Posted by
Lee Kaiser on Tue, Oct 23, 2012 @ 03:15 PM
High Volume Low Speed (HVLS) fans are a great addition to any large facility or warehouse. They are an energy efficient supplement to expensive HVAC systems, moving large amounts of air helping employees stay comfortable and productive. As a growing number of facilities are now incorporating these fans, fire protection engineers are concerned about their effect on sprinkler system operation. Many experts fear these fans will delay sprinkler operation, possibly overwhelm the sprinkler system, and cause a larger fire than necessary. New research has focused on addressing those concerns.
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While it is known that high airflow makes a fire more intense, it has taken some time to understand the impact these HVLS fans have on sprinkler performance in warehouses and other storage occupancies. The Fire Protection Research Foundation directed a collaborative industry research effort to study the issue and provide direct input to update the applicable NFPA standards. This two-part project was awarded the 2012 Fire Protection Research Foundation medal by NFPA. The report from the most recent study was issued in January 2011.
The central problem uncovered during the study and fire testing was the unnecessary fire damage that occured when the fans were not shutdown. The study showed sprinklers will activate while the blades rotate and the down-flow of air increases fire damage to contents requiring more sprinklers to operate to control the fire. Fire test results showed less damage when the fans were shut down upon sprinkler activation.The research results are guiding new code requirements within NFPA 13, the Standard for the Installation of Sprinkler Systems. The 2013 edition of the standard will be issued next year. NFPA technical committee documents indicate that the following code changes will be issued for sprinkled warehouses with HVLS fans.
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Maximum allowable fan diameter of 24 feet.
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Fans must be approximately centered between four adjacent sprinklers.
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There must be a 3 foot minimum clearance from the sprinkler deflector to the fan.
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Fans must be interlocked to shut down immediately upon receiving a water flow signal from the fire alarm system.
These requirements will be placed in the NFPA 13 chapter on storage occupancies. Undoubtedly, there are other types of occupancies where HVLS fans are installed; however, all indications are that the code will not address those locations in the new edition.
If you have further questions about the effects of HVLS fans on sprinkler systems, information regarding NFPA 13 or industrial fire suppresison, click here to Ask the Experts at ORR Protection Systems.
For more than 20 years, cross-zone detection has been a best practice for the design of fire suppression systems. Cross-zone detection is all about verified detection or the requirement for two detectors in alarm before activating the release sequence. Detectors which rely on smoke to alarm can be more sensitive to ambient factors such as dirt and dust which cause false alarms. Because of this, cross-zone release has been the industry standard when smoke detectors are involved in the automatic actuation of fire suppression systems such as Pre-Action Sprinkler or Clean Agent. However, many fire suppression system owners don’t understand the various installation and programming options available to them.
Single vs. Multiple Detection Methods
A common cross-zone detection technique involves the use of a two different methods of fire detection with each assigned to a separate zone. The advantage of this approach is an increased assurance that a fire is present before releasing the suppression agent. The table below lists several examples of cross-zone detection arrangements utilizing multiple detection methods.
A typical approach involves the cross-zoning of spot smoke detection like ionization and photoelectric type smoke detectors. The characteristics of an ionization detector make it ideal for detecting fast flaming fires which produce smaller particles of combustion. Photoelectric detectors are most suited for slow smoldering fires that tend to produce larger smoke particulates. Depending on the type of fire, the response times will vary for these two types of detectors, but eventually both will detect the fire. Cross-zone detection utilizing multiple detection methods minimizes the potential for a false alarm to result in a non-fire discharge of the suppression agent.
Alternatively, some cross-zone detection designs utilize only one type of detector. Many refer to this as a “counting-zone” since the control logic involves counting the number of detectors in alarm. This approach can only be accomplished with an intelligent fire alarm system using addressable panels having the unique ability to indentify individual detectors in alarm and the software intelligence to “count” them. When an alarm signal is received from the first detector, this constitutes a pre-alarm condition for the fire suppression system. Once a second detector initiates an alarm signal, the control panel will begin the release sequence.
Conventional vs. Addressable Control Panels
With a conventional fire alarm system, cross-zone detection always requires the installation of two physical detection circuits. Detectors are arranged such that adjacent detectors are separated into two individual circuits or zones (see Figure 1). In other words, half of the detectors are installed to Circuit 1 and the other half are installed to Circuit 2. The control panel is configured to activate a pre-alarm signal if one or more detectors alarm on a single zone. Once a detector initiates an alarm signal on the second zone, the control panel will begin the release sequence.
