IEC 60079-13 Explained: Pressurized and Artificially Ventilated Rooms

Explosion protection is not always achieved by protecting each electrical item individually. In certain installations, the room or building containing the equipment can itself form part of the explosion protection arrangement.

IEC 60079-13 addresses equipment protection by pressurized rooms “p” and artificially ventilated rooms “v”. These arrangements are relevant where personnel need to access a protected space containing electrical equipment, instruments or other potential ignition sources.

The protection depends on more than installing a fan or supplying pressurized air. Room construction, air movement, potential internal sources of release, monitoring, safety controls and operating procedures must work together as part of the designed system.

What Is IEC 60079-13?

IEC 60079-13 is part of the IEC 60079 series covering equipment and installations in explosive atmospheres. It specifies requirements for the design, construction, assessment, verification and marking of equipment protection by pressurized rooms and artificially ventilated rooms.

The 2017 edition, Edition 2.0, introduced the protection types pb, pc and vc, replacing the earlier designations associated with the previous edition.

For a project, engineers should verify the applicable edition against the project specification, certification requirements and current IEC publication information rather than relying on an older datasheet or drawing.

IEC 60079-13 vs IEC 60079-2

Both standards address protection involving pressurization, but they cover different protected objects.

Standard	Scope
IEC 60079-2	Equipment protection by pressurized enclosure “p”.
IEC 60079-13	Equipment protection by pressurized room “p” and artificially ventilated room “v”.

IEC 60079-2 is concerned with a pressurized equipment enclosure. IEC 60079-13 addresses larger spaces that can accommodate personnel, including individual rooms, interconnected rooms, buildings and certain personnel-accessible structures.

The distinction matters because a room introduces additional design considerations, such as doors, building penetrations, ventilation ducts, room leakage and possible sources of flammable gas or vapour inside the protected space.

What Does “Room” Mean?

The term “room” is not limited to a conventional room inside a building. Depending on the application and the standard's scope, it can include:

• A single room.
• Multiple interconnected rooms.
• A complete building.
• A room located within another building.
• A room with associated air inlet and outlet ducts.
• Personnel-accessible acoustic hoods or similar structures.

The common consideration is the protected space and the way its construction and protective systems control the explosion risk.

Pressurized Room Protection “p”

A pressurized room uses a controlled supply of air or another permitted protective gas to maintain the protective conditions specified for the selected protection arrangement.

For a room exposed to an external hazardous atmosphere, pressurization can prevent that atmosphere from entering the protected space when the required pressure conditions are maintained. The design must account for room leakage, openings, doors, air supply and the required protective controls.

Where an internal source of flammable gas or vapour release exists, the design problem becomes more complex. Maintaining pressure alone may not be sufficient to address the internal hazard. The selected protection arrangement must account for the release conditions and the requirements of the applicable protection type.

Artificially Ventilated Room Protection “v”

An artificially ventilated room uses a controlled ventilation arrangement as part of its explosion protection concept. The airflow is designed to manage the atmosphere within the protected space under the conditions defined for that arrangement.

Unlike a concept that relies primarily on maintaining positive pressure, artificial ventilation focuses on the intended airflow and the control of potentially hazardous gas or vapour concentrations.

The ventilation design must consider air supply, extraction, flow paths, possible release sources and the protective actions required if ventilation is lost or becomes inadequate.

A normal HVAC system should not automatically be treated as an explosion protection system. Its suitability depends on whether its design, monitoring, controls and verification meet the applicable requirements.

Pressurized Room vs Artificially Ventilated Room

Consideration	Pressurized Room “p”	Artificially Ventilated Room “v”
Primary approach	Controlled pressurization.	Controlled artificial ventilation.
Design focus	Pressure conditions, leakage, protective-gas supply and controls.	Airflow, ventilation paths, release sources and controls.
Room construction	Must support the required pressure conditions.	Must support the intended ventilation arrangement.
Monitoring	As required by the selected protection type and design.	As required by the selected protection type and design.
Internal release	Must be considered where applicable.	Must be considered where applicable.

These approaches are not interchangeable by default. The appropriate protection method depends on the room location, hazardous-area conditions, internal sources of release and the requirements of the selected protection type.

Protection Types: pb, pc and vc

IEC 60079-13:2017 introduced three protection designations:

Designation	Protection Concept
pb	Pressurized room protection at the protection level defined by the standard.
pc	Pressurized room protection at a different, lower protection level defined by the standard.
vc	Artificially ventilated room protection.

These designations are technical protection classifications, not interchangeable labels for any room fitted with a fan or pressurized air supply. Their application and required safeguards must be established from the applicable edition of IEC 60079-13.

Older drawings and specifications may refer to earlier designations such as px, py, pz or pv. When reviewing legacy documentation, confirm the applicable standard edition and avoid converting an old designation to a new one without checking the actual protection requirements.

Hazardous-Area Location and Internal Sources of Release

The room's location and the possibility of an internal release are important inputs to the protection design.

