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Transcript of chemistry 4.05
All smoke detectors consist of two basic parts
a sensor (to sense the smoke)
a very loud electronic horn (to wake people up or alert them when smoke is detected)
Smoke detectors can run off of two things
a 9-volt battery
a 120-volt house current Smoke detectors Different Types of Fires & Extinguishers Fire Extinguishers How They Work Carbon monoxide Detectors By:
Whitney Burrows and Gino Saborse photoelectric detectors and ionization detectors Photoelectric Detectors Is less sensitive of the two
Uses light beams
Has a light and a sensor that are positioned at 90-degree angle to one another
Photoelectric detectors are better at sensing smoky fires
How it works
- The light from the light source usually shoots straight across and misses the sensor
- When smoke enters the chamber the smoke particles scatter the light
- The light will hit the sensor then, set off the horn in the smoke detector. Ionization Detectors Uses an ionization chamber and a source of ionizing radiation to detect smoke
This type of smoke detector is more common because it is:
better at detecting the smaller amounts of smoke How It Works
Consists of two plates with a voltage across them and a radioactive source of ionizing radiation
Uses a type of electrical current
When smoke enters the ionization chamber, it disrupts this current
The smoke particles attach to the ions and neutralize them
The smoke detector senses the drop in current between the plates and sets off the horn A small silicon microchip sends an electronic charge to the other parts of the detector
The chip is fused to a copper-wired, integrated electronic circuit panel, which is the base for the unit.
Light-emitting diodes use lights to let you know how the unit is functioning and whether the battery needs to be replaced
Some detectors also have a liquid crystal display (LCD) panel that shows CO levels
Wires to the building's electrical system or a battery provide power to the unit.
A test/reset button lets you make sure the alarm is working.
A detection chamber houses the CO gas sensor.
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. Suggestions for use Smoke Detectors
Number in home: One for every room
Mounting locations: On the ceilings
How often to replace the battery: Twice a year
How often you should clean your smoke detector: Every 6 months
How often you should replace your smoke detector: Every 10 years
Carbon Monoxide Detectors
How often you should replace your carbon Monoxide Detector: Every 2 years
Number in home: At a minimum, a single detector should be placed on each sleeping floor with an additional detector in the area of any major gas burning appliances such as a furnace or water heater.
Mounting locations: In the garage, above any fuel burning thing such as a, fireplace. on every floor level Class A extinguishers are for ordinary combustible materials such as paper, wood, cardboard, and most plastics. The numerical rating on these types of extinguishers shows the amount of water it holds and the amount of fire it can extinguish.
Symbol - green triangle
Class B fires involve flammable or combustible liquids such as gasoline, kerosene, grease and oil. The numerical rating for class B extinguishers shows the number of square feet of fire it can extinguish.
Symbol - red square
Class C fires involve electrical equipment, such as appliances, wiring, circuit breakers and outlets. Never use water to extinguish class C fires!!! the risk of electrical shock is far too great! Class C extinguishers do not have a numerical rating. The C classification means the extinguishing agent is non-conductive.
Symbol - blue circle
Class D fire extinguishers are commonly found in a chemical laboratory. They are for fires that involve combustible metals, such as magnesium, titanium, potassium and sodium. These types of extinguishers also have no numerical rating, they are also not given given a multi-purpose rating - they are designed for class D fires only.
Symbol - Yellow Decagon
Class K fire extinguishers are for fires that involve cooking oils, trans-fats, or fats in cooking appliances and are typically found in restaurant and cafeteria kitchens.
Symbol - black hexagon Facts That May Be Helpful
Always keep a smoke detector in the kitchen
Never leave a car running in the garage with the door shut
Usually if a smoke detector is beeping that means the battery is dying
Even a small amount of CO2 can cause symptoms of the flu and make you sick
NEVER try to put out a fire in an electrical oven with water! You could get shocked
When putting out a grease fire use things like baking soda instead of water