Hydrogen Gas and Flame Resistant PPE: Closing the Safety Gap

Hydrogen is moving from pilot projects to live infrastructure. Production, blending and transmission programmes are accelerating across utilities, transport and industrial sectors. As this shift gathers pace, a critical question remains insufficiently answered. Is the flame resistant protective clothing currently used in natural gas environments suitable for hydrogen?

Existing guidance generally treats hydrogen and natural gas in a similar way when specifying heat and flame PPE. Garments compliant with standards such as ISO 11612 for heat and flame protection and ISO 1149-5 for antistatic performance are commonly considered appropriate. This approach assumes that a change in fuel does not materially alter the level of protection required from the garment. That assumption deserves closer examination.

The purpose of protective clothing in explosive atmospheres is well established. PPE must resist ignition and not continue to burn after exposure. It must insulate the wearer from thermal energy to reduce burn injury. It must also prevent static accumulation that could act as an ignition source. These principles remain valid regardless of the fuel involved. The question is whether hydrogen’s combustion profile exposes limitations in how current garments are tested and certified.

Hydrogen is not simply another flammable gas. Its physical and combustion characteristics differ significantly from methane and propane. It has a much wider flammability range in air. It requires a far lower minimum ignition energy. Its burning velocity is higher, increasing the potential for rapid flame acceleration and, in certain geometries, transition from deflagration to detonation. These properties alter both the likelihood and severity of certain fire and explosion scenarios.

At first glance, hydrogen may appear less severe in some respects. Its combustion produces little soot and emits significantly less radiant heat than hydrocarbon flames. Hydrogen flames are almost invisible in daylight and produce limited infrared radiation compared to methane or propane. However, this lower radiative output does not equate to lower hazard. The flame temperature of hydrogen in air is higher than that of natural gas. Objects engulfed in a hydrogen flame may heat more rapidly. The flame may be harder to detect visually. Hydrogen combustion also emits ultraviolet radiation capable of causing skin and eye effects, a factor rarely addressed in PPE discussions.

Explosion behaviour introduces further complexity. Hydrogen vapour clouds can form following delayed ignition. In partially confined or obstructed environments, rapid flame acceleration can generate significant overpressures. Hydrogen is more susceptible to detonation phenomena than most hydrocarbons due to its high burning velocity and diffusivity. The resulting pressure wave and heat flux profile may differ from those typically associated with methane events.

These differences matter because PPE performance is influenced by both heat flux and exposure dynamics. Garment shrinkage, char formation, seam integrity and predicted body burn are all affected by the nature of the thermal event. A hydrogen jet flame, with high mass flow and focused energy release, may impose different stresses on fabrics compared to the propane based exposures used in standardised testing. Without hydrogen specific experimental data, it is difficult to quantify how existing garments behave under these conditions.

Current British and international standards for flame resistant clothing rely on hydrocarbon fuels for testing. Small scale ignition testing under BS EN ISO 15025 specifies commercial grade propane. Large scale instrumented manikin testing under BS EN ISO 13506-1 also specifies propane to achieve defined heat flux conditions. The standards recognise that changing the test gas can influence results. However, hydrogen is not incorporated into the test protocols.

This raises two concerns. First, if the test fuel influences flame temperature, heat flux distribution and combustion characteristics, then results obtained using propane may not fully represent hydrogen exposure. Second, most test houses and laboratory setups are not configured to handle hydrogen safely. Hydrogen embrittlement of metal components, leak risk due to its small molecular size, and the near invisibility of its flame introduce technical challenges that standard equipment may not be designed to address.

The absence of hydrogen based flammability testing means that there is limited data to compare predicted body burn outcomes under propane and hydrogen exposures. There is also little quantitative evidence regarding the effect of hydrogen jet flames on fabric shrinkage, char brittleness or seam performance. The potential impact of ultraviolet radiation from hydrogen combustion on garment durability has not been systematically evaluated. In addition, hydrogen and methane blends, which are likely to form part of transition strategies in gas networks, may produce intermediate or variable combustion characteristics that further complicate risk assessment.

None of this implies that existing flame resistant garments are inadequate. It does mean that confidence in their adequacy should be supported by evidence specific to hydrogen exposure. Where the hazard profile changes, the test regime should at least be reviewed.

A structured, scientific approach is therefore required. This begins with adapting laboratory equipment to safely handle hydrogen. Burner systems, flow control and pipework must be compatible with hydrogen to prevent embrittlement and leakage. Detection systems capable of identifying near invisible flames and ultraviolet emissions should be integrated into the setup.

Modified small scale tests could then evaluate fabric response under hydrogen ignition, including front face and bottom edge exposure. In addition to standard afterflame and afterglow measurements, quantitative assessment of char length, char brittleness and dimensional change should be recorded. These data would help identify whether hydrogen exposure produces different degradation mechanisms compared to propane.

Fabrics that perform well in small scale hydrogen tests could progress to large scale manikin trials in open air or controlled fire training facilities capable of simulating hydrogen jet flames. Comparative analysis of predicted body burn under hydrogen and propane exposures would provide evidence on whether performance margins are materially different. UV exposure effects, garment shrinkage and seam integrity should form part of the evaluation.

Where existing products meet defined performance thresholds under hydrogen testing, confidence in their suitability increases. Where deficiencies are identified, targeted material development can follow. Fibre blends, fabric weights, finishes and garment construction techniques may require refinement to address hydrogen specific exposure characteristics.

The growth of hydrogen infrastructure presents an opportunity to align PPE standards with emerging hazards before incidents drive reactive change. Hydrogen introduces a distinct combustion profile. It combines lower radiative heat with higher flame temperature, broader flammability range, lower ignition energy and potential ultraviolet emission. These factors justify careful examination rather than assumption.

The path forward is not to discard existing standards but to expand them. By incorporating hydrogen specific testing protocols and generating robust experimental data, the industry can define what “hydrogen ready” protective clothing truly means. Clear criteria, evidence based performance thresholds and updated guidance will provide assurance to operators, regulators and workers alike.

As hydrogen becomes embedded within energy systems, protective clothing must evolve with it. The goal is not to create unnecessary complexity, but to ensure that garments worn in hydrogen environments are validated against the realities of hydrogen combustion. Only through disciplined testing and transparent evidence can claims of readiness move from assumption to proof.

To request the full technical report, detailed gap analysis, and proposed testing framework, contact Dobtho. We are available to share the complete findings and discuss how to benchmark and develop hydrogen ready flame resistant uniform programmes for your organisation.