TM 5-6640-212-14
2-35. Dry Ice Machine.
2-36. Utility Bath.
a. Description. The dry ice machine (fig. 2-33) is
a. Description. The utility bath, designed to meet
the requirements specified in ASTM Methods D91 and
designed to comply with the requirements specified in
D1796 (TM 10-1166) is stored in drawer B5 (figs. 1-2
ASTM Method D2386 (TM 10-1166). It is mounted on a
and B-8). It is a constant temperature, thermostatically
platform in the rear compartment immediately forward of
controlled general utility bath. The hydraulic thermostat is
the carbon dioxide cylinders. The dry ice machine is
sensitive to within plus or minus 0.1 degrees C. The unit
capable of producing fifteen to twenty 12-ounce cakes of
can control the bath liquid at temperatures up to a
dry ice from a standard 50-pound cylinder of compressed
maximum of 100 degrees C plus or minus 0.3 degrees
carbon dioxide. The machine is connected to the gas
C. Thorough mixing of the heated solution is obtained by
cylinder by copper tubing. Dry ice cakes are made only
means of a perforated diffuser shelf.
as required and are used primarily for cooling cloud and
b. Operation.
pour point test baths and wherever required for
application of low temperatures.
The machine is
(1) Place the unit on the countertop and plug the
equipped with a hinged cover and safety valves, and is
service cord into a 120-volt convenience outlet.
provided with strainer, copper tubing, and fitting for
(2) Fill the bath with water to the desired level.
attachment to the carbon dioxide cylinders.
(3) Insert the thermometer in the space provided at
b. Operations.
the top of the bath.
WARNING
(4) Set the temperature control knob for the desired
temperature. Observe the immersed thermometer and
Wear safety goggles and cloth gloves
refine the control setting until the exact temperature is
while operating dry ice machine.
indicated
NOTE
(5) Refer to ASTM Methods D91 and D1796 (TM
Do not invert carbon dioxide
10-1166) for detailed test instructions.
cylinders.
2-37. Copper Strip Corrosion Bath.
(1) Both carbon dioxide cylinders are equipped with
a. Description. The copper strip corrosion bath,
an internal pipe extending from the valve to the bottom of
designed to comply with the requirements specified in
the tank to facilitate removal of the liquid carbon dioxide
ASTM D130 (TM 10-1166), is stored in drawer B5 (figs,
to the dry ice machine. Connect one end of tubing to the
1-2 and B-8). The apparatus consists of a constant
cylinder and the other to the valve on the side of the dry
temperature bath having a temperature range from room
ice machine. Make certain fiber washers are properly
temperature to 110 degrees F plus or minus 0.6 degrees
positions.
F, openings for four test bombs, four rubber stoppers, a
NOTE
thermometer well, copper Soxhlet condensers,
When recharging cylinders, make
thermostat, and drain plug. It is also provided with two
certain that internal pipe and valve
test bombs and an ASTM 12F thermometer having a
connected to the pipe remain with the
range of minus 5 degrees F to plus 215 degrees F
charged cylinder.
(minus 11.6 degrees C to 101.5 degrees C). The test
(2) Close the cover of the ice machine, engaging the
bombs, copper strips, and copper strip corrosion
handle securely. Close gas control valve on side of
standards are stored in drawer D3 (fig. B-10). The overall
machine. Open the cylinder valve.
dimensions of the apparatus are 7 inches wide by 12 1/2
(3) Open the gas control valve slightly until gas can
inches deep by 24 inches high (178 mm wide by 432 mm
be heard entering the machine and hold open for about
deep by 609 mm high). The apparatus requires a
30 seconds or until safety valve on top of machine
minimum of 750 watts.
discharges or the cover is raised by the safety valve on
the cover hinge, indicating that cavity is filled with dry ice.
b. Operation.
It is normal for excess gas to escape on the sides and
bottom of the machine while the dry-ice cake is being
(1) Fill the bath with water through the bomb hole.
formed.
To heat the constant temperature bath to operating
(4) Close gas control valve and remove dry-ice
temperature, connect the power cord and turn the line
cakes.
switch to the ON position. Adjust the bath to the desired
temperature by turning the graduated dial on the
thermostat.
2-62
