Your fire safety system depends on the accurate detection of smoke by your smoke detectors. In order to ensure your smoke detectors are working properly, and able to protect your people and assets, you must have sensitivity testing completed on a regular basis.
Smoke detectors are designed to function effectively within a specific range of sensitivity to smoke. This range is set by the manufacturer and the devices are required by NFPA to be tested regularly to ensure they remain within it. If a smoke detector is not as sensitive as it should be, then it may not react as quickly as it should to a fire. However, if the smoke detector is too sensitive, then you could have recurring nuisance alarms.
There are several options for performing sensitivity tests on smoke detectors. Sensitivity tests can be conducted by a recognized, calibrated test method with smoke or listed aerosol, or with equipment specifically designed for calibrating sensitivity in smoke detectors. There are listed control equipment arranged to perform sensitivity ranges and calibrated sensitivity test instruments designed by the smoke detector manufacturers. You can also use a combination smoke detector/control unit where the detector causes a signal at the control panel unit when its sensitivity is outside its listed sensitivity ranges.
During sensitivity testing, if a detector fails, it will need to be cleaned and retested. Cleaning smoke detectors should be left to your Life Safety Partner, as they will clean the smoke detector screen and chamber using a non-electrostatic vacuum specifically designed to prevent damage to the detector. After cleaning, the detector will be retested, if it fails again then it needs to be removed from service.
Sensitivity testing must be completed within one year of installation and every other year after that. After the second test, if the detector is within its listed sensitivity range for two consecutive tests, then the next sensitivity test is required in five years.
Working smoke detectors or smoke alarms greatly decrease the risk of injury or death in a fire. Like any Life Safety device, smoke detectors and alarms need to be inspected, tested and replaced on a regular schedule to ensure they work effectively.
Smoke Alarms and Smoke Detectors
As we discussed in our blog Smoke Alarms, there is a difference between a smoke alarm and a smoke detector. A smoke alarm is a stand-alone device with a built-in sounder, a power supply, and a sensor. A smoke alarm is not connected to a fire alarm control panel, but may interconnect with other smoke alarms within the building. A smoke detector is part of a commercial fire protection system, it has only a built-in sensor and sends information to the fire alarm panel.
However, the sensing technology within smoke alarms and smoke detectors are the same – primarily, photoelectric smoke detection. This sensing system can become less responsive as it ages. To ensure your people and assets are protected, you should replace all smoke detectors and smoke alarms when they are 10 years old. To determine the age of your alarm/detector, look at the back where you will find the date of manufacture.
You should test your smoke alarms once a month by pushing the test button. Twice a year you should replace the batteries in all of your smoke alarms, it is encouraged that you do this when your clocks change for daylight savings as it serves as a regular reminder. You can clean your smoke alarms by vacuuming the outside, do not remove the alarm’s cover to vacuum.
Smoke detectors will be professionally inspected on an annual basis when your fire alarm system is inspected and tested. Your Life Safety Partner will check for the proper signal reception from the detectors at the alarm panel, clean your smoke detectors, and, when required, perform a sensitivity test.
Active vs Passive Smoke Detection
Air sampling smoke detectors are “active” systems which constantly sample the air from multiple points throughout the environment. Other smoke detection devices are “passive” systems. They rely on the heat of the smoke and the airflow of the room, for the smoke or heat to reach the detector. This can be a problem in rooms with constant air flows like server rooms, with smoldering fires which generate relatively little smoke, and with incipient stage fires where the smoke is not hot and therefore has very little thermal lift. Since these environmental conditions are particularly prevalent in server rooms, this is one space where air sampling smoke detectors are best used.
Server Room Fire Prevention with Air Sampling Smoke Detectors
Air sampling smoke detectors are classified as Very Early Warning Smoke Detectors (VEWSD). This is especially important in server rooms where the incipient stage of an electrical fire may not be detected by EWSD (Early Warning Smoke Detectors). This stage, which can last for hours or even days, is not a visible fire but the human nose may smell the fumes.
Smoke from a server room fire is harmful to other electrical equipment in the space. The by-products of smoke from PVC and digital circuit boards are gases such as HCL, and these gases will cause corrosion of IT equipment. Even at very low levels, the gas can cause moderate corrosion with long-term effects on electronics.
