IEC 60079-13 Explained: Pressurized and Artificially Ventilated Rooms

A hazardous area does not always have to be protected by placing each individual electrical component inside an Ex enclosure. In some installations, an entire room or building can be protected by controlling the atmosphere inside it.

This approach is particularly useful where personnel need to enter the protected space or where multiple items of equipment are installed together.

IEC 60079-13 defines requirements for rooms protected by pressurization and artificially ventilated rooms in explosive atmospheres. The standard covers the design, construction, assessment, verification and marking of these rooms, together with the safety devices and controls needed to establish and maintain the protective conditions.

The current edition is IEC 60079-13:2017, Edition 2.0. Unlike IEC 60079-2, which addresses pressurized enclosures, IEC 60079-13 specifically addresses rooms and similar spaces intended for personnel entry.

Quick Answer

What Is IEC 60079-13?

IEC 60079-13 is part of the IEC 60079 series of standards for explosive atmospheres.

Its full title is:

The standard applies to rooms used to protect internal equipment through controlled pressurization, artificial ventilation, or a combination of the two protection arrangements.

The term "room" has a relatively broad meaning in IEC 60079-13. It can include a single room, multiple rooms, a complete building, or a room contained within a building.

It can also include an acoustic hood or similar enclosure where personnel are able to enter.

Why Is IEC 60079-13 Different From IEC 60079-2?

This distinction is important because both standards involve pressurization but address different types of protected spaces.

Standard	Main Application
IEC 60079-2	Pressurized enclosures used to protect electrical equipment.
IEC 60079-13	Pressurized rooms and artificially ventilated rooms that can facilitate personnel entry.

IEC 60079-2 specifically excludes pressurized rooms and analyser houses from its scope and refers these applications to IEC 60079-13.

This means IEC 60079-13 should not be treated as simply another version of IEC 60079-2. The engineering problem is different because the protected space can be large enough for personnel to enter and can include multiple pieces of equipment.

What Does "Room" Mean in IEC 60079-13?

The word room in this standard is broader than a conventional indoor room.

IEC 60079-13 includes:

• Single rooms.
• Multiple interconnected rooms.
• Complete buildings.
• Rooms contained within buildings.
• Rooms with inlet and outlet ducts.
• Personnel-accessible acoustic hoods and similar structures.

The key characteristic is that the protected space is intended to facilitate the entry of personnel.

This is one of the major differences between a pressurized room and an ordinary equipment enclosure.

Pressurized Room "p"

Pressurization protects a room by maintaining an internal pressure condition that prevents the surrounding explosive atmosphere from entering the protected space under the conditions defined by the protection concept.

The protective system therefore depends on maintaining the required pressure and associated operating conditions.

A pressurized room can contain electrical equipment or other potential ignition sources that would otherwise require protection against the surrounding hazardous atmosphere.

The room itself becomes part of the explosion protection arrangement.

Artificially Ventilated Room "v"

IEC 60079-13:2017 introduced artificially ventilated room protection as an explicit part of the standard.

Artificial ventilation uses a controlled airflow arrangement to reduce or prevent the accumulation of a hazardous atmosphere within the protected space.

Unlike pressurization, the protection principle is based primarily on controlled ventilation rather than maintaining the protected room at a specified positive pressure.

The distinction between pressurization and artificial ventilation is an important technical change introduced in the 2017 edition.

Pressurization vs Artificial Ventilation

Characteristic	Pressurized Room "p"	Artificially Ventilated Room "v"
Primary principle	Controlled pressurization	Controlled artificial ventilation
Main objective	Prevent ingress of the surrounding hazardous atmosphere	Control the atmosphere within the protected room through ventilation
Protection designation	"p"	"v"
Typical engineering focus	Pressure, leakage, supply air and protective controls	Airflow, ventilation, release sources and protective controls

The two concepts should therefore not be treated as interchangeable. The selection depends on the room configuration, location, internal sources of release and the protection strategy required by the installation.

Types of Protection in IEC 60079-13

The 2017 edition introduced the protection types pb, pc and vc.

Protection Type	Protection Concept
pb	Pressurized room protection.
pc	Pressurized room protection at the corresponding lower protection level.
vc	Artificially ventilated room protection.

These designations replaced the previous px, py, pz and pv protection designations used in the earlier edition.

The change was part of the technical revision of IEC 60079-13:2017.

Where Can IEC 60079-13 Be Applied?

IEC 60079-13 covers several different installation arrangements.

The standard includes rooms:

• Located in Zone 1 or Zone 2 without an internal source of gas or vapour release and protected by pressurization.
• Located in Zone 21 or Zone 22 without an internal source of gas or vapour release and protected by pressurization.
• Located in Zone 2 with or without an internal source of gas or vapour release and protected by artificial ventilation.
• Located in a non-hazardous area but containing an internal source of gas or vapour release and protected by artificial ventilation.
• Located in Zone 1, Zone 2, Zone 21 or Zone 22 with an internal source of gas or vapour release and protected by both pressurization and artificial ventilation.

The exact applicability depends on the protection arrangement and the conditions defined by the standard.

