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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

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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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Answer

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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Answer

Ball valve/Flush valve/Floater valve

Step 11

Explain the function of A.

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Answer

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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Answer

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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B – Balancing device

Step 17

Draw the SANS approved symbols for the following hot-water systems: 4.8.2

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J – Pressure control valve

Step 18

Draw the SANS approved symbols for the following hot-water systems: 4.8.3

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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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Answer

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

  1. Use the same type of material (metal) throughout a system.
  2. 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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Answer

White rust is known as zinc oxide.

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