Air sampling smoke detectors can detect smoke at this incipient stage to activate alarms so that a response can be taken (whether through a fire suppression system or by an individual trained to respond) to put out and address the cause of the fire. Because the system monitors the space for overheating materials, and can detect this even before an actual fire develops, air sampling detectors act as a fire prevention tool.
How Air Sampling Smoke Detection Works
Air sampling smoke detectors are quite different from conventional spot type smoke detectors. Aspirating systems are typically made up of a number of small-bore pipes laid out above or below a ceiling in parallel runs, some feet apart. Small holes, also some meters apart, are drilled into each pipe to form a matrix of holes which are the sampling points, providing an even distribution across the ceiling. Air or smoke is drawn into the pipework through the holes and onward to a very sensitive smoke detector mounted nearby, using the negative pressure of an aspirator (air pump).
While air sampling smoke detectors are more sensitive to detecting smoke, they are less susceptible to the major sources of false alarms – dust, draughts and electrical interference. False alarms are a definite annoyance to building owners, managers and tenants. They also have a higher cost for our fire service providers, click here to read about the true cost of false alarms.
Sensitivity Settings of Air Sampling Smoke Detection Systems
Aspirating Smoke Detectors can have the sensitivity settings for alarm levels adjusted. The levels are typically set for an Alert, Action, and Fire 1. An Alert sends notice to local staff so they can investigate the threat of fire that has been detected. The Action level is generally used to initiate smoke control, begin a warning sequence via the evacuation system, and alert further staff members to the situation. The Fire 1 alarm indicates a fire condition is very close or has started. This alarm would activate evacuation procedures for the building, the fire alarm panel for the affected zone is activated, notifying the monitoring company and fire services. An additional Fire 2 threshold can be set; this level would act as confirmation of a serious fire event with the option to activate a suppression system. This should be a safety net setting, as the building’s fire systems and procedures should have operated properly before this point to prevent the fire.
For more in-depth information about the advantages of 725 psi clean agent systems, check out A1’s Lunch & Learns for architects and engineers.
A1 is a leading expert on the latest technology in life safety. To find out more information or to ask a question, click here or call us at 1-800-859-6198.
In 2015, there was a fire every 23 seconds totaling 1,345,500 fires in the US alone, causing in excess of $14.3 billion in property damage. The goal of a fire protection system is to detect and alert of fire in the early stages and then bring the fire under control. The advantages of early detection are to allow as much time as possible for evacuation and to protect assets from extensive damage.
Server rooms are small spaces designed to accommodate valuable electronic systems which generate a large amount of heat, therefore requiring heavy cooling and ventilation. The combination of heat producing devices and the sensitivity of the electronic equipment put specific requirements on the fire safety system.
A highly sensitive Aspirated Smoke Detector created specifically for smaller areas is the preferred choice for smoke detection in server rooms. Air-aspirating, or air-sampling detectors, are able to detect a fire in its incipient stages and therefore provide earlier warning and faster response time for the suppression system. Air-aspirating detection has the ability to detect smoke at differing levels and provide corresponding alarms; for example, if the detector finds a very low level of smoke, indicating that a fire is about to begin (such as an overheated wire that is smoking), a pre-alarm signal can be activated to alert staff to investigate and take action. If high levels of smoke are detected the suppression system can be discharged to control the fire.
Another option is cross-zoned, spot-type smoke detectors, using multiple technologies. These detectors often have multiple analog sensors so that they respond to smoke, heat and carbon dioxide sensing elements. You can use photoelectric smoke detectors, as they are cheaper than the ones using multiple technologies, but they do not react as quickly to every fire scenario. The multi-criteria detectors are often able to respond faster than traditional type detectors and reduce false alarms. Cross-zoned smoke detection is the preferred strategy to use in server rooms with spot-type smoke detectors as it relies on the activation of two alarms before the suppression system is activated. While this limits the potential for false alarms setting off the suppression system, it can result in a delay of activation when the suppression system is needed. However, with the increased ventilation and airflow in the server room, the cross-zoned system is necessary with spot-type smoke detectors to ensure the space is sufficiently protected.
Some server rooms utilize a pressurized raised floor to provide cold air to IT equipment and an above-ceiling area as a hot air return. Due to the potential for fire within these areas, because of HVAC piping, electrical feeders, or IT cables, detectors should be placed within these spaces.