On the other hand, cross-zone detection with an addressable control panel does not depend on the use of multiple individual circuits. Rather each detector is assigned a unique identifier (address) and transmits alarm signal data including this address to the control panel. Programming the control panel for cross-zone logic involves separating adjacent detectors by assigning them each to one of two software zones. In other words, half of the detectors are assigned to Software Zone 1 and the other half are assigned to Software Zone 2 (see Figure 2). Once the first detector alarms, the control panel recognizes the software zone it belongs to and activates a pre-alarm signal. As other detectors alarm concurrently, the control panel continues checking for their software zone assignment. Once an alarm signal is received from a detector assigned to the second (alternate) software zone, the control panel will begin the release sequence.
Air Sampling Smoke Detection
When designing a fire suppression system for the protection of a data center or telecommunication facility, it is important to balance the need for the earliest warning possible with the need to prevent an unnecessary suppression release. For this reason, an increasing number of fire protection designers are now incorporating Air Sampling Smoke Detection (ASSD) into the cross-zone detection scheme. In many cases, ASSD is cross-zoned with spot-type photoelectric smoke detectors to trigger the suppression system. ASSD is capable of detecting very low concentrations of smoke and will offer the earliest possible warning of a fire in most mission-critical facilities. This cross-zone detection technique involves configuring the ASSD as Zone 1 and the spot-type smoke detectors as Zone 2. Typically, an alarm signal will be received from the ASSD first and will act as a pre-alarm condition for the fire suppression system. Often times, facility personnel will have several minutes or more to respond and possibly stop the fire in its incipient stage. If not, then the initiation of an alarm from a spot-type smoke detector will further verify the presence of a growing fire and trigger the release of the suppression system.
Incorporating cross-zone detection into the design of a fire suppression system makes good sense. The question you must answer is: What options and configurations are most appropriate for my application? If you want some help answering that question, contact one of our many fire protection professionals. ORR Protection Systems has proven experience assisting hundreds of companies with the design of cross-zone detection systems. If you have further questions regarding cross-zone detection, ask the EXPERT! Click Here
Posted by
Lee Kaiser on Mon, Jul 16, 2012 @ 06:03 PM
It is common knowledge that lead-acid batteries, when they are charging, release hydrogen gas that can potentially result in an explosion. In 2001, a hydrogen gas explosion occurred in a California data center in the UPS room where batteries were charging. Fortunately no one was harmed; however, the Data Center did sustain significant damage including the collapse of several walls and ceilings. The explosion also resulted in a large hole in the roof of the building.
Unfortunately, in this case the cause of the explosion remains unknown. The data center owner had installed both a ventilation system and a hydrogen gas detector in the UPS room. When the fire department arrived on the scene, the hydrogen gas detector was reporting an alarm signal. During the investigation, several occupants reported hearing the alarm for three days prior to the explosion. Both a hydrogen gas detector and a ventilation system are required for a safe battery charging room, but somehow in this case that equipment did not perform adequately. The question is, “How can you avoid this unfortunate event in your data center?”
In Article 320 of NFPA 70E, Standard for Electrical Safety in the Workplace, designers and building owners can find requirements for safely designing a battery charging room. This standard requires a ventilation system to exhaust air from the room to the outdoors. Since hydrogen gas is lighter than the air in the room, it should be arranged to exhaust from high in the room. Configure the ventilation system so that it will limit hydrogen gas concentrations to less than 1% concentration by volume. When the hydrogen concentration rises to levels above 4% there is a substantial risk of an explosion.
But how should the fire protection system interact with the ventilation system and what role should it play in notifying the occupants? The answer is simple. The fire detection system can monitor for both smoke and hydrogen, notify occupants of either, and control the battery room’s exhaust fan(s).
Data Center Managers who are focused on achieving maximum uptime recognize the importance of providing good fire protection not only in the server rooms, but also in spaces containing power distribution equipment. It is common for consulting engineers to specify Air Sampling Smoke Detection (ASSD) for protection of data processing rooms, power rooms and battery rooms. The VESDA air sampling smoke detection system by Xtralis offers Data Center Managers a unique opportunity to address both the fire and gas detection needed for the protection of battery rooms. Xtralis’ VESDA ECO gas detection product leverages the air sampling pipe network within the battery room to easily and economically detect harmful levels of hydrogen gas. The ECO gas detectors are installed in-line with the sampling pipe downstream of the battery room. TheECO sensor provides both a relay output and an analog output (4-20mA) which can be monitored by either the fire alarm system or other building control system. These systems can use that signal to activate the exhaust fan(s) in the battery room. It will also be necessary for these systems to monitor the operation of the fan(s) using either a current switch or an airflow proving switch.
