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Options 7 - 25
Standard Turntable Power Washer v.
4
.0 The MART Corporation
4. Chemical Conductivity Controller
After you have determined an effective chemical concentration, as described in chapters
"Overview" and "Advanced Operations: Process-Control," you must monitor and
maintain that concentration to provide consistent cleaning performance.
The optional Chemical Conductivity Controller automatically monitors and maintains
chemical concentration by electronically measuring the (electrolytic) conductivity of the
cleaning solution. This is a useful technique for figuring out when to add more detergent
to a high-ionic strength cleaning solution such as those based on salts. ( Potassium
hydroxide, sodium hydroxide, or sodium metasilicate ) This is
not a useful technique for
monitoring high emulsifying cleaners that rely on surfactants for a significant part of the
cleaning mechanism.
Electrolytes are ionic compounds such as salts, acids, or bases. Added to water, or a
water-based (aqueous) solution, they increase its conductivity.
Conductivity is defined as the ability of a substance to conduct electric current. All
aqueous solutions conduct electricity to some degree. The addition of electrolytes
increases conductivity. Since conductive liquids consist of ionic compounds
(electrolytes) dissolved in water, more ions in the solution indicate higher conductivity.
In applications using very pure to very concentrated chemical solutions, a rising
conductivity reading indicates a generally increasing chemical concentration.
Thus, a simple electronic conductivity test can measure the makeup of a ionic solution
and indicate its approximate chemical concentration. Unfortunately, compounds other
than cleaning chemicals affect the conductivity of the solution (These compounds
include iron oxide (rust) and carbon, both commonly found in most washing
applications.) And some cleaning compounds are not conductive. Conductivity
measuring systems provide an
estimate of the strength of the chemical in the solution by
measuring the relative conductivity of the solution.
Conductivity is expressed in millionths of a Siemen: microSiemens/cm, or
m
S/cm. One
mS/cm equals 1000
m
S/cm.
Contact your chemical supplier for a chart of conductivity vs. concentration for your
chemical and to determine if conductivity measurement is an appropriate technique for
controlling the concentration of your solution.