Smoke Detectors
Smoke Detectors, Fire Alarm Saves Lives
Smoke Alarms Saves Live 

How Do Smoke Detectors Work?

Photoelectric & Ionization Smoke Detectors
Here are two main types of smoke detectors: ionization detectors and photoelectric detectors. A smoke alarm uses one or both methods, sometimes plus a heat detector, to warn of a fire. 

Types of Smoke Detectors

Ionization Detectors 
Ionization detectors have an ionization chamber and a source of ionizing radiation. The source of ionizing radiation is a minute quantity of americium 241 (perhaps 1/5000th of a gram), which is a source of alpha particles (helium nuclei). The ionization chamber consists of two plates separated by about a centimetre. The battery applies a voltage to the plates, charging one plate positive and the other plate negative. Alpha particles constantly released by the americium knock electrons off of the atoms in the air, ionizing the oxygen and nitrogen atoms in the chamber. The positively charged oxygen and nitrogen atoms are attracted to the negative plate and the electrons are attracted to the positive plate, generating a small, continuous electric current. When smoke enters the ionization chamber, the smoke particles attach to the ions and neutralize them, so they do not reach the plate. The drop in current between the plates triggers the alarm.

Photoelectric Detectors
In one type of photoelectric device, smoke can block a light beam. In this case, the reduction in light reaching a photocell sets off the alarm. In the most common type of photoelectric unit, however, light is scattered by smoke particles onto a photocell, initiating an alarm. In this type of detector there is a T-shaped chamber with a light-emitting diode (LED) that shoots a beam of light across the horizontal bar of the T. A photocell, positioned at the bottom of the vertical base of the T, generates a current when it is exposed to light. Under smoke-free conditions, the light beam crosses the top of the T in an uninterrupted straight line, not striking the photocell positioned at a right angle below the beam. When smoke is present, the light is scattered by smoke particles, and some of the light is directed down the vertical part of the T to strike the photocell. When sufficient light hits the cell, the current triggers the alarm.
Which Method is Better?
Both ionization and photoelectric detectors are effective smoke sensors. Both types of smoke detectors must pass the same test to be certified as UL smoke detectors. Ionization detectors respond more quickly to flaming fires with smaller combustion particles; photoelectric detectors respond more quickly to smouldering fires. 

In either type of detector, steam or high humidity can lead to condensation on the circuit board and sensor, causing the alarm to sound. Ionization detectors are less expensive than photoelectric detectors, but some users purposely disable them because they are more likely to sound an alarm from normal cooking due to their sensitivity to minute smoke particles. 

However, ionization detectors have a degree of built-in security not inherent to photoelectric detectors. When the battery starts to fail in an ionization detector, the ion current falls and the alarm sounds, warning that it is time to change the battery before the detector becomes ineffective. Back-up batteries may be used for photoelectric detectors.
For Professional Security System Installation. Call Today 416-250-7398 
Monitored Smoke Detectors Saves Lives

Monitored smoke detectors can help prevent substantial loss in situations that a non-monitored smoke detector simply cannot. 
Whether you did arm your alarm system or not monitored alarms are always ready to communicate to our monitoring stations. ones they detect a smoke it will trip the alarm system, the siren will sound and your system will let us know so we will be alert you and your fire department .   
Why put the safety of your home, and loved one at risk? call today to 416-250-7398  to get your monitored smoke detectors.
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Blaze Alarms has been serving customers in and around Toronto since 1990. Blaze Alarms can install a FREE security system in your home or place of business. All our alarm systems can be monitored by our monitoring station 24 hour a 7 days a week. 

Contact us today to get your family protected with our Free alarm system offer. 
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