Meta description: A pressurised PDU container provides a dedicated enclosure for power distribution equipment in projects that need a controlled workspace. Its layout is planned around the equipment, cable access and the way the container will be used.

 What is a pressurised PDU container?

A PDU distributes electricity to connected equipment. When the equipment is installed in a hazardous offshore or industrial area, the project may require it to be housed in a pressurised container. The container creates a protected space for the specified equipment and is designed to suit the project’s operating conditions.

TLS has supplied pressurised PDU containers as a distinct product type. They are separate units, just as a pressurised work cabin and a pressurised office shop are separate units. Each has its own purpose and layout; they are not three functions combined in one container. ([TLS pressurised container solutions]

 The equipment determines the layout

Power distribution equipment needs room for installation, operation and routine checks. The position of the panels, the direction from which people access them, and where cables enter the container all affect the layout.

These details are easier to plan before the container is built. Early coordination helps the equipment fit the space and keeps access routes clear. It also gives the project team a chance to agree where the container connects with equipment and services outside it.

 Pressurisation is part of the overall design

In simple terms, a pressurised container supplies air to keep its internal pressure above the surrounding atmosphere. This can help limit outside air entering the enclosure, when the system is designed and operated for the project’s conditions.

The container, the power equipment and the pressurisation arrangement need to work together. The protection required depends on the site and project specification, so the same setup should not be assumed for every PDU container. TLS configures pressurised containers to the project requirements, with applicable standards and certification confirmed for each unit. ([TLS pressurised container solutions]

 A purpose-built container for a clear role

A pressurised PDU container gives power distribution equipment a dedicated place within the project. When the equipment arrangement, cable access and protection requirements are considered together, the container is easier to install and use as intended.

For TLS, a PDU container is one specific configuration in a broader range of pressurised units. The final arrangement follows the equipment and project requirements, while work cabins, PDU containers and office shops remain distinct products designed for different uses.

FAQ

What does PDU mean?  

PDU means power distribution unit. It distributes electricity to connected equipment.

Does every project need the same pressurisation arrangement?  

No. The required arrangement depends on the project and its operating environment.

Can the container layout be planned around the equipment?  

Yes. Equipment positions, cable access and normal operating needs can be considered during project design.

Project Overview

A client in Türkiye ordered three types of customised positive-pressure containers from TLS: PDU, workshop and office units. TLS supplied the container structures and specified pressurisation and safety systems, detectors, piping and Ex electrical components. The customer was responsible for installing the operational equipment inside.

The project requirements included Zone 2 protection, A60 fire protection and an operating temperature range of −20°C to +60°C. Preparation and production took approximately five months, followed by the customer’s final video inspection before delivery.

Read the original project report

1. Engineering Focus: How CPFG Coordinates Pressurisation and Safety Functions

A positive-pressure container is an engineered enclosure, not simply a container fitted with a ventilation fan.

Its protective function depends on maintaining the specified pressure conditions and coordinating monitoring, alarms and protective actions. For this project type, the Combined Pressurisation, Fire and Gas (CPFG) system is a key part of that arrangement.

A typical CPFG configuration may incorporate:

• Differential-pressure switches and airflow monitoring.
• Combustible-gas, smoke and heat detectors, according to the specified scope.
• A pressurisation fan and associated air-control components.
• An explosion-protected CPFG control cabinet.
• Audible and visual alarms, emergency-stop functions and defined electrical shutdown interfaces.

How the protection sequence works

Step 1 — Purging and pressurisation

The pressurisation system supplies air to purge the enclosure and establish the required internal pressure conditions. The required purge duration and pressure setpoint depend on the approved design.

Step 2 — Verification before energisation

The control system checks whether the specified conditions for safe operation have been achieved. Where the approved design requires it, the relevant non-Ex electrical circuits remain isolated until the required conditions are satisfied.

Step 3 — Continuous monitoring

During operation, pressure and other specified safety parameters are monitored. A loss of required pressure, gas detection or another abnormal condition may initiate alarms and protective actions according to the approved cause-and-effect logic.

