Basic Science and Technology JSS 2 Third Term Scheme of work With Lesson Notes

THIRD TERM E-LEARNING NOTE

SUBJECT: BASIC TECHNOLOGY

CLASS: JSS2

SCHEME OF WORK

WEEK TOPICS

Revision of Last Term’s work
Belt and Chain drives

Belt and Chain drives (Contd.)
Gears
Gears (Contd.)

Hydraulics and Pneumatic Machines
Building Construction I: Site Preparation
Building Construction II: Setting Out

Building Services: Taps and Water supply
Practical Projects

REFERENCE MATERIALS

MELROSE, Basic Science and Technology Book 2
NERDC, Basic Technology for JSS, Book 2

WEEK ONE

TOPIC: Revision of Last Term’s Work

A plane figure bounded by four equal sides is called ___ (a) square (b) rectangle

Opposite sides of a parallelogram are ___ (a) diagonal (b) parallel (c) vertex (d) straight
___ is a plane figure enclosed by three straight lines(a) Triangle (b) Quadrilateral

An octagon is a polygon with ___ sides ___ (a) 5 (b) 6 (c) 7(d) 8
The sum of angles in a quadrilateral is ___(a) 90 (b) 180 (b) 270 (d) 360
What is the center rule formula used to construct a polygon? (a) 360 – N (b) 360 x N

(c)³⁶⁰/₂(d) 360 + N

A regular polygon has ___ of its sides and angles equal (a) five (b) all (c) three (d) four
The opposite angles in a parallelogram are ___ (a) equal (b) unequal (c) positive

(d)negative

Plane figures are identified by the number of ___ enclosing them(a) points (b) sides

(c)values(d) circle

A line that joins two opposing corners of a quadrilateral is called ___(a) plane

(b)diagonal(c) angle (d) vertex

Each angle in a regular pentagon is ___ (a) 60 (b) 72 (c) 82 (d) 92

A machine that is used to resaw or prepare timber into suitable sizes for articles of joinery and furniture is known as (a) Circular sawing machine (b) Surface planing machine

A machine that is used exclusively for planing wood to a specific thickness after surface planing operation is called ___ (a) Circular sawing machine (b) Surface planing machine (c) Milling machine (d) Thicknessing

A wood working machine, which can also be used as machine tools, used for performing various operations such as boring, sanding and mortising is known as (a) Drill press

(b) Surface planing machine (c) Milling machine (d) Thicknessing

Which of the following is not a type of scale drawing? (a) Reduced (b) Enlarged

A quadrilateral with only two parallel sides is called ___ (a) square (b) rectangle

Which of the following is used to rotates the work and transmits movement to saddle of a lathe? (a) the bed (b) the headstock (c) the saddle cross slide (d) main spindle
The following are work holding methods except (a) catch and carrier (b) face plate

Which of the following provides a plane surface for mounting and moving accessories at a constant level on a lathe machine? (a) the bed (b) the headstock (c) the saddle cross slide (d) main spindle
Which of the following permits movement of tool at angle other than right angle? (e.g. for conical work) (a) the compound slide (b) the head stock (c) the slide cross slide (d) main spindle
The space occupied by a plane figure is called ___ (a) diagonal (b) area (c) volume

(d) theorem

The lubricant commonly used in transmission system is (a) diesel(b) gear oil (c) grease (d) hydraulic
Constant lubrication of a machine is to prevent (a) corrosion (b) exhaustion (c) high speed (d) sulphation

Which of the following will not reduce friction? (a) lubrication (b) use of rollers (c) use of pulleys (d) drying
Which of the following is not a practical application of friction? (a) belt drive (b) cable drive (c) chain drive (d) clutches
MRO stands for (a) Machine, relevance and operations (b) Maintenance, repair and operations (c) Maintenance, relevance and organization (d) Machine, repair and organization

Which of the following is not a part of lathe machine? (a) head stock (b) main spindle

(d) steadies (d) shaper

Which of the following triangles has none of its side equal Equilateral B. Scalene C. Isosceles D. Right-angled

The rougher the surfaces in contact, the …….. the frictional force (a) greater (b) lesser (b) partial (d) equal
Maintenance of metal work machines should include (a) periodic servicing (b) drying

WEEK TWO

TOPIC: BELT AND CHAIN DRIVES

CONTENT

Definition

Types
Uses

BELT DRIVES

A belt is a looped strip of flexible material used to mechanically link two or more rotating shafts. A belt drive offers smooth transmission of power between shafts at a considerable distance.Belt drives are used as the source of motion to efficiently transmit power or to track relative movement. When the belt is used for speed reduction, the smaller sheave is mounted on the highspeed shaft, like the shaft of an electric motor. The larger sheave is then put on the driven machine.

