A diver’s headgear is the item of equipment the rest of the spread is built around. It is the primary life support interface, the communications link to the supervisor, and often the last line of physical protection between the diver and the structure. Select it on weight and price alone and the consequences surface later, in gas planning that will not sustain the dive, communications that fail in the conditions you are working in, or an item of plant that cannot be certified when an inspector asks for the paperwork. Selecting headgear is a compliance decision as much as an operational one.
In short: Under the Diving at Work Regulations 1997 and HSE Approved Code of Practice L104, surface supplied diving is the preferred method for the vast majority of inland and inshore commercial diving operations. As a minimum the diver must wear a full face mask fitted with either an oral nasal or a mouthpiece, carry an independent secondary source of breathing gas, be tended on a lifeline, and have appropriate two-way communication with the surface. Whether a full face mask or a heavy duty helmet best meets those requirements is determined by depth, breathing gas, water quality, thermal load and physical hazard.
What the Regulations Require Before Any Product Comparison
The Diving at Work Regulations 1997 place the main duties on the diving contractor. Regulation 6(3)(b) requires that suitable and sufficient plant is available whenever needed, and regulation 6(3)(c) that it is maintained in a safe working condition. The Approved Codes of Practice set out what that means in practice. For civil engineering, marine related projects and fish farming inland and inshore, that is L104 (Second edition, 2014). Offshore projects fall under L103 instead. An Approved Code has a special legal status: if you are prosecuted and it is proved you did not follow its relevant provisions, you must show you complied some other way, or a court will find you at fault.
| Requirement | What L104 states | Clause |
|---|---|---|
| Preferred method | Surface supplied breathing apparatus is the preferred method, because it is considered the safest for the vast majority of operations covered. | Para 42 |
| Minimum headgear | The diver wears a full face mask, fitted with either an oral nasal or a mouthpiece. | Para 43(a) |
| Secondary gas | The diver carries an independent secondary source of breathing gas, for example a bail-out cylinder. | Para 43(b) |
| Lifeline | There is a lifeline from diver to surface, and it should be tended. | Para 43(c) |
| Communications | Appropriate two-way communication with the diver is provided. | Para 43(d) |
| Standards | All items of equipment worn by the diver should comply with appropriate national, European or international standards. | Para 97 |
| Standby diver | The standby diver need not be wearing a mask or helmet, but that equipment should be immediately to hand. | Para 84 |
| Standby method | Where surface supplied apparatus is in use, it should also be used by the standby diver. | Para 85 |
Two points are routinely misread. First, L104 sets a floor of a full face mask, not a helmet. A helmet exceeds that floor comfortably, but the Code does not mandate one by name, so the decision sits with the risk assessment. Second, paragraph 97 is what pulls the EN standards into play: suitability can be established by a competent person’s evaluation, manufacturer statements, physical testing or previous use in similar circumstances, but the equipment worn by the diver still has to meet a recognised standard.
The Standards Behind the Marking
Surface supplied headgear is covered by a small family of European standards. The split between demand and free flow apparatus matters, because it decides both which standard applies and how much gas the operation consumes.
| Standard | Scope | Applies to |
|---|---|---|
| EN 15333-1 | Open-circuit umbilical supplied compressed gas diving apparatus. Part 1: Demand apparatus. | Surface supplied demand helmets and masks |
| EN 15333-2 | Open-circuit umbilical supplied compressed gas diving apparatus. Part 2: Free flow apparatus. | Free flow helmets and hats |
| EN 250 | Open-circuit self-contained compressed air diving apparatus. Requirements, testing and marking. | SCUBA-derived full face masks and second stages |
| EN 14143 | Self-contained re-breathing diving apparatus. | Rebreather-based systems |
| EN 12021 | Compressed gases for breathing apparatus. | Gas quality feeding the headgear |
EN 15333-2 repays close reading, because its scope carries hard boundaries. It applies to a maximum depth of 50 metres for apparatus using air, oxygen, oxygen in nitrogen, oxygen in helium or trimix; to water temperatures between 4 and 34 degrees Celsius; and to environmental temperatures between minus 20 and 50 degrees Celsius, in each case unless the manufacturer specifies otherwise. If your operation sits outside those envelopes, the manufacturer has to have declared it.
CE, UKCA and what the marking tells you
Diving headgear is personal protective equipment, and under Regulation (EU) 2016/425 it falls into Category III, the category reserved for risks that may cause death or irreversible harm. Annex I lists oxygen-deficient atmospheres and drowning among them. Category III carries the heaviest conformity route: EU type-examination followed by either supervised product checks at random intervals or an audited production quality system, so approval is subject to continuing surveillance rather than a single test.
Two consequences are worth knowing, because both are checkable. On Category III equipment the CE marking must be followed by the identification number of the notified body, so a bare CE mark with no number after it should prompt questions. And the manufacturer must either supply the Declaration of Conformity with the equipment or tell you the address where it can be read, so you are entitled to see it.
In Great Britain the same Regulation applies as amended to apply in GB, with a parallel vocabulary: a harmonised standard becomes a designated standard, a Notified Body becomes an Approved Body, and CE marking becomes UKCA marking. Northern Ireland does not recognise UKCA and continues to use CE or the UKNI mark. In either regime, conformity is presumed only where the reference to the standard has been published, and that status can change. A standard number on a datasheet is not by itself evidence of current conformity.
