Walchem WDIS Series Instruction Manual - page 8
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6. Push the cable onto the end of the sensor, aligning the pins with the holes. Turn the connector
until hand tight to seal the cable connection.
Flow Cell Placement
Instructions for mounting the sensor into the process can vary greatly with the circumstances that are
encountered in your application. Here are some general guidelines to assist you. Refer also to the
typical installation drawings.
The sensor should be mounted such that the measuring surfaces will always stay wet. If the membrane
dries out, it will respond slowly to changing disinfectant values for 24 hours, and if dried out
repeatedly, will fail prematurely.
The flow cell should be placed on the discharge side of a circulation pump or downhill from a gravity
feed. Flow into the cell must come from the bottom side that has the ¾” x ¼” NPT reducing bushing
installed.
The reducing bushing provides the flow velocity required for accurate readings and
must not be removed!
A “U” trap should be installed so that if the flow stops, the sensor is still immersed in the water. The
outlet of the flow cell must be plumbed to open atmosphere unless the system pressure is at or below
1 atmosphere. If the flow through the line cannot be stopped to allow for cleaning and calibration of
the sensor, then it should be placed in a by-pass line with isolation valves to allow for sensor removal.
Install the sensor vertically, with the measuring surface pointing down, at least 5 degrees above
horizontal. (Refer to Installation drawings)
Flow rate regulation must be done upstream from the sensor, because any flow restriction downstream
can increase the pressure above atmospheric and damage the membrane cap!
The sensor should be installed in an area where there is good solution movement and where it will
respond rapidly to chemical additions. The placement of the sensor relative to the placement of
chemical replenishment, along with the quality of the mixing, and the replenishment chemical flow
rate are critical to accurate process control.
Installing Sensor into Flow Cell
1. Assemble the flow cell as shown below from the top down. The reducer should already be
installed in the flow cell body.
2. Slide the 102586 nut over the membrane end of the sensor, followed by the 103419 top washer,
followed by the 103422 o-ring, followed by the 103419 bottom washer (concave side up),
followed by the 103421 clip ring. The clip ring must be pushed up until it snaps into the groove in
the sensor body.
3. Place the 102594 o-ring in the top o-ring groove of the 102881 flow cell body.
4. Place the sensor body into the flow cell body, and tighten the 102586 nut until it is hand-tight.
Before tightening completely, pull the sensor up until the clip ring is up against the bottom
washer.
5. Insert the 191303 cable into the connector at the top of the sensor. The connector is keyed and
will only insert in one orientation.