RO Plants Flashcards
Give 6 uses of demin water
Gas turbine wash
Helicopter engine wash
Medical uses
WE cooling
Chilled water systems
Diesel coolant systems
What are 6 uses of fresh water?
Drinking.
Upper decks wash down.
Laundry.
Bathrooms.
Galley.
Mess deck.
weapon magazine space.
Fuel seps
What is the purpose of a conductivity meter?
To give a visual indication of the presence of salt in the sea and technical water of certain engine room machinery.
Describe the working principle of a conductivity meter
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.
What factors affect current flow in conductivity meters?
Distance between electrodes.
The amount of salt in the water.
Temperature of the water.
How are the probes cleaned on a conductivity meter?
Isolate electrical supply.
Disconnected probe.
Scrub using nylon brush (50:50 detergent : demin water).
Rinse thoroughly and refit.
What is seawater purity?
Approximately 35000ppm
What is water purity measured in?
PPM or TDS (Total dissolved solids)
What is the standard and who sets them for the purity of drinking water?
WHO - 1500ppm max
What purity is UK drinking water?
200 - 250ppm
What are the purity standards for fresh water and demin water in the RN?
Fresh - 250-300ppm
Demin - 2.5-25ppm
Submarine Demin - <0.1ppm
What should the chlorine level in a fresh water tank be?
0.8ppm
What should the chlorine level at the tap be?
0.5ppm
What should the concentration of chlorine be during super chlorination?
50ppm
What is superchlorination?
The process of sterilising a FW system using an extremely high dose of chlorine.
When should superchlorination take place?
On commissioning
After the cleaning / re-coating of a tank.
Whenever considered necessary to sterilise a tank or system.
Describe how to carry out the portable water chlorine test.
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.
What is the formula for determining the quantity of chlorine to be added to sterilise a tank.
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)
What steps are taken to avoid contamination and stagnation in water systems?
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.
What temperature do calorifiers heat water to? Why no hotter?
66 degrees. Any hotter can cause scalding.
How are temperature adjustments made on calorifiers?
Adjusting the bimetallic strip deflection using a screwdriver or appropriate tool in accordance with BRs.
What are you looking for when inspecting plumbing?
Physical damage to systems caused by human neglect.
Vibration damage causing leaks.
Noise shorts.
Define osmosis
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.
Define reverse osmosis
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.
