4.1 FIGURE 4.1 below is a drawing of a device used in cold-water systems - NSC Civil Technology Civil Services - Question 4 - 2021 - Paper 1
Question 4
4.1 FIGURE 4.1 below is a drawing of a device used in cold-water systems. Study FIGURE 4.1 and answer the questions that follow.
4.1.1 Name the device in FIGURE 4.1... show full transcript
Worked Solution & Example Answer:4.1 FIGURE 4.1 below is a drawing of a device used in cold-water systems - NSC Civil Technology Civil Services - Question 4 - 2021 - Paper 1
Step 1
Name the device in FIGURE 4.1.
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Answer
The device in FIGURE 4.1 is a full-way valve.
Step 2
Identify parts A, B and C.
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Answer
A – Hand wheel/Wheel
B – Valve head
C – Valve body
Step 3
Explain the function of D if part D is turned anticlockwise.
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Answer
Part D will move upwards, the tapered gate will open, and the water will start to flow.
Step 4
Differentiate between a pillar tap and a bibcock by referring to the way in which it is installed to/on a sanitary fitment.
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A pillar tap is fitted to the sanitary fitment itself in a vertical position. In contrast, a bibcock is fitted to the pipework in the wall.
Step 5
Choose a description from COLUMN B that matches an item in COLUMN A.
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Answer
4.3.1 F, 4.3.2 G, 4.3.3 E, 4.3.4 H, 4.3.5 J, 4.3.6 C, 4.3.7 A, 4.3.8 B
Step 6
Identify the tool to be used in the following scenarios: 4.4.1
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Answer
Dumpy level
Step 7
Identify the tool to be used in the following scenarios: 4.4.2
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Answer
Centrifugal pump
Step 8
Identify the tool to be used in the following scenarios: 4.4.3
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Answer
Drain cleaning machine/Jetting machine
Step 9
Explain ONE method that can be used to limit the usage of the water closet by using an ordinary pot.
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Answer
Placing a bottle or solid object inside the cistern limits the volume of water used to fill the cistern.
Step 10
Name the device that prevents the water from inside a cistern.
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Ball valve/Flush valve/Floater valve
Step 11
Explain the function of A.
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A vacuum breaker allows air to enter the pipe when needed to prevent siphonage.
Step 12
Name the device that regulates the incoming water pressure at B.
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Answer
Pressure control valve
Step 13
Identify C.
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Answer
Stopcock/Full-way valve
Step 14
Is the water in pipe D HOT or COLD? Motivate your answer.
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Cold water enters at the bottom of the geyser and hot water will exit at the top of the geyser.
Step 15
Identify E.
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Answer
Drip tray
Step 16
Draw the SANS approved symbols for the following hot-water systems: 4.8.1
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Answer
B – Balancing device
Step 17
Draw the SANS approved symbols for the following hot-water systems: 4.8.2
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Answer
J – Pressure control valve
Step 18
Draw the SANS approved symbols for the following hot-water systems: 4.8.3
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Answer
PS – Pressure switch
Step 19
Predict what could be the cause if water splutters through the taps.
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Answer
The cause could be air trapped in the pipes.
Step 20
Explain how this fault can be prevented.
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Pipes shorter than 1 meter must be installed horizontally or with an upward slope in the direction of flow.
Step 21
State TWO precautionary methods to avoid an electrolytic reaction in a water system.
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Answer
Use the same type of material (metal) throughout a system.
Use a non-metallic coupler when joining copper to galvanized pipes.
Step 22
Name ONE type of acid that can be used to remove the galvanised layer on these sheets before soldering.
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Answer
Hydrochloric acid
Step 23
Give the scientific name of the white rust/corrosion that can occur when zinc is dissolved and removed from an alloy.
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