1. .1 List the basic principles that should be
followed when planning a drainage system for a dwelling.
2. 2 Explain one method of protecting a drain passing
through a wall.
Answer- By leaving a space of at least 50mm
all round and packing with rock wool or facing with sheet metal , or by using “
rocker pipes’ either side of the wall.
3. 3 What safety precautions should be taken when working?
·
In a trench 2.5m deep?
·
To unblock an existing drain requiring Roding in
a deep inspection chamber.
Answer- (i) Ensure that the sides of the trench cannot collapse by
boarding and strutting the sides.
Answer- (ii) Allow time for any sewer gases to dissipate before
descending into the inspection chamber; station an assistant at ground level to
man a safety rope.
(iii) Prevent
contaminated water from entering cuts and body orifices and wash
Thoroughly
after completing the work.
4. 4. Why it is important to ensure that drains are
ventilated.
Answer-To allows sewer gases to escape to atmosphere
safely and to prevent loss of trap seals due to siphon age.
5. 5. A drain is to be laid with a fall of 1:40. By
how many mm will the pipe fall per meter run?
Answer- 1000/40=25mm/m
6. 6. How can the outlet from a gully be traced if it
runs to an inspection chamber that has multiple inlets?
Answer- By using the fluorescent dye, Colored
water is poured down the gully; the inspection chamber can then be observed to
see which inlet it issues from.
7. 7. How can the correct fall of a short run of drain
be established?
Answer- By using an incidence board and
spirit level.
8. 8. Explain the term-self cleaning velocity into
drainage system.
Answer- Self- cleaning velocity occurs when
the drain is laid with a fall that enables the water flow to carry a way any
solids effectively.
9. 9. Sketch a section through a simple bottle –trap
and identify clearly where the dimensions of the trap sea are.
10.10. List the main advantages and disadvantages of
the two pipe system of sanitary pipe work over the one pipe system.
11.11. Describe the problems associated with using
plastic rain water goods in countries with very hot climates.
12.12 Describe in simple terms using a sketch to
illustrate, how a trap seal may be lost due to compression.
13.
13. A trap
that loses its seal a result of air being drawn from the trap branch pipe is
said to have seal loss due to :-
·
Momentum.
·
Induced siphonage.
·
Capillarity.
·
Compression.
14.14. Define briefly the following properties of
materials used in plumbing:-
(a)
Density.
(b)
Melting point.
(c)
Durability.
15.15. Give the functions of the following items kept
in the first aid kit:-
(a)
A pairs of scissors, safety pins, bandages,
cotton wool.
(b)
Antibiotic solution.
(c)
Soap.
(d)
Plaster, spirits.
16.16 Distinguish between:-
(a)
Elasticity and plasticity.
(b)
Ductility and malleability.
17.17 (a)Different between shallow wells and deep
wells.
(c)
Mention three service(3)kinds of water.
1818. (a) Name three services of supply of water.
(b) Briefly explain two types of caulked
joint used to join cast iron pipes.
19.19 (a) There are three basic pipe work systems that
are in use for above the ground drainage system namely;
One-pipe system, dual / two- pipe system
and single- stack system. Clearly explain the difference in each other.
(b) Give 2 advantage and disadvantages of
using dual or two- pipe system.
20.20 (a) What do you understand by the term back-drop
in man holes?
(b) How can you differentiate between a
soak away pit and a septic tank?
(c)Name four considerations that are taken
into an account when designing an efficient soak away pit.
21.21 (a) Outline points to bear in mind when deciding
the design and route of drains.
·
A drain has to be run under a building.
·
A drain has to pass through a wall.
22.22 (a) What is the difference between neutral
flame, oxidizing flame and carbonizing flame in gas welding?
(b) What is color for:-
·
Oxygen cylinder.
·
Acetylene cylinder.
23.23 (a) In gas welding the event of backfire is
likely to happen. What is the meaning and causes of backfire?.
(b)Name four uses of flux in gas welding.
24.24 (a) Define the term roof guttering.
(b) What are the functional requirements of
roof gutters. Mention any five.
25.25 (a)With the aid a simple sketch show the
following:-
·
Water main.
·
Ferrule valve.
·
Goose neck.
·
Boundary stop valve.
·
Communication.