Of equal importance to the form of gas detection used is programming a proper sequence of controls. The exhaust fan should be set to cycle on and off or modulate its speed to maintain a safe level of hydrogen. The fire alarm control panel can be used to provide a local alarm signal when the hydrogen concentration exceeds one percent. Alarm notification appliances such as a specially labeled horn and strobe light can be placed both inside the battery room and outside each room entrance. Additionally, one should consider providing warning signs to accompany these local alarm devices which include emergency response instructions. Depending upon the facility, it may be appropriate to evacuate the entire building when the hydrogen level exceeds 4%. A fire alarm service provider can program the control panel’s notification appliance circuits to achieve these different levels of notification.
Finally, one should consider whether it would be appropriate to shut down the battery charging system when an unsafe hydrogen level exists. This will depend upon the arrangement of the facility’s power delivery equipment and on-site personnel training levels. When the facility has an additional backup UPSpower source, then it makes sense to shut down the battery charging equipment creating the problem. If no backup UPS power source exists, then this becomes a more difficult decision to make. The battery charging equipment should most definitely be shut-down when on-site personnel are not trained to respond to unsafe hydrogen gas conditions.
Hydrogen buildup in UPS rooms and battery charging areas will occur slowly and protecting against the danger of explosion can be easily accomplished using a well designed ventilation system. Remember that ventilation systems can fail. Be certain to include a hydrogen monitoring system and means for notifying occupants so hydrogen gas problems can be mitigated before an explosion occurs.
This week I joined industry leaders and experts in Las Vegas for the NFPA Conference and Exposition. The mission of the National Fire Protection Association is to reduce the worldwide burden of fire and other hazards on the quality of life by providing and advocating consensus codes and standards, research, training and education. Each year I find this conference to be a tremendous opportunity to connect with so many of my peers and to learn about the new trends in Fire Protection. I’d like to share just a few of my observations from the three days I spent at the conference.
1. The upcoming new edition of NFPA 75 and 76 standards will include much needed new requirements for protection of Data Centers and Telecommunications facilities.
On Monday morning, I listened to Jonathan Hart, NFPA associate fire protection engineer, review the latest updates to these important standards. Both standards (75 and 76) will now include entirely new sections addressing the use of Hot and Cold Aisle Containment, which is a growing trend in these facilities. Other changes involve selective depowering, abandoned cables, pre-fire planning, documentation of risk assessment and suppression in raised floors. Water Mist Fire Suppression Systems are now recognized as a possible acceptable protection solution for these mission critical facilities. Click here to read more about this conference session.
2. The University of Maryland is performing interesting research related to Clean Agent extinguishing concentrations for electrical energy augmented fires.
The University of Maryland and 3M are working together on a research project to examine Clean Agent extinguishing performance for fires with various heat flux rates. Although his testing isn’t complete, Romil Patel (Fire Protection Engineering Student at the University of Maryland) shared some preliminary data which may ultimately be used to substantiate changes to the NFPA 2001 standard for required gaseous agent concentrations to extinguish electrically energized fires. The driver for studying this topic is the dramatic increase in power densities in typical data center and telecommunications facilities. Energy densities of 10 – 20 kW per rack are becoming the norm in many of these facilities. Those involved in the project want to assure the NFPA standard prescribes appropriate minimum agent concentrations for this type of fire hazard. Click here to read more about this research.
3. The membership of NFPA voted to approve a new edition of NFPA 72, The National Fire Alarm and Signaling Code including several significant changes.
Once approved by the NFPA Standards Council in August, the 2013 edition of the National Fire Alarm and Signaling Code will be published. Over the past three years, the members who serve on the 10 Technical Committees that oversee this document responded to 700 public proposals and then 500 public comments related to revising this standard. Before the final document was approved this week, those attending the Annual Technical Session in Las Vegas heard and voted on 15 different motions to amend the document. These motions are made by members who wish to overturn an action made by the Technical Committee, which in many cases means overturning one of the new or revised requirements. I wasn’t able to attend the Technical Session to hear the outcome of these motions. If you are interested, check the NFPA Conference Blog to find out the final results of these 15 motions.
