PRODUCT INFORMATION
INDEX
DATE
Dep. 2
IO-C-M-20-001e D
February 2016
COOLING WATER QUALITY AND TREATMENT
6/6
3. COOLANT TREATMENT
Maintaining cooling water in good condition will avoid the aforementioned trouble with and failure of the cooling
system, as well as helping us to detect possible engine malfunction.
For instance, a decrease of the pH value together with an increase in the sulphate contents may be symptomatic of
water pollution by exhaust gases. On the other hand, a rise in chloride contents may be due to contamination by
seawater, and in this event, it would be advisable to inspect the engine and look for the source of the leak.
In closed circuits, where fluid refilling is infrequent, a complete corrective treatment can be applied initially, while
cooling water properties can be checked subsequently on refilling large amounts of water, but at least once a year.
It is advisable to clean the engine cooling circuit as described below:
Prepare a concentrated detergent solution (for cooling circuits) in warm fresh water (40-50°C) and shake until
the detergent is completely dissolved and there is no sediment. The maximum concentration should be 2%.
Insert said solution into the engine cooling circuit and start the engine up until it is hot. The engine must be
operating at full load for approximately two hours. Once this time has elapsed, stop the engine.
Then clean the cleaning fluid using fresh water. Once rinsed and clean, immediately fill the water circuit with
treated antifreeze.
In open systems that operate on large volumes of water, water treatment is very expensive. Input treatments are
usual practice or, if the installation allows, chemical cleaning will be undertaken periodically. For this type of system,
water tests must be made at least once a month, both at the cooling tower and in the water circuit to the engine.
Companies specialising in water analysis and treatment have test kits available so users can check the cooling
system periodically.
If the results of periodic checks fail to match the values shown in Table 1, the customer must contact the water
treatment specialist, who has to participate actively in preparing and in defining the protection method most suitable
for the installation concerned.
Antifreeze decomposes into corrosive acids due to the cooling system's temperature cycles; contamination can
build up in the system and the corrosion inhibitors will eventually get exhausted. It is therefore recommended
that the antifreeze concentration in the system should be checked with a refractometer or hydrometer when
testing the water quality. This will aid to ensure that the glycol concentration remains within adequate limits. By
measuring the coolant density as shown below, you can determine whether the antifreeze concentration is
correct:
Glycol Concentration % weight
Coolant density @ 20ºC
Freezing point of coolant
10%
1.02 g/l
-3.4 ºC
20%
1.03 g/l
-7.9 ºC
30%
1.04 g/l
-13.7 ºC
40%
1.06 g/l
-23.5 ºC
50%
1.07 g/l
-36.8 ºC
4.1.10
O&M_2.002211.810_A_10_2016
