DAY 9: CHAPTER 26, SMOKE, HEAT, AND CO2 DETECTORS

SMOKE DETECTORS ARE FOUND IN NFPA 72 (NATIONAL FIRE ALARM CODE)

FOR FIRES TO OCCUR, 3 THINGS ARE REQUIRED.1. FUEL2. OXYGEN3. IGNITION SOURCE

O2

FUEL IGN SOURCE

SMOKE DETECTORS SAVE LIVES. MOST FATAL FIRES OCCUR AT NIGHT WHEN PEOPLE ARE ASLEEP. OFTEN, VICTIMS NEVER WAKE UP. A WORKING SMOKE DECTECTOR WILL DETECT SMOKE AND SOUND AN ALARM TO ALERT YOU, GIVING YOU PRECIOUS TIME TO ESCAPE.

TYPES OF SMOKE DETECTORS

BATTERY POWERED

A/C POWERED

A/C WITH BATTERY BACKUP.

A/C WITH BATTERY BACKUP INTERCONNECTED TO OTHER SMOKE DETECTORS.

Interconnecting powered smoke alarms is essential to provide the earliest possible warning of a fire. But hard wired interconnection is expensive, time consuming and disruptive. A hard wired system is also difficult and expensive to reconfigure when circumstances (or standards) change. With RadioLINK, mains powered smoke alarms are interconnected by wireless signals rather than cabling. It's so much simpler, more convenient - and easier to change or extend as and when required.

Wireless Smoke Detector Hidden Camera DVR Spy 4GB

The Smoke Detector Spy Camera will activate only when it detects motion. A wireless remote control allows for control of the Smoke Detector Camera without having to physically touch the Smoke Alarm unit

This Self Contained Smoke Detector Hidden Camera may easily be charged via USB. Built-in 4GB flash memory gives you up to 100 minutes of recording time. Not functional as a smoke detector.

SMOKE DETECTORS MUST BE REPLACED AFTER 10 YEARS

http://www.engineerguy.com/videos/video-smoke.htmHow smoke detectors work

The most commonly used detectors are the ionization detectors and the photoelectric detectors. Ionization detectors are prone to malfunction when used in noisy, dusty, or damp environments and are subject to frequent maintenance. Ionization detectors also produce radiation pollution. Therefore, the popularity of ionization detectors has been on decline while photoelectric detectors are increasing in popularity. Photoelectric detectors detect the intensity of ultraviolet light pulses that are reflected from the smoke in order to deduce the density of the smoke.

TWO TYPES OF SMOKE DETECTORS

1.Ionization2.Photoelectric

Ionization type smoke detector

Ionization sensor smoke alarms contain a small amount of radioactive material, americium embedded in a gold foil matrix. The ionization chamber is basically two metal plates a small distance apart. One of the plates carries a positive charge, the other a negative charge. Between the two plates, air molecules-made up mostly of oxygen and nitrogen atoms-are ionized when electrons. As they migrate to charged plates In the smoke-free chamber, positive and negative ions create a small current.

Ionization Technology

An Americium container from a smoke detector. Half Life 243 years

Smoke particles and combustion gases interact with the ions generated by the alpha particles, restoring them to their neutral electronic state and decreasing the electrical current passing through the cell. As fewer ions are available to migrate to the plates, the disrupted current triggers the alarm

Ionization smoke detection is generally more responsive to flaming fires. . Ionization technology is generally for detecting small particles, which tend to be produced in greater amounts by flaming fires, which consume combustible materials rapidly and spread quickly. Sources of these fires may include paper burning in a wastebasket or a grease fire in the kitchen.

Inside a basic ionization smoke detector. The black, round structure at the right is the ionization chamber. The white, round structure at the upper left is the piezoelectric buzzer that produces the alarm sound.

SECTION VIEW OF AN IONIZATION SMOKE DETECTOR

Photoelectric technology used in the sensor is generally for detecting large particles, which tend to be produced in greater amounts by smoldering fires, which may smolder for hours before bursting into flame. Sources of these fires may include cigarettes burning on couches or bedding.

How they work: Photoelectric-type alarms aim a light source into a sensing chamber at an angle away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering the alarm.

Optical Smoke Detector1: Optical chamber2: Cover3: Case moulding4: Photodiode (detector)5: Infrared LED

OPTICAL SMOKE DETECTOR WITH THE COVER REMOVED.

SMOKE DETECTORS FOR THE HEARING INPAIRED WITH FLASHING LIGHTS.

Be sure to install alarms in the following places.

– Install an alarm inside each bedroom and outside each separate sleeping area. (hallways)

– Install an alarm on each level of the home including the basement.

