Tektrak Potable Water Standard Operating Procedure “C”
Potable Water Super-Chlorination Procedure for merchant ships using Shipsan® or Sodium Hypochlorite
To be carried out at 12 monthly intervals or more frequently as required- super chlorination of potable water storage tanks and pipework (including hydrophore tank).
Whenever the potable water tanks and systems or any of their parts have been placed in service, repaired or replaced or have been contaminated, they must be cleaned and disinfected before returning to operation.
Cold Potable water storage tanks should be opened, emptied, ventilated and inspected for condition and cleanliness. The tanks should then be recoated if necessary and cleaned/disinfected. The cleaning process will involve adding SHIPSAN or an equivalent disinfectant SUCH as Sodium Hypochlorite to 50ppm and allowed to stand for a minimum of 1 hour. (at least 2 hours at 20ppm) The test should be carried out using the TEKTRAK free-chlorine High Range test procedure.
Shipsan® can be added at dilution of 1.25 litres/100litres of water to give a solution of 50ppm. Or, Sodium Hypochlorite can be added at a rate of (Typical example): To achieve 50ppm Chlorination – use 0.333ltrs of sodium hypochlorite per tonne. Please note that Sodium Hypochlorite can vary in strength dependent on the date of manufacture between 3 and 15 ppm. It has a fast depletion rate. Shipsan depletes very little in an unopened can.
Test frequently during the process (every 15 minutes), increase the amount of sodium hypochlorite as required to maintain at 50 ppm.
The tank should then be emptied and recharged with clean freshwater chlorinated to a minimum concentration of 0.2ppm free chlorine at the tap. This should be tested immediately and again after one day. A full water test should then be carried out. The procedure should be repeated if the PHA or independent lab report is not SATISFACTORY.
In addition all the potable water pipework system and (calorifiers) from machinery space to furthest outlets should be charged with Shipsan or Sodium Hypochlorite to 50ppm free chlorine for a period of 12 hours (using TEKTRAK free-chlorine HR test kit and then flushed out and refilled to a residual free chlorine level of 0.2ppm (using TEKTRAK standard chlorine test).
The procedure should not be carried out by untrained personnel. The procedure should be closely supervised. Crew should be warned that the water is heavily chlorinated in case of drinking and fumes. If the tanks contain excessive debris or scale then this concentration of debris should be pre-super-chlorinated prior to a second super-chlorination. Persons inspecting or working in freshwater tanks must wear clean protective clothing and footwear which has not been used for any other work area and they should not be suffering from any skin infection or communicable disease. Ensure that no Aerosol is produced at any stage of the cleaning or super-chlorination process..
Super-Chlorination cannot be carried out using Sodium Hypochlorite. However, it CAN be done using Shipsan® Please request a separate data sheet for this procedure. Spray method saves time, money and water.
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