FW & RO Flashcards
(44 cards)
() 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
