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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. 7 –
Total Ammonia Analysis in Wastewater
Total Ammonia Determination
through online ammonium ion and pH monitoring
Industrial grade ammonium ion
selective membrane and application engineered solid state conductive polymer
reference can withstand the rigors of industrial process lines
Ammonium calibration system has
been optimized to yield reproducible results in a variety of wastewater
systems
Ammonia gas resistant pH sensor
delivers the accuracy needed for total ammonia computation via a PLC or DCS
from the ammonium ion and pH input values
The Problem
A
sweetener manufacturer wanted to control the total nitrogen content in their process.
This was a difficult proposition since they had a mixture of dissolved
ammonia gas and ionized ammonium ions in solution. Fluctuation of process pH
did not allow for a simple mathematical correction or computation, and made
real time control arduous. The complex process solution necessitated
significant interaction between ASTI and the customer to develop the proper custom
calibration solutions. The total nitrogen must be calculated based upon an
equation whose variables are pH and ammonium activity. Creating an accurate
calibration system is a challenge in a complex system, whose primary function
is not to determine simple activity, but rather a computed or derived total
concentration. Common TISAB (total ionic strength adjustment buffer)
solutions are often inadequate ISE standards for industrial calibrations
because they do not accurately reflect the ionic strength and pH of the
process solution. This application then necessitated not only determining the
proper multi-point calibration for both pH and ammonia/ammonium, but also developing
an interactive curve and standard ion buffer background which accurately
reflected the process. Getting agreement and consistency between laboratory
titrations and on-line measurement or process values was accomplished by using
custom calibration solutions as the common reference standard for both the laboratory
and process measurements.
The Solution
The solution was a ammonia gas resistant pH
sensor and an industrial grade organic polymer ammonium ion selective sensor.
Both the pH and ammonia sensor were sealed against any dissolved ammonia gas
which may attack the reference element at lower pH. The reference element was
designed to be insensitive to the interferences experienced by the ammonium polymer
membrane. The ammonium ion analyzer, in combination with the PLC, was capable
of computing
the total nitrogen concentration via a multi-parameter algorithm. The
multi-point calibration developed for this application allowed the PLC to
create an accurate curve at any point along the operating pH range. The total
ammonium analysis system was able to deliver reproducible and accurate
results, replacing slow and inaccurate grab sample laboratory analysis.
The Ammonium Ion Sensor
Used:
Model: AB 6410-873DPX-25 Ammonium Ion Sensor
Description: ¾”- 1” MNPT Immersion ULTEM Bodied Ammonium Ion
Selective Sensor with integrated 100 Ohm Platinum Temperature Element, Stainless
Steel Solution Ground and Foxboro 873DPX compatible preamplifier; 25 feet
cable to connect directly to Foxboro 873DPX (Dual Channel Auto pH
Compensation) pH/ISE Analyzer/Transmitter
The pH Sensor Used:
Model: PNA 6031-873DPX-25 pH Sensor
Description: ¾”- 1” MNPT Immersion ULTEM Bodied Dissolved
Ammonia Gas Resistant General Purpose pH Sensor with integrated 100 Ohm
Platinum Temperature Element, Stainless Steel Solution Ground and Foxboro
873DPX compatible preamplifier; 25 feet cable to connect directly to Foxboro
873DPX (Dual Channel) pH/ISE 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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