FW & RO Flashcards
() What are the issues that potable water management are concerned with
- Water requirement
- Identification of potential contamination
- health risk assessment
- Implementation and monitoring of effective control strategies and procedures
BRd 820 Chapter 2
() List the potential hazards which can contaminate a FW supply
- bacteria
- viruses
- Protozoa
- Helminths
- chemicals
- Radioactivity
() List and four essential services that would continue to be supplied with FW
Medical and dental spaces
Galleys and associated space
Drinking water coolers
Bridge window sprays
() How is the control of legionella maintained
Regular cleaning of shower heads and tap fittings
Shower heads flexible hoses are soaked in 50mg/l solution of chlorine for 1hr every 6 months
() Briefly list when and how to carry out a FW tank clean
Indicated in the hull maintenance schedule .
Physically fit
All ppe to be clean
Wash tanks with clean water
use clean cloths and scrubbing brushes.
Pump dirty water overboard.
Rinse tank thoroughly with fresh clean water and pump out.
Wipe down and dry the tank.
On completion, before closing tanks, tanks must be inspected by ME SR.
After cleaning, tanks must be sterilised by super chlorination before discharging to waste and topping up with chlorinated water for use.
() Why is chemical cleaning necessary
Removes and reduces fouling from mebranes
() State the chemicals used and their purpose for cleaning
Cleaner A - sodium hydroxide - used for organic sedimentation and fouling
Cleaner C - citric acid - used for iron/scale fouling
Cleaner D - membrane biocide - disinfectant
() When is a chemical clean required
Whenever normalised permeate flow drops below 10%
() What is the role of institute of naval Medicine (INM)
Reference authority for potable water standards
Sample testing
() State two hazards and list the safety precautions associated with them
High voltage - isolate before any work - correct ‘TAG OUT’ procedure
High Pressure - shut down before any work - check security of all fittings and fastenings
() When are FW tanks inspected
regular intervals in accordance with PM schedules
() State position and operating ranges for low pressure trip
between cartridge filter and HP pump
1bar
() State position and operating ranges for the 3 high pressure trips
Relief valve - between HP pump and pulsation dampener - 69 bar
HP trip - between pulsation dampener and first membrane - 69 bar
Permeate trip - between rehardener filter and chlorine injection - more than 3 bar
What is the chemical compound for chlorination
Calcium hypochlorite
What is the solution strength for normal chlorination
0.8mg/L(ppm) in tanks
0.5mg/L(ppm) at point of use
State and describe the formula used to determine the amount of chlorine required
D = c/1000 x 100/A x V
D = quantity of chlorine compound required in grams
C = initial concentration of chlorine required
A = available percentage of chlorine in compound
V = Volume of water to be treated in Litres
When is it necessary to carry out a detailed investigation of FW system
- Failure of a routine bacteriological or chemical water sample
- Illness or medical conditions, where water is suspected as the cause of infection or chemical contamination suspected
- Suspicion of contamination of the ships water supply due to faults occurring in tanks or distribution system
- The procurement of supplies from a previously untested source
State and briefly explain the effective risk control methods
Engineering controls - removal systems such as filtration. RO or evaporation plant
Potable water filtration unit - if significant risk from gut parasites in port water
Chemical controls - used to disinfect potable water storage and distribution systems
Avoidance - alternative sources such as bottled water
Name those personnel to be informed prior to embarking FW from ashore outside the UK and state the responsibilities of each
CO - provision of potable water
MEO - operation and maintenance of all collection, storage, treatment and distribution equipment
Medical Officer - any ME staff suffering with infectious disease or condition are excluded from fresh water duties
State 6 steps of the risk management matrix for the ships FW supplied
Potential hazards
Hazard identification
Risk assessment
Risk control methods
Monitoring
Review
Name two sources where information can be gathered as part of the risk management algorithm
NATO sources
Port guides
Port Agent
British consulate
State how super chlorination is achieved
Adding 50mg/L(ppm) chlorine to each ton of water and allowed to remain for 12 hrs but not less than 4 hours.
