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IR-Drop Compensation
for Accurate Measurements in Any Environment
 The
new Model PR4500 Polarization Resistance
Monitor accurately determines polarization resistance
even in high resistance environments such as those encountered
in soil and concrete. - Unique IR-Drop Compensation technology
enables the independent measurement of the solution resistance,
permitting accurate and reliable corrosion rate measurements
even under very noisy (AC) conditions.
- The Model PR-4500 can extract a polarization
resistance measurement even under conditions in which the
solution resistance is significantly greater than the polarization
resistance.
The Model PR4500
employs a notebook computer for self-contained data acquisition
and analysis. The personal computer enhances the data analysis
capability of the instrument. The PR-4500 has the following
capabilities:
- Unique corrosion rate determinations
for concrete studies
- A special guard ring counter electrode
for concrete studies
- Linear regression analysis and graphical
analysis for extraction of maximum information from all
data
- On board intelligence for analyzing the
system’s stability so the quality of the data is maximized
- Automated data logging
- Menu-driven operation
The Model PR4500
Polarization Resistance Monitor has the versatility
to operate in your laboratory as well as in the field. It
adds these excellent qualities:
- Rugged, weather-proof case
- External line power, external 12 VDC power
source, or internal 2-hour battery operation
The Model PR4500
employs two different measurement techniques to determine
the actual polarization resistance at the corroding interface.
- A DC technique determines the total resistance,
including solution resistance as well as polarization resistance.
The instrument then uses an AC technique to measure the
solution resistance.
- At the AC measurement frequency utilized,
the double layer capacitance in parallel with the polarization
resistance, is an extremely low impedance and nullifies
the polarization resistance’s effect in the measurement.
The difference between the DC and AC measurement is the
true polarization resistance.
The user has the flexibility of determining
the initial potential for a scan and the scan rate.
The Model PR4500
will also perform multiple scans at programmed time intervals.
With the ability to take 999 scans at 22-day time intervals,
the Model PR4500 becomes an
automated, unattended data logger.
The quality of the measurement makes the Model
PR4500 an excellent tool in any application. The built-in
intelligence permits the instrument to assess the integrity
of the measurement by analyzing the reporting system stability;
the Model PR4500 quantifies
potential drift and noise. The user can then identify and
correct a problem prior to the collection of significant data.
A linear regression manipulation is performed
on the raw data. The instrument strives to obtain a regression
coefficient in excess of 0.975. The instrument also does a
post-test analysis of the data and will recommend a re-run
of the test if improved measurements can be made.
The Model PR4500
will automatically determine a new, initial potential and
voltage step size to enhance results further. The Model PR-4500
provides a permanent record of any error messages or overrides
that occurred during the test within the stored data file.
This permits the engineer to more carefully review and analyze
the data taken in the field.
For concrete studies, the new Model
PR-1200 Guard-Ring Counter Electrode ensures the most
accurate measurements possible. A separate guard ring counter
electrode surrounds the primary counter electrode. The guard
ring confines the primary counter electrode current to the
area below the electrode, thus enhancing the accuracy of corrosion
rate measurements.
The unique ability to measure and correct
for solution resistance errors extends the purview of instantaneous
corrosion rate measurements to high resistivity electrolytes
that were formerly amenable only to much slower measurement
techniques (e.g. weight loss and electrical resistance).
Some of the more important applications that
fall within the measurement capabilities of the PR4500 are:
Inherently high resistively
electrolytes
Thin film electrolytes
- atmospheric corrosion
- refinery overhead corrosion
- flue gas stack corrosion
Situations where scaling or fouling of
electrodes can occur
- oily water
- oil field brines
All the sophistication of the Model
PR4500 is programmed from only four major menu selections.
In less than an hour, you take good, quality data in your
laboratory or in a harsh environment. The Model
PR4500 can serve all your polarization resistance measurement
needs. The built in intelligence greatly minimizes errors
with the instrument and makes it possible for even novice
users to make good quality measurements.
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