TM 5-6640-212-142
NOTE
2-30. Refractometer.
a. Description.
The ink level should be kept as low as
(1) The refractometer (fig. 2-28) is designed to
possible for cleanest lines and
comply with the requirements specified in ASTM Method
shortest drying time.
D1218 (TM10-1167) and FTMS 791, Method 5340. It is
stowed in cabinet K3 (figs. 1-2 and B-16). The
refractometer is used to determine the refraction index of
2-29. Extraction Heater. The extraction heater is
percent of total dissolved solids.
The instrument
stowed in cabinet F1 (figs. 1-2 and B-12). It is a
consists of a refracting prism system, a scale, a
thermostatically controlled hot plate with four sets of
compensation system consisting of Amici prisms which
extraction clamps supported on four vertical rods
permit the use of white light, and a telescope with
attached to the back of the unit. The clamps and rods
crosshairs which permit the borderline of total reflection
are stored in drawer E2 (fig. B-12). A repeatable heat
to be observed and set precisely. The refracting prism is
control and a percentage timer provide accurate and
fixed and horizontal and the observing eyepiece is
reproducible temperatures over the entire working
directly above the measuring prism. A pivotal mirror is
surface within a range of 150 degrees F to 800 degrees
used to move the total reflection dividing line. The index
F (66 degrees C to 427 ,degrees C). The extraction
scale is attached to the pivotal mirror. The single
heater may be used as a Utility hot plate by removing the
eyepiece is used to observe both the total reflection field
extraction clamp rods.
and the scale
Figure 2-28. Refractometer
2-49
