“ Highlighting the risks and challenges presented by modern data-center cooling systems in fire detection and suppression applications. “ Dave Boyack Sales Manager-Special Hazards Tyco Fire Protection Products

Background Influencing factors Airflow Containment isle/multiple suppression zones Detection Suppression agents comparison

Background Containment systems for data centre cooling are becoming widely adopted but to date fire codes and standards don’t make allowance for the challenges they present to fire detection and suppression systems. A compliant system may not provide adequate or correct levels of equipment protection or safeguard business continuity. Many codes still advocate AHU shutdown on first level activation (1st knock) This is however not always possible. Detection and suppression activation therefore need to take place with cooling systems operational.

Containment System Deployment Market penetration Adoption profile * The Containment Chronicles

Airflow

Effects of Airflow Dramatic dilution of the small amounts of smoke present at incipient stage makes accurate smoke detection challenging. Air movement affects suppressant concentration: Can assist in providing an even concentration of agent throughout the space Will draw agent into/away from the contained isle so total flooding is still required. Reduce airflow on 1st knock if possible. A chemical agent may provide some cooling effect. Image: www.42u.com

Effects of airflow Reducing airflow after first level of detection activation will (1st knock) will: Shut off any fresh air intakes. Aid in achieving accurate activation of suppression system at second level activation (2nd knock) by reducing dilution of smoke sample. If smoke level reduces after 1st knock then this could be an indication that smoke was drawn in from an external source. Aid in suppression agent circulation once system has been activated. Ensure even concentrations of agent throughout the space. Draw agent through the electronic equipment thus suppressing fire at it’s source.

2. Containment isle/multiple suppression zones

Containment isle/multiple suppression zones Suppression nozzles required in each space to avoid pressure differentials Discharge agent into all spaces to ensure even concentration Amount of suppressant required calculated on the entire volume Ensure system topology is taken into consideration eg: in-row coolers vs wall mount CRAC units. Where multiple containment systems are housed in a single area consider the total volume. Image: www.42u.com

3. Detection

Detection 400+ ACH possible but current detection standards only allow for 60 ACH. 2nd stage detection system activation must be achieved with AHU operational Room space and containment isle to be provided with detection. ASD is the only option. Each ASD sampling hole is considered equivalent to a smoke detector.

Detection Point type smoke detectors become less effective from 7m/s airflow ASD remains effective. However, ASD with drift compensation may not be desirable due to the need for very accurate suppression release as a result of high airflow. Positioning of sampling holes as per codes and standards may not provide the best result Sampling hole spacing may relate to position of in-row coolers A “room sampling” system may still be required to achieve minimum compliance Image: Xtralis

Detection and Suppression Extract from BS 6266-Computer and data accommodation standard: Careful consideration should be given to the inter-relationship between the ventilation and fire detection systems. Where ventilation is essential for the correct functioning of the electronic equipment, as is likely to be the case with Category D and Category E electronic equipment installations, shutting down ventilation at an early stage following operation of fire detection in the electronic equipment area might be undesirable.

4. Suppression Agents Comparison

Next-generation Suppression Agents “Life of Data Centre” products. Environmentally friendly Clean Agent: (Oxygen reduction) Design Concentration required: 35-40% IG55/IG541 Chemical Agents: (Heat removal) Design Concentration required: 4.2-5.6% Sapphire/NOVEC 1230 Provides some general cooling effect No impact on electrical equipment therefore safe ( even beneficial) to keep AHU’s operational. Lower physical footprint suits smaller applications such as HACS/CACS

Storage Footprint FM-200®: 7,9% = 0,63 kg/m³ 126 kg - 1 x 147 ltr. Footprint: comparison for 200 m³ class A hazard (1) INERGEN/IG541 : 39,9% = 0,72 kg/m³ CO2: 50% = 1,35 kg/m³ Novec™1230: 5,3% = 0,78 kg/m³ FM-200®: 7,9% = 0,63 kg/m³ 126 kg - 1 x 147 ltr. 144 kg - 5 x 80 ltr. (300 bar) 156 kg - 1 x 180 ltr. 270 kg - 6 x 45 kg Clean agent examples based on regular class A acc. to ISO14520 September 19, 2018

Agents: Environmental factors Modern cooling systems are more efficient and therefore reduce power consumption and environmental impact. Suppression systems should follow the same trend.

Agents: Environmental factors

Agents: Environmental factors

Design Concentrations Small footprint and high safety margin mean that higher design concentrations are possible in order to overcome the effects of rapid air movement and pressure zones within a containment system. An agent with a greater safety margin allows for an increase in design concentration to compensate for the influence of the containment system while maintaining human and environmental safety.

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