GF Signet 8860 Dual Channel Conductivity-Resistivity Controller - Manual (Page 7)

7 8860 Dual Channel Conductivity/Resistivity Controller
0 ºC to < 5 ºC 0.6
5 ºC to < 10 ºC 0.8
10 ºC to < 15 ºC 0.9
15 ºC to < 20 ºC 1
20 ºC to < 25 ºC 1.1
25 ºC to < 30 ºC 1.3
30 ºC to < 35 ºC 1.4
35 ºC to < 40 ºC 1.5
40 ºC to < 45 ºC 1.7
50 ºC to < 55 ºC 1.8
55 ºC to < 60 ºC 2.1
60 ºC to < 65 ºC 2.2
65 ºC to < 70 ºC 2.4
70 ºC to < 75 ºC 2.5
75 ºC to < 80 ºC 2.7
80 ºC to < 85 ºC 2.7
85 ºC to < 90 ºC 2.7
90 ºC to < 95 ºC 2.7
95 ºC to < 100 ºC 2.9
100 ºC to < 105 ºC 3.1
The USP limit
(μS) is:
When the
temperature
range is:
USP Limits
USP (United States Pharmacopoeia) has defi ned a set of conduc-
tivity values (limits) to be used for pharmaceutical water moni-
toring. This standard requires non-temperature compensated
conductivity measurement be used to warn if the con ductance
approaches the USP limit. The limits vary according to the tem-
perature of the sample.
The 8860 has the USP limits stored in memory. It will automati-
cally determine the proper USP limit based on the measured
temperature.
Using the USP function
In the 8860, USP setpoints are defi ned as a percentage below
the USP limit, so a USP alarm is always a HIGH alarm. The 8860
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 CALIBRATE menu:
• RELAY MODE must be set to USP.
• RELAY SOURCE must be Chan 1 or Chan 2 Cond.
• SOURCE UNITS must be set to μS.
2. In the OPTIONS menu:
• The TC Mode of the USP channel must be set to None.
(Service tip: If a relay is constantly on when it should be off,
check the relay settings listed above.)
Example:
• The USP setpoint is 40%.
• The water temperature is 19 ºC, so the USP limit is 1.0 μS.
• The relay will be activated when the conductivity value reaches
0.6 μS, or 40% below the 1.0 USP limit.
• If the water temperature drifts to more than 20 ºC, the 8860 will
automatically adjust the USP limit to 1.1.
• The relay will now be activated when the conductivity value
reaches 40% below 1.1 μS, or 0.66 μS.