IT rooms are laid out with the basic premise to isolate hot aisles and cold aisles from each other and prevent hot and cold air from mixing. This system helps to keep IT equipment cool while also being an energy and cost-saving measure for server rooms. If this system is in place in your server room, the layout of the room and any barriers constructed need to be taken into consideration when designing the fire detection and suppression system – if it prevents the flow of air it will prevent the flow of smoke and suppression gas.
What does in-rack detection and suppression mean?
Smoke detection and suppression systems have been designed to fit in an enclosed IT rack. While this type of system is optional in a server room fire suppression system, it has advantages of early detection within the server rack. Being placed within the IT equipment, the system can detect smoke in the earliest stages shut down the connected equipment while activating fans to prevent a fire from overheating devices. Should the fire continue the system will release a suppression agent within the rack enclosure. Read more about these systems here.
Learn more about server room fire protection, and why clean agent systems are the best choice to protect electronics.
Because the terms “smoke detectors” and “smoke alarms” are used almost interchangeably it can be confusing to distinguish between the two devices. A smoke detector is part of the fire alarm system, it has a built-in sensor for smoke and sends a signal to the fire alarm panel. A smoke alarm is a stand-alone device with a sensor for smoke, a sounder, and a power supply. A smoke alarm is not connected to a fire alarm control panel, but may be interconnected with other smoke alarms within the building.
Legal requirements of Smoke Alarms in Rental Properties
In Ohio, every apartment or rental property must have a smoke alarm installed in the immediate vicinity outside of all sleeping rooms, as well as inside each sleeping room. Alarm signaling devices must be clearly audible in all bedrooms within the unit when all internal doors are closed. Outside of the apartment units, property owners are required to have alarms installed in or near the return air stream for each floor. If the apartment does not have central return air systems, alarms need to be installed on each floor on the corridor or lobby side and within five feet of all stairway and elevator doors. If the apartment complex has fire walls and fire doors, smoke alarms must also be placed on each side of, and within fifteen feet of, the fire doors. Ohio also requires the smoke alarms to be interconnected within each unit and to have the primary power for smoke alarms to be from the building wiring with a battery backup.
In Indiana, an apartment or rental property must have at least one functional smoke alarm installed outside of each sleeping area in the immediate vicinity of the bedrooms. Smoke Alarms must be on each additional story of the dwelling, including basements, cellars, and habitable attics. Unless there is a door between levels in dwellings with split levels, a smoke alarm must be installed only on the upper level if the lower level is less than one full story below the upper level. All smoke alarms must be battery operated or hard wired into the dwelling’s electrical system, accessible for servicing and testing, maintained, and tested at least one time every six months by the unit occupant.
In Kentucky, smoke alarms are required to be installed in each sleeping room, outside each sleeping area in the immediate vicinity of bedrooms, and on each additional story of a dwelling, including basements. Smoke alarms are prohibited from being installed in locations where the temperatures fall below 32 degrees F or rise above 100 degrees F. It is not recommended to install smoke alarms in crawl spaces, uninhabitable attics, or closer than 3 feet from the door to a kitchen or bathroom with a tub or shower, with the exception of alarms specifically listed for the application.
Check your Local Laws
Wherever you are, it is important to review your local laws for requirements. For example, in Cincinnati it has been legally required since 2013 for all rental properties to have photoelectric smoke alarms installed outside the structure’s sleeping quarters. In addition, rental property owners are now required to inspect the photoelectric smoke alarms annually and when executing new lease agreements, and document their findings on the proper form which is checked by the Cincinnati Fire Inspectors and Community Development Building Officials.
Placement and Mounting of Smoke Alarms
NFPA 72 has guidelines for the placement of smoke alarms on walls or ceilings. A smoke alarm mounted on a ceiling is not to be closer than 4 inches from a wall. If mounted on a wall, the top of a smoke alarm must be between 4 to 12 inches from the ceiling. Mounting of a smoke alarm on a sloped, pitched, or cathedral ceiling, must be at or within 3 feet of the highest point of the peak.
