Emerson Rosemount MCL-220 Reference Manual page 77

Reference Manual
00809-0100-3414
6. Is the membrane fouled or coated? A dirty membrane inhibits diffusion of
7. If cleaning the membrane does not remove the sensor response, replace the
9.5.4 Process readings are erratic.
1. Readings are often erratic when a new sensor or rebuilt sensor is first placed in
2. Verify that wiring is correct. Pay particular attention to shield and ground
3. Is the membrane in good condition, and is the sensor filled with electrolyte
9.5.5 Readings drift.
Recommended actions
1. Check to see if the sample temperature is changing.
2. Make sure the membrane is clean. For the sensor to work properly,
3. Make sure the sample flow is within the recommended range. Gradual loss of flow
Rosemount MCL
may start to drop rapidly. At this point, the electrolyte solution and membrane
should be replaced. Refer to
monochloramine through the membrane, reducing the sensor current and
increasing the response time. Clean the membrane by swirling it vigorously in a
beaker of water or by washing with a stream of water from a washer bottle.
CAUTION
EQUIPMENT DAMAGE
Do not use a tissue to wipe the membrane.
membrane and electrolyte solution. See the sensor instruction sheet for details.
service. The current usually stabilizes after a few hours.
connections.
solution? Replace the fill solution and electrolyte. Refer to
Membrane permeability is a function of temperature. The transmitter automatically
corrects for changes in sensor current caused by temperature changes. The time
constant for response to a temperature change is about five minutes. Therefore,
the reading may drift for a while after a sudden temperature change.
monochloramine must diffuse freely through the membrane. A coating on the
membrane will interfere with the passage of monochloramine, resulting in a slow
response. Clean the membrane by rinsing with a stream of water from a wash bottle
or by swirling it vigorously in a beaker of water.
CAUTION
Equipment damage
Do not use a tissue to wipe the membrane.
will cause downward drift. Be sure the liquid level in the constant head flow
Monochloramine sensor.
Troubleshoot
May 2019
Monochloramine sensor.
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