4. The NFPA has launched a clever advertising campaign about the benefits of becoming an NFPA member.
Those who attended the opening general session got to be the first to see three short videos which will be used in an upcoming campaign to promote membership in the NFPA. These videos seemed to be well received by those attending and generated a lot of laughter. One of the videos featured an NFPA member whose membership card displayed the name “Code Weenie” who exhibited several amazing supernatural abilities. The video leads you to believe that you also can have these abilities if you become an NFPA member. I thought they were quite funny. I hope you enjoy them as much as I did.
Video 1: Become an NFPA member. You won’t believe the perks.
Video 2: Find your Edge. Join NFPA today!
Video 3: Don’t be an NFPA wannabe. Join NFPA today!
5. Many NFPA members volunteer a great deal of time and give so much of themselves to promote the cause of Fire Safety.
Each year at this conference, the NFPA recognizes a few people who have served diligently to support the mission of the association. Before each deserving volunteer is presented with their award, a brief video is shown to tell the story of their exemplary service. Most have been volunteering their time and effort for 30 or even 40 years and have played a big role in moving the fire safety industry forward. I am inspired by the personal sacrifice and giftedness of these men and women who have the same passion that I do for protecting people and business from the risk of fire.
The Standards Medal was awarded to Edward Budnick of Hughes Associates.
The Research Foundation Medal was awarded to Garner Palenske of AON Fire Protection Engineering.
The Fire and Life Safety Educator of the Year was Marsha Geisler of the Downers Grove, IL Fire Department
The Industrial Fire Protection Section Fire Prevention Week Award was awarded to Raytheon Space and Airborne Systems of El Segundo, CA.
We frequently are asked to respond to questions about fire protection of mission critical facilities. From time-to-time we get a really great question and share our answer on this blog to benefit anyone else who may have a similar question.
“I am continuously looking for ways to reduce the cost of maintaining the systems in our buildings. What is one significant way I can lower the cost of the periodic Inspection, Testing and Maintenance program for my fire protection systems?”
In today’s business climate, Facility Managers are under constant pressure to reduce maintenance costs while at the same time improving the quality of service. While it may seem almost impossible to accomplish both of these objectives at the same time, it can be done. Using a Fire Protection Service Provider who offers online reporting of all your inspection reports can save you a tremendous amount of administration time while at the same time improve the quality of the inspection reports you receive.
Some service providers simply provide online inspection reports which are simply a scanned copy of a handwritten report and this really offers no improvement in quality. However, an effective online reporting system allows you to download high quality digital inspection documents. Additionally, these online reporting systems will allow the user to run analysis reports and will offer the ability to maintain a detailed inventory of every facility, every fire system and every system device. All reports can be easily accessed through a secured, password protected website. Managers, depending upon their level of responsibility, will have access to a single facility, multiple sites or all locations nationwide.
If you do not have access to online reporting, then you may want to ask your current fire protection service provider the following questions:
Do you offer an online reporting system for inspection reports and other documents?
If so, is there an additional charge for this service?
Is your online reporting platform your own proprietary system? If not, is there anything that could potentially affect my access to critical facility data?
What data will your online reporting system provide me?
Is there any software I’ll be required to install or maintain?
Are there any license or support fees I will incur?
At ORR Protection Systems, online reporting is just the way we do business and there is no extra charge for this service. If you would like to learn more about ORR’s online reporting capabilities, check out the NetSITE and NetREPORT sections of our website.
Last week I presented an Educational Session at the National Facilities Management and Technology conference in Baltimore, MD. Facilities Managers have the challenging responsibility of maintaining so many different building systems, including the fire systems that are so important to life safety and protection of the business operation. I shared with these Facility Managers 5 things they DO want to do and 5 things they DON’T want to do as they manage the Inspection, Testing and Maintenance of the Fire Protection Systems in their buildings. Click here to download a copy of the slides that accompanied my presentation.
DO these 5 things:
1. DO take responsibility for your fire systems
Often times, fire systems can be forgotten about and no one really takes responsibility for ensuring the ongoing reliability of these systems. NFPA 72, The National Fire Alarm and Signaling Code, makes it clear that the property or building or system owner is responsible for the inspection, testing and maintenance of these systems. Taking responsibility means being proactive and intentional about managing the ITM program and knowing what it takes to maintain a high level of reliability your fire systems.
2. DO understand how your fire system works
Do you know the difference between the Trouble signal and the Supervisory signal in your Fire Alarm system? What’s the correct response to these different signals? What button should you press? It's questions like this that many Facility Managers don’t know how to answer. It’s important that you find ways to learn how the system operates so you are prepared to interact with the equipment in the case of an emergency. I encourage you to make an effort to understand how your particular fire systems are designed to operate.
