Here are five reasons why you should be their provider and three reasons why your customers will want to buy CO detection from you.

Why You Should Provide CO Detection

1) Capitalize on an expanding market.

As public awareness grows, new local, state and national legislation for CO detection is being adopted. For example, recent CO poisoning tragedies in Colorado were the impetus for passing CO legislation in that state. More than half of the U.S. states already have CO legislation. Several more have legislation pending. (System Sensor keeps an ongoing legislation tally at www.systemsensor.com/co.)

One thing all this new legislation means for you is that CO detection is a growing market with a built-in customer base. Many of your customers are required now or will likely soon be required to have CO protection. Why shouldn’t you be their provider? With a CO offering, you can differentiate yourself from your competition with an additional service offering while increasing your commission and providing needed life safety protection for your customers.

2) Build longer-term relationships and extend your revenue stream.

Another big reason to offer CO detection is that customers who subscribe to fire protection monitoring are less likely to cancel their security monitoring service. The same is likely to be true for CO detection services. So if you sell CO detection as part of your overall security offering, this can result in less customer attrition and longer-term recurring monthly revenue for you.

3) Gain referrals as a life safety expert and grow your income stream.

While your customers are becoming more educated about the dangers of CO in their homes, they may not be aware that monitoring options are available. In fact, it’s likely that they believe retail detectors are their only option. By providing expertise around life safety solutions and legislation that your competition can’t and offering a CO detection solution, you can gain customer trust and build your business through recommendations to their friends and family.

4) Win jobs over your competition.

With a CO detection option, you can differentiate yourself from your competition with a solid product and service offering while increasing your commission.

5) CO detector guidelines are more clearly defined than ever.

The revised 2009 edition of NFPA 720 is a complete rewrite of the CO detection standard. It provides you with information on detector installation, placement, testing and maintenance, and off-premise signal transmission for both commercial and residential occupancies. So you now have the guidance you need to enter confidently into this growing market and provide your customers with the highest level of CO protection available. (System Sensor also offers a free Applications Guide for system-connected CO detectors that you can access at www.systemsensor.com/co.)

Why Your Customers Will Buy CO Detection from You

1) CO protection saves lives!

This is the obvious selling point for CO detection. Your customers may have heard about some of the recent CO tragedies, but what they may not have heard is how CO detectors are already saving lives. The most common factor with CO tragedies is there are no operational CO detection devices installed in the occupancy. But all across America, CO detectors are averting tragedies in schools, office buildings and homes.

For your customers, CO detection can provide peace of mind against the “silent killer” of carbon monoxide. There is no other way to protect against it.

2) System-connected detectors provide more protection.

One of the biggest reasons that your customers should be getting their CO protection from you is that monitored detection connected to the security or fire system provides a much higher level of protection than stand-alone retail detectors. Specifically, you can offer 24/7 central station monitoring capabilities that protect your customers when they cannot respond to a local alarm for any reason (i.e., they are not home, they are sleeping or they are already suffering from the effects of CO poisoning). Also, system-connected devices can be monitored to provide proactive maintenance to ensure that CO detectors are providing constant protection with no system downtime due to damage, the end-of-life of the CO cell, or technical and mechanical problems.

3) Many of your customers are already required to have CO protection.

More and more states are requiring CO detection. To meet these requirements, many of your customers are going to get CO protection from somewhere. Service providers who already offer fire and/or security monitoring capabilities are uniquely positioned to provide customers with comprehensive, monitored CO protection services, while ensuring that CO detection is properly installed and maintained.

In addition, if the CO legislation is new in your area, many of your customers may be unaware that they must have CO detection. You can educate them on the laws for your area, while offering them an excellent solution for meeting their CO requirements.

There are certain fire-protection applications where smoke detectors are not suitable, such as non-life-safety installations where the environment has too many airborne particulates due to excessive steam, moisture, dust, humidity or temperature, such as in attics, garages, warehouses, storage facilities, elevator machine rooms and electrical closets. Smoke detectors applied in those environments are cost prohibitive from a maintenance standpoint.

