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pH VALUES AT VARIOUS TEMPERATURES
Temperature has a significant effect on pH. The calibration
buffer solutions are effected by temperature changes to a lesser
degree than normal solutions.
For manual temperature calibration please refer to the fol-
lowing chart:
TEMP
pH VALUES
°C
°F
4.01
7.01
10.01
0
32
4.01
7.13
10.32
5
41
4.00
7.10
10.24
10
50
4.00
7.07
10.18
15
59
4.00
7.04
10.12
20
68
4.00
7.03
10.06
25
77
4.01
7.01
10.01
30
86
4.02
7.00
9.96
35
95
4.03
6.99
9.92
40
104
4.04
6.98
9.88
45
113
4.05
6.98
9.85
50
122
4.06
6.98
9.82
55
131
4.07
6.98
9.79
60
140
4.09
6.98
9.77
65
149
4.11
6.99
9.76
70
158
4.12
6.99
9.75
For instance, if the buffer temperature is 25°C, the display
should show pH 4.01, 7.01 or 10.01 at pH 4, 7 or 10
buffers, respectively.
At 20°C, the display should show pH 4.00, 7.03 or 10.06.
The meter reading at 50°C will then be 4.06, 6.98 or 9.82.
RELAYS AND LEDS
Relays and LEDs selftests are executed as follows:
First all of the relays and LEDs are switched off, then they are
switched on one at a time for a few seconds and cyclically.
User can interrupt the otherwise endless cycle, as indicated
by the scrolling message, by pressing a key.
Note
Relays and LEDs test has to be carried out with the relay
contacts disconnected from external plant devices.
WATCHDOG
When a dead loop condition is detected a reset is automati-
cally invoked.
The effectiveness of watchdog capability can be tested through
one of the special setup items. This test consists of executing
a dummy dead loop that causes watchdog reset signal to be
generated.
