Section VI. ELECTRONIC EQUIPMENT

TM 38-260

g. Preserving. Precision measuring instruments are generally manufactured from nonferrous metals that do not

require a preservative. There are, however, a few large items in the category of measuring instruments, such as bench-

type micrometers and carriages of comparators that will require preservation. Be sure the preservative used will not

cause damage. If items are to be shrouded or packaged to prevent contamination from dust, the item shall be coated

with preservative compound P-2 or a light preservative oil such as P-9 or P-10, grade 10, of table 2-1.

Section VI. ELECTRONIC EQUIPMENT

4-24. ENVIRONNMENTAL CONDITIONS AND THEIR EFFECTS

a. General. Most electronic equipment is designed to withstand conditions beyond those of normal operating

criteria of heat, cold, or humidity. It is, however, another matter when it becomes necessary to store equipment for

indefinite periods of time.

(1) As an example, normal operating conditions generate enough heat to eliminate excessive amounts of

humidity, thereby preventing corrosion and fungus growth.

(2) There are times when moisture will affect certain electronic components if the moisture is not controlled or

eliminated. Variable and adjustable resistors may be affected because of exposed metal surfaces; various kinds of

capacitors may be damaged by moisture, dust, and leaking electrolyte; inductors may absorb moisture in their windings;

transformers have a tendency to rust; alternate heat and cold will cause insulation deterioration; connector sockets will

rust and corrode from moisture; relays, timers, solenoids, and switches suffer from corrosion on contact points and

fungus growth on coils; and wires and cables are damaged due to chemical attack on the insulation from contact with

organic solvents. There are many other electronic components, too numerous to list in this manual, that require

protection from environmental conditions.

b. Environmental hazards. All electronic assemblies or components shall be stored with adequate protection from

physical damage, dust, insects, rodents, and aerial contaminants, as well as the more obvious influences of extreme

heat, cold, or high humidity.

c. Electrostatic discharge. All electronic assemblies and components subject to electrostatic discharge shall be

stored with adequate protection from electrostatic discharge (ESD) and electromagnetic induction (EMI). A metal cabinet

containing electronic components is probably sufficient to provide static protection for enclosed components because of

the equal potential between the cabinet and components. The electronic assemblies and components should not be

handled directly without a wrist grounding strap or other static protection device as defined by DOD-STD-1686. The

manufacturer should provide a warning label to this effect. If there is not a warning label, a tag should be taped or wired

in an obvious location on the outside of the cabinet with the following warning: DO NOT OPEN CABINET WITHOUT

USING AN APPROVED STATIC CONTROL DEVICE.

4-21