TYPES OF BELT DRIVES

The types of belt drives are diverse. The list of its kinds include the flat belts, synchronous timing belts, cog belts, vee-belts, round belts, multi-groove belts, ribbed belts, film belts, metal belts, endless round belts and speciality belts. Some of them are explained below:

The Flat belt: The simplest type is often made from leather or rubber-coated fabric. The sheave surface is also flat and smooth, limiting the driving force by the pure fiction between the belt and the sheave.
Synchronous Belts, or Timing belts: These ride onsprockets that have mating grooves that the teeth on the belt seat. It is a positive drive, limited only by the tensile strength of the belt and the shear strength of the teeth.

Cog Belts: These are applied to standard V-grooved sheaves. The cogs give the belt greater flexibility and higher efficiency compared with standard belts.
Vee-Belts: The V-shape causes the belt to wedge tightly into the groove, increasing friction and allowing high torques to be transmitted before slipping occurs.

BELT AND PULLEY ARRANGEMENT

There are various types of belt and pulley arrangement. These include:

Open belt: An open belt connecting two pulleys makes them run in the same direction

Crossed belt; this changes the direction of pulleys.
V-belt: V-belts run on V-pulleys. A common use of the V-belt and V-pulley is the fan belt of an automobile.

EVALUATION

What is a belt drive?
State the types of belt drive

Explain each type of belt drive

CHAIN DRIVES

A chain is a power transmission element made as a series of pin-connected links.The design provides for flexibility while enabling the chain to transmit large tensile forces.Chain drive is a way of transmitting mechanical power from one place to another. When transmitting power between rotating shafts, the chain engages mating toothed wheels, called sprockets.

TYPES OF CHAIN DRIVES

Roller Chain Drives: The most common type of chain is the roller chain, in which the roller on each pin provides exceptionally low friction between the chain and the sprockets. Roller chain is classified by its pitch, the distance between corresponding parts of adjacent links. The pitch is usually illustrated as the distance between the centers of adjacent pins. Standard roller chain carries a size designation from 40 to 240.
Conveyor Chain : Rollers sit proud of links and can roll along supporting surface It can be used for transporting materials, as rollers can support weight. Can also be used just to support weight of chain if transmitting power over long distances

Inverted Tooth (or silent) Chain: Sprocket teeth mesh with shaped links instead of rollers on chain. Joints between links use rolling rather than sliding contact. Profiles of links are more like involute gear teeth. Overall effect is to reduce noise.

Leaf (or lifting) Chain:It is designed for lifting rather (than power transmission). Do not have to mesh with sprockets, hence no rollers. Therefore can narrower than roller chain with equivalent strength. Example: fork-lift truck.

EVALUATION

What is a chain drive?
State the types of chain drive

Explain each type of chain

GENERAL EVALUATION

Differentiate between a belt drive and a chain drive
State four(4) types each of belt and chain drives

READING ASSIGNMENT: Read more on belt and chain drives (NERDC Basic Tech. for JSS3 page 148-153)

WEEKEND ASSIGNMENT

The most common type of chain is the ……… chain. (a) inverted tooth (b) roller

Which of these types of chains can be used for transporting materials?(a) roller chain (b) conveyor chain (c) inverted tooth chain (d) leaf chain

……….. is a power transmission element made as a series of pin-connected links.

(a) Iron (b) Belt (c) Chain (d) magnet

Which of the following offers smooth transmission of power between shafts at a considerable distance(a) Belt drives (b) Chain drives (c) Magnetic drives

(d) Electrical drives

Which of the following types of chain is used for lifting rather (than power transmission) (a) roller chain (b) conveyor chain (c) inverted tooth chain (d) leaf chain

THEORY

(a) What is a belt? (b) State the types of belt we have?
(a) State four (4) types of Chain drives (b) Explain any two

WEEK THREE

TOPIC: BELT AND CHAIN DRIVES (CONTD.)