When is super chlorination carried out
Due to contamination or necessary sterilise
After refits or commissioning
After cleaning
Every 12 months
What equipment is available to filter out chlorine resistant parasites
FWEU - fresh water embarkation unit
Who would normally authorise release of FWEU when not held
FOMO (fleet operations and maintenance officer)
How is the equipment preserved when not in use
What is the role played by the Navel Environmental Health Officer (NEHO)
Check the fresh water supply and distribution system
Name 4 of the test equipment and briefly describe what it monitors (ref FW purity)
SDI kit - measures particulate and colloid
Chemets K2500 - measures amount of chlorine in water
Lovibond 200 chlorine Comparator
Lovibond Hardness Test - test amount of minerals in fresh water
Explain the responsibility the MEO has for ensuring
Appropriate number of fresh water samples are collected
Make sure results are to be recorded in the ME logistics log
Maintenance and use of fresh water equipment
Why is there a requirement for potable water sampling and testing
Assuring that fresh water management maintains the required high standards for water quality
Name the different types of water sampling and testing and frequency of each test
Bacterial contamination - 4 times a year
Chemical contamination - every 12 months
Where are the results of testing recorded
ME Logistics Log
Name the factors and give an example of information that should be taken into account for each (ref to conducting risk ass)
Population at risk - higher risk if larger number are consuming water
Medical information - info for operations, exercises and deployments
Geographical factors - climate, topography, flora, fauna
Epidemic and endemic diseases - types and prevalence of disease, local measures
Special environmental and occupational hazards - radiation hazards, industrial hazards
Exposure
Local history
State 6 tests which can be conduced using the water test kit (WTK) when in an NBC environment
Arsenic
Pesticide/Nerve agent
Mustard gas
Color
TDS
PH
Chemiluminescence
Describe how the conductivity meter operates
Two electrodes at a set distance apart
Current applied at the positive side
If fluid has electrolytes in the current will flow to the negative side
Completing the circuit
Indicating the quality level
Describe the purpose, benefit and typical hardness expected when carrying out the Lovibond hardness test
Test the amount of minerals in the fresh water
Minerals help to reduce erosion of tanks and pipework
Typical is 40-80mg/L
Briefly explain the potential problems encountered and list the actions to be taken
Silk
Run one plant
Cease during periods of tide
Suggest moving ship during breaks in operation (deep water/max water production)
If you remain where you are, ensure command are fully aware of risks
Chemically clean your plants or replace membranes
Additional filters and extra chlorine
Where are the samples taken and the official guidance found
Taken after cartridge filters
BRd 820 chap 4 Annex A/B
Silt density index test
Correct pressure
Normal amount of sample calculated at each test
Size of the filter pores
At what intervals are the samples normally collected
After measuring of the sample, what is recorded
2.07 barg / 13psi
500ml
0.45micron
5, 10, 15min
Time taken to collect 500ml
Reject control valve
Flow meter
Boost pump
State the function
State where they are fitted
And operating parameters
Reject control valve - maintains pressure in system, react to high saline content - after membrane - operation up to 65bar
Flow meter - indication of the permeate flow - after the membrane but before conducting meter - L per hour
Boost pump - delivers feed water - between sea and bag filter - 2.5 to 4.5bar
What problems can be encountered due to slippage in water quality
Bacterial and viral infections - compromise operational capabilities
Chemical contamination - can lead to poisoning off the ships company
Explain how FW tanks are constructed
Arranged so that air pockets will not form
Man holes fitted weigh coatings and water tight covers
Ladders, popes strum and aerators are not coated
Tanks are unpainted and made from galvanised carbon steel
Only supply and suction FW pipes are to run through the tank
State the function
Where fitted
and operating parameters
Cartridge filter - filters 10microns or more in size - after bag filter and before LP trip - 2.5bar
De-acidification filter - (dolomite filter) change PH to avoid corrosion damage - after conductivity meter - ph 6.5 - 6.8
HP pump -delivers feed to the DT modules - between LP trip and pulsation dampener - 69bar
State the function
Where fitted
and operating parameters
Bag filter - filters 50micron or more - between boost pump and cartridge filter - 2 to 2.5bar
Conductivity sensor - measures salinity & contaminants - between flow meter and de-acidification filter
Pulsation dampener - - smoothens out pulsations - after HP pump - 30 bar