3. DO know the inspection, testing and maintenance requirements
The NFPA standards provide the minimum requirements for the Inspection, Testing and Maintenance of fire systems. Facility Managers should not overlook the importance of periodic visual inspections to verify all system components are in good operating condition, free from physical damage and nothing appears to have changed that would impact system performance. Testing should be performed on a periodic basis to verify the functionality of the fire system including simulating the events and conditions that are to be expected during an emergency situation. One must also remember those maintenance tasks that are necessary to keep the system in good operating condition. These include both periodic preventative maintenance activities and making the required repairs revealed by the inspection or testing of the system components. Take the time to learn what’s required so that you can be certain a proper ITM program is in place at your facility.
4. DO train your people
When it comes to training, Facility Managers must answer the following questions: Who should be trained? When (or how often) should they be trained? How can I train these people? Certain people should receive varying degrees of training depending upon their role. Some must understand how to operate the system so they can interact with the system when something happens. Others must simply be ready to react appropriately when an event happens. Some fire systems, like Clean Agent Extinguishing Systems have very specific NFPA requirements for training of personnel. If you decide that more training is needed, don’t forget to turn to your fire system service provider for help.
5. DO pay attention to recordkeeping
More times than not, system owners can’t put their hands on any of the documentation for their fire systems. When it comes to fire systems, there are several different types of records that are important to maintain. Every Fire Alarm System should have what is called a “Record of Completion” document that is maintained up-to-date with any and all system changes made over the life of the system. Other important records include as-built drawings, owner’s manuals, site-specific software, and a written sequence of operation. Facility Managers should also be certain to keep records of past inspections and service of the system.
DON’T do these 5 things:
1. DON’T ignore reoccurring problems
Some fire systems are plagued by reoccurring trouble conditions that just don’t seem to go away on their own. Common intermittent troubles include ground faults, circuit problems, battery faults and device failures. An experienced fire system service technician can track down the root cause of the problem and know how to make the necessary repairs. Resist the temptation to ignore these problems because of their sporadic nature. You may have a bigger problem than you think and your system may be rendered ineffective because of it.
2. DON’T let building occupants become apathetic to fire alarms
Maybe you have noticed this, but most people hesitate to respond when they hear the fire alarm evacuation signals in a building. Unfortunately, most of us have experienced more than one “false alarm” from a fire system in our lifetime and this has led many to be apathetic about evacuating. Facility Managers should do what they can to avoid false alarms, but when they do happen take steps to make whatever changes are necessary to prevent them in the future. When possible, inform occupants about the source of each false alarm in hopes of maintaining their future confidence in the system.
3. DON’T cause an accidental discharge
Many facilities will have one or more spaces protected by an automatic fire extinguishing system (i.e. FM-200, Inergen). Unfortunately, too many system owners have had to deal with an accidental discharge of a system. Facility Managers should take steps to avoid this at all costs. Without question, the most common reason for a false discharge is human error. It’s important to put in place and enforce procedures and policies that will minimize the chance for this sort of error. The single biggest contributor to the prevention of accidental discharges is training the personnel who work in and around these spaces. You should also continuously monitor operational changes that could have a negative impact on these fire suppression systems.
4. DON’T allow unqualified personnel to service your fire system
Who is qualified to service your fire system? The NFPA standards have a lot to say about this. Facilities Managers should ensure those who are performing these tasks are trained on the equipment they are servicing. I would also suggest you look for personnel who are certified by NICET in the specific type of fire system being serviced. NICET has certification programs in Fire Sprinkler, Fire Alarm and Special Hazard Fire Suppression. Facility Managers should not hesitate to ask not only the service provider, but also the specific technician about their level of experience in the type of work they are performing. The reliability of your life safety and business continuity is depending upon this person.
5. DON’T forget to consider the fire system when your facility changes
One thing is for certain, your building will eventually change and each time it does the Facility Manager must not forget to evaluate the impact those changes will have on the fire systems protecting the building. The need for this was highlighted in Lee Kaiser’s recent blog titled Clean Agent Fire Suppression: When rooms get smaller, recalculate. Other types of fire systems and components will no doubt be impacted including detector placement, notification appliance location, sprinkler coverage and obstructions to manual pull stations. When you realize your building will be undergoing a change, begin planning up-front for the necessary changes to the fire systems.
We frequently are asked to respond to questions about fire protection of mission critical facilities. From time-to-time we get a really great question and share our answer on this blog to benefit anyone else who may have a similar question.
