MIL-HDBK-1005/9A
(O) = Optional
Items described may be required
(contingent on specific plant needs).
(S) = Special Cases
Items are sometimes used in large
installations or where process variable
control is critical.
4.4
Policies. Devices and systems should be as simple as
possible. In any installation or facility, equipment
procurement should be limited to the smallest practicable number
of manufacturers.
4.4.1
Primary Measurement. Provide elements to measure any
function essential to proper operating control and evaluation of
plant performance.
4.4.2
Instrumentation. Provide remote readouts only where
operating convenience and cost savings outweigh added
maintenance needs or where hazardous wastes are being treated.
Record functions that significantly affect public health, the
environment, or economy of operation. Consider data logging
devices where costs can be offset by reduced operating manpower
needs.
4.4.3
Controls. Consider automatic controls where
significant improvement in performance will result or where cost
can be offset by reduced operating manpower needs or where
treating hazardous wastes; otherwise, keep controls as simple as
possible. Wherever feasible, use fixed or manual controls (for
example, weirs, launders, siphons, or throttling valves) in
preference to mechanical devices. Use direct acting controls
(for example, float valves) in preference to electrically or
pneumatically actuated devices. Always consider the effects of
possible control malfunctions.
4.4.4
Standardization. Standardize equipment wherever
possible. Use identical or similar components to the maximum
extent. Instrumentation, control, and feeding equipment should
be homogeneous (that is, all self-powered, all pneumatic, and so
forth).
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