26.26. Name
and explain two ways of tapping water mains.
2727. Name
three pipe systems used for the above ground drainage, and then clearly state
where each system is used.
28.28. Mention
seven (7) methods of trap seal loss.
29.29. Name
three (3) drainage systems as can be classified from the below ground drainage.
30.30. (a)
Define the term ‘solder ‘.
(b) Name four (4)
types of fluxes and state its recommended use to each type.
(a)
Name three types of water mains.
(b)
Why water mains are to be buried at a depth of
not less than 750mm?
31.31. (a)
What is the difference between Natural gas, Liquefied Petroleum Gas (LPG) and Bios?
(c)
Name three types of pipes which can be suitably
used to convey gas (gas main).
32.32. (a)
Differentiate between a septic tank and a cesspool tank.
(b) What is a
gully trap? Name four types of gully.
33.33. Clearly
state the use of the following hand tools:-
(a)
Reamer. The purpose of reamer is used to remove
internal burrs from steel pipes or copper pipes.
(b)
File. Is used for general shaping of metal and
the preparation of pipes before jointing, including the removal of burrs and
swarf.
(c)
Stilson pipe wrench- They are used for
tightening or loosening fittings and pipes.
(d)
Swaging tool- Is an a tool which used to open out pipe ends to form sockets or lips
on copper pipe.
(e)
Caulking tool- Used mainly in the joining of
cast-iron pipes, they consist of a range of cranked pieces of steel which are
used with a lump hammer to pack jointing yarn into the sockets of cast iron pipes. They are used compress or
caulk lead down into the joint which may have been poured in a molten state and
allowed to set, or was placed in the joint as fine lead wool.
(f)
Plumb-bob – These are used setting out vertical pipe work runs so that when clips or
blackest are fixed.
(g)
Hand-powered wheel brace-Is a type of hand drill
which driven by hand to perform it’s activities.
34.34. Define
the following terms:-
(a)
Density.
(b)
Durability.
(c)
Elasticity.
(d)
Plasticity.
35.35. (a)
How can you define the term water hammer.
(b) Give any six
types of traps.
36.36. (a)
How can you differentiate between a Globe valve and Gate valve.
(b)
Differentiate between a ball valve and safety valve.
37.37. (a)
Mention four (4) major sources of water.
(b) Clearly
explain the difference between Sedimentation and coagulant.
(c) Write short
notice on Base Exchange process.
38.38. (a)
Sanitary fitments falls under two major groups, name them and give three examples
from each group.
(b) Name and
clearly explain two types of water closets.
39.39. (a)
Clearly outline three disadvantages of one-pipe system as used in above ground
drainage.
(b) Clearly
describe what should be done if the drain pip is to pass below the building.
(c) What is the
function of gully trap.?
40.40. Calculate
the dimensions of the square storage tank which has the capacity of 64000
liters.
41. (a)
How do we fix ball valves in storage tanks?
(b) Name five
essential parts of the ball valves.
42.41. Drainage
system can be of below the ground or above the ground.
Name three
systems than are involved in each class of drainage system.
43.42. Differentiate
clearly the following terms:
(a)
Septic tank.
(b)
Cesspool tank.
44.43. (ii)Differentiate
uses of the following sanitary appliance.
(a)
Pedestal basin.
(b)
Lavatory basin (water closet pans).
(c)
Bidet.
ii. Name five chief materials suitable for the
manufacturing sanitary appliances.
45.44. Define
the following terms as they relate to water supply.
(a)
Consumer.
(b)
Supply pipe.
(c)
Communication pipe.
(d)
Distribution pipe.
46.45 (a)
How can the correct fall of a short run drain be established?
(c)
Explain the term self-cleaning velocity.
47.46 (a)
What is meant by the term private sewer?
(b) Give two (2)
reasons which necessities the provision of private sewer.
48.47 List
five basic principles that should be followed when planning a drainage system
for a dwelling house.
49.48 If
there is a difference in the invert levels between the incoming drain and the
sewer, give three solutions you will apply when making connection.
50.49 (a)
A rectangular enclosing a space of 0.45m and with sides 400mm and 500mm will
have depth?
(b) If the
tank(12a) is full of water, and 1 liter
of water has a mass of 1kg .Calculate the weight of
water in the tank.
