APG KA Cable Suspended user manual - Manual (Page 9)

Rev. A2, 12/08 KA Series
9
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• Selecting the Right Switch
The following procedure should be used to select the optimum switch or
switch combination:
1. Determine the number of control points needed; for example, one point
for alarm, two points for empty/fi ll, etc.
2. Select required model(s) from the Type Detail Table. If necessary, special
switches may be ordered with nonstandard switching logic.
3. The smaller, lower cost M series switches may be used if the three
following conditions are met:
a. No solid fl oating materials are present
b. The
specifi c gravity of the liquid is greater than 0.95
c. No more than a two conductor cable is needed
4. Note that if a special material compatibility situation exists, there are a
number of options available as indication in the Options section on page
5.
This publication describes how the switching levels are related and
how they are adjusted. If it is found that the required levels cannot be
accommodated by standard units, a special switch can be ordered. For use
in still liquids, a two level switch with a smaller diff erential than the standard
minimum (10 inches) may be ordered. Sometimes a combination of switches
needs to be used to achieve the required switching heights or range of
adjustment capabilities. For example a Model 3HE can be replaced by a model
2H plus a separate model 1H, or a model 2LH by a model 1H plus model 1L.
Our Applications Engineering Department is pleased to assist users to select