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Mech theory 4 Refrigeration, ventilation, hydraulics and fresh water > Fresh water > Flashcards

Fresh water Flashcards

1
Q

State the uses of fresh water.

A
  1. Drinking
  2. Washing
  3. Cooking
  4. Cleaning
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2
Q

What services are provided by the fresh water system?

A
  1. Laundries
  2. Galleys
  3. Showers and sinks
  4. Water heaters
  5. Medical use
  6. bridge window washers
  7. Fresh water hose reels
  8. Machinery cooling
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3
Q

What is osmosis?

A

The transfer of pure water through a semi-permeable membrane into salt water.

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4
Q

What is reverse osmosis?

A

Is the transfer of water from salt water through a semi-permeable membrane into pure water.

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5
Q

Define TDS

A

Total dissolved solids

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6
Q

What is TDS the measurement of?

A

The measurement of water purity

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7
Q

What is the TDS of sea water?

A

34,000ppm

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8
Q

What is the TDS of water after desalination?

A

Between 250 and 300ppm

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9
Q

What percentage of sea water is ejected after fresh water is produced?

A

80%

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10
Q

What is desalinated water called?

A

Permeate or made water.

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11
Q

What is the waste water called after desalination?

A

Concentrate

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12
Q

What does CCV stand for?

A

Concentration control valve.

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13
Q

What happens if the CCV is closed?

A

Back pressure increases and permeate production increases.

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14
Q

What happens if the CCV is opened?

A

Back pressure is reduced and permeate production is reduced.

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15
Q

What will happen to the RO plant if the water passing through it contains too much chlorine.

A

Chlorine will cause irreversible damage to the membranes.

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16
Q

How are the cushion membranes joined together at the edge?

A

Using ultrasonic welding

17
Q

What is the pressure of the water supplied by the piston pump in the RO plant?

A

65 bar

18
Q

What does the bag filter in the first stage of filtration within the RO plant filter down to?

A

60 microns

19
Q

What does the bank of cartridge filters in the second stage of filtration within the RO plant filter down to?

A

10 microns

20
Q

Why is chlorine added to the permeate?

A

To kill off any harmful bacteria.

21
Q

How often are chlorine levels checked in the fresh water tanks?

A

Daily and before embarkation.

22
Q

What level are chlorine levels maintained at?

A

0.2ppm

23
Q

Who authorises and supervises the addition of chlorine?

A

The section head

24
Q

State the 3 fresh water tests that are carried out?

A
  1. CHEMets
  2. Visual
  3. Taste
25
Q

How often is fresh water testing carried out?

A

Daily and prior to embarking

26
Q

What is used to heat water on board ?

A

Calorifiers

27
Q

What causes a ‘‘water hammer’’?

A

Air in the fresh water system

28
Q

What colour are fresh water hoses?

A

Blue

29
Q

What should be done to the fresh water hoses before they are used?

A

They should be flushed with fresh water.

Mech theory 4 Refrigeration, ventilation, hydraulics and fresh water (3 decks)

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