51.50 (a)
What is meant by the term Gas welding?
(b) List down ten
(10) essential tools and equipment that are necessary if you want to perform a gas
welding.
52.51 (a)
Why every sanitary fixture should be provided with a trap?
(b) Name five (5)
qualities of an efficient trap.
(c)Draw a bottle
trap, showing:-
i. Inlet point.
ii. Cleaning
eye/cap.
iii. Outlet
point.
iv. Water seal.
53.52 Steel
cutting left in a galvanized storage cistern are likely to cause:
(a)
Plumb-solvency.
(b)
Dezincification.
(c)
Electrolytic action.
(d)
Electrostatic action.
54.53 A
5m head of water will produce an intensity of pressure in KPa(KN/m2) of:
(a)
49.05 (b) 4.967 (c) 48.15 (d) 490.5
55.54 Water
at normal atmospheric pressure will
expand continuously if its temperature increases from:
(a)
0 to 4 degree centigrade.
(b)
0 to 100 degree centigrade.
(c)
0 to 40 degree centigrade.
(d)
4 to 100 degree centigrade.
56.55 The length of water pipe on a drawing measures
55mm. If the water pipe was drawn to a scale of 1:200, the actual length in the
ground would be:
(a)
11000m (b) 11m (c) 11m (d) 3.6m.
57.56 Which
of the following is a soil appliances:
(a)
Bidet (b) Bath (c) Lavatory basin (d) slope
sink.
58.57 (a)
Plastic pipe can be bent after being heated and softened. The accepted methods
of heating plastic pipes prior to bending are of four types , mention them.
(b)
Name three (3) methods used for bending copper tube
(pipes)
59.58 Define
the following essential properties of metals:
(i)Durability (ii) Elasticity (iii) Plasticity (iv)
Melting point.
60.59 Compression
joints and capillary joints are the suitable joints for copper pipes:
(i)Name two types of compression
joints.
(ii) Name three types of
capillary joint.
(61) Plastic and ceramic materials are preferably
used to manufacture sanitary appliances and underground drainage pipes.
(i)List at least six(6) main
plastics types used by the plumber.
(ii) Mention three ceramic
materials used to manufacture sanitary
fittings.
(61) (a) Clearly define the term
“ below ground drainage system”.
(b) Below ground drainage systems can be
classified into three types.
Name them and give difference between
each.
(62) Distinguish between one
–pipe system , dual –pipe system and single-pipe stack system.
(63) (a) What is an inspection
chamber.
(b) Name five (5) reasons which
necessitate the provision of an inspection chamber in the drainage system.
(64) How many heating energy in
Kilo Joules (KJ) is needed to raise 20 liters of water from 30 degree
centigrade to 80 degree centigrade , if the specific heat capacity of water is
4.186KJ/ kg degree centigrade.
(64) Briefly the following
properties of materials used in plumbing:-
(a) Density (b) Melting point (c) Durability.
(65) Give the functions of the
following items kept in the first aid
kit:-
(a) A pairs of scissors (b) safety pins
(c) Bandages (d) Cotton wool (e) Antibiotic solution (f) soap.
(g) Plaster (h)spirits.
(66) Distinguish between:-
(a) Elasticity and plasticity.
(b)Ductility and malleability.
(67) (a) Differentiate between shallow wells and deep wells .
(b) Mention three(3) kinds of water.
(68)(a) Name three services of
supply of water.
(b) Briefly explain two types of
caulked joint used to join cast iron
pipes.
(69) (a) Name three services of
supply of water.
(b) Briefly explain two types of caulked
joint used to join cast iron pipes.
(70) (a) There are three basic pipe work
systems that are in use for above the ground drainage system
Namely;
One-pipe system, dual / two-pipe
system and single-stack system, Clearly explain the difference in each other.
(b)Give 2
advantages and disadvantages of using dual or two- pipe system.
(2) (a) What do
you understand by the term back-drop in
man holes?
(b) How can you differentiate between a soak a way pit and a
septic tank?
(c)Name four considerations that are taken
into an account when designing an efficient soak a way pit .
(71) (a) Outline points to bear in mind when
deciding the design and rout of drains.