Power Requirements and Interconnected Smoke Alarms
Smoke alarms are also required to be interconnected such that the activation of one alarm will cause all the alarms in the individual unit to sound. This is to ensure that every occupant in that unit can hear the alarm regardless of any closed doors between the individual and the sounding alarm.Smoke alarms are required to receive their primary power from the electrical service and a secondary power source of a battery. While it is the responsibility of the property owner or manager to install and maintain smoke alarms, it is generally the responsibility of the tenant or occupant to regularly test the smoke alarms and notify the landlord of any required maintenance. Owners are responsible for all smoke alarms in common areas, and should test smoke alarms inside apartments at a change of tenancy.
You can read more about smoke sensing technology here.
Widespread use of smoke alarms began in the 1970s, and have greatly reduced the number of home fire deaths. Prior to the 1970s, the average number of annual deaths by home fires was roughly 6,000. While there has been a dramatic decrease in home fire deaths, there is still more work to be done. Three out of every five home fire deaths occur in a home with no smoke alarms or no working smoke alarms. No smoke alarms were present in more than 1/3 of home fire deaths. In reported home fires where smoke alarms were present, but did not operate, almost half of the smoke alarms had missing or disconnected batteries. A quarter of the smoke alarm failures were due to dead batteries. NFPA estimates that there are about five million homes nationwide without smoke alarms.
In 2015, 3,280 civilians died in fires. Most fire deaths are not caused by burns, but by smoke inhalation. An individual can become incapacitated by smoke so quickly that they are overcome and can’t make it to an otherwise accessible exit. Having smoke detectors and alarms in your home and business can provide valuable time to evacuate, preventing injury and death.
A smoke alarm is a stand-alone device with a built-in sounder, a power supply, and a sensor. A smoke alarm is not connected to a fire alarm control panel, but may interconnect with other smoke alarms within the building. A smoke detector is part of a commercial fire protection system, it has only a built-in sensor and sends information to the fire alarm panel.
There are two main types of smoke detection technology used both in stand-alone devices and as the sensor in smoke alarms, ionization and photoelectric. Each has advantages, for best protection you should use both types of smoke detection technologies. There are units available which utilize both technologies in a single device for both detectors and alarms.
Ionization Smoke Detection
Ionization Smoke Detectors are generally more responsive to fires that have flames. The detectors have a small amount of radioactive material between two electrically charged plates, this ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions thus reducing the flow of current and activating the alarm.
Photoelectric Smoke Detection
Photoelectric Smoke Detectors are more responsive to fires that begin with a long period of smoldering. Photoelectric-type detectors aim a light source into a sensing chamber at an angle away from the sensor. When smoke enters the chamber, it reflects the light onto the light sensor which triggers the alarm.
Smoke detectors have advanced technologically to be more user friendly. In addition to combination detectors which include both photoelectric and ionization technology, you can also get detectors that combine CO detection, or many have features for silencing nuisance alarms. Smoke alarms can be interconnected to allow an alarm to sound throughout the house or building when one unit detects smoke; some of these devices can be programmed to provide audio messages that state for which room the alarm has sounded.
Regular maintenance and testing can only help your facility. As they say, “don’t judge a book by its cover.” Your fire protection equipment may appear to function on the surface, but failing to check the working order will leave you in a world of hurt. Systems will break down unexpectedly, and you may even shorten the life of your systems altogether. Here are 6 elements to building safety that are often neglected.
- Fire Sprinklers: On the surface, your system may seem to be in full working order. Unfortunately, most of the serious threats to a sprinkler system happen within. Pipe corrosion and valve trouble are just two examples. Follow the NFPA guidelines for regular sprinkler inspection and maintenance for your facility.
- Blocked Equipment: Any blocked safety equipment is not compliant and is a hazard. Check your sprinklers, exit signs, emergency exits and any other safety system that could be obstructed.
- Old Batteries and Lights: Exit signs use light bulbs and back up batteries to function. Neglected signs can have old, leaky batteries or light bulb outages. These issues are not detectable without opening the apparatus. Check each exit light according to NFPA standards to prevent deficiencies. Another option is to install photoluminescent lights. You can read about them here.
- Smoke Detectors: Smoke detector sensitivity should be tested regularly as well. Detectors that are too sensitive will trigger nuisance alarms. Conversely, detectors that are not sensitive enough may not detect the presence of smoke and will put occupants in danger.
