A fire in a data processing center is not measured in square meters burned, but in hours of service interruption and in the value of the information compromised. The high electrical power density per cabinet, the constant airflow of precision cooling, and the proliferation of low-voltage switchboards make technical rooms one of the most demanding risks to design within the current fire protection (PCI) framework.
For a facilities or operations manager at a CPD, fire protection stops being a regulatory formality and becomes another layer of the business continuity policy.
In this article we walk through the technologies that underpin any serious PCI project in a data center: aspirating smoke detection, gaseous agent extinguishing, the alternatives to gas that are now worth evaluating, and dedicated protection of electrical cabinets and rack cabinets. And we do it from the practical experience of Pefipresa, specialists in Fire Protection.
Why fire in a CPD requires a different approach
Fire in a data center has three differential traits that condition the entire PCI design:
- Prolonged incipient combustion: the most likely origin is the overheating of an electronic component or a conductor; before any flame develops there are minutes —sometimes hours— of pyrolysis of plastics and insulation, with smoke of very low optical density.
- Forced air flows: precision cooling moves large volumes of air that dilute the smoke and carry it away from the actual source, delaying the response of conventional point detection.
- Extreme sensitivity to water: an uncontrolled water discharge or a conductive residue can disable electronic equipment to an extent equivalent to the fire itself.
That is why the PCI design for rack rooms and data centers is never solved with a single system, but with layered protection that detects earlier and acts while minimizing collateral damage.
Early detection and agent suited to the risk are the two criteria that any CPD PCI specification must recognize. A proposal that does not develop them is incomplete for this type of risk.
Aspirating smoke detection: the first critical layer
Aspirating smoke detection (ASD) is the reference solution in CPDs because it simultaneously solves the problem of the low optical density of incipient smoke and that of forced air flows. Instead of waiting for smoke to reach the detector, a network of pipes continuously samples air and conducts it to a high-sensitivity measurement chamber.
How an aspirating smoke detection system works
An aspirator built into the unit draws air from multiple sampling points —ceiling, false ceiling, raised floor, return plenum, and inside the cabinets or hot aisles themselves— and conducts it to the detection chamber. The achievable sensitivity identifies combustion particles well below the threshold of a conventional point detector.
Staged alarm levels and sensitivity classes
A properly designed ASD system delivers several staged thresholds —pre-alert, alert, action, and fire— that let the operator investigate before any extinguishing activation.
In the European framework, sensitivity is specified through the classification in the UNE-EN 54-20 standard (class A, very high sensitivity; class B, high; class C, normal), and the design of the detection installation is developed in accordance with UNE 23007-14, to which the RIPCI refers. In critical CPD areas it is common practice to specify class A.
As an international reference, the NFPA 76 standard on fire protection of telecommunications facilities is the one that defines the concepts of Early Warning Fire Detection (EWFD) and Very Early Warning Fire Detection (VEWFD) and sets its coverage and transport-time criteria. NFPA 75, on fire protection of information technology equipment, refers to NFPA 72 for detection. It is worth not attributing requirements from one standard to the other.
The value of an ASD system is not only that it detects earlier: it lies in separating the minor incident from the critical incident before the extinguishing system has to act.
Gaseous agent extinguishing: protecting sensitive assets
When prevention and detection are not enough, the technical room requires an agent that extinguishes without leaving conductive or corrosive residues. Automatic gas extinguishing is the most widespread solution in CPDs, although it is not the only one available (see the section dedicated to alternatives).
Halocarbon agents: what today’s fluorinated gas framework allows
Halocarbon agents extinguish mainly by thermal absorption and by interfering with the chain reaction. This, however, is the point where the regulatory framework has changed substantially, and it is worth being precise:
- HFC-227ea and HFC-125. These are included in Annex I of Regulation (EU) 2024/573 on fluorinated greenhouse gases, which repealed Regulation (EU) 517/2014. Its Annex IV, point 11.c), sets 1 January 2025 as the date from which it is prohibited to place on the market fire protection equipment containing these gases or whose operation depends on them, unless they are necessary to meet safety requirements applicable in the area of operation. In practice, they are not today the reference option for a new installation in the EU.
- FK-5-1-12. It does not appear in Annex I but in Annex III of the Regulation, so it is not affected by that ban or by Annex I’s leak-control requirements; it is, however, subject to certification, training, and notification obligations. It should be kept in mind that it is affected by the proposed restriction on PFAS substances currently under discussion within the REACH framework, an evolution worth following.
- Maintenance of existing installations. The Regulation allows the maintenance and repair of already-installed systems provided the equipment’s capacity and the quantity of fluorinated gas are not increased, and it is not replaced with a gas with a higher global warming potential.
Inert gases
Inert gases (IG-01 argon, IG-100 nitrogen, IG-55, and IG-541) work by reducing the oxygen concentration in the enclosure below the combustion threshold. They have zero ozone depletion potential (ODP) and zero global warming potential (GWP), are not affected by the fluorinated gas framework, and have an indefinite shelf life, at the cost of greater cylinder-room storage capacity.