•Don't place alarms where it is inconvenient or unsafe to test them, like in tall foyers or high over a stairway.

•A smoke alarm installed in a stairwell must be located in such a way that smoke rising in the stairwell cannot be prevented from reaching the alarm by an intervening door or obstruction.

•A smoke alarm installed to detect a fire in the basement must be located close to the stairway leading to the floor above.

AVOID PUTTING SMOKE DETECTORS IN THE FOLLOWING PLACES • Kitchens

– Garages

– Bathrooms

– Most attics, unless the local jurisdiction requires them in walk up attics

There are certain locations to avoid such as near bathrooms, heating appliances, windows, or close to ceiling fans. Don't place smoke detectors in kitchens, bathrooms, furnace rooms, workshops, garages, or in other spaces where temperatures can fall below 32°F, or exceed 100°F. These areas are subject to fumes, steam, dust and smoke, which can generate false alarms and contaminate the alarm. Don't install detectors where air movement can delay the alarm. This means they should be away from windows and at least 3 ft from warm or cold air ducts or return ducts. Also, don't install them between an air return and a bedroom door. Smoke alarms should not be located within 3 ft of doors to a kitchen or bathroom with tub or shower.

SMOKE DETECTORS MUST BE PLACED AT LEAST 3 FEET AWAY FROM HVAC REGISTERS AND CEILING FANS OR INSTALLED PER THE MANUFACTURES INSTRUCTIONS.

3 FEET

INSTALLATION OF SMOKE DETECTORS

KEEP SMOKE DETECTORS OUT OF DEAD SPACES WHERE WALLS MEET THE CEILING

Smoke detectors should be mounted on the ceiling at least 4 inches from a wall or on a wall with the top of the alarm not less than 4 inches, or more than 12 inches, below the ceiling.

DO NOT INSTALL INTHIS AREA.

4”

INSTALL IN THIS AREA.

36” 36”

WHERE TO INSTALL SMOKE/HEAT DETECTORS IN CATHEDRAL CEILINGS

WHERE TO INSTALL SMOKE/HEAT DETECTORS IN SLOPED CEILINGS

36”

4”

DO NOT INSTALL IN THIS AREA.

INSTALL IN THIS AREA.

•IF SMOKE ALARMS ARE PLACED IN A ROOM WITH SLOPED CEILINGS, THE ALARM SHOULD BE LOCATED ON THE HIGH SIDE OF THE CEILING.

THESE SMOKE DETECTORS ARE INTERCONNECTED, IF ONE GOES OFF, THEY ALL GO OFF.

HEAT DETECTORS

Heat Detectors respond to fire, not smoke. While Smoke detectors get all the attention, heat detectors are another useful component of any modern fire detection system. Some environments can trigger nuisance alarms in conventional smoke alarms due to shifts in temperature and humidity as well as dust, fumes and insects. Heat detectors are intended for use in locations where standard smoke alarms are not suitable because they are virtually unaffected by these adverse conditions. Heat detectors are useful in Kitchens, Unfinished Attics, Basements, Garages, and other areas where high levels of dust and fumes are present.

DO NOT install heat detectors in areas with high humidity. Also do not install in rooms where temperatures may fall below -10 degrees F or rise above 100 degrees F or near fluorescent lights (electrical noise and flicker).

CO alarms have a limited life-span. (3-5 YEARS)

CARBON MONOXIDE DETECTORS

More CO detectors

The new state building code is designed to protect you from carbon monoxide gas, which kills 500 people a year and sickens 20,000 others. It's dubbed the "silent killer." It's colorless, odorless, and tasteless. So unless you actually see visible smoke that often occurs with carbon monoxide, you won't know.

Carbon Monoxide Detectors http://www.youtube.com/watch?v=CAYHMu1F7ww

When CO comes into contact with the circuitry, it lowers the electrical resistance. The processor detects the change and causes the alarm to sound. These sensors require lots of electricity, so they generally plug into wall outlets rather than using batteries.

The CO sensor identifies and measures CO gas concentration in the atmosphere in parts per million (ppm). When the sensor detects dangerous levels of the gas, it sends an electronic pulse to the alarm. The higher the concentration, the faster the alarm will respond. For example, the alarm will respond to concentrations of about 70 ppm in as little as an hour but will respond to concentrations of 400 ppm in as little as four minutes The alarm sounds at about 85 decibels (dB), just a little quieter than a typical lawnmower, but often very shrill.

How to Choose a Carbon Monoxide Detector Location.

FLOOR PLAN VIEW

COMBINATION SMOKE AND CO DETECTOR