7 Reference
7.5 Dissolved oxygen measurement
D-52/53/54/55
199
when air is made to saturate water at a high elevation,
where the air pressure is, for example, 506.5 hPa (which
is equal to 1013 hPa
×
1/2), the DO will be 4.06 mg/L
(which is equal to 8.11 mg/L
×
1/2).
As explained above, careful attention must by paid to
atmospheric pressure when calibrating a DO meter. Air
pressure does not present any special problem when a
DO meter is used near sea level, but when it is used at
especially high altitudes, it is necessary to correct for the
air pressure.
The D-55 meter has a built-in air-pressure correction
function.
Set the atmospheric pressure in the pH meter when
calibrating and the meter will automatically be calibrated
using the air-pressure corrected value. Air-pressure
correction is calculated using the equation below.
When calibration is finished, the value derived from this
equation is displayed.
Compensated value = (1013/P) x measured value
P is the air pressure (hPa) set in the meter.
Saturated DO levels in water at various
temperatures (with a salinity concentration of
0.00 ppt)
Temp.
(ºC)
Saturated
DO
(mg/L)
Temp.
(ºC)
Saturated
DO
(mg/L)
Temp.
(ºC)
Saturated
DO
(mg/L)
Temp.
(ºC)
Saturated
DO
(mg/L)
1
13.77
11
10.67
21
8.68
31
7.42
2
13.40
12
10.43
22
8.53
32
7.32
3
13.04
13
10.20
23
8.39
33
7.22
4
12.70
14
9.97
24
8.25
34
7.13
5
12.37
15
9.76
25
8.11
35
7.04
6
12.06
16
9.56
26
7.99
36
6.94
7
11.75
17
9.37
27
7.87
37
6.86
8
11.47
18
9.18
28
7.75
38
6.76
9
11.19
19
9.01
29
7.64
39
6.68
10
10.92
20
8.84
30
7.53
40
6.59
Summary of Contents for D-25
Page 2: ......
Page 11: ...CONTENTS VIII HORIBA ...
Page 31: ...1 Overview of the Meter 1 9 Using the protective cap D 53 54 55 20 HORIBA ...
Page 75: ...2 Taking Measurements 2 9 Dissolved oxygen DO measurement D 55 64 HORIBA ...
Page 139: ...4 RS 232C communications 4 5 Communication example using the HyperTerminal 128 HORIBA ...
