What is a hazardous area keyboard?
A hazardous area keyboard is a keyboard, keypad or pointing device that has been assessed and certified by a competent body for use in a defined explosive atmosphere. The certification states which zone it can be used in, which gases or dusts it is suitable for, and the maximum surface temperature it will reach. Without that certification the device is not suitable for the zone, however well sealed or rugged it is.
Explosive atmospheres arise in refineries, chemical plants, fuel and gas handling, paint and coating areas, grain and flour handling, woodworking, pharmaceutical powders, and some offshore and marine locations. The problem for an input device is ignition: a spark, a hot surface or stored electrical energy in the wrong place can set off a flammable mixture. Certification addresses exactly that.
How are hazardous areas divided into zones?
In Great Britain the zones are defined in Schedule 2 of the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR). Zones are based on likelihood, not on how bad an explosion would be. Gas, vapour and mist are covered by Zones 0, 1 and 2. Combustible dust is covered by Zones 20, 21 and 22.
| Zone | Atmosphere | Likelihood of an explosive atmosphere |
|---|---|---|
| 0 | Gas, vapour or mist | Present continuously, or for long periods, or frequently |
| 1 | Gas, vapour or mist | Likely to occur occasionally in normal operation |
| 2 | Gas, vapour or mist | Not likely in normal operation; if it occurs, only for a short time |
| 20 | Combustible dust cloud | Present continuously, or for long periods, or frequently |
| 21 | Combustible dust cloud | Likely to occur occasionally in normal operation |
| 22 | Combustible dust cloud | Not likely in normal operation; if it occurs, only for a short time |
The zone is not something a supplier chooses. The employer, as duty holder, classifies the area through a risk assessment and records it. The keyboard is then selected to suit that classification.
Which equipment categories are allowed in which zone?
Schedule 3 of DSEAR sets the equipment categories that suit each zone, unless the risk assessment finds otherwise. Categories come from the equipment directive and its GB equivalent. Category 1 gives a very high level of protection, Category 2 a high level, and Category 3 a normal level.
| Zone (gas / dust) | Equipment category allowed |
|---|---|
| 0 / 20 | Category 1 |
| 1 / 21 | Category 1 or 2 |
| 2 / 22 | Category 1, 2 or 3 |
Each category has a G (gas) or D (dust) suffix in the marking. A device marked for gas only is not automatically suitable for a dust zone, and the reverse is also true.
How do ATEX categories compare with IECEx protection levels?
IECEx certifies equipment to the IEC 60079 series and expresses suitability as an equipment protection level (EPL). The two systems map to each other as follows.
| ATEX category | IECEx EPL (gas) | IECEx EPL (dust) | Typical zone |
|---|---|---|---|
| 1G / 1D | Ga | Da | 0 / 20 |
| 2G / 2D | Gb | Db | 1 / 21 |
| 3G / 3D | Gc | Dc | 2 / 22 |
The mapping is a guide to reading markings, not a licence to treat one scheme as another. A product certified under one route still needs the documentation your jurisdiction and your site require. How to read an Ex marking explains each element of a full marking string.
What does UKEX mean, and is CE marking still accepted?
Equipment placed on the Great Britain market for potentially explosive atmospheres is governed by the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016 (SI 2016/1107). Amendments made in 2019 introduced UK marking, so UKEX-certified equipment carries the UKCA mark alongside the Ex symbol, and, for most Category 1 and 2 equipment, conformity assessment involves a UK approved body.
The government has extended recognition of CE marking on the Great Britain market. The detail of what is covered and for how long is set out in official guidance that has been revised more than once, so we do not restate it here. Before you buy, check the current gov.uk guidance, or ask the supplier to state in writing which marking route the product follows and which declaration of conformity applies.
Is a North American Class and Division approval the same thing?
No. North America classifies hazardous locations by Class (the type of hazard) and Division (how often it is present), under a separate set of standards and approval bodies. A Class I Division 2 approval, for example, is a North American approval. It does not make a device certified for a Zone 2 location in the UK or EU, and it is not a UKEX, ATEX or IECEx certification. Where the same site uses both schemes, treat each approval on its own terms. The difference between the two safety concepts is covered in intrinsically safe vs non-incendive keyboards.
It is the whole system, not just the keyboard
Specifying a certified keyboard is necessary but not sufficient. These points decide whether the installation is acceptable:
- Protection concept and barriers. An intrinsically safe keyboard works by limiting energy, and it relies on associated apparatus, such as a barrier or galvanic isolator, installed in the safe area. The barrier’s output parameters must be compatible with the keyboard’s input parameters in the certificates.
- Where the PC sits. The computer is often outside the hazardous area, with only the keyboard inside. If the PC must be in the zone, it needs its own suitable certification or enclosure.
- Cable and connector. The cable length, type and capacitance and inductance can be part of the safe limits. A cable swap or an extension can invalidate the assessment.
- Ambient temperature. The marking includes an ambient temperature range. Operating outside it takes the equipment outside its certified conditions, so it can no longer be relied on as suitable.
- Surface temperature against the substance. The temperature class or maximum surface temperature must be below the ignition temperature of the gas or dust present.
- Gas group. The device’s gas group must cover the substance in the zone.
- Conditions of use. An X at the end of a certificate number means special conditions apply. They must be read and followed.
- Installation and inspection. Installation, maintenance and inspection by competent people is part of keeping the equipment compliant.
The risk assessment and the duty holder decide what is suitable for the location. Neither a supplier’s brochure nor a keyboard’s rugged build can replace that decision.
Who decides what is suitable?
Under DSEAR the employer is the duty holder. The duty holder carries out the risk assessment, classifies the areas into zones, and records the result, including the zone classification, as part of its DSEAR risk assessment. Suppliers, installers and certifying bodies all contribute information, but none of them takes over that responsibility. In practice the decision follows a sequence:
- Identify the flammable substances and whether they can form an explosive atmosphere.