QUESTION: “I manage 200+ mission critical facilities all across the country. I’ve been given the assignment of standardizing our fire protection system service. What are the most important factors to consider when choosing a fire protection partner? What are the pit-falls I should watch out for?”
The biggest challenges that an organization with numerous facilities across the country will face are the result of having to work with multiple vendors each having various levels of expertise. Another struggle they have is with tracking and filing all of the inspection reports for hundreds of different types of fire systems. From my experience, there are 3 key factors that make or break a national service program and these must be considered when selecting a fire protection partner.
1. Single Point of Contact: What this means is that every one of your facility managers at every location across the country can call the same phone number and speak to the same person who has the assignment of coordinating all of your fire protection services. This allows you to go to one place to get any and all questions answered or problems resolved. Whether it’s scheduling routine service, getting an invoicing question answered, or any other issue that needs resolution – the buck stops here. This will alleviate any chance for miscommunication or finger-pointing.
2. Experienced, well-trained Field Technicians: It is not uncommon for an organization like yours to have dozens of unique make and model fire systems in your many facilities across the country. On top of that, you probably are relying upon several unique types of fire protection equipment (fire alarm, sprinkler, portable fire extinguishers, etc.) for the protection of these facilities. It takes well trained and experienced technicians to properly inspect, test, and maintain all these different fire systems, not to mention troubleshoot and make repairs when there are problems.
3. Online Reporting: When the local fire marshal walks in the door, will you have the necessary inspection reports at your fingertips to prove your facilities are in compliance with local codes and standards? Will they be legible or understandable? One of the most valuable services a quality service partner can provide you is to maintain ALL of your fire protection equipment records in a secure, online database which is accessible to you 24/7. What you need is a system that gives you anywhere, anytime access to an up-to-date inventory of every component of every fire system at all of your sites as well as detailed inspection reports of the most recent and all past inspections. Simply put, this will result in saving you time, money and will contribute to assuring your facilities are protected.
Are these three things all that is needed to successfully manage a national service program? Not necessarily, but I can assure you that without these three key items you will be jeopardizing your program’s success. This is simply a suggestion of where to start and these elements should be the foundation for your company-wide service program.
Click here to learn more about ORR's National Account Program.
Maintaining reliability throughout the entire life cycle of a fire alarm system involves three distinct and equally important tasks which must be performed on a periodic basis: (1.) visual inspections, (2.) functional testing and (3.) maintenance activities. Many overlook the need to visually inspect the fire system and concentrate only on the functional testing of the components. However, each of these tasks are necessary and contribute to the assurance of a fire system that is ready to perform in the case of a fire.
Periodic Visual Inspections
A periodic inspection is a visual examination of the equipment to verify that nothing has changed from the initial design and installation that would affect its performance. Those charged with performing an inspection should be looking for a number of conditions which might affect the system’s ability to perform when called upon. A proper visual inspection should consider whether building modifications or occupancy changes would have an impact. A fire alarm strobe light designed and located to disperse light throughout an entire room may now be ineffective due to a reconfigured floor plan. Another important consideration is a change in environmental conditions. Increased cooling systems to support greater heat loads might be producing airflow rates impacting the need to adjust the design spacing of the ceiling smoke detectors. Building owners should also ensure that a visual inspection of the equipment includes identification of changes such as physical obstructions, device orientation, physical damage, degree of cleanliness and any other obvious problem that may not be indicated by the control panel automatically through electrical supervision. A minimum standard for these periodic visual inspections can be found in Table 14.3.1 Visual Inspection Frequencies of the National Fire Alarm and Signaling Code (NFPA 72).
Periodic Testing
Periodic testing is intended to validate the functionality of the fire protection system. Tests are performed by operating each component of the system to assure it performs as required in the case of an actual emergency event. A simple example of this sort of testing is to pull the lever of each Manual Fire Alarm Pull Station to ensure it performs as intended and initiates the required alarm condition. A proper testing program should also include testing the operation of all Emergency Control Functions in the system such as elevator recall or HVAC shutdown. NFPA 72, the National Fire Alarm and Signaling Code (2010 Edition), requires these functions to be tested at the same frequency as the device which initiates the action. For instance, if corridor smoke detectors activate the closure of fire doors, then this function must be tested annually to match the testing requirement of the smoke detector. Beyond just a simple functional test, the test method for many components may also involve the use of calibrated test equipment. One example of this is a duct smoke detector used to control the spread of harmful smoke. A proper test of this device not only must verify smoke will initiate an alarm, but also that the airstream of the ductwork is effectively being sampled. So in addition to the functional smoke entry test for the smoke detector, a pnumometer is used to measure the airflow from the sampling tube. This measurement is then compared to the acceptable range published in the manufacturer’s instructions to determine if the device is performing as designed. A minimum standard for these periodic tests can be found in Table 14.4.5 Testing Frequencies and Table 14.4.2.2 Test Methods of the National Fire Alarm and Signaling Code (NFPA 72).