CONTENT

Advantages and Disadvantages of Belt and Chain drives
Uses of Belt and Chain Drives

ADVANTAGES OF BELT DRIVES

Belt drives are simple and economical
They don’t need parallel shafts

Noise and vibration are damped out
They are lubrication-free
They are provided with overload and Jam protection

They are highly efficient in use (up to 98%, usually 95%)

DISADVANTAGES

They can slip or stretch which makes the angular velocity ratio not necessarily constant
Heat buildup occurs
Operating temperatures are usually restricted to -35 t0 85^oc
Adjustment of center distance or use of an idler pulley is necessary for wearing and stretching of belt drive compensation

ADVANTAGES OF CHAIN DRIVES

Chain drives do not slip or creep, and so are more efficient than belt drives
They are more compact than belt drives
They are often easier to install than belt drives
They do not deteriorate due to oil, grease, sunlight, or age
Operate effectively at high temperatures
Can withstand abrasive conditions
Can operate in wet conditions
Can be used on reversing drives

DISADVANTAGES

The production cost of chains is relatively high
Require more precise alignment than belt drives
Typically require frequent lubrication
Are noisy and can cause vibrations
Cannot be used in applications where the drive must slip
Do not have the load capacity or service life of gear drives

EVALUATION QUESTION

1 State five advantages and four disadvantages of Belt drives

Mention five advantages and six disadvantages of Chain drives

USES OF BELT DRIVES

Belt drives are used for smooth transmission of power between shafts at a considerable distance
They are used to track relative movement
The sewing machine makes efficient use of synchronous timing belts
Automobiles also make use of the timing belt/ cam belt system
The treadmill is also a great example of a belt driven mechanism

USES OF CHAIN DRIVES

Chain drives are used inrigging and moving heavy materials
They are used in hydraulic lift truck operation
They are used in increasing or decreasing a driver’s output speed by altering gear ratios between the driver and the sprocket being driven
They also used as overhead hoists
They are also used in operating conveyer belts

Differences between Belt Drives and Chain Drives

Belt Drives Chain Drives

Belt drives are made up of polymers Chain drives are made of alloys
They can operate under high speed Chain drives can operate under high load conditions
They do not need lubrication They need lubrication
They need dry condition to work properly They can work in high temperature and

moist condition

They make nonoise They make noise
They are powered by a belt They are powered by a chain loop

Similarities

Both belt drives and chain drives are methods to transfer power and objects within a machine

EVALUATION QUESTION

1 State five (5) uses of Belt drives

Mention five (5) uses of Chain drives

GENERAL EVALUATION

State five(5) advantages of belt drives and five(5) disadvantages of chain drives
Mention five (5) uses each of belt and chain drives

READING ASSIGNMENT

Read about Gears (NERDC Basic Tech. for JSS3 page 154-156)

WEEKEND ASSIGNMENT

………. can be used as overhead hoist (a) Belt drives (b) Chain drives (c) Magnetic drives (d) Electrical drives
The sewing machine makes efficient use of ……. (a) The flat belt (b) synchronous timing belts (c) cog belts (d) V-belt
…………. are used for smooth transmission of power between shafts at a considerable distance (a) Belt drives (b) Chain drives (c) Magnetic drives

(d) Electrical drives

Which of the following require frequent lubrication? (a) Series drives (b) Parallel drives (c) Belt drives (d) Chain drives
Automobiles also make use of the (a) timing belt/cam belt system (b) Series/parallel system (c) current/potential system (d) hydraulic/lift system

THEORY

State five (5) uses/applications of (a) Belt drives (b) Chain drives
(a) Mention two (2) differences between belt and chain drives (b) State two(2)

Similarities between belt and chain drives

WEEK FOUR

TOPIC: GEARS

CONTENT

Definition
Types
Lubrication of gears
Uses

GEARS

A gear is a wheel with teeth around its rim that mesh with the teeth of another wheel to transmit motion.

OPERATION

When two gears mesh, one is the driver and the other becomes the driven. A gear is a driver gear because the power to drive the system is generated by it, while the other is the driven because it is only being driven, and does not produce the power/energy.

TYPES OF GEAR

There are various types of gears, namely: Spur gear, Bevel gear, Rack and Pinion gear, Helical gear and Worm gears

Spur gears: They are used for transmitting drive between parallel shafts.

2. Bevel gears: These are used for transmitting power/drive between shafts at angles.

Rack and pinion gears: These gears are used for converting rotary motion of the pinion to linear motion of the rack.

Helical gears: These gears can transmit motion and power between either parallel or right angle shafts.

Worm gears: These gears operate silently and smoothly. They can be used for reducing speed and increasing torque.

LUBRICATION OF GEARS

Lubrication is the application of oily or greasy substance to machine parts in order to reduce friction. The substance applied (such as oil or grease) is called lubricant.