The engineering assessment should distinguish between:

• The hazardous atmosphere that may surround the room.
• The possibility of flammable gas or vapour being released inside the room.
• The protection method selected for the room.
• The operating conditions under which the protection is intended to remain effective.

These conditions cannot be resolved by looking at the external Zone designation alone. A room with no internal release source presents a different design problem from a room containing process equipment or analysers that could release flammable substances.

The applicable combinations of Zone, internal release conditions and protection type must be checked against IEC 60079-13 itself. Do not assume that every protection type is permitted for every Zone or internal-release scenario.

Why Internal Release Changes the Design

Consider a room located in a hazardous area but containing no identified internal source of flammable gas or vapour release. The protection design may primarily need to address the possibility of the surrounding hazardous atmosphere entering the room.

Now consider a room containing equipment that can release flammable gas or vapour. The protection design must also consider how the release could affect the atmosphere inside the room.

This difference affects the ventilation or pressurization philosophy, monitoring requirements, protective actions and assessment of the complete room. Depending on the application, a combination of pressurization and artificial ventilation may be relevant.

Safety Devices, Monitoring and Protective Actions

The protection system must be able to establish and maintain the required protective conditions. Depending on the design and selected protection type, the system may include:

• Pressure monitoring.
• Airflow or ventilation monitoring.
• Protective air or gas supply controls.
• Alarm functions.
• Automatic shutdown or other defined protective actions.
• Controls for establishing the required conditions before operation.

The exact devices and actions are design-specific. They should be defined in the protection design, control philosophy and operating instructions rather than assumed from a generic checklist.

Purging Before Operation

Where required by the selected protection arrangement, purging establishes the necessary initial conditions before equipment is operated in the protected room.

The purge sequence, airflow, duration and associated safety controls must follow the engineered design and applicable standard. A generic purge duration should not be assumed for all rooms.

The design and operating procedures should clearly identify the conditions that must be achieved before normal operation and the response required if those conditions cannot be established.

Room Integrity, Doors and Penetrations

Room construction is part of the protection system. Openings and penetrations can affect pressure conditions, airflow and the ability to control the atmosphere within the space.

The assessment should consider:

• Doors and access openings.
• Cable and instrument penetrations.
• Pipe penetrations.
• Air inlet and outlet ducts.
• Joints and interfaces in the room boundary.
• Other openings that may affect the protective conditions.

For a pressurized room, leakage can affect the ability to maintain the required pressure. For an artificially ventilated room, the location and arrangement of openings can influence airflow and ventilation effectiveness.

The complete installed arrangement must therefore be assessed, including ducts and interfaces added during site installation.

Equipment Inside the Protected Room

A protected room does not automatically make every item inside suitable for every operating condition. Equipment selection must remain consistent with the certified protection arrangement and the conditions under which the room protection is valid.

The engineering review should consider electrical equipment, potential ignition sources, internal release points and any equipment operating conditions that could affect the room protection.

The room protection design, equipment specifications and operating procedures should be coordinated rather than reviewed as separate, unrelated packages.

Assessment, Verification and Marking

IEC 60079-13 includes requirements for the assessment and verification of protected rooms. The objective is to demonstrate that the designed arrangement meets the applicable requirements.

Depending on the application, the review may include:

• Room construction and integrity.
• Pressurization or ventilation arrangement.
• Air inlet and outlet systems.
• Monitoring devices and safety controls.
• Internal sources of gas or vapour release.
• Operating sequences and protective actions.
• Required marking and technical documentation.

The required assessment and verification activities must be determined from the applicable standard, protection type and project requirements. A checklist alone does not establish conformity.

Marking should be interpreted together with the applicable certificate, drawings, operating instructions and verification records. These documents help establish the intended operating conditions and limitations of the protected room.

Relationship With Hazardous-Area Classification

IEC 60079-13 does not replace hazardous-area classification. The surrounding hazardous area must be classified using the relevant methodology, and the room protection must be suitable for the resulting conditions.

• IEC 60079-10-1: Classification of areas where explosive gas atmospheres may occur.
• IEC 60079-10-2: Classification of areas where combustible dust atmospheres may occur.
• IEC 60079-13: Equipment protection by pressurized rooms and artificially ventilated rooms.

These standards address different parts of the engineering process. Area classification establishes the hazardous conditions; the room protection design addresses how the protected space is intended to manage the relevant explosion risks.

Applications in Analyzer Houses and Modular Facilities

Analyzer houses are a useful example because they may contain instruments, process connections and potential internal sources of flammable gas or vapour release. Their protection strategy must reflect the actual configuration and release conditions.

Depending on the design, pressurization, artificial ventilation or a combination of methods may be relevant. Not every analyzer house uses the same protection arrangement, so the applicable requirements must be established for each project.

IEC 60079-13 may also be relevant to modular rooms and offshore facilities. Where the room is fabricated separately and installed at site, the final configuration—including doors, ducts, penetrations and connections—must be considered during verification.

