FSSA Annual Forum Fajardo, Puerto Rico February 2016 Containment Aisle Fire Detection Strategies Steven Joseph Director Market Development, Xtralis Inc.
Steven Joseph Director Market Development, Xtralis Inc.
Presenter
Presentation Notes
Title: Air Containment Aisle Fire Protection Strategies Abstract: Fire detection is a crucial element of any fire protection strategy and is often relied upon providing first line of defense triggering sequential systems, including suppression. Air containment aisles presents a challenge to both early and reliable fire detection. Transitions within the IT/Communications industry have outpaced prescriptive measures, which have largely been outclassed by cooling configuration innovations. In a containment aisle, detecting smoke using conventional or prescriptive methods, technologies, placement and spacing can be challenging, if not impossible. Given these unique challenges there is an increasing emphasis on performance-based approaches that address individual environmental requirements within containment aisles. When properly implemented Air Sampling Smoke Detection technologies uniquely address containment aisle detection challenges providing effectiveness and efficiencies in terms of performance, cost and reliable suppression interface. This presentation provides insight as to the application of air sampling smoke detection technologies in air containment aisles and suppression interface strategies for various hot/cold aisle configurations. Presenter: Steven Joseph, Xtralis Inc.
The Age of Big Data Proliferation of Data Centers… Exponential data growth Implication for storage and compute
requirements Significant buildout to support
consumption
Significant Convergence Infrastructure Transitions… High density Increased heat loads Lower PUE Innovative cooling strategies Reliability essential
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Presentation Notes
Transitions outpacing how we apply traditional prescriptive approach
High Density Cooling Strategies Air containment aisles… Improved airflow
management
Reduced cooling cost
Improved PUE
The norm
Many configurations
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Presentation Notes
With respect to other types of heating, ventilation, and air conditioning (HVAC) systems, data centers are designed for computers, as opposed to people. The heat that needs to be removed is generated by the continuous operation of IT equipment, which must be removed for proper operation of the data center. Hot Aisle / Cold Aisle configuration, which had been the industry standard, is no longer a viable solution as power densities have significantly increased, outpacing improvements in HVAC technology. Air containment aisles improves air-flow management within a data center by focusing cooling to the more narrow scope of cooling individual components as opposed to the wider scope of cooling the entire room. This cooling techniques has been proven efficient and effective at reducing cooling cost and today is the norm.
Containment Types Cold Aisle Containment (CAC)…
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In a Cold aisle containment (CAC) configuration, cold aisles are closed off and contained with the use of solid obstructions. The goal of this is to prevent cooled air from mixing with air in the room, providing air to the server inlets that is close in temperature to that supplied by the air conditioning unit. The goal of the confinement is to maximize the utilization of the cold air percolating through server inlets.
Containment Types Hot Aisle Containment (HAC)…
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Hot aisle containment is used to prevent hot air from the hot aisle from escaping and recirculating to the server inlets. This is accomplished by adding solid obstructions to close off the hot aisle.
Fire Risks Threaten Reliability Common Instigators… Electrical Mechanical Administrative
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The most common instigator of fire events in Datacom facilities are building systems. This includes but is not limited to: Electrical systems, such as: Power Distribution Systems. Shorts, overloading, component degradation and other electrical system malfunction. Overheating of cabling, components and equipment result in combustion of polymers, which can release toxic and corrosive gases that overtime may damage electronic devices. Mechanical systems, such as: HVAC system malfunction. HVAC systems aid in the circulation of smoke and gases to other compartments, which ultimately can lead to damage of electronic devices in other compartments. Generators, fuel lines, exhaust lines. Administrative -Bad house-keeping and storage practices. Densely packed arrangement of equipment and fuel sources will encourage the spread of fire and smoke contamination.
Fire Protection Required What’s driving requirements… Codes and standards Economic loss Regulatory impact (e.g. maintain network
reliability) Brand Image Life and welfare of public relying on function
of network Building occupants or exposed property Military and government installations relying
on function of network
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Fire detection strategy is often driven by requirements, such as: Life safety, which for IT/Communication operation extends beyond simply the occupants and to the community relying on the reliability of the function or service provided by the the operations. Compliance with codes & standards Reliable initiation of suppression systems And of course uptime objectives, which extends beyond network reliability, addressing needs for operational efficiencies by providing more information about the physical environment.