The purpose of lubricating gears is as follows:

To promote sliding between teeth to reduce the coefficient of friction
To limit the temperature rise caused by rolling and sliding friction.

Methods of Lubrication

There three gear lubrication in general use

Grease lubrication
Splash lubrication (oil bath method)
Forced oil circulation lubrication

There is no single best method or lubricant. Choice depends upon tangential speed and rotating speed. At low speed, grease lubrication is a good choice. For medium and high speeds, splash lubrication and forced oil circulation are more appropriate, but there are exceptions. Sometimes, for maintenance reasons, a grease lubricant is used even with high speed.

USES OF GEAR

Gears are used to transmit power from one shaft to another.
They are used to change the speed of shafts to either high or low speed.
They also change the running direction of a shaft.

EVALUATION

Define (a) Gear (b) List three types of gear and the uses
State the uses of gear
State the methods of gear lubrication

GENERAL EVALUATION

Mention three (3) types of gear and their applications.
Sketch a spur gear.

READING ASSIGNMENT

Read about gear ratio and gear speed (NERDC Basic Tech. for JSS3 page 157-159)

WEEKEND ASSIGNMENT

………. are used for transmitting drive between parallel shafts (a) Bevel gears

(b) Spur gears (c) Rack and pinion gears (d) Lift

Which of the following is used for transmitting power/drive between shafts at angles (a) Spur gears (b) Leaf gears (c) Rack and pinion gears (d) Bevel gears
In Rack and Pinion gears,……… generate rotary motion (a) rack (b) spur

A wheel with teeth around its rim that mesh with the teeth of another wheel to transmit motion is called (a) Belt (b) Chain (c) Gear (d) Clutch
……… are used to change the speed of shafts to either high or low speed(a) Chain

(b) Belt (c) Clutch (d) Gear

THEORY

What is a Gear? (b) State three uses of gears
State three types of gears (b)Briefly describe the operation of gears

WEEK FIVE

TOPIC: GEARS (CONTD.)

CONTENT

Gear Ratio
Gear Speed

GEAR RATIO

Gear ratio is defined as the ratio of number of teeth of output to input gear or input speed relative to output speed. It is calculated by dividing the number of teeth on the driven gear by the number of teeth on the driver gear.

Gear ratio= Number of teeth on the driven gear

Number of teeth on the driver gear

Example: Calculate the gear ratio if a gear with 15 teeth is used to drive a gear with 30 teeth.

Gear ratio= Number of teeth on the driven gear= 30/15= 2/1

Number of teeth on the driver gear

Gear ratio= 2:1

Ratio of a Series of Gears

When power flows through a series of gears, the ratio can be calculated in a similar manner. For example, if a 20-tooth driver gear drives a 24-tooth cluster gear, and the second speed cluster gear has 16 teeth driving a 20-tooth second speed driven gear, this could be calculated as follows:

Driven/Driver x Driven/Driver= 24/20 x 20/16= 1:5:1

GEAR SPEED

Gear speed is a measurement of how quickly a gear spins, often in a relation to the rotations of other gears. The speed of rotation of a gear is directly proportional to the number of teeth of the gear. For example, the speed of a 5-tooth gear will be twice the speed of a 10-tooth gear.

Example: A gear has 20 teeth. Its speed of rotation is 10 rpm. The gear drives another gear with 10 teeth. Determine the speed of the 10-tooth gear.

Solution

20 teeth x 10 rpm= 10 teeth x X rpm

X rpm= 20 teeth x 10 rpm/10 teeth

X rpm= 20 rpm

EVALUATION QUESTIONS

What is gear ratio?
Explain gear speed

GENERAL EVALUATION

Calculate the gear ratio if a gear with 20 teeth is used to drive a gear with 40 teeth.
A gear has 10 teeth. Its speed of rotation is 20rpm. The gear drives another gear with 15 teeth. Determine the speed of the 15-tooth gear.

READING ASSIGNMENT

Read about hydraulics and pneumatic machines (NERDC Basic Tech. for JSS3 page 170-180)

WEEKEND ASSIGNMENT

Calculate the gear ratio if a gear with 12 teeth is used to drive a gear with 16 teeth. (a) 4:3 (b) 3:4 (c) 2:1 (d) 1:2
A gear has 15 teeth. Its speed of rotation is 25rpm. The gear drives another gear with 25 teeth. Determine the speed of the 25-tooth gear. (a) 10rpm (b) 20rpm (c) 15rpm (d) 30rpm
The ratio of input speed relative to output speed is…… (a) gear speed (b) gear ratio

The speed of rotation of a gear is ……………. to the number of teeth of the gear (a) equal (b) unequal (c) inversely proportional (d) directly proportional
………. is a measurement of how quickly a gear spins (a) gear ratio (b) gear speed

THEORY

Explain (a) Gear Speed (b) Gear Ratio
(a) A gear has 32 teeth. Its speed of rotation is 4rpm. The gear drives another gear with 8 teeth. Determine the speed of the 8-tooth gear.

