Dwyer TFLS - Manual (Page 4)

MAINTENANCE
Upon final installation of the Series TFLS Tuning Fork Level
Switch, no routine maintenance is required. A periodic check of the
system calibration is recommended. The Series TFLS is not field
serviceable and should be returned if repair is needed (field repair
should not be attempted and may void warranty). Be sure to
include a brief description of the problem plus any relevant
application notes. Contact customer service to receive a return
goods authorization number before shipping.
Bulletin L-33
page 4
©Copyright 2012 Dwyer Instruments, Inc. Printed in U.S.A. 5/12 FR# 85-443478-00 Rev. 1
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3. Sensitivity Selection: The sensitivity selection adjusts the fork
sensitivity to material bulk density. The more dense the material,
the lower the sensitivity needed. After installing the probe and
making all electrical connections, set the Fail Safe Selection
switch to the MAX position. Set both the CVD and UNCOVD time
delays to their minimum by rotating them counter-clockwise to the
end position. Rotate the SENSITIVITY potentiometer counter-
clockwise to its end position (See Figure 4). If there is no material
in the tank then the green LED will be illuminated. Fill the tank so
that the fork tines are covered by material. If the green LED turns
off and the red LED turns on then no adjustments are necessary.
If the green LED stays on then rotate the sensitivity potentiometer
clockwise to the point where the green LED goes out and the red
LED comes on. Setting is completed.
4. Time Delay Selection: The time delay is the programmed time
between when the probe senses the presence or absence of
material and when the relay changes state. A time delay is good
for applications that could have false or rapid pulsing of level
indications from sloshing or agitated material. Choose a delay
setting appropriate for the specific application. There are two
potentiometers for adjusting the delay time. The potentiometer
labeled COVD sets the delay time between when the probe is
covered and when the switch changes state. The potentiometer
labeled UNCOVD sets the delay time between when the probe
becomes uncovered and when the switch reverts back to its
normal state (See Figure 4). Adjust the time delay potentiometers
by turning them fully counter-clockwise to their end position. This
setting is no delay. To then set a delay time turn the potentiometer
clockwise to the desired time setting. The delay can be set
anywhere from 2 to 20 seconds.
TROUBLE SHOOTING
If the instrument fails first check that the wiring connections are
correct and that the set up is correct for the application. Next,
check to see if the tines vibrate when free of material.
Condition
Probe Covered
Red LED Off
Green LED Off
Probe Covered
Red LED On
Green LED Off
Probe Uncovered
Red LED Off
Green LED On
Relay Status
Terminals 6 & 7 Open
Relay De-energized
Terminals 6 & 7 Open
Relay De-energized
Terminals 6 & 7
Closed
Relay Energized
Probable Cause
No power supplied
Voltage too low
Material too light
Material has formed cavities
Vibration of vessel wall at 85 Hz
Heavy material deposit on fork
Fork Damaged
Vibration of vessel wall at 85 Hz