- Classify the area into zones, based on the likelihood of that atmosphere.
- Select equipment whose category or EPL, gas or dust group and temperature rating suit each zone and substance.
- Check the whole installation, including interfaces, cables, barriers and the location of the computer.
- Install, inspect and maintain it, and keep the documents.
A change to the process, the substances, the ventilation or the layout can change the zone. When that happens, the equipment choice needs to be reviewed. A keyboard that suited the old classification may not suit the new one.
Which mistakes come up most often?
- Treating a high IP rating as explosion protection. The two are unrelated tests for unrelated hazards.
- Reading “intrinsically safe” on a datasheet as meaning ATEX or IECEx. The term is also used in North American approvals. The marking and certificate show which scheme applies.
- Forgetting the dust. A device certified for gas is not automatically certified for dust, and the reverse also holds.
- Using the keyboard outside the stated ambient range. Cold stores, outdoor sites and hot process areas can fall outside the marked range.
- Swapping the cable or adding an extension. Cable length and parameters can form part of the safe limits.
- Ignoring the special conditions. An X on the certificate number means conditions that must be followed.
- Assuming zone numbers translate directly to Divisions. They are separate systems.
An uncertified keyboard is never suitable
IP ratings, stainless steel construction, military test reports and sealed membranes do not demonstrate explosion protection. A keyboard may be waterproof and still be a source of ignition. Equipment in a classified zone needs a certification that covers that zone. DSEAR does let the duty holder’s risk assessment depart from the standard equipment category in specific, documented cases, but that is a competent person’s decision, not a reason to fit an uncertified keyboard. Do not accept a verbal statement that a keyboard is “safe for hazardous areas”. Ask for the certificate.
What to check on the datasheet and certificate
- The full Ex marking, including group, category, gas or dust letter, protection concept, gas or dust group, temperature class or maximum surface temperature, and EPL.
- The scheme named on the certificate: ATEX, UKEX, IECEx, or a combination. Request the certificate numbers.
- Whether the certificate number ends in X, and what the special conditions are.
- The ambient temperature range for which the marking is valid.
- Whether the keyboard needs a barrier or isolator, and its permitted input parameters.
- Permitted cable type and length, and whether the cable is fixed or detachable.
- The marking route for Great Britain: UKCA, or the CE basis for placing it on the market.
- The suitability for dust, if relevant, as well as gas.
- The name of the certifying body, so the certificate can be verified with it or on the IECEx online register.
What to tell us for a quote
Tell us the zone, the substances present with their gas or dust group and ignition temperature, the ambient temperature range, the type of interface, where the computer will be, and the scheme your site requires. With that, we can check suitability. Our ATEX keyboards, intrinsically safe keyboards and non-incendive keyboards categories list models by the approval they carry; ask us if you need a different format. For the wider picture of standards across ingress, impact and military testing, see the standards cheat sheet.
Sources and standards
- The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR), Schedules 2 and 3
- The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016 (SI 2016/1107)
- HSE guidance on hazardous area classification and DSEAR
- Directive 2014/34/EU (ATEX equipment directive)
- IEC 60079 series, Explosive atmospheres
- IECEx System, certification of equipment for explosive atmospheres
Related guides and ranges
- How to read an Ex marking on a keyboard (Ex ib IIC T4 Gb explained)
- Intrinsically safe vs non-incendive keyboards: ATEX and Class/Division compared
- Hazardous-area keyboards: zones, Class/Division and certification
- Keyboards for oil, gas and chemical plants and hazardous areas
- Standards cheat sheet for industrial keyboards and mice
Frequently asked questions
Can I use a normal keyboard in a Zone 2 area?
No. An ordinary office keyboard has no hazardous-area certification and should not be used in a Zone 2 area. Zone 2 is where an explosive atmosphere is not likely in normal operation and, if it occurs, lasts only a short time. Equipment there needs a certification that covers the zone, Category 3 (gas) or EPL Gc or better. DSEAR lets the duty holder’s risk assessment depart from that in specific, documented cases, but that is a competent person’s decision, not a way round certification.
What is the difference between Zone 1 and Zone 2?
Zone 1 is where an explosive gas atmosphere is likely to occur occasionally in normal operation. Zone 2 is where it is not likely in normal operation, and if it occurs it will only exist for a short time. Zone 1 therefore needs equipment with a higher level of protection, Category 2 or better, than Zone 2.
What is the difference between ATEX, UKEX and IECEx?
ATEX is the European Union scheme, UKEX is the Great Britain scheme under SI 2016/1107 with UKCA marking, and IECEx is an international certification scheme. They use similar technical standards and similar marking, but they are separate legal or certification routes. Check which one your site, your insurer and your risk assessment require.
Is CE-marked ATEX equipment still accepted in Great Britain?
The government extended recognition of CE marking on the Great Britain market, so CE-marked equipment can still be placed on that market in defined circumstances. The scope and dates are set in the current official guidance, which changes. Read it directly, or ask the supplier to confirm the marking route in writing.
Do I need a barrier for a hazardous area keyboard?
If the keyboard is certified as intrinsically safe, it normally connects through an associated apparatus such as a barrier or isolator that sits in the safe area, and the certificate states the limits. Other protection concepts may not need one. The keyboard certificate and the system documentation tell you which applies.
Is an IP rating the same as an explosion protection rating?
No. An IP rating describes ingress of dust and water. Explosion protection describes whether the equipment can ignite a surrounding explosive atmosphere. A keyboard can be IP68 and still be unsuitable for a hazardous zone, because the two are tested to different standards for different hazards.
