Error In Measured Value; When "Snr Alarm" Is Displayed - Fuji Electric FSJ Instruction Manual

Error in measured value

State
The reading appears with
"-" (minus).
Measured value
fluctuates though flow
rate is constant.
Measured value remains
the same though flow
rate is changing. (LED lit
in red)
Error in measured value

When "SNR ALARM" is displayed

Measurement is performed, however, the wave receipt status is poor.
• Monitor the measurement status, and check "6.3.1.2 Checking the LED lit in red" if there are times when the LED turns red.
• Even if the LED does not turn red, it is recommended that you refer to "(1) Diagnosis of no/weak reception and wave
receipt shape error in 6.3.1.2 Checking the LED lit in red", and check the flowmeter status.
Probable cause
 Pre-amplifier and sensor cable
connection (+ and - are reversed.)
 Flow of fluid is reversed.
 Straight pipe length is inadequate.
 Pump, valve, or others which
disturb the flow are located nearby.
 Pulsation exists in flow.
See "6.3.1.2 Checking the LED lit in red".

Input piping specifications differ
from the actual ones.

Insufficient linear pipe length
(Refer to "3.2.1 Conditions on
straight pipe")

There is a build-up of drainage
or solid matter, etc. inside the
pipe.

The detector has not been
thermally insulated.
Connect properly.
Move to a location that can secure "3.2.1
Conditions on straight pipe".
Mount the instrument with a clearance of
80D or more.
Set the damping to increase the response
time.
A difference of 1% in inner diameter
causes an error of about 3%.
Input the correct specifications.
 Input scale as lining.
Find another mounting place (upstream
of disturbing objects).
No disturbing objects in flow within 80D
upstream
combined pipe, etc.
 Mount the sensor at different angles
with respect to the cross section of
pipe to fine the location where mean
value is obtainable. The mount the
sensor at that location.
There tends to be much build-up at
locations with small cross-sectional
area.

The detector will be exposed to the
effects of external environmental
temperatures, resulting in
measurement errors.

－117－
Troubleshooting
without pump,
Remove the drainage or solid
matter, etc., or relocate the sensor
to a location with no drainage or
solid matter, etc.
Thermally insulate the pipe to
which the detector is mounted, and
the detector with thermal insulating
material.
valve,