It is worth avoiding the common but inaccurate message that the discharge is harmless to people. All inert gases share roughly the same safety margin (NOAEL of 43% and LOAEL of 52%), and UNE-EN 15004-1 limits the maximum exposure time based on the design concentration:
- Design concentration below 43%: maximum 5 minutes in occupied rooms.
- Between 43% and 52%: maximum 3 minutes in occupied rooms.
- Between 52% and 62%: maximum 30 seconds, and only in unoccupied rooms.
- Above 62%: unoccupied rooms; exposure not permitted.
Critical design conditions: discharge time, tightness, overpressure, and noise
- Discharge time and concentration. The project must reach 95% of the design concentration within a maximum time of around 10 seconds for halocarbon agents and 60 seconds for inert gases. The design concentration is not the extinguishing concentration: it incorporates a safety factor according to the fire class. Values should be verified against the current edition of UNE-EN 15004-1.
- Enclosure tightness. Without an enclosure integrity test (door fan test), performed in accordance with Annex E of UNE-EN 15004-1, there is no guarantee that the concentration will be maintained for the hold time defined in the project —typically 10 minutes. This test must be repeated periodically throughout the life of the installation, not only at commissioning.
- Overpressure relief. This is the aspect most often omitted. The discharge generates a pressure transient capable of damaging the enclosure of the protected room; the design must include correctly sized and oriented overpressure relief vents.
- Discharge noise and hard drives. The sound pressure level generated by the diffusers, especially in inert gas systems, can degrade performance or damage mechanical hard drives. FM Global’s Data Sheet 5-32 sets out criteria for diffuser placement based on declared sound level. It is a real risk, documented in actual CPD incidents.
- Interlocks. HVAC shutdown, damper closure, cross-zoned double detection for release, and the timing sequence must all be defined in the cause-and-effect matrix.
Regulatory framework for gaseous agent systems
In Spain, the design, installation, and maintenance of these systems are governed by the RIPCI (Royal Decree 513/2017, current version in force) and by the UNE-EN 15004 series on fire extinguishing systems using gaseous agents (equivalent to the ISO 14520 series). Carbon dioxide systems are treated specifically under UNE-ISO 6183. Each project should verify the current edition of each document in force.
Alternatives to the gaseous agent worth evaluating
Presenting gas as the only possible solution is incomplete today. Depending on the risk profile, the insurer’s criteria, and the continuity strategy, at least four additional options should be put on the table:
- Water mist. Regulated by UNE-EN 14972 and accepted by FM Global for data processing areas within the air velocity limits of its approval. It uses a fraction of the water used by a conventional sprinkler.
- Hybrid water + inert gas systems. Covered by FM Global in its Data Sheet 4-6 for certain configurations.
- Oxygen reduction (hypoxic atmosphere). Prevention systems based on the permanent control of oxygen concentration, in accordance with UNE-EN 16750 and FM Global’s Data Sheet 4-13. They prevent ignition rather than extinguish, with significant implications for personnel accessibility.
- Double-interlock pre-action sprinklers. It is worth being honest about the insurer’s criteria: FM Global does not automatically consider clean agent or oxygen-reduction systems as substitutes for sprinkler protection unless the project’s specific criteria allow it. NFPA 75 and Data Sheet 5-32 develop double-interlock pre-action configurations with independent double VEWFD detection. In many CPDs the correct solution is the coexistence of both, not substitution.
Dedicated protection of electrical cabinets and rack cabinets
The third layer protects the interior of the assets where fire most frequently originates: electrical cabinets, main switchboards, uninterruptible power supply (UPS) systems, server rack cabinets, and cable trays.
Dedicated systems for switchboards and electrical cabinets
Systems for electric cabinet fire protection integrate linear detection via heat-sensitive cable or microaspiration with autonomous extinguishing inside the switchboard’s own enclosure. The advantage is that detection and action occur before the event has any effect on the room.
Automatic extinguishing for rack cabinets
For environments where cabinets house critical equipment —contained aisles, hyperscale rooms, edge data centers—, automatic fire protection extinguishing systems for racks offer a layer integrated into each cabinet, with its own detection and a localized discharge that isolates the incident without affecting the rest of the room.
Lithium batteries: a risk the gaseous agent does not solve
The gradual replacement of lead batteries with lithium-ion in UPS units and cabinets introduces a different scenario: no gaseous agent stops a thermal runaway, because the reaction does not depend on ambient oxygen. The strategy here relies on early detection of venting gases, compartmentation, and sustained cooling, together with testing criteria such as UL 9540A. This is a point that must be addressed explicitly at the consultancy stage.
The design criterion is clear: contain the fire at the asset where it starts before it escalates to the room. That is the difference between a service incident and a total loss.
How it all integrates into a CPD PCI project
A serious data center project does not choose between technologies: it combines them into a layered architecture, aligned with the criticality of each zone.
- Layer 1 — Aspirating detection in the room: full coverage of the air volume, with sampling in the false ceiling, raised floor, and return plenum.
- Layer 2 — Detection inside critical assets: heat-sensitive cable or microaspiration in electrical switchboards and high-density cabinets.
- Layer 3 — Room-level suppression: gaseous agent, water mist, or oxygen reduction, with hydraulic or concentration calculation, enclosure integrity testing, overpressure relief, and interlock with HVAC.
