Figure 4-49.—Sounding tape.
Sounding Procedure
Spread a thin coating of water-indicating paste
from the tip of the plumb bob to about the 2-foot mark
on the tape. Lower the plumb bob through the
sounding tube until, it touches the striker plate. The
tape must be kept taut because slack would cause an
inaccurate reading. Slowly withdraw the tape. The
highest level where the JP-5 “wets” the tape is read
in feet and inches. If the “wet” mark is difficult to see,
use fuel-indicating paste. Dry the tape and spread a
thin coating of the fuel-indicating paste in the
approximate area of the first “wet” mark. When the
tape is removed, note the line of color change on the
fuel-indicating paste. This reading is then converted
to gallons by use of a tank capacity chart. When the
plumb bob is removed, note the line of color change of
the water-indicating paste. The normal color, when
applied, is gray. This level, in feet and inches, is
converted to gallons and subtracted from the JP-5
reading to determine the quantity of JP-5 in the tank.
Figure 4-50.—Thief samplers.
NOTE
The water-indicating and fuel-indicating
pastes are different colors. They also change
into
different
colors.
They
are
NOT
interchangeable.
To obtain a sample from the very bottom of the
tank, remove the plumb bob and attach the type-B
sampler shown in figure 4-50. Lower the sampler into
the sounding tube. (The distance from the sounding
tube cap to the striker plate will have been
determined during sounding operations.) As the tip of
the valve disk guide touches the striker plate, it will
be depressed by the weight of the sampler, raising
both upper and lower disks off their seat. After
retaining this position momentarily, retract the
sampler and dump the contents into a clean jar.
If water droplets or discoloration are noted on
the sounding tape during the sounding and bottom
sampling procedure, it is an indication of entrained or
free
4-61