Internal Source of Release

One of the important engineering considerations in IEC 60079-13 is whether the protected room contains an internal source of gas or vapour release.

An internal source of release changes the protection problem because the hazardous substance may originate from inside the room rather than only from the surrounding atmosphere.

The ventilation or pressurization strategy therefore has to account for the internal release condition where applicable.

This is particularly important for rooms containing process equipment, analysers or other equipment where flammable substances may be present.

Pressurization and Internal Release

A room containing an internal source of release may require a combination of pressurization and artificial ventilation.

The objective is not simply to keep the surrounding hazardous atmosphere outside the room. The protection system may also need to control flammable material generated inside the protected space.

This is why IEC 60079-13 treats external hazardous atmosphere and internal release conditions as separate engineering considerations.

Safety Devices and Controls

A pressurized or artificially ventilated room cannot rely only on the physical construction of the room.

IEC 60079-13 also includes requirements for the safety devices and controls necessary to establish and maintain the protective conditions.

Depending on the design, these systems can include:

• Pressure monitoring.
• Airflow monitoring.
• Ventilation monitoring.
• Protective gas or air supply controls.
• Alarm functions.
• Automatic shutdown or other protective actions.
• Control systems associated with purging and pressurization.

The exact arrangement depends on the protection type and the room design.

Purging Before Operation

Where a protected room uses pressurization, establishing the required protective condition can involve a purging process before normal operation.

Purging is intended to remove an unwanted hazardous atmosphere from the protected space before the equipment is placed into the relevant operating condition.

The purge sequence, airflow, duration and associated safety controls are part of the engineered protection system.

The important principle is that the required protective condition has to be established and verified before relying on the protection.

Inlet and Outlet Ducts

Ventilation and pressurization systems depend on controlled air movement.

IEC 60079-13 therefore addresses rooms together with associated inlet and outlet ducts.

The duct arrangement is not merely a general HVAC consideration. It forms part of the protective system and can affect how air enters, moves through and exits the protected space.

Poorly designed ducting can undermine the intended protection strategy.

Room Integrity

For a pressurized room, the integrity of the protected space is critical.

Doors, penetrations, cable entries, ducts, joints and other openings can affect the ability of the system to maintain the required protective condition.

The engineering assessment therefore has to consider the room as a complete system rather than looking only at the pressure source.

This is another important difference between a pressurized room and a conventional Ex enclosure.

Equipment Inside a Protected Room

The presence of a pressurized or artificially ventilated room does not automatically mean that every item installed inside can be treated as ordinary equipment without consideration.

The equipment arrangement must remain consistent with the protection concept and the conditions under which the room protection is valid.

The room protection strategy, internal equipment, internal release sources and safety controls therefore have to be considered together.

Assessment and Verification

IEC 60079-13 includes requirements for the assessment and verification of rooms using these protection concepts.

This is important because the effectiveness of a protected room cannot be determined simply from its physical dimensions.

The assessment considers the engineered protection arrangement and whether the necessary protective conditions can be established and maintained.

Verification can involve checking:

• Room construction.
• Pressurization arrangements.
• Ventilation arrangements.
• Air inlet and outlet systems.
• Pressure or airflow monitoring.
• Safety devices.
• Control systems.
• Internal sources of release.
• Marking and documentation.

Marking

IEC 60079-13 includes requirements for the marking of protected rooms.

The marking communicates information about the applicable explosion protection arrangement and allows personnel to identify the protection concept associated with the room.

Depending on the design, the marking can be associated with the relevant protection type and other information required by the standard.

Marking should always be interpreted together with the installation documentation and operating instructions.

IEC 60079-13 and Hazardous Area Classification

IEC 60079-13 does not replace hazardous-area classification.

The hazardous area still needs to be classified according to the applicable requirements, and the room protection has to be appropriate for the resulting conditions.

For gas atmospheres, hazardous-area classification is addressed by IEC 60079-10-1.

For combustible dust atmospheres, classification is addressed by IEC 60079-10-2.

IEC 60079-13 vs Ex p Equipment

The relationship between IEC 60079-13 and Ex p equipment can be confusing.

The distinction is primarily the protected object.

Application	Relevant Standard
Pressurized electrical enclosure	IEC 60079-2
Pressurized room	IEC 60079-13
Artificially ventilated room	IEC 60079-13

The distinction matters during engineering, procurement and certification because a pressurized enclosure and a pressurized room are not assessed using the same standard.

Applications of IEC 60079-13

The standard can be relevant to installations where personnel need to work inside a protected space containing equipment that could otherwise present an ignition hazard.

Potential applications include:

• Analyzer-related rooms.
• Electrical rooms.
• Control rooms in hazardous areas.
• Equipment rooms.
• Specialized offshore modules.
• Protected technical buildings.
• Personnel-accessible acoustic hoods.

The suitability of a particular application depends on the detailed design and the conditions defined by IEC 60079-13.

Analyzer Houses and IEC 60079-13

Analyzer installations are a particularly relevant example because they can contain equipment and internal sources of release while being located within or close to hazardous areas.

The protection strategy can involve artificial ventilation, pressurization, or a combination depending on the configuration.

