RO Plants

Question 1

Give 6 uses of demin water

Answer 1

Gas turbine wash
Helicopter engine wash
Medical uses
WE cooling
Chilled water systems
Diesel coolant systems

Question 2

What are 6 uses of fresh water?

Answer 2

Drinking.
Upper decks wash down.
Laundry.
Bathrooms.
Galley.
Mess deck.
weapon magazine space.
Fuel seps

Question 3

What is the purpose of a conductivity meter?

Answer 3

To give a visual indication of the presence of salt in the sea and technical water of certain engine room machinery.

Question 4

Describe the working principle of a conductivity meter

Answer 4

Two electrodes placed at a predetermined distance apart in an uncontaminated feed water system.
Current is applied in series with a lamp. Fresh water being high resistance allows only a small current to flow, which is insufficient to burn the indicating lamps. Salt reduces resistance and allows current to flow, lighting up lamp.

Question 5

What factors affect current flow in conductivity meters?

Answer 5

Distance between electrodes.
The amount of salt in the water.
Temperature of the water.

Question 6

How are the probes cleaned on a conductivity meter?

Answer 6

Isolate electrical supply.
Disconnected probe.
Scrub using nylon brush (50:50 detergent : demin water).
Rinse thoroughly and refit.

Question 7

What is seawater purity?

Answer 7

Approximately 35000ppm

Question 8

What is water purity measured in?

Answer 8

PPM or TDS (Total dissolved solids)

Question 9

What is the standard and who sets them for the purity of drinking water?

Answer 9

WHO - 1500ppm max

Question 10

What purity is UK drinking water?

Answer 10

200 - 250ppm

Question 11

What are the purity standards for fresh water and demin water in the RN?

Answer 11

Fresh - 250-300ppm
Demin - 2.5-25ppm
Submarine Demin - <0.1ppm

Question 12

What should the chlorine level in a fresh water tank be?

Answer 12

0.8ppm

Question 13

What should the chlorine level at the tap be?

Answer 13

0.5ppm

Question 14

What should the concentration of chlorine be during super chlorination?

Answer 14

50ppm

Question 15

What is superchlorination?

Answer 15

The process of sterilising a FW system using an extremely high dose of chlorine.

Question 16

When should superchlorination take place?

Answer 16

On commissioning
After the cleaning / re-coating of a tank.
Whenever considered necessary to sterilise a tank or system.

Question 17

Describe how to carry out the portable water chlorine test.

Answer 17

Fill sample beaker to 25ml.
Snap glass test tube tip in water.
Water mixes with solution.
The presence of chlorine will discolour the sample within one minute.
It’s colour is compared with a chart to show chlorine content in water.

Question 18

What is the formula for determining the quantity of chlorine to be added to sterilise a tank.

Answer 18

D = C/1000 x 100/A x V

D - quantity of chlorine compound required in grams.
C - initial concentration of chlorine required (mg/ltr)
A - available percentage of chlorine in compound.
V - volume of water to be treated (Ltr)

Question 19

What steps are taken to avoid contamination and stagnation in water systems?

Answer 19

Swap tanks every 24 hours.
Aerators fitted to filling lines.
Chlorine via injection valves.
Non return valves prevent backwash of contamination.
Lockable sounding tube caps.
Leak off lines for recirculation.
Air escape tubes.
No dead legs.

Question 20

What temperature do calorifiers heat water to? Why no hotter?

Answer 20

66 degrees. Any hotter can cause scalding.

Question 21

How are temperature adjustments made on calorifiers?

Answer 21

Adjusting the bimetallic strip deflection using a screwdriver or appropriate tool in accordance with BRs.

Question 22

What are you looking for when inspecting plumbing?

Answer 22

Physical damage to systems caused by human neglect.
Vibration damage causing leaks.
Noise shorts.

Question 23

Define osmosis

Answer 23

A natural process where a solution of low concentration will flow through a semi permeable membrane to dilute a solution of high concentration. This will continue until equilibrium.

Question 24

Define reverse osmosis

Answer 24

Reversing the natural osmosis process by applying sufficient pressure to the salt solution. The level of pure water will increase, leaving a greater concentration of salt solution. This removes 90 - 99% of dissolved solids. Water must be chlorinated before drinking.

Question 25

Describe the boost pump

Answer 25

2.5 to 4.5 bar low pressure centrifugal pump. Fitted before the filters and draws suction from the sea inlet strainer.

Question 26

Describe the sand / bag filters.

Answer 26

Revoves large particulates down to 50 microns.

Question 27

Describe the anti scalant dosing pump

Answer 27

Reciprocating plunger pump connected to cartridge filters. Continually injects anti-scalant into feed water.