2. Heat detectors can be electronic or mechanical.

Electronic heat detectors use a thermistor as the primary heat sensing device. A thermistor is a component that changes resistance with temperature. Typically, electronic heat detectors have additional features, such as LED indicators that blink to indicate proper standby operation.

Mechanical heat detectors are bi-metallic or pneumatic. Bi-metallic heat detectors have a strip consisting of two dissimilar metals. When the strip is heated, the metal distorts and closes a contact. These detectors tend to be very inexpensive.

Pneumatic heat detectors, on the other hand, use an air chamber that is sealed with a moveable diaphragm. When the air inside the sealed chamber gets warm, the chamber expands and distorts the diaphragm. This, in effect, puts pressure on a set of contacts, which makes an electrical connection. Pneumatic detectors are often used in harsh environments because they can be sealed against corrosive elements.

In general, mechanical heat detectors are less expensive than electronic heat detectors; however, because they have a fixed temperature, they are not restorable after a field test.

3. Heat detectors can be fixed-temperature or rate-of-rise.

Fixed-temperature heat detectors are designed to alarm at a particular temperature. Because of thermal lag, however, if the rate of temperature rise is fast, the detector may actually alarm when the room temperature is higher than the set point. Furthermore, these detectors are not restorable after a field test. The alarm is destroyed.

A rate-of-rise component is sometimes added to a fixed-temperature design. This way, when either the fixed temperature or a pre-set temperature increase rate is exceeded, the detector will alarm. Heat detectors with a rate-of-rise feature tend to produce a higher level of protection in many applications, but should be used with caution. One should verify that the intended environment does not have naturally rapid temperature rises that exceed the detector’s trip point. This may be the case in an attic, for example. Additionally, these detectors are restorable. They reset to a non-alarm condition after a field test.

4. Heat detectors can be spot type or linear.

Spot type detectors essentially have their “detection mechanism” at one location. That is, the sensing element is in one physical location. Contrast that with linear heat detection, where the sensing element is spread out over a large physical area.

In linear heat detection, a special multicore wire or cable is utilized. The cable has two conductors that are fitted with an insulating jacket with a specific melting point. That melting point corresponds to the detection scheme’s fixed temperature set point. When the temperature increases enough, the insulating jacket separating the conductors melts and they come into contact with one another, shorting out. This short can be detected. These linear heat detection cables can be hundreds of feet in length, making them ideal for conveyor or cable tray applications.

5. Heat detectors can be rate-of-rise, compensated, fixed-temperature detectors.

In a slowly developing fire, this form of detector responds when the temperature of the air surrounding the detector reaches a predetermined level. In a rapidly developing fire, the detector anticipates the air temperature reaching the operating point, accelerating the operation of the detector. This produces a fixed-temperature detector with virtually no thermal lag.

As the manufacturer, System Sensor complies with those regulations regarding the proper disposal of ionization smoke detectors. For each detector returned to the company for disposal, System Sensor charges $3 per smoke detector to cover internal handling costs and to recycle the sealed source.

System Sensor only disposes of these detectors on a pre-paid basis. If detectors are returned without appropriate payment, the detectors will be returned to the sender with freight-collect terms. Note: The recycling fee does not apply to ionization smoke detectors returned under warranty or withdrawn from service at the direction of System Sensor.

Exempt Status

Purchasers and secondary distributors of ionization smoke detectors are exempt from regulations pertaining to the disposal of smoke detectors. According to Nuclear Regulatory Commission regulations, a purchaser or secondary distributor in the United States can dispose of ionization detectors in a manner consistent with the disposal of any nonhazardous household refuse.   

Applications Outside of the U.S.

A similar exemption may exist in other countries. System Sensor will continue to verify exemptions on a case-by-case basis. In the event of a return, contact your System Sensor representative for appropriate direction regarding the return.

Packaging

Each ionization smoke detector returned to System Sensor must be enclosed in a sealed plastic bag. The sealed bags must be placed in new and sturdy corrugated overpack with shock-absorbing material to fill the empty spaces. Any single mailed package may not exceed 45 pounds (20.4 kilograms). Shipments to or within the United States are subject to Department of Transportation regulations.