Step 4 — Protective response

If the required conditions cannot be restored within the specified period, the system may isolate designated non-Ex electrical equipment. The actual response depends on the approved control philosophy and the equipment connected to the system.

This sequence is important because positive pressure is only one part of the protection concept. Monitoring, electrical isolation and the response to abnormal conditions must also be considered.

For PDU, workshop and office containers, the internal equipment and operational requirements may differ. The enclosure and its protection systems therefore need to be coordinated with the customer's intended installation rather than designed around an assumed standard equipment package.

For further technical background, see TLS's published guide, What Is CPFG and How Does It Work?.

2. Engineering Focus: What Does Factory Acceptance Testing Verify?

Factory Acceptance Testing (FAT) provides a structured way to check the supplied systems against the approved drawings, functional requirements and agreed acceptance criteria before shipment.

For a positive-pressure container, the test scope should cover both the physical installation and the behaviour of the protection system.

Key inspection and test areas

One important distinction is that achieving the normal pressure target does not, by itself, demonstrate that the complete protection sequence works correctly.

The FAT should also verify the specified responses to conditions such as pressure loss or sensor disconnection. The test procedure should define the relevant thresholds, timing requirements, expected actions and acceptance criteria.

TLS's published FAT guide for PDU and workshop pressurised containers describes visual inspection, CPFG checks, sensor-integrity testing and emergency-shutdown testing as part of the testing methodology.

These are examples of the checks that may be required by a project. The exact tests completed on the Turkish units, and their individual results, should be stated only where supported by the relevant project records.

Applicable Standards and Certification Scope

The standards applicable to this project were determined by the specified operating conditions, hazardous-area classification and contractual requirements. Individual certification claims should be based on the relevant project certificates and approved documentation.

• IEC 60079-13: Addresses the design, construction, assessment, verification and marking of rooms protected by pressurisation or artificial ventilation, within the applicable scope and edition.
• DNV-ST-E271 (DNV 2.7-1): Covers the design, approval, testing and certification of offshore containers and associated lifting sets, where applicable.
• A60 fire protection: Specifies a fire-resistance performance classification. Compliance should be supported by the applicable design, test and approval documentation.
• Hazardous-area electrical equipment: Explosion-protected electrical components and instrumentation must meet the requirements applicable to their intended installation, with certification verified against the actual equipment supplied.

The applicable standards, editions and certification scope must be confirmed against the approved project documents and relevant certificates. References to these standards should not be interpreted as confirmation that every container, component or customer-installed item is independently certified to all of them.

See the TLS pressurised-container technical overview for the published range of design options and applicable requirements.

4. Inspection and Delivery

The published Turkish project account reports quality checks covering structural fabrication, welding, lifting, coating thickness, positive-pressure performance and watertightness. It also records the customer's final video inspection before delivery.

These checks address different aspects of the finished product. Structural and lifting inspections concern the container's physical integrity and handling requirements, while pressure and functional tests address the performance of the specified protection system.

The published account does not provide detailed pressure-test readings, complete signed FAT records or unit-by-unit test results. Those details should not be inferred from the reported successful inspection and delivery.

Conclusion

A positive-pressure container must be designed around the intended application, the equipment that will be installed and the required safety functions.

For PDU, workshop and office applications, the enclosure, pressurisation system, CPFG controls, detection devices and specified explosion-protected electrical components form part of a coordinated design. Clearly defining the supply boundary and verifying the agreed functions before shipment helps establish a sound basis for subsequent equipment installation and commissioning.

TLS provides customised positive-pressure containers for industrial and offshore applications, with the configuration and supply scope defined according to project requirements.

An intelligent pressurized container is an engineered enclosure that uses controlled ventilation, pressure monitoring, HVAC, electrical systems and safety controls to create a suitable internal environment in a hazardous offshore or industrial area. It is not simply a container with an air-conditioning unit. The pressure concept, hazardous-area classification, fire protection, gas detection, electrical equipment and certification scope must be developed together.

TLS designs pressurized containers for offshore, marine and hazardous-area applications, including Zone 1 and Zone 2 environments. Its published applications include mud logging cabins, MWD/LWD cabins, ROV control cabins, laboratories, workshops, accommodation cabins, control rooms, MCC shelters, switchgear shelters and generator enclosures. TLS Intelligent Pressurized Containers

What Does Pressurization Do?

