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|  MIL-S-19819C(OS)
4.4.4.2 Pigtail wire securement test. This test shall also be performed
on Weight Assembly, 1277875 before it is hermetically sealed inside the
shell. Apply a pull of one pound using (4.4.3.2) to the pigtail wire along
the axis of the weight base. The pigtail wire shall meet the requirements
of 3.4.2.
4.4.4.3 Airtightness test. This test shall be performed upon the Firing
Switch Subassembly 1277873 before it is finally assembled into the plastic
case. Fill a container with sufficient water so that the subassembly can
be completely submerged. Place this water bath in the evacuation chamber
(4.4.3.3) and reduce the air pressure to at least 15 inches of mercury in
order to remove the air which is dissolved in the bath. Bring the pressure
back to ambient and submerge the firing switch subassembly in the deaerated
water bath. Evacuate the chamber to a pressure of 15 inches of mercury (max-
imum), and observe the bath and switch for a period of 2 minutes. Leakage
from the switch subassembly will be shown by escaping air bubbles. The fir-
ing switch subassembly shall show no leakage, to meet the requirements of
3.4.3.
4.4.4.4 Sensitivity and contact resistance test
4.4.4.4.1 Calibration of oscilloscope. Prior to performing the sensitivity
and contact resistance test, it is first necessary to calibrate the oscillo-
scope (4.4.3.5) to present a one-ohm deflection in fractions thereof. Connect
the test equipment as shown on the wiring diagram (Figure 1). The resistor
cutout switch shall be in the open position during the entire calibration.
Throw the calibration switch to position 1, and adjust the sweep so it is
deflected five scale divisions below center scale. Then throw the calibra-
tion switch to position 3, and adjust the sweep deflection five scale divi-
sions above center scale. Repeat these steps until the sweep remains properly
positioned when the calibrate switch is changed from position 1 to position 3
and the centrifuge is operating. The scope is now calibrated so that each
scale division represents one-tenth of an ohm, that is, the relationship be-
tween scale deflection and resistance will be linear.
4.4.4.4.2 Conversion of revolutions per minute (rpm) to gravity units.
Draw up another table or graph of rpm versus gravity units according to the
formula:
Where the following units apply:
A = gravity units of acceleration
R = Radial arm of centrifuge in feet; the radial arm of the centrifuge
shall be defined as the perpendicular distance from the axis of
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