Matching the Headgear to the Operation
Depth and breathing gas
L104 sets the maximum depth for breathing mixtures of compressed air or oxygen and nitrogen at 50 metres of water, with a recommended maximum partial pressure of oxygen of 1.4 bar. Where decompression tables call for a higher partial pressure, the risk assessment has to account for the increased risk of oxygen toxicity. Separately, and coincidentally at the same figure, EN 15333-2 applies only up to 50 metres. Depth also drives the gas calculation: L104 requires quantities for primary, secondary and therapeutic supplies to be calculated at planning stage with allowances for leakage, wastage and contingencies, and diving to stop if the available quantity falls below the planned minimum. Free flow apparatus delivers gas continuously rather than on inhalation, so a demand or free flow decision changes the compressor, quad and panel capacity the project needs.
Contaminated water
Where the risk assessment identifies contamination, the degree of isolation between diver and water becomes the dominant selection driver. L104 requires the diving project plan to identify the methods put in place to protect the diver, and points to IMCA D 021, Diving in contaminated waters, for detailed guidance.
Thermal load
L104 requires appropriate personal protective equipment and procedures to maintain thermal balance, with DMAC 08, Thermal stress in relation to diving, as the reference guidance. Cold water performance is not a property of the headgear alone. The OTS Spectrum full face mask we supply is designed for water temperatures below 10 degrees Celsius, but its cold water performance is ultimately dictated by the second stage regulator fitted to it. Check what the manufacturer has declared rather than assuming the shell defines the envelope.
Physical hazard and task
The work itself is the last driver and often the decisive one. L104 restricts self-contained apparatus to simple tasks such as visual inspection in clear water with no risk of entrapment. Heavy construction, work around structures, overhead environments and anything involving cutting, welding or hydraulic tooling raises impact and entanglement risk, and that is where the rigidity and coverage of a helmet earns its weight penalty.
| Operation type | Dominant selection drivers | Key references |
|---|---|---|
| Shallow inspection, clear water | Manoeuvrability, low task loading, no entrapment risk | L104 paras 43, 79 |
| Civil engineering and construction | Impact protection, entanglement, tool interaction, duration | L104 paras 42, 43, 97 |
| Contaminated or polluted water | Isolation from the water, sealing, decontamination regime | L104 para 49, IMCA D 021 |
| Cold water, long duration | Declared temperature envelope, second stage performance | L104 para 69, DMAC 08, EN 15333-2 |
| Deeper air and nitrox work | Depth limit, partial pressure of oxygen, gas volume | L104 paras 45, 61, IMCA D 048 |
Headgear Choice Constrains the Rest of the Spread
Pricing headgear in isolation is a mistake. The choice sets requirements that run back up the umbilical to the panel and the gas supply.
- Gas supply. Each diver’s breathing gas must be of the correct composition, temperature and flow for all foreseeable situations, with independent primary and secondary supplies arranged so an interruption to one diver does not affect another. Each diver must also carry an independent reserve, quickly switchable into the breathing circuit, with enough capacity to reach a place of safety. That reserve is normally a bail-out cylinder.
- Communications. All divers in the water should have direct voice contact with the supervisor and the supervisor with them. L104 states a clear preference for hard-wired systems, because through water systems can be degraded by acoustic shadow, sediment, air bubbles and turbulence, and recommends practical testing in the operational location. There are also benefits to recording communications until the dive is complete.
- Umbilical and panel. The connector arrangement on the helmet or mask has to match the umbilical build and the panel outlets. For inland and inshore work, ADC 5/95 sets out the minimum criteria for a surface supply air diving panel, and L104 references it directly.
- Standby provision. Where surface supplied apparatus is in use, the standby diver should use it too. In practice that means a second, compatible set of headgear rigged and immediately to hand, not a spare of a different type.
Certification, Examination and Whole Life Cost
Headgear is diving plant, and diving plant carries a documentation burden that outlasts the purchase. L104 requires plant to be maintained, examined and tested regularly, and inspected immediately before use by a competent person. The diving contractor must run a planned maintenance system accounting for passage of time and usage alongside the manufacturer’s recommendations, recording the item, the date of check, any limitations on use, any repairs or modifications, and the signature of the competent person. The dive team then carries out its own pre-dive visual inspection.
The industry reference for the certification regime is IMCA D 018, Code of Practice for the Initial and Periodic Examination, Testing and Certification of Diving Plant and Equipment, currently Revision 3 (June 2026). For the bail-out cylinder, AODC 037 covers periodic examination, and L104 warns that cylinders used underwater can suffer accelerated corrosion. This regime is what turns a purchase price into a whole life cost, and it is the part most often missing from a comparison. Before committing, establish the following.
- The Declaration of Conformity, the standards claimed on it, and the notified or approved body number.
- The manufacturer’s recommended examination and test intervals, and what each interval involves.
- Availability and lead time for spares and the wear items replaced at every service.
- Whether your own technician can be trained to service the unit, or whether it must return to the manufacturer.
- For used equipment, the full certification history and the date of the last examination.
How We Can Help
At iSubC we supply commercial diving equipment for sale or hire, and our sale stock covers both new and used items. Our Helmets & Masks range includes the Drass D-One modular helmet alongside full face masks from Ocean Technology Systems and others, and we can advise on how a configuration sits alongside your existing umbilicals, communications and control panels rather than treating the headgear as a standalone purchase. There is no single right answer between buying and hiring, or between new and used. Used headgear can be entirely sound where the examination history is complete and unbroken; where it is not, treat the item as unproven whatever its condition.
We understand commercial diving is fast paced and time critical, so we pride ourselves on extensive high quality stock, honest and realistic delivery timeframes, and flexible operating procedures across global time zones. We ship worldwide by sea or air freight, door to door. To talk through a requirement, no matter how big or small, call +44 1253 767 788, email info@isubc.com, or request a quote and we will come back to you.