After following these packaging instructions, the shipper must visit http://www.systemsensor.com/pdf/bulletins/ion_recycling.pdf. Then print the file and place it inside the package before sealing it to certify that:

THIS PACKAGE CONFORMS TO THE CONDITIONS AND LIMITATIONS SPECIFIED IN 49 CFR 173.424 FOR RADIOACTIVE MATERIAL, EXCEPTED PACKAGEARTICLES, UN2911.

If there are any questions or concerns, please contact the System Sensor Customer Service

Department at 800-736-7672 or 630-377-5680.

Disclaimer: These packaging requirements are believed to meet the applicable ground and air transport regulations. To verify the current version of this bulletin, contact System Sensor Customer Service or check on-line at www.systemsensor.com/techbulletins

Fire codes and standards are part of any commercial construction or renovation job, and the same is true for government work. While fire- and life-safety requirements differ slightly for government buildings, it is the process that can present the most challenges for a commercial fire-protection engineer who is unfamiliar with the ins and outs of working within the government system.

To date, the U.S. General Services Administration (GSA) owns, operates and manages more than 400 million square feet of space in 9,000 owned and leased buildings, which are occupied by a million federal employees in 2,000 communities across the country. GSA is the government’s civilian landlord, responsible for meeting office and other space requirements of the federal workforce.

As the demand for government-operated space rises, so will the demand for fire-protection engineers who are experienced in this type of work. “There’s definitely some different terminology in government jobs that you have to be aware of and know how to deal with,” explains Paul Hayes, F.P.E. and vice president of American Fire Technologies, based in Wilmington, N.C. American Fire Technologies specializes in the integration of fire-protection and detection management and design. “It’s hard to take a commercial engineer, roll him over into government work and expect the same results. You have to have someone who knows what he’s doing on the government side.”

According to GSA, a registered fire-protection engineer is required to be a full participant of the architect/engineer (A/E) design team for each phase of a government project, from concepts through design, construction, final acceptance and occupancy. The fire-protection engineer must also have at least six years experience of which at least three consecutive years are directly involved in the fire-protection engineering field.

Finding an engineer who meets these specific requirements is not too difficult, according to Hayes. “Some teams push for either a P.E. (professional engineer) or a N.I.C.E.T. (National Institute for Certification in Engineering Technologies). NICET is the certification for fire system professionals. Basically, that’s what gives people credentials in this industry. If they are not an engineer, then NICET is what people shoot for.”

GSA requires the team’s fire-protection engineer to analyze and provide criteria for: building construction, occupancy classification, means of egress, fire-alarm systems, water-based fire-extinguishing systems, non-water-based fire-extinguishing systems and smoke-control systems. The fire-protection engineer must also perform calculations for: egress, water supply, smoke control (fire dynamics)/timed egress, audibility for fire alarm systems and design of all fire-protection and life-safety systems.

Qualifications aside, the fire-protection engineer must not only be able to work with the design team, but is also required by GSA to establish an ongoing dialog with the GSA regional fire-protection engineer, who is the Authority Having Jurisdiction for all technical requirements, fire-protection and life-safety code interpretations and code-enforcement requirements.

Commercial vs. Government Work

Once the A/E design team is established, the process — and challenges — begin. “It’s a different world dealing with government projects because you’re not there to please the individual; you’re there to honor the contract,” explains Hayes. “On the commercial side, a lot of times you’re there to make the client happy. But on the government side, it doesn’t matter whether the clients are happy; it matters whether you’ve met every letter of intent of the contract.”