Pressurization maintains the internal environment at a defined pressure relative to the surrounding atmosphere. Depending on the protection concept, this can help reduce the risk of hazardous external gas entering the enclosure and reaching personnel or equipment.

Pressurization does not remove every hazard. It must be supported by:

• Suitable clean-air supply.
• Pressure monitoring.
• Controlled doors and openings.
• Emergency response logic.
• Appropriate electrical equipment.
• Gas and fire detection.
• Defined shutdown actions.
• Inspection and commissioning.

A pressurized cabin should therefore be evaluated as a complete protection system rather than as a structural container with a positive-pressure fan.

How Is a TLS Cabin Configured?

TLS states that each pressurized container is configured around the operational, equipment and certification requirements of the project. Layouts and dimensions can be adapted for compact control cabins, process shelters and larger offshore modules.

The configuration may include:

• Integrated HVAC.
• Electrical power control.
• Pressurization systems.
• Data and communication networks.
• Fire and smoke detection.
• Flammable-gas detection.
• H₂S detection.
• Emergency shutdown.
• Fire dampers.
• Fire suppression.
• Ex-approved pressurization equipment.
• Airlock entrances.
• Emergency escape hatches.
• Battery-backed emergency lighting.

The final scope should distinguish between standard features, optional systems and customer-supplied equipment. A cabin described as “pressurized” does not automatically include every detection, suppression or control function.

How Are Fire and Gas Risks Addressed?

TLS lists fire and smoke detectors, flammable-gas detectors, H₂S detectors, emergency shutdown, automatic fire dampers and fire suppression among its available safety systems.

These systems perform different functions:

• Detection identifies a hazardous condition.
• Alarm communicates the condition.
• Shutdown isolates defined equipment or processes.
• Fire dampers limit the spread of fire or smoke through ventilation paths.
• Suppression controls a fire after activation conditions are met.
• Pressurization helps manage the movement of external atmosphere into the enclosure.

The cause-and-effect schedule should state what happens when each alarm is triggered. It should also define the response to loss of pressure, loss of ventilation, power failure, fire detection and gas detection.

What Standards and Certifications May Apply?

TLS states that its containers can be designed in accordance with project requirements involving DNV 2.7-1, EN 12079, IEC 60079-13, ATEX, IECEx, SOLAS, A0/A60 passive fire protection, ISO container standards and CSC requirements.

The applicable standard depends on the project. For example, offshore lifting and transportation requirements are not the same as hazardous-area electrical requirements. A fire rating does not replace a hazardous-area assessment, and a hazardous-area approval does not automatically establish offshore structural certification.

Third-party certification may be provided by organizations such as DNV, Bureau Veritas, Lloyd’s Register or CCS when required by the project.

The quotation should identify the exact certificate, design code, test scope and issuing body rather than simply listing several standards without defining applicability.

What Should Be Tested Before Delivery?

TLS lists factory acceptance testing and pre-commissioning for electrical and instrumentation systems among its pressurized-container capabilities.

The project should define the factory and site test responsibilities. Factory testing may include:

Electrical continuity and insulation tests.

• Instrumentation checks.
• Alarm and shutdown logic.
• Pressure-system checks.
• Fire and gas panel testing.
• HVAC operation.
• Emergency lighting.
• Equipment labeling and documentation.

Site commissioning should verify the completed installation, external connections, clean-air supply, pressure behavior, host alarms and emergency interfaces.

FAQ

1. Is a pressurized container suitable for every hazardous area?

No. Suitability depends on the area classification, protection concept, equipment certification, operating conditions and project approval requirements.

2. Does pressurization replace gas detection?

No. Pressurization and gas detection perform different functions. Detection identifies a hazardous condition; pressurization controls the intended enclosure environment.

3. What information should be provided to TLS?

Provide the area classification, intended application, equipment list, occupancy, layout, fire rating, certification requirements, utilities, lifting requirements and host-facility interfaces.