regulating valve may remain constant until all cylinders
have been filled. This will reduce packing wear.
Do not allow the cylinder filling unit to idle at
charging pressure for long periods of time.
This will cause pressure build-up within the
pressure vessels and wear to the cylinder
j. After the cylinder filling operations are
complete, adjust valve 14 (fig. 2-25) counterclockwise
to reduce the gage pressure to approximately 300 psi
(21.18 kg per sq cm). Disengage the cylinder filling unit
clutch (2, fig. 2-3) and set the valves for the normal
position as indicated in Figure 2-13. Set the controls for
automatic operation, and engage the refrigeration clutch
(3) (fig. 2-3). Remove the cylinder filling hoses, and
replace in the storage compartment.
2-15. Determining Liquid Level While Pumping
a. Liquid Level Gage. The unit is equipped so that
the liquid level gages (2 and 4, fig. 2-4) indicate the
contents of the pressure vessels (in tenths of capacity)
even during pumping. Thus the contents can be
Cylinder filling operation .
determined by reading the gages and allowing for slight
b. Liquid in Vapor Equalizing Line. When filling
operator will determine a suitable charging pressure.
g. Open valve on cylinder to be filled and
the pressure vessels, it is usually desirable to fill them
corresponding valve 16 or 18 (fig. 2-25).
completely. The normal course of the carbon dioxide
during filling is for liquid to enter at the bottom of the
As the empty cylinder starts filling, the
vessels while carbon dioxide vapor flows out at the top
charging pressure, indicated on the pressure
of the vessels, returning to the tank from which the
gage, will decrease and gradually regain the
liquid is being pumped. When the liquid level in the
charging pressure as the cylinder fills.
pressure vessel rises until it reaches the bottom of the
vapor equalizing dip tube inside the vessel, the tank is
h. Allow the cylinder to fill until the proper v/eight
at full capacity.
is reached. When the cylinder is full, close the valve on
the cylinder and the corresponding valve 16 or 18.
If pumping is continued after capacity is
Bleed off pressure trapped in the hose through valve 17
reached, liquid carbon dioxide will enter
or 19. Do not overfill the cylinder. The total weight of a
the vapor equalizing line instead of
completely charged cylinder is stamped on the cylinder.
vaporous carbon dioxide. The cold liquid
in the vapor equalizing line will cause that
line to accumulate frost, and indicate that
If a cylinder is overfilled, discharge the
complete filling has been obtained.
excess carbon dioxide so that the
c. Pressure Gage. Another method of determining
frangible disc on the cylinder is not
when the tank is full is to observe the pressure gages (1
i. If cylinders of the same size are being filled
and 3, fig. 2-4). As long as liquid enters the bottom of
the vessel and vapor returns through the vapor
alternately, in pairs, with continuous charging taking
equalizing line, the pressure will remain approximately
place, one connection is used for filling and the other
constant. 'As soon as the liquid level reaches the vapor
connection is used for attaching or removing the second
equalizing dip tube and liquid is forced into the vapor
cylinder. Setting of the pressure
equalizing line, the pressure will suddenly begin to rise.