Fire codes and standards are factors in any GSA contract and can vary from commercial requirements depending on the category. For example, in the Fire Protection & Life Safety section of GSA’s “Facilities Standards for the Public Buildings Service” guidelines (see www.gsa.gov),GSA states that smoke detectors shall be installed in accordance with the requirements in NFPA 72, the International Fire Code (IFC) and the International Mechanical Code (IMC), except in the following instances:

• Area smoke detectors shall not be installed in the following areas: mechanical equipment room, electrical closet, telephone closet, emergency generator room, uninterruptible power service and battery rooms, and other similar rooms.
• Smoke detection appropriate for the application shall be installed in each of the following rooms: electrical switch gear, transformer vaults and telephone exchanges (PABX).

In regard to audible notification appliances, GSA requires that the performance, location and mounting of the devices shall be in accordance with the requirements in NFPA 72. However, the following requirements take precedence over NFPA 72 requirements:

• To ensure audible signals are clearly heard, the sound level shall be at least 70 dBA throughout all office space, general building areas and corridors measured 1524 mm (5 feet) above the floor. The sound level in other areas shall be at least 15 dBA above the average sound level or 5 dBA above any noise source lasting 60 seconds or longer.
• The design for achieving the required minimum dBA levels shall take into consideration all building construction materials, such as carpeting, hard surfaces, walls, doors and any other materials that can cause sound-level attenuation and/or clarity problems due to the placement and location of the audible notification appliances. The SFPE Handbook of Fire Protection Engineering’s chapter on Design of  Detection Systems or other audio design guides should be used to provide guidance and methodology to achieve the required dBA levels.
• Where emergency voice/alarm communication systems are provided, fire alarm speakers shall be installed in elevator cars and exit stairways; however, they shall only be activated to broadcast live voice messages (e.g., manual announcements only). The automatic voice messages shall be broadcast through the fire alarm speakers on the appropriate floors, but not in stairs or elevator cars.

Modifying GSA Contracts

The design team must also be careful when making alterations to GSA contracts. Any modifications have to be made well in advance, with extensive documentation. This, according to Hayes, is one of the greatest differences between commercial and government work.

“You have to be on top of the paperwork. It is a paperwork shuffle that you have to be much more aware of than you would for a standard commercial building or a hotel,” says Hayes. “He who documents best, wins.”

GSA doesn’t necessarily discourage making modifications to the project, but doing so requires a lot more effort than simply brainstorming with the design team. “You can’t sit down with the design team and say, ‘Well, you know you’re right. This would make it a little bit better. We can make this modification,’” explains Hayes.

“You’ve got to do what the contract says unless a change is issued to that contract because somebody else will get a hold of it and call you on it. They’ll ask if you documented it, and if not, then it’s your problem. It doesn’t matter if it was better the way you did it. That’s not what the contract says, and you can get burned.”

The positive side is that a qualified fire-protection engineer who gains experience and learns to deal with the documentation can do well in government work, according to Hayes. “There’s a good opportunity if you know how to work the system within government.”

Photoelectric detection is preferred for several reasons, including:

1. Detection Capability — Photoelectric detection responds better to the larger smoke particles found in ductwork during a fire.
2. NFPA Recommends Photoelectric — The National Fire Alarm Code Standard 72, section A.5.14.4.2 explicitly states, “In almost every fire scenario in an air-handling system, the point of detection will be some distance from the fire source, therefore, the smoke will be cooler and more visible because of the growth of sub-micron particles into larger particles due to agglomeration and recombination. For these reasons, photoelectric detection technology has advantages over ionization detection technology in air duct system applications.”
3. Environmental Immunity — High humidity and condensation can cause false alarms with ionization detectors. Photoelectric detectors operate more efficiently, generating fewer false alarms.
4. Industry Preferred — Photoelectric detection is preferred by the fire alarm industry, manufacturers of commercial packaged air conditioning units and major retailers.
5. Low-Flow — Photoelectric detectors are capable of operating in air speeds as low as 100 feet-per-minute to meet new HVAC applications and codes with variable air volume systems and fire smoke dampers.

Can I interconnect more than 10 Innovair (4-wire, conventional) duct smoke detectors?

Absolutely. Refer to, Interconnecting more than 10 Innovair 4-Wire Conventional Duct Smoke Detectors, on System Sensor’s website (www.systemsensor.com) under Technical Field Bulletins for the simple, two-step connection method.

