Titan Metraflow 240-020, Инструкция по эксплуатации

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©Titan Enterprises Ltd 2018 www.flowmeters.co.uk MetraflowManual_v1219
When the null measurement is complete the
local display will revert to normal 000.00 as
formatted and the software screen will show
“Nulled”
This cannot be done if liquid is flowing. This
zeroing will affect future calculations and the
meter will give the best accuracy over the whole
flow range for the temperature at which the
system was zeroed. If the temperature of the
tube changes, the position of the noise and its
effect on the calculation will change. This is in
the order of ±0.25 to 0.5% FSD if the system is not “zeroed” at the actual fluid running temperature. If
measurements are required over a temperature range we would recommend stopping the flow and
nulling the system at a mid-point in the desired temperature range. This will reduce the FSD error
considerably.
After the unit is zeroed lower flows than specified can be registered but the accuracy is likely to be poor.
To register these lower flows the “Cut off” in the “Calibrations settings box” should be set to just above
0.00 and at a flow rate above the point the meter records flow when none is happening but below the
minimum flow specified for the meter. If it is set to 0.000 residual background noise will cause small
readings even when there is no flow. If readings are seen, increase the value sequentially until no output
is recorded, typically around 0.002 l/min.
REMOVING NULL: This can be done via the software using the REMOVE button in the Advanced Tab
or resetting the flowmeter by cycling the power off and back on.
Fluid Speed of Sound Adjustment:
The Metraflow ultrasonic flowmeter is factory calibrated on clean water at about 20°C and therefore the
window of calibration is based around the measured time of flight of the ultrasonic signal based on the
speed of sound of water. When a fluid is used in the meter that has a significantly different speed of
sound to that of water, the stable signal may move outside of the window causing the meter to read
incorrect and unstable time of flight signals whilst the automatic ranging tries to find the correct position
of the flow signal. In this scenario you can compensate this delay in response by manually adjusting
the measurement window of the meter in the advanced tab feature for Fluid Speed of Sound
Adjustment. A bar is seen in the graph indicating whether a strong signal is being measured. If a fluid
has a faster speed of sound the user can click the FASTER button to adjust the measurement window
a stronger signal point. A
RED graphic is a very poor signal, ORANGE indicates a weak signal and
GREEN is a good strong signal.