TM 5-6640-212-14
and remove the partition. Unscrew knurled knobs (4 and
(4) Pilot light.
5, fig. 3). Separate the upper part of the weight carriage
(a) Turn muffle furnace on its side, tag and
from the lower while holding the lower to prevent it from
remove wires going to pilot light.
falling into the weighing compartment. Take out the
(b) Remove spring nut attaching light to lower
lower part and switch the weight decade slowly from 9 to
chassis and remove pilot light (2, fig. 3-1 and 3-3).
8 to 7, etc., to zero. While doing this, remove the
3-14. High Pressure Steam Boiler.
corresponding weights which will be lying freely in their
a. Inspection.
respective hooks. Clean the weights thoroughly. Do not
(1) Inspect the terminal end of the heater to be
leave fingerprints on the surface. Handle weights with
sure it is protected from drippings, condensation, spray,
forceps only. After cleaning, reassemble the balance
or direct spillover of material.
check zero, calibrate, and adjust sensitivity, if necessary.
WARNING
(2) To clean the weighing compartment interior,
Disconnect power before removing
arrest the balance, remove the weighing pan and wipe
the interior clean, using a water-damp chamois. Wring
(2) Remove the heating element and scale
the chamois dry and wipe again, removing all traces of
periodically and inspect for signs of deterioration.
water. Remove dust particles, using a camel's hair
b. Cleaning. Clean the exterior of the boiler with a
brush. Clean and replace the weighing pan. Sliding
clean cloth and mild soap and water solution.
glass doors may be removed for cleaning. Wipe the
3-15. Gum Bath.
exterior of the balance clean, using the waterdamp
a. Inspection. Check to see if the gooseneck tubes
chamois.
Do not attempt to clean the balance
are installed. Visually inspect condition of switches on
mechanism other than the weights and knives unless the
lower side of gum bath for smooth action, any breakage
balance malfunctions.
or foreign matter. Check stainless steel housing and top
CAUTION
ring for foreign matter. Inspect thermocouple leads
DO NOT ATTEMP TO REPAIR THE
going to pyrometer for breaks or defective insulation.
BALANCE. Only a skilled service
Check for breaks or defective insulating on power cord.
repairman with factory facilities
Check thermostat tubing from high pressure boiler
available should attempt repairs.
control to gum bath for breaks or kinks.
Adjustment and calibration can be
b. Cleaning. Clean the exterior of the boiler with a
accomplished by the laboratory
clean cloth and mild soap and water solution.
technician.
3-16. Analytical Balance. Figures 2-21, 3-4 and 3-5
c. Calibrating.
give various views of the analytical balance. The
(1) Check zero the balance (fig. 2-21) by rotating
cleaning and calibrating procedures explained below
weight control knobs until the macro scale shows zero;
refer to these figures.
then rotating the micrometer drum knob until the optical
a. Inspection. Inspect the glass doors and glass
scale is zeroed, or until the micrometer line is as nearly
weighing chamber for cracks and chips.
on zero as the mechanical lash in the knob control will
b. Cleaning.
allow; and finally, rotating the zero control knob until zero
(1) From time to time clean the weights of the
shows on the micro scale. If exact zeroing of the micro
balance with a camel's hair brush or chamois leather. To
scale cannot be achieved, zeropoint adjust the balance
remove the weights, arrest the beam and take off the
as noted in (4) below. If the range of the zero control
hood. Move all knobs to the maximum setting so that
knob does not permit zeropoint adjustment, readjust
scales show 99.9999. Remove the weighing pan from
range as noted in (5) below. If macro scale cannot be
the weighing compartment. Lift the weight carriage and
zeropoint adjusted, the range of the weight control knobs
swing the weight carriage bridle forward to detach it from
must be adjusted as described in (6) below.
the bearing (stirrup) plate. Unscrew two large knurled
(2) Scale illumination can be increased by
head screws in the ceiling on the weighing compartment
adjusting bulb contact to provide maximum bulb
brightness. If additional illumination is desired, remove
the hood and loosen the knurled head screw (7, fig. 3-4)
which holds the cover on the
3-23