WEEK SIX

TOPIC: HYDRAULICS AND PNEUMATIC MACHINES

CONTENT

Definition
Types
Uses

DEFINITION – HYDRAULICS AND PNEUMATICS

Hydraulics is the branch of science and technology concerned with the conveyance of liquids through pipes and channels, especially as a source of mechanical force or control. When compressed air (gas) is the liquid, it is called Pneumatics. Hydraulic systems tend to be used at a much higher pressure than pneumatic systems. Consequently, the former can produce much larger forces and torque than the latter.

SIMPLE HYDRAULIC AND PNEUMATIC MACHINES

Simple Force Pump: Pumps are used to move gases and liquids by applying pressure greater than those of the gases or liquids. The simplest pump is the bicycle pump that moves air through the pump to the bicycle. Another simple pump is the suction pump. It is used for lifting liquids from a low level.
Centrifugal pump: This has a set of moving vanes which receive the the fluid (air or water) at a smaller radius
Hydraulic Jack: The discharge action in the hydraulic jack moves the liquid into a high pressure compartment. The piston is equipped to carry heavy loads such as cars.
Garden sprinkler: This consists of one or more water jets which can revolve about the center as it sprinkles water in a lawn or garden.
Reaction turbine
The waterwheel

USES/APPLICATION OF PNEUMATICS

Air brakes on buses, trucks and trains
Air compressors
Air engines for pneumatically powered vehicles
Pressure sensor
Pressure regulator and switch
Vacuum pump etc

USES/APPLICATION OF HYDRAULICS

Hydraulic Press
Breaks in cars, motorbikes and bicycles often use hydraulic systems to force to break pads
Office chairs
Boats and airplanes
Excavators and dump trucks use hydraulic pistons to control their equipment

EVALUATION

Define (a) Hydraulics (b) Pneumatics
State five (5) hydraulic and pneumatic machines
List five(5) applications of Hydraulics and Pneumatics

GENERAL EVALUATION

Differentiate between Hydraulic and Pneumatic Systems
State five (5) applications each of Hydraulics and Pneumatics
List five (5) Hydraulic and Pneumatic devices

READING ASSIGNMENT

Read about Site Preparation (NERDC Basic Tech. for JSS2 page121-123)

WEEKEND ASSIGNMENT

The branch of science and technology concerned with the conveyance of liquids through pipes and channels, especially as a source of mechanical force or control.

(a) Pneumatics (b) Hydraulics (c) Gearing system (d) Mechanical system

Which of the following can be used to carry heavy loads such as car?

(a) Centrifugal pump (b) Garden sprinkler (c) The waterwheel (d) Hydraulic Jack

Examples of application of pneumatic include the following except (a) Pressure sensor (b) Office chairs (c) vacuum pump (d) pressure regulator
The following are applications of hydraulics except (a) Hydraulic press (b) Air compressor (c) Boats (d) Excavators
Excavators and dump trucks use __________ to control their equipment

(a) hydraulicjack (b)hydraulic press(c)hydraulic pistons (d) hydraulic fluid

THEORY

List five application each of hydraulic and pneumatics
State five types of hydraulic and pneumatics machine with their uses

WEEK SEVEN

TOPIC: BUILDING CONSTRUCTION: SITE PREPARATION I

Site preparation involves the removal of trees, demolishing buildings, removing any and all old underground infrastructures, and any other things that might affect the construction process in the future or hinder the project to be done.

In various building projects, site preparation is very essential. The site may be a thick bush with big trees or a swampy and waterlogged area or a site with small hills and valley covered with stones and rock, or even a site with old and abandoned buildings.

