Owner's manual

61
9900 Transmitter
USP (United States Pharmacopoeia) has defi ned a set of conductivity values (limits)
to be used for pharmaceutical water. The standard requires that conductivity
measurement without temperature compensation be used for these applications.
The limits vary according to the temperature of the sample. The 9900 has the USP limits
stored in memory. It will automatically determine the proper USP limit based on the
measured temperature.
Using the USP function
USP setpoints are defi ned as a percentage below the USP limit, so a USP alarm is
always a HIGH alarm. The 9900 can be set to warn you if the conductivity approaches
within a set percentage of the USP limit.
The following settings and conditions are required for a USP relay function:
1. In the RELAY menu:
• RELAY MODE must be set to USP.
2. In the INPUT menu:
• COND UNITS must be set to μS.
• TEMP COMP must be set to None.
Example:
• The water temperature is 19 ºC, so the USP limit is 1.0 S.
• The USP PERCNT is set to 40%.
• The relay will be activated when the conductivity value reaches 40% below the
1.0 USP limit, or 0.6 S.
• If the water temperature drifts to more than 20 ºC, the 9900 will automatically
adjust the USP limit to 1.1. The relay will now be activated when the conductivity
value reaches 40% below 1.1 S (0.66 S).
Temperature
Range (ºC)
USP limit
(μS)
0 to < 5 0.6
5 to < 10 0.8
10 to < 15 0.9
15 to < 20 1.0
20 to < 25 1.1
25 to < 30 1.3
30 to < 35 1.4
35 to < 40 1.5
40 to < 45 1.7
45 to < 50 1.8
50 to < 55 1.9
55 to < 60 2.1
60 to < 65 2.2
65 to < 70 2.4
70 to < 75 2.5
75 to < 80 2.7
80 to < 85 2.7
85 to < 90 2.7
90 to < 95 2.7
95 to < 100 2.9
100 to < 105 3.1
Appendix
USP Limits
 Clean the instrument case and front panel with a soft cotton cloth dampened with a
mild liquid soap solution.
 Never wipe the front window with static retentive cloths such as wool or polyester
which may induce a static charge. If a static charge develops on the window,
you may notice temporary blotches form on the screen.
When this occurs, clean the front window with an anti-static cloth, or a soft cotton
cloth and anti-static spray or a mild liquid soap solution to remove the static charge.
Maintenance