What is the best procedure for testing System Sensor duct-mounted smoke detectors?

There are four simple steps to test System Sensor’s duct-mounted smoke detectors:

1. Verify the detector is installed per NFPA 72 guidelines and is in accordance with the manufacturer’s installation instructions.
2. Employ the detector’s built-in test feature, such as the test magnet or accessory test switch. These features are designed to meet NFPA and Underwriters Laboratories functional test requirements that ensure the detectors are operable and will respond to minimum smoke requirements.
3. Measure the pressure differential across the sampling tubes (exhaust and intake) with a manometer to ensure the detector will respond to smoke in the duct airflow. This is the manufacturer’s acceptable test.
4. Apply smoke directly to the detector head to initiate an alarm. The sampling tubes may need to be blocked off for this test and then reopened afterwards.

Why is a smoke bomb test not recommended for ionization duct smoke detectors?

Based on evidence with in-house and field-testing of ionization, duct-mounted smoke detectors, there are three notable reasons:

1. Ionization smoke detectors are most sensitive to smoke particles ranging from .01 to .3 microns. Particles produced by smoke bombs tend to become larger the farther they travel from the source, triggering a slow response.
2. Smoke bombs produce cold smoke particles, which are larger and not as easily detected by ionization smoke detectors. These particles are also dependent on relative humidity, distance traveled from the source and time of activation. This phenomenon is caused because the smoke is more of a mist than suspended solids in warm gases. In other words, the smoke doesn’t represent a true smoke composition or fire signature for smoke detector activation.
3. It is possible to pass a smoke bomb test, but to be out of the required manometer range for sampling, giving the installer a false sense of proper operation.

Although unadvisable, if you choose to conduct a smoke bomb test, use a photoelectric smoke detector, which typically responds to smoke particles between .3 and 10 microns, and, if you have a respiratory ailment, use a self-contained breathing apparatus.

Where can a System Sensor duct-mounted smoke detector be installed in relation to the duct?

System Sensor duct-mounted detectors can be installed horizontally and vertically to — and on top of, within and underneath — the duct. However, we do not recommend installing underneath the duct because condensation may drain into the electronic circuitry and cause electrical damage.

To determine the best location, System Sensor recommends comparing the pressure differential between the sampling and exhaust tube. The pressure differential must be within specified limits of .0015 to 1.20 inches/water for photoelectric smoke detectors. The detector housing cover must be securely fastened to complete the airtight enclosure for proper air sampling and to restrict contaminants from entering the detector head.

In order to shut down the HVAC system, what do I connect my HVAC or RTU (Roof Top Unit) to?

To provide immediate shutdown during an alarm, connect to the controller voltage from the RTU. Connecting to the thermostat will only allow a gradual shutdown of the HVAC system. In some cases, the RTU manufacturer requires a shutdown of this type because, if stopped too fast, the bearings could become damaged. Be sure to review each situation accurately.

Can System Sensor test stations and other accessories be used with duct smoke detectors manufactured by other companies?

No. They are not compatible due to a different electrical makeup. This includes the SSK451 Multi-Signaling Device, which features:

1. An audible and visible alarm annunciation.
2. A key activated test and reset functions.
3. Green, amber and red LEDs that provide visual indication of power, trouble and alarm indications.
4. An optional snap-on smoke strobe.

The proper installation of duct smoke detectors is critical to preventing the transfer of smoke and other toxic gases during a fire. Unlike standard smoke detectors that are set up by a single installer, heating/ventilation/air conditioning (HVAC)-contaminant monitors can be set up by installers of various trades, making communication imperative.

Installers of at least four crafts may be involved in a duct smoke-detector installation, including an air conditioning or roof top unit (RTU) installer; a mechanical contractor responsible for duct work; an electrician for handling high-voltage wiring and conduit; and a technician who installs the building control panel.

“Traditionally, it goes by union guidelines,” says Chuck Harding, general manager and founder of Harding Heating in Schaumburg, Ill. “Sheet metal workers do the duct work. So, they connect the smoke detector to the HVAC system. The electricians then provide the power. Those are the traditional jurisdiction lines that are pretty much defined throughout the country, as far as the unions are concerned.”

