TM 9-243
USING A LEVEL
A level may be checked for accuracy by placing it on a
known level surface and noting the position of the
bubble. Reverse the level end for end. Observe the
position of the bubble. If the relative position of the
bubble was the same for both readings, the level is
accurate.
HORIZONTAL SURFACE
Place the level on a flat horizontal surface. Check the
horizontal vial (1). The bubble should be between the
two etched lines on the vial. If it is not, the surface is
not horizontal.
ANGLED SURFACE
Place the level on an angled surface. If the angle is 45
degrees, the bubble will appear between the notched
lines on the 45 degree vial (2).
VERTICAL SURFACE
Place the level against a flat vertical surface. Check the
vertical vial (3). The bubble should be between the two
etched lines on the vial. If it is not, the surface is not
vertical.
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