44
Stage 3
- this is an off-line test.
Test steps:
• Take the water sample from the previous stage and increase its ionic strength for a pH measurement at
25 °C;
• Record the pH and round it to the nearest 0.1 pH;
• Look up the corresponding conductivity value measured in Stage 2 above;
• If the conductivity is lower than the conductivity from the below table, then the sample has met the USP
requirements. Otherwise, the water didn’t meet the USP requirements.
To access the USP menu:
• Select the
Direct/USP reading mode (see Conductivity Setup);
• Return to measure mode;
• Press (USP) and then select the desired USP stage.
H
p
yt
iv
it
c
u
d
n
o
C
)
m
c/
S
µ
(
H
p
yt
iv
it
c
u
d
n
o
C
)
m
c/
S
µ
(
0.
5
7.
4
1.
6
4.
2
1.
5
1.
4
2.
6
5.
2
2.
5
6.
3
3.
6
4.
2
3.
5
3.
3
4.
6
3.
2
4.
5
0.
3
5.
6
2.
2
5.
5
8.
2
6.
6
1.
2
6.
5
6.
2
7.
6
6.
2
7.
5
5.
2
8.
6
1.
3
8.
5
4.
2
9.
6
8.
3
9.
5
4.
2
0.
7
6.
4
0.
6
4.
2