TM 5-813-3/AFM 88-10, Vol 3
CHAPTER 4
MEASUREMENT AND CONTROL
b. Semiautomatic control. Semiautomatic control
4-1.
Measurement
of
process
variables.
utilizes instruments to automatically control a func-
In order to determine the degree of effectiveness of the
tion or series of functions within control points that
different treatment processes, several physical and
are set manually. The operator manually starts the au-
chemical parameters associated with water treatment
tomatic sequence of operations. An example of semiau-
must be measured. After they are measured, the infor-
tomatic control is the automatic backwashing of a fil-
mation must be evaluated so that necessary adjust-
ter after operator initiation of the program,
ments can be made in the treatment processes.
c. Automatic control. Automatic control involves
a. Minimum analyses. The minimum type, number,
the use of instruments to control a process, with neces-
and frequency of analyses for military water treat-
sary changes in the process made automatically by the
ment plants will conform to paragraph C-1 of appen-
controlling mechanisms. When a process variable
dix C.
changes, the change is measured and transmitted to a
b. Laboratories. Laboratories at military water
control device which adjusts the mechanisms control-
treatment plants must have the minimum amounts of
ling the process. Automatic control systems have been
laboratory furniture, laboratory equipment, and labo-
developed which are reliable, but provision for emer-
ratory chemicals prescribed in paragraphs C-2, C-3,
gency manual control must be included.
and C-4 of appendix C.
c. Records of analyses. Results of laboratory analy-
ses will be recorded and maintained in an orderly fil-
ing arrangement.
All instruments and control devices should be placed
in readily accessible locations in order to facilitate ob-
._
4-2. Control.
servation, maintenance, repair, and replacement. In-
Water treatment plant processes may be controlled by
struments should not be located in environments
manual, semiautomatic or automatic methods, which
which might lead to premature failure of the instru-
ments. Examples of such environments are areas sub-
are defined as follows.
a. Manual control. Manual control involves total
ject to high temperatures or corrosive vapors. Provi-
operator control of the various water treatment proc-
sions should be made for many of the instruments to
esses. The personnel at the water treatment plant ob-
actuate alarms if critical process variables exceed or
serve the values of the different variables associated
fall below predetermined tolerable levels. Such alarms
with the treatment processes, and make suitable ad-
should include both audio and visual signals.
justments to the processes.
4-1
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