is less about the material itself, and more about how it accumulates and behaves over time. What looks like a routine housekeeping concern can, under the right conditions, become a credible but unrecognised DSEAR risk.
Redundant or “Decommissioned” Tanks and Equipment
Tanks and vessels that are no longer in active use are often assumed to fall outside DSEAR—particularly if they’ve been described as “decommissioned”. However, unless they have been fully cleaned, purged, and formally taken out of service, they can still present a credible source of hazardous atmospheres.
In many cases:
- Residues of flammable liquids or gases remain inside
- Vapours can continue to accumulate over time
- Pipework connections or vents may still be open to the system
Simply isolating or abandoning a tank does not remove the risk. From a DSEAR perspective, these assets should still be considered until they are demonstrably gas-free and incapable of generating a hazardous atmosphere. In practice, this means that even redundant or rarely used tanks should remain within the scope of assessment—challenging the common assumption that “out of use” automatically means “out of risk”.
Small Containers and “Low Quantities”
A frequent misconception is that small volumes don’t matter. In reality:
- Aerosols, solvent sprays, and small chemical containers can still create localised explosive atmospheres
- Improper storage (e.g. in cabinets, workshops) can lead to a vapour build-up
- The risk is often about concentration and confinement, not about total volume
Final Thought
The common thread across all these examples is simple:
- The biggest DSEAR risks are often not the most obvious—they’re the ones that feel routine, controlled, or too small to matter.
- Compressed gases, dusts, drains, maintenance activities, and everyday plant systems can all sit just outside the spotlight, creating gaps in compliance and, more importantly, in safety.
A good DSEAR assessment doesn’t just look for hazards—it challenges assumptions about where they can and cannot exist.