WSC 8820
is an exceptionally effective, concentrated
liquid scale and corrosion inhibitor. It is designed for use in a wide range of
open recirculating cooling water systems where clean, scale and deposit-free
surfaces are required for maximum system life and efficiency.
WSC 8820
accomplishes this with one easy to use product, without the need of the
synergistic use of a scale inhibitor.
WSC 8820
contains a special blend of anodic and cathodic corrosion inhibitors, designed
to inhibit corrosion of ferrous metals by creating a passivating barrier. A
specific inhibitor is included also to protect copper alloys from corrosion.
WSC 8820
is used for corrosion and scale control in systems with corrosive or high
scaling makeup water and system operating conditions.
DESCRIPTION
WSC 8820
contains no chromate, phosphate, polyphsphate or zinc. It is a blend of
molybdenum and dispersants designed to provide minimum environmental impact
while providing a highly effective corrosion control alternative.
WSC
8820 is very effective in high hardness, highly alkaline scaling waters. It
contains a proprietary blend of organic and polymeric sequestrants, penetrants
and dispersants to minimize system fouling from contaminants such as calcium,
silica, iron, sludge and organics. It also contains a unique blend of organic
and actives to corrosion sites.
WSC
8820 is very effective also in low hardness, low alkalinity corrosive
waters. It contains special filming ingredients to establish protective barriers
against corrosion on ferrous metal surfaces. It also contains special filming
ingredients to establish a protective barrier against corrosion and pitting on
both yellow metal and ferrous metal surfaces.
WSC 8820
is environmentally safe for discharge with the cooling system bleedoff.
The formulation contains no heavy metals, chromates, or other pollutants
requiring removal or treatment prior to discharge at normal usage rates.
Molybdate does not provide a nutrient
source as do many other corrosion inhibitors. This eliminates a food source
for algae and bacteria in the water system and makes control of microorganisms
easier at lower microbiocide dosage rages.
WSC
8820 may be used alone as a single product for control of corrosion in
systems where hardness and alkalinity does not pose a scaling problem, or in
high hardness and/or high alkalinity waters where higher cycles of concentration
and lower bleed rates are desired.
WSC
8820 offers superior corrosion protection for all metals typically found in
cooling water systems. The blend of cathodic and anodic inhibitors provides a
durable corrosion inhibitive film for maximum system protection and minimal
corrosion rates.
BENEFITS
·
WSC 8820
contains no
chromate, phosphate, polyphosphate or zinc.
·
WSC 8820
ANTIFOULANT properties maximize heat transfer, minimize under-deposit corrosion.
·
PROTECTS against galvanic
corrosion in mixed-metal systems.
·
EXCEPTIONALLY EFFECTIVE control of pitting of ferrous metals.
·
Controls corrosion
of both ferrous and non-ferrous metals. Protects most metals, including sweated
copper lines from corrosive attack.
·
Superior
corrosion inhibition.
·
Scale
control agent
·
Minimizes
heat-absorbing sludge and mineral scale deposits in system.
·
Remains effective
at skin
temperatures of 300o C and above.
·
Helps extend
equipment life.
·
Reduces maintenance
time and costs.
·
Does not affect
non-metallic materials in cooling systems.
·
Low toxicity,
easy to handle and apply.
·
EFFECTIVE corrosion control at
stability indices as high as 10.
·
CONVENIENT single-package
treatment for corrosion and fouling.
TECHNOLOGY BEHINDS
Open
recirculating cooling systems can include mild steel, galvanized steel,
stainless alloys, copper and copper alloys, and aluminum. These metals are
subject to a range of corrosion problems such as generalized corrosion, galvanic
attack, pitting, crevice attack and stress cracking
WSC 8820
is designed for systems using makeup water of
moderate hardness and alkalinity, and discharging to a city sewer or other
treatment plant.
Corrosion protection is provided through the
use of molybdate, phosphonate, and azole compounds which have been shown in
tests to be superior to most corrosion inhibitors available, and throughout a
broad pH range.
·
Corrosion
Inhibition
Sodium molybdate has been used for decades as
a substitute for chromates for the inhibition of corrosion in mild steels over a
wide range of pH. Molybdates have a very low toxicity and are less aggressive
oxidants toward organic additives that are often used in corrosion inhibiting
formulations. The protection of mild steel used in the construction of
air-conditioning cooling water and heating systems is a prime application.
Molybdate solutions protect against rusting of steel parts during machining, and
are used in water based hydraulic systems. It is also used as an additive in
automobile engine anti-freeze.