However, Harding has seen jobs during 20 years of running his own business that were not as traditional. “I’ve also seen each one of the crafts do the entire job by themselves. It just depends on who is on the job. You can’t always assume that all the crafts are involved. If it is a smaller job, it’s not uncommon for the HVAC guy to do it all.”

Which Code Authorities Prevail?

The importance of top-down communication can also be critical in making sure a job follows the strict body of laws that govern it. But, sometimes the installers are unaware of which code prevails: national or local. Therefore, communicating the certified code of the Authority Having Jurisdiction (AHJ) is a critical first step for every installer.

For example, installation may be originated by the ductwork installer or the RTU installer. However, if the voltage to power the detector is 120 VAC, in accordance to the National Electrical Code, an electrician must install the conduit and run the wire. Who, then, is responsible for connecting the RTU to the auxiliary relays for shutdown during a fire?

“Fortunately, in larger jobs, this is normally written in the specification,” explains Harding. “The engineer’s orders tell you who is the authority having jurisdiction. These are written commonly in a way that identifies such-and-such trade will provide ‘X’ service, while another provides different service. A lot of it depends on the detector; some are high voltage, some are low voltage. Again, it all comes back to the engineer’s order, but I have seen it where the owner dictates this. Some dictate a lot on a job.”

Knowing who the AHJ is, therefore, must be relayed to the installers for each job. Companies like Harding Heating, which take on jobs in Illinois, Wisconsin and Indiana, have to be aware of the many different codes that may be applicable.

“It’s village-to-village and depends on the authority having jurisdiction,” says Harding. “Some villages have more emphasis on some things than others do. For duct smoke detectors in particular, the Building Officials and Code Administrators code says they must be installed in buildings that have 2,000 cubic feet of airflow per minute. But, some village codes exceed this; some don’t. Just like some have remote testing requirements and others don’t. It makes communication very important.”

Another code-adherence tip Harding offers is to make sure the duct smoke detector’s installation paperwork is handed down the line to the craftsmen who will handle the final phases of installation, as is required by national code. “Passing off the installation manual is a must. We leave it in the detector,” says Harding. “But, somewhere down the line, someone takes it or does not think to leave it for the next guy. It’s not intentional, but it is a violation of the code.”

Start-up and Maintenance

System Sensor smoke detectors are designed to be as maintenance-free as possible. However, due to the environment they are in, dust, dirt and other foreign matter can accumulate inside detectors, changing the level of sensitivity. This is especially true with duct smoke detectors. More sensitivity results in unwanted alarms. Less sensitivity results in reduced protection. Both cases are undesirable. Detectors should be tested periodically and maintained at regular intervals (see “Typical Testing Procedures for Duct-Type Smoke Detectors”).

“I always tell my customers to follow a stringent testing program,” says Harding. “Of course, they work the first day, but what about three years down the road? You have to follow the maintenance procedures set out by the manufacturer, as well as the code. Remember, the building code is there for a purpose: It is the minimum for safety. It is not to be violated or ignored for installation or maintenance.”

In general, all smoke detectors should be tested or inspected at least annually. This will ensure the detectors are sampling the air stream, are operative and are producing the intended response.

Duct fires should not be used to test duct smoke detectors. This procedure does not provide a consistent, measurable method of determining if the detectors are performing properly. The test procedures and test equipment recommended by the detector’s manufacturer are the best way to test these detectors.

Most detectors are equipped with a built-in test mechanism, electronic metering equipment or aerosol test apparatus (refer to manufacturer’s specifications for details). However, you still have to notify the proper authorities, including those who would automatically receive a real fire alarm signal, to prevent unnecessary responses.

Always restore the zone or system at the completion of the testing. Then, notify all the people contacted at the beginning of the test and let them know that testing has been completed and the system is operational.