(b) What should be done if:-
i. A drain has to be run under a
building .
ii. A
drain has to pass through a wall.
(72) (a) What is
the difference between neutral flame, Oxidizing flame, and Carbonizing flame in
gas welding?
(b) What is the color for:-
i. Oxygen cylinder.
ii. Acetylene
cylinder.
(73) (a) In gas
welding the event of back fire is likely to happen. What is the meaning and
cause of back fire?
(b) Name four uses of flux in gas
welding .
(74) (a) Define the term roof guttering.
(b) What are the functional requirements
of roof gutters.?
Mention any five.
(75) (a) With
the aid simple sketch show the following:-
(i) Water main
(ii) Ferrule valve.
(iii) Goose neck.
(iv) Boundary
stop valve.
(V) Communication
pipe.
(b) Name and
Explain two ways of tapping water mains.
(76) Mention
qualities of good trap into plumbing works system.
(77) Mention
characteristics of material used for manufacturing sanitary appliances.
(78) The ability
of a metal to be worked or rolled into thin sheet without splitting or cracking
is a property known as:
(a) malleability.
(b) elasticity.
(c) ductility.
(d) tenacity.
(79) Annealing
is a form of heat treatment that will make metals:
(a) easier to
work.
(b) less
ductile.
(c) more
conductive.
(d) harder to
search.
(80) The
commonest method of jointing steel pipe is to use:
(a) Capillary joints.
(b) solvent welded joints.
(c) threaded joints.
(d) compression
joints.
(81) Brass
is a mixture of which two metals?
(a) Steel and
copper.
(b) copper
and zinc
(c) zinc and
lead.”
(d) lead and
tin.
(82) Plastics
are popular materials used throughout the world because:
(a) they are
relatively cheap and easy to mass produce.
(b) they can
withstand all forms of wavering and degradation.
(c)they have a
low thermal expansion rate and are easy to paint.
(d) they will
not burn and they need fewer fixings.
(83) Which type of steel pipe is the most suitable for
carrying cold water supplies and why?
Answer-
Galvanized steel pipe is the most suitable steel for carrying cold water
supplies because it is resistant to corrosion and is relatively cheap and easy
to joint.
(84) On a
screwed joint between steel pipes, where would you find the “ washout” thread
and why should it be found there?
Answer- The
washout thread is the incomplete part of a thread formed by the dies to enable
them to start cutting into the has been screwed on to the pipe. If this
incomplete threads formed part of the joint inside the fitting it may not form
a watertight joint.
(85) List the
main points to consider when installing
thermoplastic pipes for domestic hot and cold water supplies.
Answer-Consider
allowances for expansion because of their high expansion rate, secure sitting
and fixing because of their low impact strength, sitting and protecting to guard against degradation caused by
excessive sun-light or ultra-violet light.
(89) Why is vitreous china a good material to use
for the manufacture of sanitary appliances?
Answer- Good
material for manufacture of sanitary appliances because it is impervious to
water is easily molded before firing.
(90) List the
relative advantages and disadvantages of ceramic materials and stainless steel
for sanitary appliances.
Answer- Advantages
–Strong, durable, inexpensive, resistant to most acids and alkalis, easy to
clean, easy to fix.
Answer-Disadvantages-
can creak if subject to rough use, can stain under certain water conditions.
A stainless steel- Advantages: light ,easy to
install, not easy to creak or break ,will not stain.
Answer-Stainless
steel- Disadvantages: relatively costly,
can be noisy in use.
(91)How does a
stop tap prevent back-siphonage of water into main supply.
Answer- Stop
taps prevent back-siphonage of water by
having a loose valve which acts as a non-return valve, forcing it on to the
seating in the event of back-flow, which stops water flowing back into the main.
(92) Which tap,
valve or cock should be fitted on a low- pressure cold water draw-off taps.
Answer- A gate valve should be fitted on a low pressure cold water pipeline because
it offers little resistance to the flow. Most other taps would reduce the flow
even further.
(93) What flow
control device would create water hammer if fitted on a cold water main
pipeline.
Answer-A plug
cock fitted on a cold water mains pipeline inside a building would create water
hammer because of the rapid shutting –off action.
(94) Describe
the operation of a Portsmouth ball valve.