- Fire Doors: NFPA has recently placed more stringent requirements on fire doors. Fire doors must be evaluated to make sure they’ll close and block fire when they need to.
- Emergency Plans: Besides your safety systems, you need an emergency action plan. Who uses the extinguishers? How will people get out? These questions are important for everyone’s safety. Changes in building layouts, or operations can make a plan outdated. If you already have an emergency plan, review it regularly. Most importantly, keep occupants informed. Hold a training, distribute instructions, or have signs so everyone knows how to get out.
Facilities management is an incredibly involved process. Something always needs to be fixed. Taking care of these 6 safety items would keep you ahead of the curve with less risk.
That Darn Alarm is Going Off Again!
The fire alarm goes off. You stop operation, evacuate the building, and wait for the Fire Department to tell you it was a false alarm. What set it off? More importantly, how can you avoid all the drama in the future?
Smoke detectors are sophisticated electronic devices that need periodic testing and maintenance. To maintain the integrity of any fire alarm system, it is important to have a qualified person periodically test the system. Detectors should be tested periodically and maintained at regular intervals following the manufacturer’s practices. Detectors should be given a visual inspection at installation and at least twice a year thereafter.
It should be noted that national, state, and local laws require the testing of your systems.
Probable Causes of Unwanted Alarms:
- Detectors installed in improper environments that have temperature extremes, excessive dust, dirt, or humidity, excessive air flow rates, or the normal presence of combustion particles
- Detectors and the wiring are installed improperly causing interference from induced currents and noise in adjacent wiring systems, radio-frequency transmissions, and other types of electromagnetic effects
- Inadequate maintenance causes gradual dust and dirt accumulation on the detector’s sensing chambers
- Seasonal effects from the reactivation of a building’s heating system after an extended summer shutdown can cause alarms
- Building maintenance issues, like accidental triggering of a detector’s magnetic test switch, or the introduction of plaster dust from drywall repairs
- Induced current effects from lightning storms
- Infestation from small insects
- Vandalism or mischievous acts
Besides a troublesome environment, electronics can interfere with your alarm system.
Systems that can affect the alarm system include:
- other security systems
- mobile telephones
- HVAC controls
- elevator call systems
- remote control equipment (door closers, etc.)
- installation of microwave antenna
Maintain an Alarm Log
Keep an Alarm Log to indicate which individuals responded to the alarm and whether or not they took appropriate action. Periodic review of the cumulative Alarm Log can help those responsible for the detection system discern patterns in the reported alarms. An Alarm Log can show the start date of apparently causeless alarms and can eventually help identify the cause.
The owners of smoke detector-equipped fire alarm systems are responsible for maintaining the integrity of the detection system in the following ways:
- Maintaining an Alarm Log and training appropriate personnel
- Maintaining a Detector Maintenance Log that records inspection, testing and cleaning data for each detector in the system.
- Maintaining a complete file of information on the alarm system in a readily accessible location.
- Givimg maintenance personnel or contractors working on the building’s electrical systems copies of the alarm system wiring layout and locations.
- Recording installations and modifications to all other building electromechanical systems.
- Recording all actions taken during the investigation of a series of alarms, indicating a problem exists.
The installers of smoke detector equipped alarm systems are responsible for:
- Providing specifications and installation instructions for the detectors, control panel, and auxiliary devices.
- Verifying that the alarm system installation meets all applicable code requirements.
- Testing a newly installed, expanded, or modified alarm system.
- Providing troubleshooting assistance to the owners for a specified break-in period after installation.
- Helping the owner set up appropriate Detector Maintenance and Alarm Logs for the system.
- Providing initial instruction and training to the owner’s personnel or outside organization.
- Providing troubleshooting assistance if nuisance alarm problems cannot be solved in-house.
The owner should conduct the initial investigation to find a solution, but if the personnel are unable to determine the cause for the alarms, the installer or representative of the manufacturer should be contacted to help isolate the problem.
You have your smoke detectors, now where to put them?
There is no one-size-fits-all for smoke detectors. When installing, updating, or inspecting your system, it’s crucial to account for the conditions of the facility to make the right choice.
To choose the right option for your needs, consider the following:
- Smoke detectors should be located on every level of a building.
- In areas where doors are usually closed, detectors should be located on both sides of the door.
