Page 238 - Vessel Sanitation Program 2018 Operations Manual
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VSP 2018 Operations Manual
13.5 Disinfection Calculations for Water and Equipment
13.5.1 Introduction
POTABLE WATER systems and EQUIPMENT, SWIMMING POOLS, and
WHIRLPOOL SPAS on a vessel may need to be disinfected when there is a
possibility of CONTAMINATION and as a routine part of maintenance.
This annex provides tables for calculating the amount of chlorine to be used in
emergency chlorination of POTABLE WATER and for the routine
DISINFECTION of POTABLE WATER systems and EQUIPMENT,
SWIMMING POOLS, and WHIRLPOOL SPAS.
13.5.2 Water Chlorination
Tables 1 and 2 (Annex 13.5.4) are for calculating the amount of chlorine to be
used in the DISINFECTION of POTABLE WATER systems, SWIMMING
POOLS, and EQUIPMENT.
Amounts of chlorine compound shown in Table 1 are in GRAMS.
Amounts of chlorine compound shown in Table 2 are in KILOGRAMS.
The chlorine compound column in Tables 1 and 2 refers to the amount of
available chlorine in the compound as stated on the product label. Requirements
varying from those shown in the table—for example: metric tons of water,
available chlorine compounds, or final chlorine concentrations—may be
extrapolated.
For example, POTABLE WATER TANKS or fresh water tanks must be
superchlorinated to at least 50 MG/L (ppm) available chlorine when samples
taken from these tanks indicate potential CONTAMINATION with fecal
coliform bacteria.
The total amount of 70% chlorine compound required to obtain 50 MG/L (ppm)
in 166 metric tons of water is calculated in Example 1, which illustrates how to
use the tables.
Example 1. The capacity of a potable tank from which a coliform-positive
sample was obtained is 166 metric tons. The vessel has a compound on
board containing 70% available chlorine.
The amount of chlorine required for 50 ppm is determined as follows:
• Use the 70% chlorine compound columns in Table 1.
• Find the 70% row that corresponds to 100 metric tons of water.
• Follow this 70%/100 ton row across until you reach the “50 ppm”
column (7,150 grams).
• Do the same using the 50, 10, 5, and 1 metric ton columns to
Annex 13.5: Disinfection Calculations for Water and Equipment; 185