Answer- As water
flows through the orifice it falls into the cistern which slowly fills with
water. As the water rises so too does the ball float which is connected to a
lever arm, the other end of which is connected to a valve to close against the
orifice, shutting the water off. If the water level drops, the reverse will
happen, letting water flow once more into the tank.
(95) Briefly
explain the important of gas Governor, and how it works.
Answer- The
purpose of a gas governor is to control the pressure of the gas at a
constant volume. It operates by using the pressure of the gas on the outlet
side acting on a rubber diaphragm to close or open valve against a spring
pressure thus maintaining constant pressure when the gas is flowing .
(96) Before
using ladders it is essential to:
(i) Make sure you have all tools ready
for the job.
(ii) Check that they are in good condition.
(iii) Make sure that they are painted the
right color.
(iv) Notify the
senior manager of the site or workshop
(97) Ladders
should always be erected with the tie- wires :
(i) Removed.
(ii)
underneath the rungs.
(iii) above the
rungs
(iv) loose .
(98) Never
overload a scaffold or working platform with tools or materials or it will:
(i) become
unstable and dangerous.
(ii) cut off
access to the work.
(iii) need a
hoist or lift fixing to it.
(iv) require
inspecting
(99) When using
a blow lamp, always make sure that:-
(i) The fire
brigade are notified.
(ii) The building
is evacuate
(iii) The
surroundings are protected.
(iv) You wear a
safety helmet
(100) Only use a
fire extinguisher to fight a fire:-
(i) It is a burning liquid fire.
(ii) The fire
looks like getting out of control
(iii) There is
no alarm bell to warn people.
(iv) You
consider it safe to do so.
(101). Why is
necessary to keep the back straight when lifting materials or equipment off the
floor.
Answer- It is
necessary to keep the back straight when lifting materials or equipment off the
floor to help prevent undue strain being put on the backbone which may cause
damage to the intervertebral discs.
(102.) If 60 people are employed on a building site
and 20% of them are trainees, exactly how many trainees are there?
Numbers of trainees:
=60/100*20%
=60/5
=12
(103) List the
factors that should be considered when laying an underground service.
Answer- Quality
of material to be used for the pipe, type of jointing system, the nature of the
soil through which the pipe will run, the depth that the pipe should be buried, and the route from the
water main to the point where the service enters the building, which should be
as straight and direct as possible.
(104) Where
should underground water service pipes not be buried?
Answer- In a
foul or aggressive soil or in drains, cess pits or inspection chambers.
(105) A cistern is to be installed to supply water
for domestic purposes.
(i)
Lit the requirements for the cistern.
Answer- The cistern must be made from suitable
materials; it should be supported on firm level base and fitted with a vented
lid; the overflow should be filtered; the outlet connection should be at the
opposite end to the inlet and have a valve fitted, the cistern should also be
insulated against heat gain and frost if necessary.
(ii)
What are the specific requirements relating to
access to the cistern for repair of the float-valve?
Answer- There needs to be a minimum of 350mm above the removable
lid for access. Also, a servicing valve should be installed in the supply pipe feeding the cistern.
(106) Where
should service valves be fitted to the pipe work in a cold water system ?
Answer- A
servicing valve must be fitted in the supply pipe at the boundary of the
property. Servicing valves should also be fitted on pipes feeding float-valves
and, in larger installations, at strategic points on the pipelines to allow for
turning off sections of the installation for maintenance and repair.
(107) Where
should drain-valves be fitted in a cold water supply system ?
Answer- Must be
fitted immediately downstream of the main stop-valve where the service entry
enters the building. Further drain-valves should be fitted at all trapped low
points in the system to enable draining for repair and maintenance.
(108) How
should a cistern of over 1000 capacity
be protected in a case of float-valve failure.
Answer- The
cistern should be protected by fitting a 25mm bore warning pipe that runs with
a slight fall to discharge in a conspicuous position. A separate overflow pipe
should also be fitted; this should be at least one diameter larger than the
supply pipe to the float-valve and should be run to terminate 150mm above a
suitable drain point.
(109) When
considering water economy , what is the maximum rate of fill for an automatic
flushing cistern supply .
(i) a single
urinal bowl.
Answer- No more
than 3 flushes of 2.51 per hour.
