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Features
·
Guaranteed Longest Lasting
Sensors Available with performance guarantee *
·
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. 3 – pH
Control in NOx Treatment Systems
NOx Treatment
System and pH Sensors for High Nitric Low Process Media
High Acid – Wide Range pH
Sensor for aggressive acid media
Deep Insertion Distance from Hardware
Interface Point
Retrofit to Existing pH
Transmitter for cost savings
The Problem
A
catalyst manufacturer, in order to prevent the pollution of the atmosphere
through the byproduct of its process, had to eliminate nitrogen oxides (NOx).
The process requires the monitoring of the pH value, because the process acid
has to be neutralized. Depending upon the hold on the environmental system,
the pH could range from value of 2.0 to -0.3 (well over two Molar nitric
acid). The oscillation in pH values depending upon system load and the
necessity for measurement at very low pH values caused problems for the
previously used pH sensors both in terms of drift and accuracy. The tank
configuration presented a logistical problem due to the small 1¼” MNPT process
connection suitable for 1.0” O.D. sensors when used with 1.0” compression
fitting. The process solution was more than sixty inches away from the
hardware installation point.
One
of the other major problems with this installation was the build up of precipitation
on the reference element, necessitating frequent cleaning and recalibration.
In addition, the tank would sometimes have reduced solution volumes that
resulted in the sensor being left exposed to only air for extended periods of
time. Due to the mounting configuration and thus required overall sensor
length, removal and insertion of the previously used sensor was quite time
consuming and cumbersome. The maintenance and short lifetime of the sensor
reduced the plant’s process efficiency and profitability.
The Solution
Many specialized options
from our sensor line were required to solve the various application problems.
A high acid resistant, wide range pH glass element was employed in
combination with a solid state conductive polymer reference junction. This
improved measurement accuracy greatly. The use of a solid state reference
system made pH sensor much more resistant to dehydration, minimizing the
effect of prolonged exposures to only air at various times during its service
life. The long insertion distance was accomplished by utilizing a 1.0”
compression fitting together with a 1.0” O.D. sixty inch long 316 stainless
steel insertion tube.
The solid state reference
system enabled both aggressive mechanical and chemical cleaning methods to be
employed when required, and reduce the overall necessity for maintenance time
due to reduced cleaning requirements. Due to the sensor’s stability and
reproducible slope, only one point grab sample performed remotely using a grab
sample from process. The use of grab sample calibration resulted in greatly
reduced calibration time, and better process efficiency. The pH sensor
interfaced readily to the existing Great
Lakes pH transmitter resulting in
excellent cost savings.
The pH Sensor Used:
Model: PN 6432-GLI5-25 pH Sensor
Description: ¾”- ¾” MNPT Immersion ULTEM Bodied High Acid/Fluoride
Resistant pH Sensor with integrated 301 Ohm GLI TC Assembly, Stainless Steel
Solution Ground and GLI Compatible 5-Wire Differential preamplifier; 25 feet
cable to connect directly to GLI pH 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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