Maintenance
Maintenance is the work necessary to keep the fire system operating properly. One form of maintenance is simply a response to a failure identified by a visual inspection or a test of the equipment. Service personnel should notify the system owner immediately whenever deficiencies are found during routine inspection and testing procedures. Considering the fact that life safety and/or mission continuity may be at risk, repairs should be made as soon as feasibly possible by qualified personnel. Whenever repairs are not made immediately, a temporary alternative means of protection should be put in place until the fire system is returned to an acceptable level of readiness. Another important form of maintenance is of a preventative nature. Many components in a fire protection system will require preventative maintenance at a prescribed frequency. These maintenance activities address components that degrade over time, have a finite lifespan or require periodic resetting or calibration. For example, most fire alarm systems utilize lead-acid type batteries as a secondary (backup) power supply. Although NFPA codes require routine testing to verify voltage levels are at an acceptable level, a preventative maintenance requirement exists requiring their replacement at 5 years from the date of manufacture. Another important preventative maintenance task involves regular cleaning of smoke detectors. Typically the detector manufacturer’s published instructions will provide both the recommended frequency and method for cleaning, but consideration should be given to adjusting these based on the environment where they are located.
In a survey conducted by the California State Board of Fire Services, building owners were asked about the current operational status of their fire systems and about the factors contributing to failures. 73% of the respondents cited a lack of maintenance as the cause for system failures. The truth is a proper inspection, testing and maintenance program will benefit not only in money savings over time, but even more importantly, will minimize an organization’s risk of liability.
1 Source: “Report to the Legislature in Response to House Resolution No. 14, Fire Alarm Systems,” December 30, 1983, Office of the State Fire Marshal, Sacramento, CA 95823.
When a building has a fire, its occupants rely upon the fire protection systems to perform successfully. However, all too often building owners are faced with the consequences of a fire system that has failed. What causes these failures? And what can be done to avoid another failure in the future? Having a suitable program of inspection, testing and maintenance (ITM) is one of the more important steps to be taken to assure the success of the fire protection system. The truth is, when an appropriate level of inspection, testing and maintenance is taking place, this activity will directly contribute to the high level of reliability expected of a fire protection system. But how does one determine just what is the “appropriate” level?
It all begins with having a proper understanding of the purpose of your ITM program. Its purpose is to discover failures of components that would prevent the fire system from operating as necessary during an emergency event. And of course, the goal is to discover and repair these failures prior to such an event. When developing a program, keep in mind that NFPA and other fire codes provide a minimum standard for ITM methods and frequencies. However, you may also want to consider other factors. For instance, a facility with increased risk or history of fires should consider more frequent intervals of testing or preventative maintenance. Also, a facility which supports mission-critical operations would require fire protection systems with a much higher degree of reliability than the average office building. Unfortunately, most building owners take a one-size-fits-all approach by allowing their decisions to be influenced only by the minimum requirements of the applicable fire code.
It is also important to remember that fire protection systems are the sum of many individual components, each one having the potential to fail. As you might expect, some components simply have the potential for a greater rate of failure than others. (For more on this topic, read my paper titled Inspection, Testing and Maintenance: A Window into System Reliability.) That’s why NFPA standards will prescribe a method and frequency of ITM for each individual component which is a part of the fire system. For instance, for a fire alarm system, the manual pull stations are required to be functionally tested annually, while the tamper devices supervising each sprinkler system valve must be tested semi-annually.
So, what’s the purpose of your ITM program? If it is simply to keep the Fire Marshall off your back, then you will most likely be focused on doing whatever the minimum requirements of the codes and standards. But hopefully your purpose is much greater than that and will be focused on achieving a highly reliable fire protection system, ready to respond when it is needed most.
Posted by
Lee Kaiser on Thu, Feb 02, 2012 @ 11:41 AM
Advances in computing technology, worldwide growth in data consumption, and the need for more efficient cooling of IT equipment is driving data centers to change rapidly. A significant part of these changes include the use of Hot Aisle or Cold Aisle (HACA) containment systems. The partitions that form these containment systems are affecting fire protection systems in these spaces. In the first part of this series of blog posts, I introduced how HACA systems are changing fire protection approaches in data centers. In this second part I will continue the discussion of how HACA systems are specifically challenging both fire detection and fire suppression systems in the Data Center.