(iii)
1400mm of urinal slab?
Answer-No more than 3 flushes of 5.01 per hour.
(110) Explain
how cold water system flow noises can be
minimized when installing system pipe work .
Answer- Noise
can be minimized by installing tube of adequate diameter to keep the flow
velocity below 3m/s, by removing burrs after cutting tube to length , and by
ensuring that tube is correctly supported and clipped.
(111) How can a bib tap supplying water for a
garden hose be protected against back-siphonage?
Answer- By
installing a double-check-valve assembly into the pipe supplying the hose tap,
or by using a tap that incorporates a check-valve and vacuum breaker.
(112) Sketch a
section through a simple bottle-trap and identify clearly where the dimensions
of the trap seal are.
(113) List the
main advantages and disadvantages of the two pipe system of sanitary pipe work
over the one-pipe system.
Answer-
Advantages:-
-Less pipe work.
-Shorter installation time.
-Premises can be installed
separately.
Disadvantages:-
-
More pipe work used.
-
Longer installation time.
-
More maintenance.
(114) Describe
the problems associated with using plastic rainwater goods in countries with
very hot climates.
Answer- Due to
thermal movement which may cause
distortion or breakage of pipe work, gutters and fixings unless adequate
allowances for expansion and contraction are provided. Plastics are also
subject to degradation by excessive sunlight.
(115) Plastics are popular plumbing materials used
throughout the world because:
Answer-They are
relative cheap and easy to mass produce.
(116) Which type
of steel pipe is the most suitable for carrying cold water supplies and why ?
Answer-
Galvanized steel pipe is the most suitable steel for carrying cold water
supplies because it is resistant to corrosion and is relatively cheap and easy
to join.
(117) On a
screwed joint between steel pipes, where would you find the ‘washout’ thread
and why should it be found there?
Answer-The
‘Washout’ thread is the incomplete part of a thread formed by the dies to
enable them to start cutting into the pipe and should be clearly seen on the
pipe after a fitting has been screwed on to the pipe. If this incomplete thread
formed part of the joint inside the
fitting it may not form a watertight
joint.
(118) List the
main points to consider when installing thermoplastic pipes for domestic hot
and cold water supplies.
Answer- When
installing thermoplastic pipes for domestic hot and cold water supplies you
should consider the following:- allowances for expansion because of their high
expansion rate, secure sitting and fixing because of against degradation caused
by excessive sun-light / ultra-violet light.
(119) Why is
vitreous china a good material to use for the manufacture of sanitary
appliances?
Answer- Is good
material for the manufacture of sanitary appliances because it is
impervious to water and is easily molded before firing.
(120) (a)
Explain the uses of the following fittings. (National exams 2018)
(i) Saddle clamp.
(ii)
Bottle trap.
(iii)
Male connector.
(iv)
Coupling
(b)Name two(2) common types of pipe threads cutting.
(121) (a) Explain the differences between direct cold
water and indirect cold water supply system.
(b)
Name two(2) causes of water hammer.
(122) (a)List down five(5) principles of laying
drainage system.
(b)
State the purpose of water seal in the sanitary appliance fitted on the
drainage system.
(123)(a)What is the float ball valve?
(b)Mention five(5)types of float ball valves.
(c)Explain the uses of the following:-
(c)
Valve reseating tool.
(ii) Washer
cutter.
(iv)
Swaging tool.
(124) (a) Why UPVC pipes are mostly preferred in the
provision of drainage system. Give five(5) reasons.
(125)Explain four(4) conditions which influence the
construction of an inspection chamber in the drainage system layout.
(125)(a) What is a soft soldering?
(b)Describe four(4) rules for good soldering work.
(c)What is meant by Tinning copper?
(126) Mention different methods of cleaning a blocked
of the system.
Answer- By
using plunger.
-
(Mechanical equipment) By using Roding.
(127) (a) You have been given a chance to be a
construction Manager in Juma’s Company. Describe your six (6) main responsibilities.
(b) What is delegation.
(127) (a) Define the term Septic-tank.
(b)
Draw a septic tank and show the following :-
(i)
Baffle wall.
(ii)
Scum
(iii)
Influent
(iv)Sledge
(v)Inlet
(vi)Outlet
(c)The septic tank was constructed with height of 2M,
width 1.5 M and length of 2.7 M. Find the volume in liters.