Fire Detection First Line of Defense Ensure Uptime… Detect Control Mitigate
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Certainly the most significant goal for any IT / Communication facility operator is of course uptime. A significant contributor to ensuring uptime is detection: that is the ability to overcome variables and detect before critical fire size is reached allowing personnel the time required to control the situation and mitigate the consequences. There are four stages to fire development, that is the incipient stage, growth stage, fully developed stage and the decay stage. The opportune time to respond is during the incipient phase of fire growth development, prior to flame and prolonged smoke contamination. This stage is the difference between turning what would be a fire fighting exercise into potentially a maintenance task. An ideal detection technology would be one that can monitor the entire fire progression providing alarm thresholds at each stage allowing for staged response leading up to the reliable initiation of suppression systems. Delayed fire suppression will expose the facility to unnecessary smoke and heat damage; together with all of the associated risks to life safety, business continuity and assets. Releasing suppression too late also drastically increases the possibility that the fire will not be brought under control by the suppressant. A premature release of suppression (for example, before the flaming stage of the fire) creates the risk of there being no suppressant left to minimize damage should it be required later on.
Challenging Environment With many variables… Obstructions Configuration Temperature Airflow patterns Air velocity Air circulation Dilution
Smoke barriers Accessibility Cost
Placement Spacing Listings Operability Not conducive to prescriptive
detector placement
Listings Sensitivity Predictability
Presenter
Presentation Notes
Detecting smoke within communication and IT infrastructures using conventional or prescriptive methods, technologies, placement and spacing can be challenging. The unique environments within these environments presents a challenge to both early and reliable fire detection. Consider factors such as: Obstructions present significant challenges for accessing conventional detection technologies once installed, significantly contributing to their cost. Accessing conventional detectors above or near obstructions for annual inspection, test and maintenance may be extremely difficult and subject network to outages. Fully, partially enclosed cabinets and structures, loaded cable trays, process piping, duct work and other obstructions impede smoke delivery to conventional passive type detectors. Temperatures are increasing with some industry references of as much as 140°F exceeding listed temperature of smoke detectors Airflow patterns in IT/Communication infrastructure can often times be in directions not conducive to smoke detector placement. When considering the optimum location careful consideration should be given to the inter-relationship between the ventilation and fire detection systems. Determine common airflow paths, plenums, point of filtration, makeup air entry points, temperature, airflow velocity, and so forth.
Challenging Environment Leaving to question Detection…
Suitability Placement Spacing
Challenging Environment For smoke detections systems to detect products of combustion, the products must travel from the source to a sensor or port and arrive there in sufficient density to be detectable.
Presenter
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For smoke detection systems to detect products of combustion, the products must travel from the source to a sensor or port and arrive there in sufficient density to be detectable. In this prescriptive coverage scenario detection points are outside the airflow distribution path. If an incident were to occur it would potentially go undetected until such time that the fire grows to a size at which its energy is sufficient to overcome dilution and the mechanical forces of the mechanical forced air. Resulting fire size is likely to exceed VEWFD objectives. This scenario assumes that the air is recirculating. But what if economizers are deployed where hot air, along with any tell tale signs of smoke is exhausted to the atmosphere. We now potentially lose any opportunity to alert occupants until such time that the fire incident breaches the compartment resulting in a much more significant event.
Fire Detection Strategy
Owner’s Objectives Facility Requirements
AHJ Requirements
Site Conditions Operating Conditions PBD
Performance Based Design
Performance Based Design Design Considerations… Coverage areas Performance category Conditions Technology Coverage technique Integration
Performance Based Design Smoke detection performance categories… Very Early Warning Fire
Detection (VEWFD)
Early Warning Fire Detection (EWFD)
Standard Fire Detection (SFD)
Presenter
Presentation Notes
There are three detection technology performance categories specified within performance based codes and standards. They are: Standard Fire Detection; Early Warning Fire Detection; and Very Early Warning Fire Detection Parameters regarding each category are defined by sensitivity, spacing and special coverage requirements. These performance categories address criticality by increasing sensitivity and density of detection points. Most end user practices applies these performance categories to each occupancy type thus defining performance expectations based on criticality of occupancy to be protected. Assessment of the risks and performance requirements specific to particular areas within IT / Communication Facilities forms the basis for the level of protection applied, in terms of sample point density and nominal sensitivity. Increasing placement density and sensitivity improves the chances of detecting incipient, low-energy fires, before fire conditions threaten services and network reliability.
Performance Based Design Detection within exhaust/return air distribution path, at a point prior to dilution provides best opportunity to detect incipient stage of fire development.
Presenter
Presentation Notes
Detection within exhaust/return air distribution path, at a point prior to dilution provides best opportunity to detect incipient stage of fire development. In the scenario illustrated detection at a point prior to air leaving the hot aisle and entering the plenum is an ideal location, and if properly zoned, directs personnel potentially to the origin. And if we miss detecting smoke elsewhere, detection at return paths as illustrated here provides a certain degree of redundancy. Simply removing other points feeding the plenum and relying solely on this point however would be a compromise.
Detection Technology Selection
Technology Airflow Velocity
Airflow Direction Sensitivity Temperature Placement Accessibility Cost
ASD ?
Spot-type ? ? ? ? ? ? ?
Smoke Detection selection criteria…
Presenter
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When properly implemented Air Sampling Smoke Detection technologies uniquely address detection challenges providing effectiveness and efficiencies in terms of performance and cost.
