Xylem WQ770-B TURBIDITY METER - Manual (Page 10)

Global Water
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- 10 -
Calibration
a. If the sensor is not connected to the meter, push the cable connector
gently into the meter’s connector. The outer connector ring should be
turned and locked into place so the cable will not detach from the
meter during use.
b. To enter the meter’s calibration screens hold the Menu/On button for
3 seconds. The first menu screen is for selecting the range. Use the
Down arrow key to select 50 NTU then press the Save button.
c. Press the Menu/On button to display the units available. Use the
Up/Down arrow keys to select NTU (nephlometric turbidity units).
Press the Save button to record the unit selection. Press the Menu/On
button to move to the next menu.
d. The LoSig screen shows a number with NTU. This is not an indication
of the real NTU reading. This value includes meter offsets and other
variables.
e. You may use a lint free bent cotton swab to remove any air bubbles
from underneath the detector window, ensuring that there are no
bubbles on the lenses is critical. Place the sensor into the distilled
water. Press the Save button until the display reads “saved”. This
step may need to be repeated to ensure that an accurate reading is
taken. Press the Menu/On button to move to the next menu.
f. The HiSig screen shows a number with NTU. This is not an indication
of the real NTU reading. This value includes meter offsets and other
variables.
g. Place the sensor in the clamp above the 50 NTU solution. Lower the
clamp and dip the sensor into the solution. Wipe the detector window
with a cotton swab to remove any air bubbles. Press the Save button
until the display reads “saved”. This step may need to be repeated to
ensure that an accurate reading is taken. Press the Menu/On button
to move to the next menu.
h. The LoLab screen displays the correct NTU reading for the solution
used in the LoSig calibration step. For distilled water press the arrow
keys until the display reads 0 NTU. Press the Save button to record
the LoLab unit. Press the Menu/On button to move to the next menu.