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3.6 New Sensor Installation
The industrial ISE sensor can be installed into service by use of an inline installation (in a pipe tee or
flow cell), by immersion or submersion into a tank or basin.
For any installation, be sure not exceed the flow and pressure rating of a given sensor. Optimal
performance and sensor lifetime will be achieved by having a slow continuous flow past the
sensor.
Maximum continuous flow r at e of 2 G PH In 1” schedule 40 or 80 pipe.
Do not allow air bubbles to get trapped near the fluoride ion selective organic membrane. This will
cause erroneous readings and drift. This potential problem is alleviated by installing the ISE sensor
at between 45 - 80 degrees above the horizontal (whether inline or in a tank).
Ion Selective sensors should NEVER be installed in a horizontal or inverted configuration as this may
lead to erratic and unreliable reading.
In addition, most industrial ISE sensors are liquid or semi-liquid filled and as such may have a small air
pocket inside the sensing element. To ensure that there is not an air pocket caught inside the sensing
element, shake the ISE sensor firmly downward. The small capillary force holding the air bubble in
place inside the sensing element will be overcome by a firm downward shake.
Thermal equilibrium between the sensor and process solutions at elevated or depressed temperature
(not at 25 degrees Celsius) is generally better achieved via immersion or submersion installation
styles. Submersion style sensors do require sensor cable waterproofing.
Approximate Time to Allow Sensor to Reach Process Equilibrium
pH
1/2 hour maximum
Ammonium
4 - 24 hours
Nitrate
1 - 2 days
Nitrite
1 - 2 days
Fluoride
4 - 24 hours
Conductivity
1/2 hour maximum
Ultralow Ammonium, Nitrate, Nitrite
Several days to weeks in wastewater
3.61 Submersible Sensor Installation
The sensor can be submerged into an aeration basin if it has been supplied with cable waterproofing.
Do not simply submerge the sensor into the water by the cable. Use the rear mounting threads on the
sensor body to attach a pipe or other device to secure the sensor.
The sensor should be mounted at a 15-45 degree angle to prevent an internal air pocket from
contacting the sensor tip resulting in erratic and unreliable readings.
The sensor should be placed at least 2 feet from the wall or side of the basin, and completely
submerged at least below the surface.
You may need to install the sensor into a stilling well in order to meet the less than 0.5 ft/sec. flow
velocity requirement of the sensor for stable readings and to extend sensor life.
Sensor cables should be installed in conduit to avoid interference of low level sensor signals.
3 Installation
