Operation of the
Refractometer
The refractometer is to be used in the quality
surveillance lab, not on the flight deck or on the
sponson. The light source can be a fluorescent or
incandescent bulb, but the area must be well lighted.
To use the instrument, perform the following steps:
1. Set up the ring stand assembly as shown in
figure 3-10.
2. Use prescribed sampling procedures and take
a 1-quart sample of the fuel to be tested in a clean
sample bottle.
3. Half fill the aluminum dish with tap water.
4. Fill the graduated cylinder (fig. 3-10) and the
separator funnel about one-third full with the fuel to
be tested. Rinse the cylinder and funnel thoroughly to
clear them of any foreign material and empty the
contents.
5. Now fill the graduated cylinder with exactly
160 ml of the fuel sample.
6. Check to see if the drain cock on the separator
funnel is closed. If not, close it and pour the 160 ml
from the graduated cylinder into the separator-y
funnel.
7. Using a piston pipet, add exactly 2 ml of water
from the dish to the separator funnel. Place the capon
the funnel and shake it for 3 minutes. Place the
funnel in the ringstand as shown (fig. 3- 10).
8. Open the hinged plastic cover of the refrac-
tometer’s window (fig. 3-11), make sure the window
and cover are clean, and place several drops of water
on it. Close the cover and look through the eyepiece.
Observe the shadow line. Remove the black plastic
rod from the bottom of the refractometer. Using the
rod, adjust the setscrew (on the bottom of the
refractometer) until the shadow line meets the zero
line of the scale. See figures 3-12 and 3-13. By
adjusting the set screw
Figure 3-12.—Refractometer (side view).
Figure 3-13.—Views through a refractometer.
3-24
