Ex-protected enclosures for non-explosion-proof devices

Technical classification, normative limits, and why pressure-resistant enclosures are not a mobile concept

1. Classification: What an Ex-enclosure is – and what it is not

An explosion-proof enclosure isnot an explosion-proof device, but part of arated overall system.

Explosion protection is created solely by theenclosure, not by the operating equipment used.

Normatively, it is crucial:

• The complete system is evaluatedNot the individual device inserted

• The ignition source may be present,

• Die Zündquelle darf vorhanden sein, must be safely enclosed or controlled

➡️ The equipment inside remains technicallynot explosion-proof.

2. Relevant types of ignition protection for Ex enclosures

Ex d – Flameproof enclosure

• Internal explosion permissible

• No flame or pressure transmission to the outside

• Robust construction is mandatory

• Opening in explosion hazard areanot permitted

Normative basis (safe):

• EN IEC 60079-0 – General requirements

• EN IEC 60079-1 – Flameproof enclosure "d"

• 
  

Ex p – Pressurized enclosure

• Protection through purging / overpressure

• Continuous monitoring required

• Dependence on power supply and sensors

• Increased organizational and technical effort

Normative basis (safe):

• EN IEC 60079-0

• EN IEC 60079-2 – Pressurized enclosure "p"

• 
  

Ex e – Increased safety (only supplementary)

• For terminals, connections, passive components

• No active ignition sources

• No independent protection concept for electronics

Normative basis (safe):

• EN IEC 60079-7 – Increased safety "e"

➡️ In practice, these types of ignition protection are oftencombined, which makes planning, assessment, and operationmore complex, not easier.

3. Thermal behavior – the critical point

Non-explosion-proof devices arenotdesigned for:

• defined maximum surface temperatures

• worst-case loads

• failure case considerations in the Ex environment

.

In the Ex enclosure, the boundary conditions become more stringent:

• restricted heat dissipation

• heat buildup

• local hotspots (CPU, charging electronics, power supplies)

➡️ Thetemperature class (T-class)always applies to theentire systemand must beproven through measurement.

Normative basis (safe):

• EN IEC 60079-0 – temperature limits and testing requirements

4. Stationary applications – normatively and practically sensible ✅

Typical applications:

• control and switch cabinets

• industrial PCs

• power supplies, inverters

• cameras, radio and measurement technology

Why Ex enclosures work here:

• fixed installation

• no operator access in the Ex area

• enclosure remains closed

• maintenance only in a cleared environment

➡️ Forstationary applicationsEx enclosures are state of the art and normatively manageable.

5. Mobile applications – this is where the problems arise ❌

The central question:

Who actually wants to carry and operate a pressure-resistant enclosure?

The factual answer:

Pressure-resistant enclosures are not designed for mobility.

6. Why Ex-d is not a mobile concept by design

A pressure-resistant enclosure requires:

• thick-walled housings (aluminum or stainless steel)

• massive flanges

• long ignition gaps

• screwed covers with defined torque

Consequences:

• high weight (often several kilograms)

• bulky design

• limited ergonomics

• Opening only with tools

• Opening in the Ex area is not permitted

➡️ "Portable" here usually means:theoretically transportable.

7. Opening and battery replacement in the Ex area – correctly classified

It isnot standard, that explosion-protected devices may be opened or the battery replaced in the Ex area.

On the contrary:

• Most Ex devicesare designed so thatbattery replacement

  • occurs outsidethe Ex areathe device in the Ex area

  • remainsclosedThat is:

normatively permissible

• operationally common

• safety-wise sensible

• The few exceptions

There are

a few specially designed Ex devices, where:battery replacement or defined opening procedures are allowed in the Ex area.

• Battery replacement or defined opening procedures are permitted in the Ex area.

These exceptions require:

• intrinsically safe energy concepts

• constructive separation of ignition sources

• increased testing and certification effort

➡️ They arethe exception, not the rule.

8. The systemic difference to Ex enclosures

The crucial difference remains:

• InEx devicesthe opening or battery replacement conceptis part of the certification

• InEx enclosuresany opening in the Ex area is fundamentally prohibited, because:, da:

  • the inserted device is not explosion-protected

  • the explosion protection is solely created by the encapsulation

➡️ This is not a detail, but afundamental system difference.

9. Operator responsibility and organization

The use of an Ex enclosure for mobile or user-interactive applications shifts responsibility:

• from the manufacturer

• to the operator

With consequences:

• detailed risk assessment

• operating and work instructions

• training obligations

• increased liability risk

Legal framework (safe):

• ATEX Directive 2014/34/EU (devices)

• BetrSichV (DE) – operator obligations

• TRGS 720 ff. – explosion protection (DE)

10. Objective comparison

⚠️ = only for devices specifically approved for this purpose

11. Technical conclusion

Ex-protected enclosures arenot a substitutefor explosion-protected devices, but astationary protection concept.

Meaningful, when:

• stationary

• closed

• monitored

• clearly organized

Critical, when:

• mobile

• user-interactive

• frequently opened

• thermally demanding

Pressure-resistant enclosures are designed to stand still – not to be carried.

Those who need mobility do not need an Ex enclosure, but a real explosion-protected device.