- Layer 4 — Dedicated extinguishing at asset level: micro-systems in cabinets and racks to confine the fire before it escalates.
- Layer 5 — Coordination with building management and operations: pre-alarms integrated with the control center, evacuation protocols, and shutdown and discharge sequencing.
The cause-and-effect matrix between detection, suppression, HVAC, and fire dampers is the document that distinguishes a correct project from one that only complies on paper. Its functional verification at commissioning, with a real test of every line of the matrix, is essential.
Applicable regulations: the common framework
A data center PCI project in Spain operates within overlapping frameworks, and the first decision —often overlooked— is that of use classification:
- RIPCI (RD 513/2017). Governs the installation and maintenance of active fire protection systems, including the operations and periodicities set out in its Annex II.
- CTE DB-SI or RSCIEI, depending on the case. If the CPD is located within an administrative-use building or similar, CTE DB-SI applies (evacuation, compartmentation, fire resistance). If it forms part of an industrial establishment, the applicable framework is the RSCIEI (RD 2267/2004). This is a project determination that must be explicitly justified, and to which regional or municipal fire-brigade intervention conditions may be added.
- An explicit requirement worth knowing. Annex III of the RSCIEI, in section 15.1.b), establishes that gaseous extinguishing agent systems must be installed in fire sectors of industrial establishments that constitute enclosures housing electronic equipment, computing centers, data banks, control or measurement centers, and the like, when protection by water systems could damage such equipment. This is the most direct prescriptive hook for a CPD integrated into an industrial establishment.
- Cable fire reaction. Classification into Euroclasses under Regulation (EU) 305/2011 on construction products, an aspect with direct impact on the fire load of cable trays and raised flooring.
- Fluorinated gases. Regulation (EU) 2024/573, with the implications described above.
- International references. NFPA 75 (information technology equipment) and NFPA 76 (telecommunications facilities); the UNE-EN 15004 / ISO 14520 series for gaseous agents; and, when required by the insurer, FM Global’s Data Sheets: 5-32 (data centers), 4-9 (clean agents), 4-13 (oxygen reduction), and 5-48 (automatic detection).
As introductory reading material in Spanish on gaseous agents, NTP 975, published in 2013 by the then INSHT (today INSST), remains useful as an introduction. It should be handled bearing its date in mind: it relies on the 1993 RIPCI, now repealed, and on the 2009 edition of UNE-EN 15004, and its considerations on halocarbon agents have been superseded by the current fluorinated gas framework. It is not a design criterion.
The editions of all these documents are reviewed periodically. Any specification must confirm the version in force at the time of the project.
A CPD’s PCI architecture is designed at project stage, not “installed.” That is why our engineering team approaches every data center from a prior technical consultancy phase, before any equipment is defined. Request a no-obligation technical assessment of your installation and we will work with you on the layered architecture best suited to your risk profile and your installation’s service level agreement.
Frequently asked questions about PCI in data centers
Are sprinklers enough to protect a data center?
Sprinklers are not the primary protection for the technical room, because water can damage electronics to an extent equivalent to the fire itself. That said, they don’t disappear either: NFPA 75 and FM Global’s Data Sheet 5-32 develop double-interlock pre-action configurations —water only enters the pipework after detection has triggered and a sprinkler has opened—, and FM Global does not automatically accept clean agent as a sprinkler substitute. The usual solution is a combination of ultra-early aspirating detection, residue-free suppression in the room, and a correctly configured water installation as backup.
What is the difference between a halocarbon agent and an inert gas?
FK-5-1-12 extinguishes mainly by thermal absorption and requires a smaller storage volume, which reduces the cylinder-room footprint. Inert gases such as IG-541 work by oxygen reduction, have zero GWP and ODP, and are indefinitely storable, but require greater storage capacity and specific attention to discharge sound level and overpressure relief. HFC agents (HFC-227ea, HFC-125) are affected by the marketing ban under Regulation (EU) 2024/573 for new equipment.
What is the enclosure integrity test (door fan test) and why is it critical?
It is the tightness test that verifies whether the protected enclosure can maintain the extinguishing agent concentration for the hold time defined in the project. Without it, there is no guarantee that the gas will not leak through uncontrolled openings, which would nullify the extinguishing action. It must be repeated periodically, since any subsequent building work or utility penetration alters the enclosure’s tightness.
Is dedicated protection of electrical cabinets mandatory in a CPD?
There is no generic regulatory obligation, but in projects with business continuity criteria or insurer requirements it is incorporated as an additional layer. It allows an incident to be contained at the asset of origin before triggering the room’s general system, preventing massive service interruptions.
Which regulations govern gas extinguishing systems in data centers in Spain?
The main framework is the RIPCI (RD 513/2017) together with the UNE-EN 15004 series for gaseous agents, with specific treatment of CO₂ systems under UNE-ISO 6183. Added to this is Regulation (EU) 2024/573 on fluorinated gases, which conditions which agents may be used in new installations. As international references, NFPA 75 and NFPA 76 apply, as well as FM Global’s Data Sheets when required by the insurer.