(128) (a) Explain what measures you should take if
someone in the workshop gets an electrical shock.
(b)What safety rules you should address to your fellow
workers before using step ladders. List at least five.
(129) (a) What is the difference between PPE and OSHA
?
(b)
Mention seven (7) PPE necessary when working in a noisy and toxic fume
workshop.
(130) (a) State three(3) cost factors to be considered
when installing domestic hot water supply systems.
(b)
Explain:-
(i)
Direct hot water supply system.
(ii)
Indirect storage hot water supply system.
(c)What is an insulator as applied on the hot water
system.
(131) (a) What is Priming?
(b)Name two (2) types of reciprocating pump.
(c)What is a foot valve and where can it be fixed.
(132) (a) What is PH Scale ?
(b)
What do you understand by the following terms:-
(i)Base
exchanger
(ii)Chlorination.
(133) (a) Define the term boiler .
(b)
Describe how boiler works in heating system.
(134) (a) Briefly explain how it works the following
accessories in the boilers
(i)Thermostat
(ii)Thermostatic valve.
(b)Give four points to be observed in designing direct hot water
cylinder system.
(135)(a) What is solar water heater?
(b)
Solar water heater can operates in two different methods. Discuss how is done.
(136)(a) Why corrosion occur in hot water system?
(b)Outline any five causes of corrosion.
(137)(a)Briefly explain the term D.H.W supply system.
(b)
Sketch D.H.W supply system showing
primary return, secondary flow, cold feed.
(138) (a) Write short notes of the following:-
(i)
Instantaneous (ii)Storage heater (iii)Circular heater.
(b) Why
recommended during installation of gas pipe to meter they must be temporarily
disconnected.
(139)(a) Distinguish heat from temperature.
(b)Write
short notes of the following with examples.
(i)Sensible heat.
(ii) Latent
heat.
(140) (a) Why emphasized to group fixtures closely to
the hot water storage vessel?
(b) State five
points which causes insufficient hot water supply system.
(141) Why temperature setting for temporary hard water
the thermostat should be set at 60 centigrade and for soft water set at 71 centigrade.
(142) It has
been discovered that some employer don’t
consider the employees on issue of OHS and that’s a big problems.
Justify why fail to do so??
(120) List the
relative advantages and disadvantages of ceramic materials and stainless steel
for sanitary appliances.
Answer- Ceramics
materials Advantages:-
Strong, durable , relatively
inexpensive, good availability of raw materials making widespread manufacture
possible , resistant to most acids and alkalis, easy to mould ,easy to clean,
easy to fix.
Disadvantages:-
Can crack if subject to rough use, if
the glaze does not match the clay crazing may occur, can stain under certain
water conditions.
Answer- Stainless steel:
Light and easy to install,
will not crack or break easily, will not stain.
Disadvantages:
Relatively costly , manufacturing
methods and plant needed make its availability less widespread, can be noisy in
use
(121) How does a
stop tap prevent back-siphonage of water into the main supply?
Answer- Stop
taps prevent back-siphonage of water by having a loose valve which acts as a non-return valve
,facing it on to the seating in the event of back –flow , which stops water
flowing back into the main .
(122)Which tap, valve
or cock should be fitted on a low pressure cold water pipeline and why?
Answer- A gate
valve should be fitted on a low pressure cold water pipeline because it offers
little resistance to the flow. Most other taps would reduce the flow even
further.
(123) what is
the difference between the valves or jumpers in hot and cold water draw –off
taps?
Answer- The
valves on hot water draw-off taps are fixed and the valves on cold water draw-
off taps are loose.
(124) what flow
control device would create water hammer if fitted on a cold water main
pipeline?
Answer- A plug
cock fitted on a cold water mains pipeline inside a building would create water
hammer because of the rapid shutting-off action.
(125) describe
the operation of a Portsmouth ball valve.
Answer- As the
water flows through the orifice it falls into the cistern which slowly fills
with water. As the water raises so too does the ball float which connected to a
valve. As the water rises, the lever arm causes the valve to close against the
orifice, shutting the water off. If the water level drops, the
reverse will happen, letting water flow once more into the cistern.