TYPICAL HAND TOOLS IN SITE PREPARATION

Among the typical hand tools in site preparation operations are:

Spade: Used for digging relatively loose or soft earth
Shovel: Used for lifting and throwing loose materials (aggregates) or soft earth into another position and for spreading and leveling the earth.
Matchet: Used for cutting grasses or wood like tree branches and shrubs
Hoe: Used for digging usually about the surface level of the ground.
Axle: Used for cutting bigger branches.
Chain saw: Used for felling trees and for cutting the trunk into smaller lengths

MECHANICAL TOOLS USED IN SITE PREPARATION

Mechanical tools, which are also very valuable in speedy operations of site clearing, tackle the bulk of the heavy jobs on the site. Among these are following:

Bulldozer: This is a very powerful machine, which can push down almost any obstacle on its way and clear them from the site.
Tractor shovel (pay loader): This machine has a tipping bucket at the front. It is used for lifting large quantities of loose materials at a time and loading them into trucks or tippers.
Grader is used mainly for grading, that is, for trimming of bank or edges of roads and for cutting ditches

REMOVAL OF VEGETABLE SOIL SMALL TREES AND SHRUBS

The bulldozer is moved in to push down unwanted structures like old buildings and to uproot trees and shrubs. This debris is moved away to the site where parts of the trees are later salvaged for firewood. The bulldozer then scraps or excavates the topsoil to a depth of between 150mm and 300mm for the entire surface area of the site.

To prevent weed growth, an herbicide is applied. Herbicide is chemicals that are capable of preventing the growth of weeds when applied on a building site.

Herbicides

Round up:This is a general-purpose herbicide
Grammazon:This is another trade name for a type of herbicide used on building site.

Techniques for Grubbing out roots and stumps

It is better to first fell the trees, cut the trunk and transport to the sawmill for conversion into timber. The stump left is then tackled. Some digging is done around the tree stump to expose the roots, which are then cut either with an axe or the chain saw and the stump finally pulled out by the bulldozer.

LEVELING THE SITE

When all the tree stumps and roots have seen grubbed out and the top vegetable soil excavation to a depth of between 150mm and 300mm, a grader is moved in, to level the site. Here, earth is cut from the higher ground and moved down to fill valleys, holes and gullies.

EXTERMINATION OF TERMITES AND THEIR NESTS

When termite’s nests and anthills are found on the construction site they should be destroyed. The anthill is knocked down and some poisonous chemicals like Gamaline or antitermite chemicals are mixed and poured into the nest to kill the termites.

GENERAL EVALUATION

Explain Site Preparation
State five (5)tools used in site preparation

READING ASSIGNMENT

Read about Setting out (NERDC Basic Tech. for JSS2 page123-126)

WEEKEND ASSIGNMENT

Which of the following is not a hand tools for site preparation? (a) spade (b) shovel

Which of the following is a mechanical tool used in site preparation? (a) matchet

(b) bulldozer (c) chain saw (d) hoe

Which of the following is used for lifting large quantities of loose materials at a time and loading them into trucks or tippers? (a) grader (b) bulldozer (c) matchet (d) chain saw
One of the anti-termite chemicals used to exterminate termites from sites is (a) Marline (b) Gamaline (c) Benzene (d) Ester
Which of the following chemicals is used for general purpose prevention of the growth of weeds (a) Round up (b) Grammazon (c) Gamaline (d) Benzene

THEORY

Explain the following processes (a) Techniques for Grubbing out roots and stumps

(b) Leveling the site.

State the uses of three (3) mechanical tools used in site preparation

WEEK EIGHT

TOPIC: SETTING OUT

Anybody wishing to construct a building usually first consult an architect on the need for a building and the type of building wanted. An architectural design is sent to the structural engineer, who determines and specifies the strength and type of building material to be used. The quantity surveyor studies the working drawing of the proposed building determines the cost of materials, labour and workmanship. Finally, a construction company wins the contract for the construction of the building.

SETTING OUT

Building construction start with setting out

Setting out is, therefore, a process of driving wooden pegs into the ground here and there, in a manner that agrees with the dimensions of the building specified on the architect’s drawings.

Setting out is also the process of transferring with high degree of skill and accuracy, the detail of the foundation plan from the drawing sheet on the ground, with pegs, lines and tapes.

Working drawings include following drawings:

The floor plan
The elevations
The sections
The detailed drawing
The schedules
The electrical plan
The plumbing plan

The following tools are used for setting out

Steel rule
Builder’s square
Theodolite

When the concrete footing for the foundation has been cast and cured lines for the thickness of the wall are run and plumbed down to the concrete footing and the first course of the concrete block wall is laid.

EVALUATION

1.What is setting out?

Mention the tools used for setting out

EXCAVATION

When foundation plan for a building has been transferred on to the site, by way of setting out, excavation begins. For very big structures like stadium or a multi-storey building, the trenches for the column foundation or wall foundation can be mechanically excavated. Holes are mechanically bored where bored piled foundation has been recommended.

