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Features
·
Guaranteed Longest Lasting
Sensors Available with performance guarantee *
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Sensors are compatible with most
existing pH/ORP Meters, Transmitters & Analyzers **
·
Application Specific Engineering
results in optimum Lifetime & Performance ***
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Integrated Temperature
Compensation, Preamplifiers & Solution Ground Elements
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Solid State Reference System offers superior resistance to Fouling
& Dehydration
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Applications such as Acid/Fluoride,
Hi-Temp, Saturated Sodium and Sulfide Resistant are available as standard
options
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Custom Applications are available,
often at no additional charge
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Most Installation Styles are
Supported Including: Immersion, Twist Lock, Valve Retractable
& Sanitary
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Available in a wide range of plastics,
from cost effective CPVC to thermally & chemically resilient ULTEM®
and PEEK thermoplastic
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High Pressure Applications up to
100 psi for Valve Retractable & 150 psi for Inline Installations can be
supported for continuous use
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Operating Temperatures from -30
to +150 ºC (-22 to +302 ºF) can be supported
for continuous use
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Case Study No. 12 –
pH Control in Chlor-Alkali Manufacturing
Saturated Sodium &
Dissolved Gas Resistant pH Sensors
Saturated Sodium Resistant pH
glass element and Dissolved Gas Resistant Solid State Polymer Reference
System are specifically engineered for Chlor-Alkali and functionally similar
Process Applications
High Quality PEEK plastic is not
damaged by presence of dissolved oxidizing gases such as chlorine and
chlorine dioxide
Vastly superior lifetime due to
custom engineering and component selection
Offered at very competitive
prices as compared with other more generic sensors
Ability to integrate requires
electronic components means that these sensors can be retrofitted into almost
any existing installation and mate with most process pH instrumentation
The Problem
A chlorine dioxide (bleach)
manufacturing company wanted to improve their pH control, reduce sensor
replacement and minimize maintenance time. Corrosive ClO2 dissolved
gas was causing frequent sensor failure at the reference half cell, resulting
in constant drift and eventually sensor removal. The saturated brine
solution caused problems for many pH glass formulations, resulting in large
offset errors from standard calibrations.
The stray current, something
that can occur frequently in many chlor-alkali processes, caused problems for
the silver/silver chloride half cell inside the pH and reference elements,
resulting in early expiration of the sensor. Since instrumentation was
widely standardized throughout the plant, changing out the pH instrumentation
would be very cost prohibitive. Most pH sensor manufacturers require
customers to use their make of transmitters and do not retrofit existing pH
instrumentation.
The Solution
The solution to these
manifold problems was complicated. The thermoplastic PEEK was employed due
to its excellent resistance to dissolved oxidizing gases and strong
electrolyte solutions. A truly saturated sodium resistant glass was selected
to improve measurement accuracy. The pH element was fabricated so as to be
hysteresis resistant to minimize the effect of stray electrical current. A
triple junction reference system was employed in addition to a dissolved gas
resistant solid state polymer reference junction.
The suitable electronic
components were selected to directly retrofit with the existing transmitters,
saving the customer the cost replacing their existing pH instruments. All of
these improvements were provided at a price that was quite competitive to the
previous pH sensors used. The sensor lifetime was more than doubled from
previous pH sensors.
The pH Sensor Used:
Model: PNCTJHR 6141/6941-3000-20 pH Sensor
Description: ¾”-1” MNPT Immersion PEEK Bodied High Temperature, Saturated
Sodium and Hysteresis Resistant pH Sensor with Triple Junction Reference
System; integrated with Balco 3K Temperature Element; 20 feet cable to
connect directly to TBI Analyzer/Transmitter
Choosing the Correct pH/ORP
Sensor
1.
Choose a sensor body type that
suits the physical parameters of the
installation (refer to the Configurations
Portion of pH/ORP and Ion Selective webpages).
2. Choose
a sensor that suits the process application, temperature,
chemistry, and physical
parameters of the installation (refer to Sensor Selection Guides
and call factory or local sales agent for support)
3. Choose a sensor housing material that is compatible
with the process chemistry, temperature & pressure (refer
to Chemical Resistance Charts as posted under the Technical
Documents portion of the website).
4.
Select suitable temperature compensation element, solution
ground & integrated preamplifier based upon the mating pH/ORP Instrument (refer to Electrochemical Instrumentation
Page & ask for factory support).
5.
Specify the required
cable length based
upon installation
location (refer
to Part Numbering Guide).
*
Subject to application qualification and review by an approved ASTI sales
agent and/or factory. Performance guarantee is posted on the ASTI online
application questionnaire page.
**
See list of supported pH/ORP/ISE Instruments webpages as posted on the ASTI website.
***
Completion of Application Questionnaire form is required. Other restrictions
may apply.
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