- Fires are often unpredictable in their growth, so choose your detector based on its sensing limitations and the conditions of the area it will cover.
Where You’ll Need a Smoke Detector
Smoke detectors should be installed in all areas of the premises. Total coverage include all rooms, halls, storage areas, basements, attics, lofts, spaces above suspended ceilings, closets, elevator shafts, enclosed stairways, dumbwaiter shafts, chutes, and other subdivisions and accessible spaces.
Where a Detector is a Bad Idea
Special conditions in a location can interfere with your smoke detectors and trip unwanted alarms. In some instances, a heat detector may be a better choice than a smoke detector:
- Excessively Dusty or Dirty Areas – Installing smoke detectors in excessively dusty or dirty environments may require more maintenance than NFPA recommends.
- Outdoors – Avoid using detectors outdoors, in open storage sheds, or other open structures affected by dust, air currents, or excessive ranges of humidity and temperature.
- Wet or Excessively Humid Areas – Avoid damp, wet, or excessively humid areas, including areas next to bathrooms with showers.
- Extreme Temperatures – Avoid very cold or very hot environments, or unheated buildings or rooms where temperatures can fall below or exceed the operating temperature range of the detector.
- Areas with Combustion Particles – Avoid areas where particles of combustion are normally present, such as in kitchens or other areas with ovens and burners; or in garages.
- Manufacturing Areas – Avoid manufacturing areas, battery rooms, or other areas where substantial quantities of vapors, gases, or fumes may be present.
- Fluorescent Light Fixtures – Avoid placement near fluorescent light fixtures. Electrical noise generated by fluorescent light fixtures may cause unwanted alarms.
Placing detectors in areas that may trip an unwanted alarm happens all too often. Click here for tips to manage unwanted alarms.
At bare minimum, your detector must be at least 4 inches from all corners.
Questions? Click here to ask us.
Smoke Detector ≠ Smoke Alarm
Would you call a phillips screwdriver a flathead screwdriver? I think not! So why would you call a smoke detector a smoke alarm?
A smoke alarm is a stand-alone device with a built-in sounder, a power supply, and a sensor. A smoke alarm is not connected to a fire alarm control panel, but may interconnect with other smoke alarms within the building.
A smoke detector is part of a system, has only a built-in sensor and sends information to the fire alarm panel.
What Types of Detectors are out there?
The two most common smoke detectors are ionization and photoelectric. The sensing chambers of these detectors operate differently to sense visible or invisible combustion particles from developing fires.
Ionization detectors use positively or negatively charged ions to determine if an area is safe. Once combustion particles enter the air, they alter the internal plates’ measurements to detect smoke. In an ionization detector, dust and dirt can accumulate, increasing the chance of an unwanted alarm. The characteristics of an ionization detector make it more suitable for detection of fast flaming fires.
A photoelectric detector uses a light beam passing through air. The smoke blocks or obscures the beam, or causes the light to scatter. The detector senses smoke by monitoring the light. A photoelectric detector is subject to unwanted alarms from light reflected by insects, dirt, drywall dust, and other forms of contamination. Photoelectric smoke detectors are better suited to detect slow smoldering fires.
Each type of detector can detect both types of fires, but their respective response times will vary depending on the type of fire.
But Wait, There’s More!
Sometimes a facility requires a more exotic detector for special conditions.
Laser technology smoke detectors are designed for areas that require extremely early warning of fire. They are ideal for clean rooms, computer rooms or telecommunication centers, or any area with mission critical operations.
Aspiration smoke detectors use a pipe and fan system to sense the presence of smoke particulates.
These detectors are a good choice in clean rooms, areas which contain highly flammable liquid and gases, or rooms with goods easily damaged by fire, such as electronic rooms.
Multi-criteria detection contains multiple sensors that separately respond to physical stimulus such as heat, smoke, or fire gases. An alarm signal is determined through advanced algorithms based on input from these sensors. Several types of multi-criteria detection are available. The combination of sensors offers faster response times to real fires as well as better immunity to nuisance alarms in challenging environments.
Combination carbon monoxide and smoke detectors improve installation time and cost as well as offering a more aesthetically pleasing final product. This device type provides separate signals for each event.
So What Now?
Confused? You can request more specific information by clicking here.