Emerson 228 specifications Maintenance, Troubleshooting, Problem Probable Cause Solution

MODEL 228 MAINTENANCE

MAINTENANCE

WARNING

Retraction chamber contents may be under pressure.

CAUTION

Be sure sensor has been cleaned of process liquid before handling.

Generally, the only maintenance required is to keep the opening of the sensor clear of deposits. Cleaning frequency is best determined by experience.

TROUBLESHOOTING

PROBLEM	PROBABLE CAUSE	SOLUTION
Off-scale reading	Wiring is wrong.	Verify and correct wiring.
	RTD is open or shorted.	Check the RTD for open or short circuits.
		See Figure 19.
	Sensor is not in process stream.	Confirm that the sensor is fully submerged in
		the process stream. See installation section.
	Sensor is damaged.	Perform isolation checks. See Figure 19.
Noisy reading	Sensor is improperly installed in the	Confirm that the sensor is fully submerged
	process stream.	in the process stream. See installation section.
	Sensor cable is run near high voltage	Move cable away from high voltage conductors.
	conductors.
	Sensor cable is moving.	Keep sensor cable stationary.
Reading seems wrong (lower	Bubbles are trapped in the sensor,	Install the sensor in a vertical pipe run with the
or higher than expected)	particularly in the toroid opening.	flow against the toroid opening. Increase flow
		if possible.
	Sensor is not completely submerged in the	Confirm that the sensor is fully submerged
	process stream.	in the process stream. See installation section.
	Cell constant is wrong. Wall effects are	Calibrate the sensor in place in the process
	present.	piping. See calibration section.
	Wrong temperature correction algorithm	Check that the temperature correction is
	is being used.	appropriate for the sample. See analyzer
		manual for more information.
	Temperature reading is inaccurate.	Disconnect the RTD leads (Figure 19) and
		measure the resistance between the in and
		common leads. Resistance should be close
		to the value in Table 1.
	Slow temperature response to sudden	Use an RTD in a metal thermowell for
	changes in temperature.	temperature compensation.
Sluggish response	Sensor is installed in a dead area in the	Move sensor to a location more representative
	piping.	of the process liquid.
	Slow temperature response to sudden	Use an RTD in a metal thermowell for
	changes in temperature.	temperature compensation.

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