1. U.L. Standard 268A, Standard for Smoke Detectors for Duct Applications

2. NFPA Standard 90A, Section 6.4 (2002 Edition), Installation of Air Conditioning and Ventilating Systems

3. NFPA 92A, Recommended Practice for Smoke Control Systems

4. NFPA Standard 72, Chapter 10 (2002 Edition), National Fire Alarm Code

5. NFPA Standard 101, Life Safety Code

6. ASHRAE Handbook and Product Directory, “Fire and Smoke Control”

Designing fire alarm systems for atriums, lobbies and other types of high-ceiling facilities can be tricky. This is especially true when considering potential challenges such as extreme temperatures, high air velocity and potential smoke stratification during a fire.

Beam smoke detectors are valuable components in these applications because they offer unique capabilities that can overcome many of the challenges associated with high-ceiling structures. It is important, therefore, that fire alarm designers gain an understanding of the technology and limitations of specific smoke detectors when selecting and applying them to fire alarm systems.

Projected beam smoke detectors consist of a transmitter that projects an infrared beam across the protected area to a receiver containing a photosensitive cell, which monitors the signal strength of the light beam. Some beam detectors consist of a transmitter and a receiver in one unit, with a reflector used on the other end to return the light. One of the advantages of units such as these is that wiring across the room (transmitter to receiver) is no longer required.

The detector works on the principle of light obscuration. The photosensitive element of the beam smoke detector sees light produced by the transmitter in a normal condition. The receiver is calibrated to a preset sensitivity level based on a percentage of total obscuration. The manufacturer determines this sensitivity level based on the length of the beam (the distance between the transmitter and receiver).

Typically, the installer can select from more than one setting based on the length of the beam used in a given application. For Underwriters Laboratories® (UL)-listed detectors, the sensitivity setting must comply with UL Standard 268, Smoke Detectors for Fire Protective Signaling Systems.

Operational Characteristics

Beam smoke detectors are sensitive to the cumulative obscuration (a measure of the percentage of light blockage) presented by a smoke field. This cumulative obscuration is created by a combination of smoke density and the linear distance of the smoke field across the projected light beam.

Because the sudden and total obscuration of the light beam is not a typical smoke signature, the detector will generally see this as a trouble condition, not an alarm. This threshold is typically set by the manufacturer at a sensitivity level that exceeds 90 percent total obscuration. This minimizes the possibility of an unwanted alarm due to the blockage of the beam by a solid object, such as a sign or ladder inadvertently placed in the beam path.

Very small, slow changes in the quality of the light source are also not typical of a smoke signature. These changes may occur because of environmental conditions, such as dust and dirt accumulation on the transmitter and/or receiver’s optical assemblies. An Automatic Gain Control (AGC) typically compensates for these changes.

When the detector is first turned on and put through its setup program, it assumes the light signal level at that time as a reference point for a normal condition. As the quality of the light signal degrades over time, perhaps due to dust, the AGC will compensate for this change. The rate of compensation is limited to ensure that the detector will be sensitive to slow or smoldering fires. When the AGC can no longer compensate for the loss of signal, such as with an excessive accumulation of dirt, the detector will signal a trouble condition.

Accessories to the beam smoke detector may include remote annunciators and remote test stations that allow for the periodic electronic and/or sensitivity testing of the detector. Intelligent fire alarm systems can give the beam smoke detector a discrete address to provide better annunciation of the fire location. Conventional systems may also remotely annunciate through the use of relays.

Spot-Type vs. Beam Detector Applications

Like spot-type smoke detectors, beam smoke detectors are inappropriate for outdoor applications. Environmental conditions, such as temperature extremes, rain, snow, sleet, fog and dew, can interfere with the proper operation of the detector. Outdoor conditions make smoke behavior impossible to predict.

Spot-type smoke detectors are considered to have a maximum coverage of 900 square feet or 30 feet by 30 feet. The maximum length between detectors is 41 feet when the width of the area being protected does not exceed 10 feet, as in a hallway.