Molybdate, usually in the form of Sodium
Molybdate, is used as an anodic corrosion inhibitor in a number of aqueous
systems, such as cooling water treatments, and automobile anti-freeze/coolant
products.
Molybdate
(MoO4=) is a good
corrosion inhibitor for open systems because it neither reacts with oxygen nor
evaporates. Molybdate bonds tightly to metal atoms, especially in the presence
of dissolved oxygen. The tenacious molybdate-metal complex is continuous over
the entire surface and impervious to oxygen, so oxidative corrosion (rusting) is
inhibited.
In the
presence of nitrogen was found to enhance the formation of molybdate oxyanions.
These oxyanions deposited back onto the anode surfaces as insoluble salts formed
with iron cations released from the anion electrode. The increased formation of
oxyanions is postulated to be the result of deprotonation of electrolyte in
contact with the anion electrode, and a subsequent shift in pH to higher values.
In addition to acting as a kinetic barrier, the oxyanionic species act as an
electrostatic barrier to the ingress of the Cl- anions which cause pitting. So
WSC 8820 is particularly effective against pitting corrosion.
Molybdate inhibits steel, cast iron,
aluminium, copper, brass, cadmium and solder, and is usually used
synergistically with other corrosion inhibitors.
·
Yellow Metal Inhibitors
Control
of copper corrosion is critical. While copper and its alloys are quite corrosion
resistant, the impact of even low corrosion rates can be dramatic. When copper
corrodes, soluble copper ions plate out onto mild steel components.
When
this happens, the more inert copper metal becomes a “permanent” cathode on the
metal surface. At this point, the corrosion process, which had been spread over
the entire steel surface, now becomes localized and continues at an accelerated
rate. As this proceeds, instead of having a low general corrosion rate, high
local corrosion rates will be seen.
Azoles
are used to prevent the initial corrosion of copper alloys, as well as to
inhibit copper deposits on mild steel surfaces. MBT (mercaptobenzothiazole) used
in WSC 8820,
is effective inhibitor, and has been used for many years with good results.
In
contrast to precipitating agents, the nitrogen atoms in the azoles bond to the
copper metal via copper oxide molecules on the surface. The protective layer
that is formed enhances the natural corrosion resistance of copper and copper
alloys.
Polymers can distort the crystal growth of
the scale by disrupting the crystalline lattice which causes the hard dense
adherent nature of scales. With the inclusion of a relatively large, irregularly
shaped polymer in the crystalline lattice, scale does not develop or adhere to
surfaces where it could cause heat transfer problems.
The polymer prevents normal scale development
and disperses the more amorphorus material which may form. The effectiveness of
polymers in scale control has changed the nature of many cooling water treatment
programs by allowing high cycles and/or high pH conditions to be used.
DOSAGE
WSC 8820
dosages may vary somewhat according to operating conditions, but generally
50-125 ppm of WSC 8820 should be maintained in the system water. (This is
equivalent to about ˝ to 1 pint of WSC 8820 per 1000 gallons of water.)
This dosage should be tripled for a
two-week period when initiating treatment, whenever the system is refilled with
fresh water, and after any major system upsets, in order to establish effective
corrosion control.
If the stability index of the recirculated
water is higher than 10.5, an alkalinity booster such soda ash should be fed to
reduce the index to less than 10.5.
WSC 8820
should not be used when the stability index of the system water is below 3.0.
WSC 8820
is controlled by a molybdate test which provides easy and accurate control
readings. Maintain 2 to 5 ppm MoO4= at all times.
FEEDING
WSC 8820
must be fed continuously to the system by a positive displacement chemical
feeder. For maximum results, feed should be linked to makeup of bleedoff through
the use of a flowmeter or conductivity controller.
Your Water Services Ltd representative is
available to give recommendations on the application, monitoring, and control of
this product for optimum results.
HANDLING
WSC
8170
is relatively mild material, avoid contact with eyes and skin, should contact
occur, flush with water. If discomfort persists, seek medical attention. Do not
take I
nternally. Do not freeze, Store at moderate temperature. Keep container closed.
Read
Material Safety Data Sheet for detailed handling and storage precautions.
TECHNICAL
ASSISTANCE
Our
technical staff is available to assist in the application of Water Services Ltd
products. You may request assistance through your sales representative or by
contacting Water Services Ltd at +30 210 63 94 739.
USDA
WSC 8820 is acceptable for treatment of cooling and retort water in official
establishments operating under the Federal meat and poultry products inspection
programs.
This product is USDA G7.
OTHER
REMARKS
Improper application of
this product will result in insufficient protection and/or potential damage to
the system being treated. Please follow the recommendations of your Water
Services Ltd representative.