TIMBERING

This is the process of supporting the walls of the excavated pit with timber, for the purpose of safety.

CONCRETE AND ITS MATERIALS

Concrete consists of a matrix or binding material (cement), fine aggregate (sand) and coarse aggregate (stone) mixed thoroughly with water. Concrete, therefore, is a composite material in which a binding material mixed with water o solidification binds the inert materials – the particles of well- graded fine and coarse aggregates. Green concrete is used in the construction of footings, foundations, slabs, columns, lintels, beams, steps, and walls. It resists decay moisture and corrosion from acids. REINFORCED concretes are concrete having steel rods or welding wire mesh.

A good concrete should be strong, durable, hard, dense, non-porous, fire resisting and economical.

EVALUATION QUESTIONS

Define (a) Excavation (b) Timbering
Mention the materials used for making cement.

GENERAL EVALUATION

Define the following a) excavation b)timbering (c) setting out
Mention things involve in working drawings.

READING ASSIGNMENT

Read more on setting out (NERDC Basic Tech. for JSS2 page123-126 )

WEEKEND ASSIGNMENT

The process of supporting the walls of the excavated pit with timber (a) excavation

(b) timbering (c) concrete (d) coarse aggregates

Which of the following is not used for setting out right-angled triangles and squaring

(a) steel square (b) builder’s square (c) concrete (d) Theodolite

Which of the following is not a required expectation of a good concrete (a) strong and hard (b) durable and fire resisting (c) non-porous and economical (d) weak and poor
The process of transferring with high degree of skill and accuracy, the details of the foundation plan from the drawing sheet on to the ground with pegs, lines and tape.

(a) Timbering (b) working drawing (c) setting out (d) site preparation

Which of the following professional plans and designs a building that satisfies the wishes and needs of the client? (a) Quantity surveyor (b) structural engineer (c) architect

(d) plumber

THEORY

Define (a) setting out (b) timbering (c) excavation
State and discuss six (6) working drawings used by building worker.

WEEK NINE

TOPIC: TAPS AND WATER SUPPLY

CONTENT

Definition of Tap
Types of Taps
Water Supply/ Plumbing/Fitting

Definition of Tap

A tap is a valve controlling the release of a liquid or gas. Taps are made using a wide range of materials, including stainless steel, chrome, brass, nickel and gold.

Types of Taps

They are three main varieties of washerless tap available nowadays these are

Ball taps: This work by pushing a hollow plastic or stainless steel ball over a rounded cover, which controls the temperature and flow of water.
Cartridge Taps: These have a lever controlling a plastic or brass cartridge which moves up and down to restrict flow and from left to right to change temperature.
Ceramic disc Taps: This have two ceramic plates which slide over each other to regulate temperature and flow and require the least maintenance out of all the types.

Tap Styles

Cross head tap
Lever tap

How Taps Work

Different taps also regulate the water in different ways. Many of us are familiar with the compression type of tap – when the tap is screwed down it compresses a washer made of rubber or neoprene against a metal seat, which restricts and water flow. These washers will wear out over time, and need to be replaced

Water Supply/Plumbing

Definition of plumbing

Plumbing can be defined as the system of arranging and connecting pipes with others things (fittings and machines) that supply water to and drain liquids wastes out of the building.

Domestic pipeline fitting has the following components

Stops Corks
Drain Corks
Valves (gates valves bul-valves)
Taps
Elbows
Tees
1. Stop Cork: This is used to control the flow of water through water supply pipes.
2. The Stop Cork has a crutch handle, which is turned clockwise or anticlockwise to raise or lower the jumper on valve seating.
3. Drain Cork: It is connected to a water supply pipe in order to drain off water.
4. Gate valve: It is a valve that is used in controlling the flow of water in the distribution pipes.
5. Taps: We get supply by opening a tap at the end of the supply line.
6. Elbows: These are connected to the water supply pipe to change the direction of flow through an angle. For example, it is important when a horizontal pipe is to be connected to a vertical pipe. One end of the elbow turns through the required angle (90, 112½ , 135 , 157½ )
7. Tee: A tee is used for joining three pipes meeting at a junction from one of the pipes the flow divides into the two other pipes.

EVALUATION

Define (a) Tap (b) Plumbing
State three (3)types of tap
Explain five (5) domestic line fitting and state their uses.

PIPELINE SYSTEM FOR DOMESTIC WATER SUPPLY

Pipes referred to as the mains are laid underground to distribute water to various outlets. The water from the street mains enters the compound of a building in a 30m-diameter pipe (community pipe). It connects to a side of the water authority stop cork which buried in a pit at least 80cm deep.