Beam smoke detectors generally have a maximum range of 330 feet and a maximum distance between detectors of 60 feet. This gives the beam smoke detector theoretical coverage of 19,800 square feet. Manufacturer’s recommendations and other factors, such as room geometry, may impose practical reductions of this maximum coverage.

Even with these reductions, a beam smoke detector can cover an area that would require a dozen or more spot-type detectors, which generally decrease in response as their distance from the fire increases. The advantage is that fewer devices mean lower installation and maintenance costs.

When fires start at or near floor level, the smoke produced will rise to or near the ceiling. Typically, the column of smoke begins to spread out as it travels from its point of origin, forming a smoke field in the shape of an inverted cone. The density of the smoke field can be affected by the rate of growth of the fire. Fast fires tend to produce more uniform density throughout the smoke field than slow-burning fires where there may be dilution at the upper elevations of the smoke field.

In many high-ceiling applications, such as retail space, beam smoke detectors may be more responsive to slow or smoldering fires than spot-type detectors because they are looking across the entire smoke field intersecting the beam. Spot-type detectors can only sample smoke at their particular “spot.” The smoke that enters the chamber may be diluted below the alarm threshold, which is the level of smoke needed for an alarm.

Detector of Choice

The major limitation of projected beam smoke detectors is that these units are line-of-sight devices and are, therefore, subject to interference from any object or person entering the beam path. This may make its use impractical in occupied areas with normal ceiling heights.

However, many facilities have areas where beam smoke detectors are the detector of choice. High-ceiling areas, such as atriums in multi-level facilities, lobbies, gymnasiums, sports arenas, museums, factories and warehouses might be candidates for beam smoke detectors.

Many of these applications present special problems for the installation of spot-type detectors (e.g., high air velocity, stratification, hostile environments, sensitivity, location, spacing and mounting) and even greater problems for their proper maintenance. The use of beam smoke detectors may reduce these problems because fewer devices are required and the devices can be mounted on walls, which are more accessible than ceilings.

System Sensor has restructured its Voltage Drop Calculator as a stand-alone application that users download to their computers. This new, user-friendly tool enables users to quickly plan and model notification appliance circuits (NACs) using the entire line of SpectrAlert^® Advance notification appliances as well as legacy devices.

The application’s simple step-by-step format makes it easy to create NACs from a variety of devices to meet nearly any application requirement. The step-by-step process allows users to accurately calculate the voltage drops along a NAC by analyzing each device on the circuit and determining if enough operating voltage is available at each device location. This is clearly visible as changes or adjustments to the criteria are entered. The “Used Amps” bar, for example, graphically shows how much power is being used by each circuit.

The three main steps involved in creating a circuit can be done systematically or independently, and updates/changes are done as users move through the program. In Step One, users create a panel or list of panels. The panels are generic in nature, but have defined characteristics such as DC or FWR power supplies. Step Two is where users create and name each NAC connected to the panel. In Step Three, users select the devices to add to the circuit from a series of product categories in a drop-down format.

The Device Listing and Device Ruler visually produce the NAC as it evolves. Devices can be moved by dragging and dropping them to the preferred distance from the previous devices.

The tool calculates voltage drop based on wire resistance, circuit distance, filtered vs. unfiltered panels, device settings and distances between devices. It enables users to build a NAC that can be printed or e-mailed for review by a co-worker, for submission to the Authority Having Jurisdiction or for the job file. The printing feature accommodates multiple types of submission forms. In fact, there are five different print options: Print the entire page, or print a particular panel or circuit with all the wire gauge possibilities or only selected wire gauges.

The new Voltage Drop Calculator is loaded with powerful and useful features. One feature of particular interest is that each project can be saved individually and shared as needed. Users decide how files are handled: They can start fresh with a New Project, or go to an Open Project (saved project). Job details and user preferences can be saved for each project, and all design work is accessible on one page.

Finally, to keep the tool up-to-date with the most current System Sensor device data, this Adobe Air-based application automatically searches for updates every time it is opened or any time users click the Check for Updates button while connected to the Internet.

The Voltage Drop Calculator can be downloaded at www.systemsensor.com/volt.