Water quality management systems and treatment are so important for the plastics industry. Learn what an industrial water system can do for your company.

1. Benefit from
Improved Water
Quality Management

2. Water is called the “universal solvent” because it
will dissolve to some degree anything that it comes
in contact with.

3. Prolong your plant’s equipment and maximize productivity by
maintaining good water quality.

4. Water contains various
concentrations of dissolved
minerals, salts, metals and gases.

5. Water may also carry; suspended
rust (iron oxide), airborne matter
(silica based), product fines
(such as PVC dust) and
microbiological matter (MB)

6. Microbiological
matter is often
undetectable to
the eye and
unless
sterilized, it
will be present
in all water.

7. If allowed to grow, it can form slime & algae masses in any
systems.

8. Sources of Water

9. Runoff water
Lake water
Well water
Sources of Water

10. Runoff Water
Originates from rainwater runoff into streams and lakes and is usually very
soft and has low pH.
Runoff water doesn’t have the contact time to dissolve mineral scale, the lack
of hardness tends to make it more corrosive. Its purity leads to high cycles of
concentrations in cooling water systems and efficient use of water and
chemicals.

11. Lake Water
Lake water (Great Lakes and St Lawrence River): is a combination of
spring-fed, runoff rainwater and water from river sources and results in
water of moderate hardness and alkalinity levels.
This makes for good cycles of concentrations and good water and
chemical use. Softening is not normally necessary for cooling tower
systems with a proper chemical program, and when not sending
cooling tower water to areas of high temperature.

12. Well Water
It is usually very hard and alkaline.
When used as cooling tower makeup water the cooling system
must run with limited cycles of concentrations resulting in high
water and chemical use, the water is treated by softening or pH
modification through the addition of acid.

13. Basic Terminology

14. Basic Terminology
pH
Temperature
Corrosion
Scale Corrosion Index
Impurity
Hardness
Scale Formation
Suspended Solids

15. pH
A numerical value between 1 and 14
represents the chemical balance
between acidity and alkalinity in water.
City water sources normally vary in pH
between 6.8 and 8. Great Lakes and St.
Lawrence River water pH levels are 7.5
- 7.8 which makes the water slightly
corrosive and practically non-scaling
under most temperatures.

16. Temperature
Temperature (F) is one of the most important factors
affecting one of the most common problems in water
systems - the formation of hardness scale.
Scale formation (Lime) preferentially occurs on hot heat
exchanger surfaces. Higher temperatures will also
increase the rate of corrosion.

17. Corrosion
Corrosion is a chemical or
electrochemical degradation process of
metal surfaces. The purer the water, the
more corrosive the water becomes.

18. Corrosion Example
Deionised water is the most corrosive,
followed by reverse osmosis water, softened
water, city water, and finally cooling tower
water. In general, corrosion will decrease as
the pH increases and becomes more alkaline.
Iron will show minimal corrosion at a pH of
8.3 and above in untreated waters.

19. Scale/ Corrosion Index
Scaling and corrosion exist in a balance that
can be affected by pH, temperature, alkalinity,
total suspended solids and total hardness. A
common method of expressing this balance is
in terms of a Langelier Saturation Index. (LSI)

20. Scale/ Corrosion Index Example
St. Lawrence and Great Lakes water have a
slightly positive LSI and can easily be treated
chemically in closed systems. When used in
cooling systems the LSI increases as
impurities build up. Chemical management
programs normally keep the LSI below +3
before any problems of scaling occur.

21. Impurity Concentration
Higher concentrations of impurities in
combination with other factors of
temperature, flow, pH and alkalinity will
combine to cause problems of deposition
of suspended solids, microbiological
fouling and scale formation.

22. Total Hardness
Total hardness is expressed in terms of
ppm of Ca++ and Mg++. Under positive LSI
conditions (high pH, alkalinity,
temperature, and total dissolved solids)
these cations will combine with carbonate
and bicarbonate alkalinity to form scale
on the hottest heat transfer surfaces on
any water system.

23. Scale Formation
Scale formation occurs in direct
proportion to temperature and will
reduce heat transfer in areas where it
is needed most - molds, high
temperature hydraulic oil exchangers,
TCU’s and barrel heat exchangers.

24. Suspended Solids
Airborne dirt and dust can be drawn
into a tower and cause problems of
deposition and fouling, especially in
heat exchangers. Corrosion products
and microbiological growth from the
water system can also combine and
settle in areas of low flow.

25. Deposition
Is the natural result of
over-concentrating suspended solids
and tends to occur on hot heat
transfer surfaces and in areas of low
flow, especially in areas of changing
flow. Deposition will reduce both flow
and heat transfer.

26. Types of Industrial Water Systems

27. Open loop system
Closed loop system
Closed systems
Open cooling systems
System bleed-off
Types of Industrial Water Systems

28. Open Loop Systems
Dynamic systems that require a continuous addition
of water to make-up for losses due to evaporation
and bleed-off.

29. Open Loop Systems Example
A cooling tower system relies on evaporation for
cooling. With evaporation, all impurities (anions and
cations) remain behind and concentrate several
times. The amount of solids in the water can be
limited by bleeding off the dirty water. Clean city
water is then required to make-up for losses.

30. Closed Loop Systems
No evaporation occurs and apart from some
controlled water losses when molds are changed,
no make-up water is required. In this case, the
chemistry of this water is identical to city water.
Impurities in closed systems will not normally
concentrate unless corrosion is active and adding
suspended iron to the system.

31. Closed Systems
Chilled and Hot Water Heating Systems:
Closed systems do not have the evaporation
process that increases the impurity levels that are
found in open cooling water systems. The LSI in
closed water systems will remain below scaling
levels, even under higher temperatures. This is the
preferred water system for mold cooling.

32. Open Cooling Systems
Cooling Towers:
Chemicals are best fed continuously in proportion to
make-up and will vary according to the actual load
on the system. A contact meter, on the city water
make-up, controls the chemical feed of scale and
corrosion inhibitors. As the system works harder,
more water is evaporated; more make-up water is
required which feeds more chemicals.

33. System Bleed-off
This is a way of de-concentrating dirty tower water.
The amount of bleed-off should also vary in
proportion to the load in the system. This will keep the
chemical levels constant in the system.

34. Conductivity is a measurement of
the amount of total dissolved solids in a
system. As the load and evaporation
increases, the water becomes saturated
with impurities which will increase the
water conductivity. A probe continuously
monitors the conductivity of the water. As
water evaporates, the conductivity rises
above a pre-set level and a bleed-off
solenoid valve will open to discharge a
controlled amount of cooling tower water
to the sewer.

35. The prevention of MB growth in
a cooling system is handled by
biocides. These products are to
be shot-fed to a system for
maximum impact and fed on an
alternating basis with the second
dissimilar biocide.

36. Tests for scale and corrosion, chemical
levels, conductivity, MB counts and
daily records of makeup water
readings will ensure good
control over a cooling
water treatment.

37. In general, cycles of concentration in a cooling
tower system for The Great Lakes and the St.
Lawrence River are kept around 3.5, assuming the
suspended solids do not exceed 50 ppm. This
controlled approach by bleed-off and chemical
treatment will minimize water use and maximize
chemical efficiency.

38. No matter what type of chilling system your plant
is equipped with, understanding the water in an
industrial system and applying appropriate
chemical water treatment is absolutely
necessary. Your plant’s productivity and the life of
your equipment depend on it.

39. For more information, Contact BERG
416.755.2221
bergsales@berg-group.com
www.berg-group.com