The main pipes are laid underground to distribute water to various outlets. The main is connected to the kitchen sink to outside tap and up to the elevated tank. Baths, water closet, washing hand basin and hot water system are supplied directly by gravity through a 22m diameter pipe from the overload storage tank.

WATER STORAGE TANK

Water storage tank is important when one considers the fact that regular supply of water cannot be guaranteed. Storage tank is important because:

The demand for water varies during the day from the peak period demand in the morning to low demand later in the evening.
Water is distribute from the storage tank generally at low pressure, thus if there is a leakage along the supply line, It will not as serious as leakage along the high-pressure supply mains.
There are occasions when the water authority has to cut off supply to effect repairs unless one has a storage tank there will be no supply to the building.

SINKS

They are made from stainless steel or enameled steel. Sinks are provided with piller bib taps depending on the orientation of water supply pipe. It has over flown hole to provide passage for water in case of the tap being carelessly left open. A’s tipper is used to block the water passage when the tap is open to provide a pool of water for washing.

When blockage occurs, a sink plunger down or a force cup may be used. The plunger placed over the waste outlet is then plunged down forcibly as many times as necessary.

The plunging action generates a lot of compressive force, which moves the obstruction out of the way. If the plunging fails to remove the blockage the clearing “ey” will have to be unscrewed. A wire can then be used to probe into the piping to dislodge the offending materials.

BASINS

Wash basins are usually made of ceramic. It has almost the same component as the sinks.

BATH TUBS AND SHOWERS

Baths are of different sizes and shapes. They are made of enameled cast iron or acrylic plastic. Cold water taps as well as hot water tap is provided. It also has a stopper to stop water flow as often required.

For a body wash, there is a great advantage in installing a shower:

It ensures economical use of water than a bath tub.
Showers are more hygienic.

WATER CLOSET

The water closet is one of the most important components of a household’s plumbing installation.

Human wastes are got rid of through the W.C. Any malfunctioning will lead to an unhealthy environment. The cisterns contain at least two gallons of water.

HOT WATER SYSTEM

Hot water system is required mainly for providing warm water for bathing and for brushing the teeth at washbasin. This can be achieved. This can be achieved by installing an electric water heating system. The hot water is piped to the bathtub and washbasin.

EVALUATION

Define (a) Taps (b) Sinks (c) Basins
State the types of taps we have

THE DRAINAGE SYSTEM

The importance of drainage cannot be over-emphasized. A drainage system must be provided with a pipe to get rid of liquid waste from kitchen sink, the bathtub, and the wash hand basins, water closets.

The effluents flushed from the W.C travel through the ‘soil’ pipe into the inspection chamber, which constituted the junction for all drains. The water drained from the water basins travel through a separate pipe first into a gulley where in solids are removed before the drain enters into the inspection chamber,

After the inspection chamber, the liquid waste either goes into the public sewage works or a septic tank. The septic tank is an underground chamber into which sewage from the house enters and leaves as clean effluent. The inlet of the septic tank is slightly higher than the outlet, this is to ensure that when fresh discharge of sewage enters the tank, an equal volume of old liquid in the tank is displaced into the filter tank, anaerobic bacteria (bacteria which cannot live in the pressure of free oxygen) act on the sewage to break down the solids to liquid, gas and mineral sludge.

The liquid effluent from the tank enters the second chamber or filter tank where aerobic bacteria (bacteria which live in the presence of oxygen) complete the sewage purification process by oxidation.

For septic tank to be able to perform the above-mentioned point, than these practice should be noted.

The use of disinfectants destroyed the disease germs in a toilet and at the same time destroy the bacteria in the septic tank, thus it slows down the bacterial action in the waste.
Household chemicals like bleaches, detergents etc when used excessively and sent into the septic tank interfere with the bacteria decomposition of waste. The rate of absorption of the soil is thereby reduced liquid effluent from the soil may then find its way to the surface consequence the surrounding area get polluted.
The empty of large volume of water may result in the churning up of the solids that are still being broken down by bacterial action as well as the sludge. Such products may also flow into the filter or drainage field to cause clogging
It is important to establish the absorption properties of soil in an area where septic tank is to be installed.

GENERAL EVALUATION

Explain the following
1. sink
2. water closet
3. storage tank
4. Mention three practices to be noted in the use of septic tank in our home.

READING ASSIGNMENT

WEEK THREE

WEEK FIVE

WEEK SEVEN

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