Unit 9. A smoke detector

Useful vocabulary

• to house – располагать/размещать

• an enclosure – зд. оболочка/корпус

• thick – толстый

• sensitivity – чувствительность/восприимчивость

• to power – питать/приводить в движение

• a light source – источник света

• a straight line – прямая линия

• a particle – частица

• to collimate – коллимировать/придавать параллельность

• to be prone to – быть склонным/подверженным

• to trigger an alarm – приводить в действие/запускать сигнализацию

• cheap – дешевый

• an angle - угол

• to drill a hole – сверлить отверстие

• an even distribution – равномерное распределение

Task I. Read the text

1. A smoke detector is a device that detects smoke, typically as an indicator of fire. Smoke detectors are typically housed in a disk-shaped plastic enclosure about 150 mm in diameter and 25 mm thick, but the shape can vary by manufacturer or product line.

2. Most smoke detectors work either by optical detection (photoelectric) or by physical process (ionization), while others use both detection methods to increase sensitivity to smoke. Smoke detectors in large commercial, industrial, and residential buildings are usually powered by a central fire alarm system, which is powered by the building power with a battery backup. However, in many single family and smaller multiple family housings, a smoke alarm is often powered only by a single battery.

3. An optical detector is a light sensor. When used as a smoke detector, it includes a light source (incandescent bulb or infrared LED), a lens to collimate the light into a beam, and a photodiode or other photoelectric sensor at an angle to the beam as a light detector. In the absence of smoke, the light passes in front of the detector in a straight line. When smoke enters the optical chamber across the path of the light beam, some light is scattered by the smoke particles, directing it at the sensor and thus triggering the alarm.

4. An ionization type smoke detector is generally cheaper to manufacture than an optical smoke detector; however, it is sometimes rejected because it is more prone to false alarms than photoelectric smoke detectors. It can detect particles of smoke that are too small to be visible.

5. An air-sampling smoke detector is capable of detecting microscopic particles of smoke. Most air-sampling detectors work by actively drawing air through a network of pipes laid out above or below a ceiling in parallel runs covering a protected area. Small holes drilled into each pipe form a matrix of holes providing an even distribution across the pipe network. Air samples are drawn past a sensitive optical device, often a solid-state laser, tuned to detect the extremely small particles of combustion.

Task II. Which passages contains the following information:

1. Smoke detectors are usually powered by a central fire alarm system.

1. 1 b. 2 c. 3 d. 4 e. 5

2. A network of pipes is the main element of most air-sampling detectors

a. 1 b. 2 c. 3 d. 4 e. 5

Task III. Answer the following questions

3. What is a smoke detector?

4. Where are smoke detectors usually housed? What are their typical shapes and sizes?

5. What types of smoke detectors do you know?

6. What is the principle of an optical detector operation?

7. What is good about an ionization type smoke detector?

Task IV. Complete the statements using the facts from the text

1. A smoke detector detects … .

2. Smoke detectors are usually powered … .

3. Most smoke detectors use both detection methods … .

4. An ionization type smoke detector is more … .

5. An air-sampling smoke detector is capable of detecting … .

6. A solid-state laser is tuned to detect … .

Task V. Fill in the gaps using the words from the box

thick sensitivity particles to trigger prone hole angle device single network

1. This picture was taken from an unusual … .

2. Children are … to eating junk food.

3. … is a piece of equipment used for a particular purpose.

4. The dog got out through a … in the fence.

5. She has a high … to ultraviolet light.

6. This detector can “feel” extremely small … .

7. This song … a lot of happy memories.

8. He prefers … doors for sound isolation.

9. We didn’t get a … answer to our questions.

Task VI. Paraphrase the underlined words and word combinations using the vocabulary from the text

1. Smoke is typically one of the “symptoms” of fire.

2. Some detectors give wrong alarms.

3. This device can detect particles of smoke that are too small to be seen.

4. A network of pipes is laid out above or below the opposite part of the floor.

5. A matrix of holes supplies an even distribution across the pipe network.

Task VII. Grammar focus. Practice Conditionals. Translate the following sentences

1. If you don’t install fire detectors, they won’t allow you to open the restaurant.

2. If you had more practice, you would feel more comfortable.

3. I wish I spoke English well.

4. If he was better qualified, he would get this job.

5. We will go to a café, if we have a break.

6. I wish I knew a shorter way.

7. If she had taken a taxi, she wouldn’t have been late for her plane.

8. The technician wishes the system functioned without failure.

9. If we had less cars in the streets, we wouldn’t suffer from traffic jams.

10. I would call him, if I could do it.

Task VIII. Use your own ideas to continue the sentences

1. I wish …

2. If a won 1 million dollars, …

3. If I had a chance, …

4. I would go to…, if …

5. If I could …, I …

6. I will help you, if …

7. I would feel happy, if …