Containment Coverage Techniques Placement assessment with respect to return air… Hot Aisle Containment
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Hot aisle containment is used to prevent hot air from the hot aisle from escaping and recirculating to the server outlets. This is accomplished by adding solid obstructions to close off the hot aisle.
Containment Coverage Techniques Placement Example… Hot Aisle Containment
- Placement at points where hot air exits, prior to dilution
- For collar penetrations one sampling point minimum every 6 ft
- For ducted chimneys one sample point per 4 SF of chimney opening
- Orientation 20-45° downward towards incoming airflow
Containment Coverage Techniques Spacing too far apart we might miss detecting smoke…
Presenter
Presentation Notes
As noted earlier in our presentation, smoke must reach port or sensor in sufficient concentration to detect it. In most common containment cooling configurations where the air flow is channelled directly from the exhaust end of servers vertically through a collar or chimney and into the plenum, using area coverage spacing there would likely be a number of server racks in between where if an incident were to occur would go undetected until such time that the fire grows to a size at which its energy is sufficient to overcome dilution and the mechanical forces of the HVAC containment system.
Containment Coverage Techniques For very early warning within containment structures, consider port spacing at a minimum every 6 ft (1.8m) on center.
Containment Coverage Techniques Placement assessment with respect to return air… Cold Aisle Containment
Presenter
Presentation Notes
Cold aisle containment (CAC) is identical to HACA with the exception that the cold aisles are closed off and contained with the use of solid obstructions. The goal of this is to prevent the air rising from the raised floor from mixing with air in the room, providing air to the server inlets that is close in temperature to that supplied by the air conditioning unit. The goal of the confinement is to maximize the utilization of the cold air percolating from the raised floor.
Containment Coverage Techniques Placement example Cold Aisle Containment
- Placement at points where air exits hot aisle, prior to dilution
- Every 4 sq. ft of grille area protected
- Orientation 20-45° downward towards incoming air
Containment Coverage Techniques Placement assessment with respect to return air… In Row Cooling
Presenter
Presentation Notes
In-row cooling technology is based on deploying cooling units along side the servers, directly putting cold air into the cold aisle, bypassing the need for a raised floor. In this configuration the return side of the cooling units face the hot aisle, and the supply side face the cold aisle. The goal is to shift the cooling from a room based approach to a row based approach. Cooling units are directed toward each other such that they build up static pressure in the cold aisle.
Containment Coverage Techniques Placement assessment with respect to return air… In Row Cooling (plan view)
Cross Zoning Cross zoning options… Two or more detector
zones or pipe sectors in alarm
Multiple alarm points in alarm (AND condition)
Cross Zoning Strategic use of sectors…
{ Sector 2
{ Sector 3
{ Sector 4
+
+
+
{ Sector 1
Sector 2 }
Sector 3 }
Sector 4 }
+
+
+
Sector 1 }
ZN-01 ZN-02 +
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Presentation Notes
In order to minimize the possibility of unnecessary suppression release as a result of a single detector issuing a false alarm, it is common practice that two or more detectors have to issue an alarm before a suppression dump can occur. The two detector method is known as a coincidence detection scheme, while more than two alarms constitutes a ‘counting system’.
Divide by number of sampling ports entire detector
Resulting numbers are alarm threshold set points
Commissioning Best Practices Alarm threshold settings… 10 sampling port example
0.21 10 = 0.021% obs/ft
Pre-Alarm
1 10 = 0.1% obs/ft
Fire
2.5 10 = 0.25% obs/ft
Suppression Initiation
Commissioning Best Practices Transport time (VEWFD)… 60 seconds
Measured from furthest port on each pipe run within fire zone, excluding benchmark test point
Timed from smoke introduction at last port to response at detector
- Response does not mean alarm!
Commissioning Best Practices Benchmark Test Point… Documented and labeled at time of
commissioning
Normally closed
Not included in alarm transport time objectives
Benchmark data used in subsequent tests to validate system integrity
Performance Assurance Elements of success…
Requirements
Qualifications
Placement
Spacing
Performance
Products
Commissioning
Presenter
Presentation Notes
A properly designed ASD system is paramount for the proper operation of the system and in meeting fire protection objectives. Design & Specification take into consideration: Ensure system design meets end user practice, manufacturer’s criteria and local jurisdictional requirements Qualifications of designer, Installer & commissioning technician (Authorized) Apply coverage techniques that account for all possible smoke migration paths Maximize coverage by utilizing combined coverage techniques where possible Utilize most efficient product model to adequately and efficiently protect each area Never exceed limitations specified in the products datasheet Include manufacturer in the early stages of project work Specify manufacturer design review prior to submittal Specify system programming requirements in accordance with end user practices and manufacturer guidelines. Specify commissioning requirements in accordance with end user practices and manufacturer guidelines.