Challenges to Fire Detection
The National Fire Alarm and Signaling Code (NFPA 72) gives guidance to engineers on the spacing of smoke detectors in rooms with different air change rates. The fire alarm code only provides data for smoke detector spacing in rooms up to 60 air changes per hour (ACH); this equates to data centers loaded to roughly 5 kW per rack. According to the Intel Corporation, HACA containment systems are implemented in data centers with densities of 12 kW per rack and higher. With cooling airflows sufficient for typical HACA cooling loads, air change rates within the contained aisles range from 500 to 1000 ACH and higher. These high airflows will challenge ceiling mounted spot smoke detectors due to the velocity of the air and dilution of smoke.
It has been common for fire protection engineers to specify air sampling smoke detection (ASSD) in rooms exceeding 60 ACH because of their increased sensitivity to smoke. Because of higher velocities experienced within contained aisles it makes even more sense to utilize ASSD. Engineers should consider installing ASSD sample pipes/ports arranged to sample the hot return/exhaust openings in the contained aisle. This would be done in the same manner as is commonly applied to traditional CRAC unit return air grilles.
Data center designers would do well to take notes on best practices of semiconductor manufacturing clean rooms where ASSD is often employed. Clean rooms have similar challenges of high velocities, turbulent air flows, and directional routing of air. There is an easy translation to data centers where air sampling detectors should be installed at the return air inlet to air handling units and somewhere immediately downstream of the hot side of the server at the ceiling level.
Despite the fact that more research is needed on how to detect fires in high airflow environments, many professionals believe that the detection techniques needed are already available to the industry.
Challenges to Fire Suppression
Whether the barriers included in HACA containment systems are applied horizontally, vertically or both, they can affect sprinkler pattern development and clean agent dispersion. NFPA 13: Standard for the Installation of Sprinkler Systems is very explicit in how to apply fire sprinklers to overcome obstructions in the protected space. These rules should be applied to sprinklers where HACA barriers exist in Data Centers. Many of these containment systems have provisions for “automatic” removal when a fire occurs; usually by means of a fusible link. For removal to work, the fire must grow to a point where it can melt the link(s). If the link that removes the barrier is not positioned perfectly over the location where the fire starts, the fire must grow larger to build heat in the location of the link. This also applies to systems that require fusing of multiple links for barrier removal. Be wary of containment systems that require a large fire to remove the barrier before the fire sprinkler system is given the opportunity to activate.
Plastic drop out ceiling panels, used most often in cold aisle containment systems, are another type of barrier that “automatically” removes. These panels are UL listed and melt around 135°F so that the sprinklers above the panels can operate. Data center managers should know that these panels are designed for use with standard response sprinklers that operate at a higher temperature near 155°F. Unfortunately, this sprinkler type is not installed in data centers; usually quick response sprinklers which fuse at 135°F are installed. The temperature difference is important and could lead to issues with sprinklers operating before these ceiling panels have dropped out. Installing quick response sprinklers inside the contained aisle may be the best way to avoid this issue.
In Data Centers protected by clean agent fire extinguishing systems, containment barriers must be removed prior to agent release. Containment systems which rely upon fusible action for removal are a problem because of the large fire size needed to obtain the action. Clean agent systems in data centers most often activate upon detection of smoke, not heat; and are designed to extinguished small developing fires. The problem of barrier removal can be overcome by adding extra clean agent nozzles within the contained aisle.
Clean agent nozzles have several of the same obstruction distance requirements as sprinklers. When retrofitting an existing Data Center with HACA containment, a qualified fire protection firm should be consulted to ensure the required extinguishing concentration can be obtained given the new barriers installed in the space.
It is a valid assumption that clean agents will disperse to spaces which are not in line-of-sight of the agent nozzle, such as the ability to reach the inside of server cabinets. The high airflows associated with containment systems challenges our current assumption and more research must be done on this topic.
While more research is needed to address these new challenges, one thing is for certain; hot aisle/cold aisle containment systems have the attention of data center managers, designers, and fire protection professionals. All are working to ensure a reliable means exists to detect and suppress fires in these environments. If you have added HACA to your data center and not had a qualified professional evaluate your fire protection system, you could be risking higher losses than what your business can tolerate. To learn more on this important topic, download my article that appeared in the 7×24 Exchange Fall 2011 Magazine.