Chilled water and water production

Question 1

what is chilled water used to provided cooling for?

Answer 1

• Weapons Systems
• Radars
• Ships Computer Systems
• Air Treatment Units (ATUs)

Question 2

What is the major difference between the components of the refrigeration plant and the chilled water plant?

Answer 2

The chilled water plant has a chiller in place of the evaporator

Question 3

What provides cooling water for the condenser and the motors?

Answer 3

Sea water pump

Question 4

what colour are fresh water hoses

Answer 4

Blue

Question 5

what are the uses of fresh water

Answer 5

Drinking
washing
cooking
cleaning

Question 6

what other services are provided by the fresh water system

Answer 6

Laundry
galley
showers and skinks
water heaters
medical use
bridge window washing
fresh water hose reals
machinery cooling

Question 7

What is osmoisis

Answer 7

osmosis is the transfer of pure water through a semi permeable membrane into pure water

Question 8

what is reverse osmosis

Answer 8

reverse osmosis is the transfer from salt water goes through a semi permeable membrane into pure water

Question 9

what are the measurements of water purity?

Answer 9

the measurement is TDS Total dissolved solids

the TDS of sea water is approximately 34,000ppm

the TDS of the water after desalination is between 250 to 300 ppm

approximately 80% of the supplied salt water is ejected

after the water has been desalinated water is called permeate or made water

the waste water after desalination is called concentrate

Question 10

what are the two stages of filtration in the reverse osmosis plant?

Answer 10

Bag filter which filters the water down to 60 microns
Two cartridge filters which filters down to 10 microns

Question 11

what kind of pump does the reverse osmosis plant have?

Answer 11

3 piston positive displacement pump at high pressure providing 65 bar.

Question 12

what do the cushion membranes have?

Answer 12

ultrasonically welded edges for salt water to pass through

Question 13

what does the anti scalant dosing unit prevent

Answer 13

this prevents the precipitation of calcium salts forming directly onto the membrane surfaces.

Question 14

what is added to the anti scalant dosing untit?

Answer 14

hypersperce and anti-scalant at the rate of 5ppm

Question 15

what is the CCV

Answer 15

concentration control valve

Question 16

what does the CCV do?

Answer 16

the CCV controls the back pressure of the sea water acting on the membrane cushions, by closing the valve the back pressure is increased and the amount of the permeate is increased therefor opening the valve reduces the back pressure and the amount of permeate is reduced.

Question 17

what chemical must the reverse osmosis plant not contain and why?

Answer 17

it must not contain chlorine as this can cause irreversible damage to the membranes.

Question 18

why is chlorine added after the water has passed through the membranes?

Answer 18

to kill off any harmful bacteria

Question 19

what level should the chlorine to water be and when should this be checked?

Answer 19

the chlorine should be at 0.2ppm and is checked daily and before embarkation.

Question 20

when should desalination not be done?

Answer 20

when the water is most likely contaminated such as harbours and estuaries.

Question 21

what are the 3 fresh water tests

Answer 21

1. CHEMets test kit (glass tube colour comparison and will show you how much chlorine is in the water.
2. Visual
3. Taste

Question 22

what hot water systems are used on board

Answer 22

Calorifiers are used to heat water on-board ship.

Question 23

why is an air eliminator important?

Answer 23

One symptom of air in the fresh water system is known as “water hammer” which is a loud and repetitive banging noise inside the pipes.