Figure 2-21 .
Transfer operation liquid fill, storage compartment
reaches the bottom of the vapor equalizing dip tube
has elapsed. Stop the pump immediately when either
inside the vessel, the tank is at full capacity.
indication is observed.
(2) Check for Overfilling. It is important that the
level of the liquid carbon dioxide inside the pressure
If pumping is continued after capacity is
vessel be kept no higher than the bottom of the vapor
reached, liquid carbon dioxide will enter the
equalizing line dip tube. After complete filling of the
vapor equalizing line instead of vaporous
pressure vessel and after the hoses have been
carbon dioxide. The cold liquid in the vapor
disconnected, open the vapor equalizing line valve (23,
equalizing line will cause that line to
2-8) slightly to discharge carbon dioxide to
accumulate frost, and indicate that complete
atmosphere. If the discharge is clear or only slightly
filling has been obtained.
(c) Pressure Gage.
foggy, the tank has not been overfilled. However, if the
Another method of
discharge is a dense, white cloud containing particles of
determining when the tank is full is to observe the
dry ice, the liquid level in the tank is too high. To
pressure gages (1 and 3, fig. 2-4). As long as liquid
remedy this, carbon dioxide discharge from the vapor
enters the bottom of the vessel and vapor returns
equalizing line connection should be allowed to continue
through the vapor equalizing line, the pressure will
slowly until the dense white discharge changes to a
remain approximately constant. As soon as the liquid
clear or blue fog discharge.
level reaches the vapor equalizing dip tube and liquid is
f. Disengage the transfer pump clutch, and close
forced into the vapor equalizing line, the pressure will
the liquid fill and vapor equalizing line valves on the
suddenly begin to rise.
(d) Amount of Carbon Dioxide Required to Fill
liquid supply unit.
g. Close valves 1, 2, and 9. Open valves 27 and
If the pumping rate is known, it can be
28 to bleed off the carbon dioxide trapped in the transfer
determined from the liquid level gage reading before
hoses, and then disconnect the transfer hoses. Check
pumping is started how much carbon dioxide will be
required to fill the tank and approximately how long it
will take to pump this amount of carbon dioxide. Be
alert for the indications outlined in (b) and (c) above,
several minutes before this time