Engineering Review Checklist

Review Area	Key Question
Area classification	What hazardous conditions surround the room?
Internal release	Can equipment inside release flammable gas or vapour?
Protection type	Is the selected arrangement permitted and suitable for the application?
Room integrity	Have doors, penetrations, joints and other openings been considered?
Air supply	Is the source and arrangement of protective air or gas defined?
Ventilation	Does the airflow arrangement meet the design requirements?
Monitoring	Are the required pressure or ventilation conditions monitored?
Protective actions	What happens if the required protective condition is lost?
Purging	Are the required initial conditions and operating sequence documented?
Verification	Are the required assessment and verification records available?
Documentation	Are drawings, instructions, marking and operating limitations consistent?

Procurement and EPC Review

For EPC and procurement teams, a protected room should be evaluated as a complete explosion protection system rather than as a room supplied with a fan or pressure source.

A technical bid evaluation should establish whether the vendor's scope addresses:

• The applicable edition of IEC 60079-13.
• The selected protection type and intended application.
• The room construction and air supply arrangement.
• Internal sources of release, where applicable.
• Monitoring, alarms and protective actions.
• Required assessment, verification and marking.
• Installation, operating and maintenance documentation.

Room dimensions, fan capacity or nominal pressure values are not sufficient on their own to demonstrate compliance. The vendor should explain how the complete protection concept meets the applicable requirements.

Common Engineering Mistakes

Confusing IEC 60079-13 With IEC 60079-2

IEC 60079-2 addresses pressurized equipment enclosures, while IEC 60079-13 addresses pressurized rooms and artificially ventilated rooms. The protected object and applicable requirements differ.

Assuming a Fan Automatically Makes a Room Safe

A fan is only one component of a ventilation arrangement. The required airflow, monitoring, controls and verification must be established for the protection concept.

Ignoring Internal Sources of Release

A release inside the room can change the protection requirements. Internal release sources must be assessed rather than considering only the hazardous area outside.

Treating HVAC as Separate From Explosion Protection

Where ventilation forms part of the protection concept, the air supply, airflow paths and associated controls are explosion protection considerations, not simply ordinary building services.

Ignoring Doors and Penetrations

Openings can affect pressure and airflow. They must be included in the design and verification of the complete room.

Assuming Explosion Protection Covers Every Personnel-Safety Issue

Explosion protection does not by itself establish that indoor air quality, toxicity, temperature and every other personnel-safety condition is acceptable. Applicable occupational safety, building and project requirements must also be considered.

Frequently Asked Questions

What is IEC 60079-13?

IEC 60079-13 covers equipment protection by pressurized rooms “p” and artificially ventilated rooms “v” in explosive atmospheres.

What is the difference between IEC 60079-13 and IEC 60079-2?

IEC 60079-2 addresses pressurized equipment enclosures. IEC 60079-13 addresses larger protected spaces, including rooms and certain personnel-accessible structures.

What do pb, pc and vc mean?

They are protection designations introduced in IEC 60079-13:2017 for pressurized room and artificially ventilated room protection. Their exact application depends on the standard's requirements.

Can IEC 60079-13 apply to analyzer houses?

It can be relevant to analyzer houses, depending on their construction, location, internal release conditions and selected protection arrangement.

Does IEC 60079-13 cover internal sources of release?

Yes. Internal gas or vapour release conditions are important to determining the applicable room protection arrangement.

Does a pressurized room always need purging?

Purging requirements depend on the selected protection arrangement and design. The required sequence and operating conditions must be established from the applicable standard and system documentation.

Conclusion

IEC 60079-13 provides requirements for explosion protection using pressurized rooms “p” and artificially ventilated rooms “v”. Its focus is the protected space and the complete system needed to establish and maintain the required protective conditions.

The key engineering considerations include hazardous-area conditions, internal release sources, room integrity, air supply, ventilation, monitoring, safety controls and verification. These elements must be assessed together rather than treating ventilation or pressurization as an isolated utility.

For engineering and procurement teams, the essential question is whether the complete room protection arrangement is suitable for the actual hazardous-area conditions and complies with the applicable requirements of IEC 60079-13.

Related Reading

• IEC 60079-10-2 Explained: Classification of Areas – Combustible Dust Atmospheres
• IEC 60079-14 Explained: Design, Selection and Installation
• IEC 60079-17 Explained: Inspection and Maintenance
• IEC 60079-2 Explained: Pressurized Enclosure “p” Protection

References

• IEC 60079-13:2017 — Explosive atmospheres – Part 13: Equipment protection by pressurized room “p” and artificially ventilated room “v”.
• IEC 60079-2 — Explosive atmospheres – Part 2: Equipment protection by pressurized enclosure “p”.
• IEC 60079-10-1 — Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres.
• IEC 60079-10-2 — Explosive atmospheres – Part 10-2: Classification of areas – Combustible dust atmospheres.
• IEC 60079-14 — Explosive atmospheres – Part 14: Electrical installation design, selection and erection.
• IEC 60079-17 — Explosive atmospheres – Part 17: Electrical installation inspection and maintenance.