Grade 8 Pre Tech Studies Study Notes

Foundations of Pre-Technical Studies

This strand builds the safety habits every person needs before working in a technical environment.

What this strand covers

• Sub-strand 1.1 — Fire Safety: what fire is, what causes outbreaks, how to prevent them, and how to fight a fire.
• Sub-strand 1.2 — Data Safety: threats to data in electronic devices and how to protect it.

By the end you will not just know about fire and data safety — you will be able to act on it in your workshop, at home, and in any workplace.

What fire is

Fire is the bright, hot flames produced when a material burns. A flame gives off heat, light, and smoke.

For fire to start and keep burning, three things must be present at the same time:

1. A source of fire — something that provides the first heat or spark (e.g. a lit match or a gas burner)
2. Fuel — something that can burn (e.g. wood or paper)
3. Oxygen — the gas in air that feeds burning

Remove any one of the three and the fire goes out. This is the most important idea in fire safety.

Sources of fire

A source of fire is anything that provides the first heat or spark to start burning.

• Lit matches — a matchstick that has been struck and is burning
• Lit candles — a candle whose wick is burning
• Lit cigarette butts — the burning end of a cigarette
• Lit gas burners — an open flame from a gas cooker
• Sparks from electrical faults — tiny hot particles from faulty wiring or equipment

Importance of fire in daily life

Fire is useful in many ways:

• Preparing food — cooking on a jiko, gas cooker, or firewood
• Providing heat — warming us in cold weather
• Providing light — candles and campfires give off light
• Scaring away wild animals — useful in rural and farming areas

However, fire can destroy property, cause injuries, or result in loss of lives if not handled carefully. Because fire is so useful, it is worth learning to use it safely.

Flammable materials

Flammable materials are mostly liquid or gas fuels that catch fire very easily and burn fast — sometimes just from being near a heat source.

Examples: kerosene, petrol, spirit, and cooking gas.

These are stored in labelled containers with warning symbols because they ignite so easily. Always keep them away from any source of fire.

Combustible materials

Combustible materials are solids that can burn when exposed to a flame. They need more heat to catch fire than flammable liquids, but they burn well once ignited.

Examples: wood, hair, paper, and fabric.

These are everyday items found in homes, schools, and workshops. A pile of wood shavings, dry paper, or old cloth on a workshop floor is a fire risk whenever a heat source is nearby.

Six causes of fire outbreaks

1. Poor handling of flammable or combustible materials — placing a lit match or burner near these materials causes them to catch fire.
2. Leaving fires, burners, or heaters unattended — a fire with no one watching can spread quickly to nearby areas.
3. Untidy working areas — dirt and grease build up over time and are highly combustible. A stray spark can ignite them.
4. Faulty electrical appliances — damaged plugs, poor wiring, or old appliances can overheat and produce sparks.
5. Leakage of flammable fuels — a faulty gas cooker or kerosene lamp can leak fuel. Leaked fuel ignites immediately when it meets a spark.
6. Improper use of electrical equipment — for example, leaving a device charging too long, spilling water on equipment, or overloading a socket.

What a fire outbreak is

A fire outbreak is a sudden, unwanted, or uncontrolled fire that spreads very quickly across a large area.

Preventing an outbreak before it starts is always safer than trying to fight one.

Ten fire prevention measures

1. Store flammable and combustible materials away from sources of fire. Display 'NO SMOKING' signs at storage points.
2. Never leave fires unattended. Put off any fire when it is not in use.
3. Do not overload electrical sockets. Too many appliances on one socket causes overheating.
4. Switch off electrical appliances when not in use, especially at night.
5. Keep the environment clean. Remove dry leaves, waste paper, and wood shavings regularly.
6. Have electrical appliances checked by an electrician. Repair or replace faulty ones. Never use appliances with damaged plugs or frayed wires.
7. Install smoke detectors, fire extinguishers, and fire alarms for early warning and quick response.
8. Provide fire safety training. People should know how to prevent fires, exit buildings, and use extinguishers.
9. Prevent gas leakages. Tighten regulators and knobs. If you smell gas, open windows and doors. Do not light any fire when you smell gas.
10. Monitor fire-prone areas. Where possible, assign someone to watch areas at high risk.

Three fire prevention devices

Measure 7 above requires three specific devices. Every school workshop and workplace should have all three.

Smoke detector

A smoke detector is a small, round, white disc fixed to the ceiling. It detects smoke particles in the air and sounds an alarm before the fire grows large. The slots around the disc face allow smoke to enter the sensor inside.

Fire extinguisher

A fire extinguisher is a tall red metal cylinder mounted on a wall near a door. It is filled with water, dry chemical powder, or carbon dioxide foam to put out fires. To use it, pull out the safety pin and squeeze the handle.

Fire alarm

A fire alarm call point is a red device mounted on a wall. Breaking the glass panel on its face triggers a loud alarm that tells everyone to evacuate immediately.

Every learner is responsible for checking that these devices are present and not blocked. A smoke detector covered in dust, or an extinguisher blocked by a stool, cannot do its job.

The four basic firefighting methods

We can extinguish fires using four basic methods: cooling, smothering, starving, and interrupting.

Each method works by removing one of the three things fire needs — heat, oxygen, or fuel.

Cooling fire

Cooling means reducing the temperature of the burning material until it can no longer keep burning.

This is done by pouring water on the fire. Water absorbs heat quickly. The temperature drops until burning stops.

When NOT to use water

Do not use the cooling method on:

• Fires from petroleum fuels (petrol, kerosene)
• Fires from vegetable oils
• Electrical fires

Water on a burning petroleum or cooking oil fire causes the fire to explode outward — causing serious burns. On an electrical fire, water conducts electricity and puts the person at risk of electric shock.

Smothering fire

Smothering means cutting off the oxygen supply to the fire. When oxygen is completely removed, burning stops.

Two ways to smother a fire:

1. Cover the flame or burning area with sand or a heavy blanket. This blocks air from reaching the fire.
2. Cover a person whose clothes are on fire with a blanket or heavy rag, wrapped tightly, to seal off the air supply.

Smothering works well on small, contained fires. It is not effective on large fires that have already spread, because a blanket or bucket of sand cannot cover a big enough area.

Starving fire

Starving means removing the fuel from the fire. With nothing to burn, the fire goes out.

Two ways to starve a fire:

1. Cut off the fuel supply — turn off the gas valve at the cylinder, or switch off electricity at the main switch.
2. Remove the burning solid — pull a burning piece of timber away from a larger pile so the fire cannot spread further.

Interrupting fire

Interrupting means stopping the chemical chain reaction that keeps the fire going.

This is done by applying dry chemical powder or gaseous agents to the burning material. A good example is the carbon dioxide (CO₂) foam from a fire extinguisher. It breaks the fire's chemical chain and also smothers the flame at the same time.

Important: never throw random household substances on a fire. Only approved dry powder or CO₂ foam from a fire extinguisher should be used — some household substances make fire worse.

All four firefighting methods