However, the specific application should be reviewed against the current applicable standards and project requirements rather than assuming that every analyzer house automatically falls under the same protection arrangement.

Offshore Applications

IEC 60079-13 also allows for rooms assembled or constructed on site, including offshore installations.

This is relevant to modular offshore facilities where protected rooms can be fabricated, transported and installed as part of a larger facility.

The standard recognizes that some final construction elements, such as ducting, may be completed at the installation site.

This makes the verification of the final installed configuration particularly important.

Design Considerations

When designing a room under IEC 60079-13, engineers should consider the entire protection system rather than treating ventilation or pressurization as an isolated utility.

Important considerations include:

• Hazardous-area classification around the room.
• Presence or absence of internal sources of release.
• Selected protection concept.
• Room construction and integrity.
• Air supply arrangement.
• Ventilation capacity.
• Pressure or airflow monitoring.
• Purging requirements.
• Safety interlocks and controls.
• Doors and other openings.
• Cable and piping penetrations.
• Inlet and outlet ducts.
• Alarm and shutdown functions.
• Operating and maintenance procedures.

Procurement Considerations

For EPC and procurement teams, IEC 60079-13 should be considered when the project specification calls for a protected room rather than simply individual Ex equipment.

The procurement review should identify:

• Applicable protection type.
• Room classification and location.
• Internal source of release conditions.
• Required ventilation or pressurization system.
• Safety devices and controls.
• Required documentation.
• Assessment and verification requirements.
• Marking requirements.
• Installation requirements.
• Maintenance requirements.

A vendor quotation should therefore not be evaluated solely on room dimensions or fan capacity. The complete explosion protection concept needs to be demonstrated.

Common Mistakes

Confusing IEC 60079-13 With IEC 60079-2

IEC 60079-2 deals with pressurized enclosures, while IEC 60079-13 addresses pressurized rooms and artificially ventilated rooms.

Assuming Ventilation Alone Makes a Room Non-Hazardous

Ventilation is part of a defined protection system. The design has to establish and maintain the required protective conditions.

Ignoring Internal Sources of Release

An internal release can fundamentally change the protection requirements. The source, location and behaviour of the release must be considered during design.

Treating HVAC as Separate From Explosion Protection

For a protected room, ventilation, airflow, pressure and associated controls can form part of the explosion protection system.

Ignoring Doors and Penetrations

Openings and penetrations can affect the integrity of the protected room and therefore need to be considered as part of the overall design.

Assuming Personnel Safety Is Fully Covered

IEC 60079-13 does not by itself specify every measure needed to ensure acceptable air quality for personnel with respect to toxicity or temperature. Other national or applicable requirements may apply.

Frequently Asked Questions

What is IEC 60079-13?

IEC 60079-13 is the IEC standard covering equipment protection by pressurized rooms "p" and artificially ventilated rooms "v" in explosive atmospheres.

What is Ex p room protection?

Ex p room protection uses controlled pressurization to protect a room and the equipment inside it from the surrounding hazardous atmosphere under the conditions defined by the applicable protection type.

What is Ex v?

Ex v refers to artificial ventilation used as a protection concept for rooms under IEC 60079-13.

Is IEC 60079-13 the same as IEC 60079-2?

No. IEC 60079-2 addresses pressurized enclosures, while IEC 60079-13 addresses pressurized rooms and artificially ventilated rooms.

Can IEC 60079-13 apply to a complete building?

Yes. The term "room" in IEC 60079-13 can include a complete building as well as single or multiple rooms.

Does IEC 60079-13 apply offshore?

Yes. The standard includes rooms assembled or constructed on site and specifically recognizes both land and offshore installations.

Does IEC 60079-13 cover internal sources of release?

Yes. The standard includes applications involving rooms with internal sources of gas or vapour release, depending on the protection arrangement.

What protection types are used in IEC 60079-13?

IEC 60079-13:2017 introduced the protection types "pb", "pc" and "vc". The 2017 edition removed the earlier "px", "py", "pz" and "pv" designations.

Does IEC 60079-13 cover ventilation controls?

Yes. The standard includes requirements related to safety devices and controls necessary to establish and maintain artificial ventilation, purging and pressurization.

Conclusion

IEC 60079-13 provides a specific explosion protection framework for pressurized rooms "p" and artificially ventilated rooms "v".

The standard is particularly important where the protected space is large enough for personnel to enter and may contain multiple items of equipment or internal sources of gas or vapour release.

The 2017 edition expanded the scope beyond the earlier pressurized-room approach by introducing artificially ventilated room protection and the protection types pb, pc and vc.

For engineers, EPC contractors and procurement teams, the key distinction is that IEC 60079-13 protects a room or personnel-accessible space, while IEC 60079-2 addresses pressurized equipment enclosures.

The room, ventilation or pressurization system, safety controls, internal sources of release and operating conditions must be considered as one integrated explosion protection system.

Technical Review

References

• IEC 60079-13:2017 – Explosive atmospheres – Part 13: Equipment protection by pressurized room "p" and artificially ventilated room "v".
• IEC 60079-0 – Explosive atmospheres – Part 0: Equipment – General requirements.
• 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.