Specifications

Instruction Manual Alpha DO 500
15
NOTES:
x If the displayed value is more than r10% of the high-point value, the
Transmitter indicates a calibration error by showing ‘ERR’ and blinking
electrode
annunciator. If this happens, press  and  keys together
to return to measurement mode. Restart the calibration from Step1.
x To exit from calibration mode without confirming calibration, press 
and  keys together.
x When calibrating with manual temperature compensation, the
Transmitter automatically changes from preset ‘process temperature’ to
‘calibration temperature’. After leaving calibration mode, the transmitter
switches back to the ‘process temperature’. (Refer section 5.4 for
temperature settings)
4.2.2 2-Point Calibration
The 2-point calibration is carried out at Low-point (zero dissolved oxygen
solution) and then at high-point using 8.24 mg/l of dissolved oxygen solution.
Measured value should be
<10 % of high-point
Calibration error occurs
if measured value is
<10% of high-point
during 1st point calibration
or
if measured value is not
within +/-50% of high-point
during 2nd point calibration
2
CAL
HOLD
1
ENT
ENT
ENT
CAL
HOLD
2
CAL
HOLD
2
CAL
HOLD
mg/l
MEAS
mg/l
°C
ATC
READY
4
CAL
HOLD
mg/l
READY
ERR
CAL
HOLD
3
mg/l
READY
5
+
ENT
ENT
11
From measurement mode press CAL key to enter calibration mode as
described in section 4.1. The LCD shows ‘CAL Do’. Press ENT key to
begin first calibration point.
2
Select 2-point calibration: The display shows ‘1Pt CAL’. Press  or 
key to select ‘2Pt CAL’.
Press ENT key to confirm the selection.
3
The buffer annunciator appears in LCD. The lower display shows
‘LO’, indicating the low-point is being calibrated. Immerse the electrode
in a low level of dissolved oxygen solution (0.0 mg/l). Immerse the
temperature probe in the solution if ATC is enabled. The upper display
shows the measured value of dissolved oxygen of the solution. Allow the
reading to stabilize. LCD shows ‘READY’ annunciator when the reading
is stable.
Press ENT key to confirm the reading.