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Troubleshooting
Troubleshooting the pH Probe
Temperature Swings
—Severe temperature swings will affect probe response. Very high
temperatures can cause the gel in the probe to expand and seep out through the porous
Teflon
®
junction and when temperature drops, air is sucked in through the junction. If the
temperature rises again, the air expands pushing more gel out the junction. This type of
cycling will eventually cause probe failure.
Build-Up of Contaminants on Probe
—Some sites coat the probe with contaminants
such as grease. In these environments, mount the probe so that the water “scrubs” the
probe. For example, mount the probe so that probe tip faces downstream; this lets the
cable protect the probe tip. Alternatively, mount the probe with the tip pointing into the
flow so that the flow scrubs the tip. Some sites require that the probe be mounted inside
a short piece of perforated PVC pipe. At very poor sites, mount the probe inside more
than one piece of perforated PVC with the holes offset.
Troubleshooting the Low Profile Velocity-Only Sensor
Problem
Cause
Solution
Zero Velocity
Reading
The sensor is not covered with water.
Make sure the sensor is in water.
Not enough suspended solids.
Throw dirt into the water, upstream of the sensor, to
reset the sensor.
Look at current status and watch for increased velocity
signals. Re-evaluate application.
The beveled face of the sensor is covered with
sediment/algae growth, rags, etc.
Clean the sensor.
Erratic Velocity
Readings
The sensor is not covered with water.
Make sure the sensor is in water.
Not enough suspended solids.
Throw dirt into the water, upstream of the sensor, to
reset the sensor.
The beveled face of the sensor is covered with
sediment/algae growth, rags, etc.
Clean the sensor.
Occurs only when using a laptop.
Make sure the laptop is not running on a power inverter
or malfunctioning serial port.
Electromagnetic interference near the meter or
sensor cable (i.e. a large pump motor).
Make sure there are no electromagnetic interferences.
Remove interferences or move the meter and sensor
cable away from the interferences.
Problem occurs at the same time of the day
because the sensor is not covered with water
during certain times of the day.
Make sure the probe is covered at all times, especially
during the early morning hours.
Turbulence in front of the sensor.
Make sure there is no or little turbulence up to 20 ft
away from the sensor.
Probe is not facing the right direction.
Install the sensor facing the proper direction to the flow.
Noise coming in on RS232, ac power lines, and
4–20 output lines.
Disconnect the RS232, ac power line, and/or 4–20 mA
output. Power the unit off and on to reset it.
Velocity Reading
Constant if 32 fps
The beveled face of the sensor is covered with
sediment/algae growth, rags, etc.
Clean the sensor. After cleaning, it may be necessary
to reset the unit by disconnecting power for a minute.
Electromagnetic interference near the meter,
sensor cable, or RS232 connection.
Make sure there are no electromagnetic interferences.
Remove interferences or move the meter and sensor
cable away from the interferences.
Mild power surges.
Reset the unit by disconnecting power for a minute.
Содержание Sigma 950
Страница 2: ......
Страница 6: ...4...
Страница 20: ...18 Introduction...
Страница 34: ...32 Basic Programming Setup...
Страница 50: ...48 Sensor Installation...
Страница 82: ...80 Maintenance...
Страница 83: ...81 Appendix A Program Flow Charts Figure 22 Overview of Basic Program Menus...
Страница 84: ...82 Program Flow Charts Figure 23 Setup Flow Chart...
Страница 85: ...83 Program Flow Charts Figure 24 Options Flow Chart...
Страница 86: ...84 Program Flow Charts Figure 25 Alarms Menus Flow Chart...
Страница 87: ...85 Program Flow Charts Figure 26 Calibration Menus Flow Chart Page 1...
Страница 88: ...86 Program Flow Charts...
Страница 102: ...100 Programming Features...
Страница 106: ...104 Primary Devices Head Measurement Locations...
Страница 126: ...124 SCADA Modbus System Guidelines...