Preparing For Shipping; Measuring Liquid Nitrogen Quantity - Thermo Scientific Arctic Express CK50920 Mode D'emploi

Section 4
Operation
Measuring Liquid
Nitrogen Quantity
Preparing for
Shipping
4-2 Cryogenic Dual Shippers
1. Use a wooden yardstick to measure liquid nitrogen level. Never use a
hollow tube or plastic dipstick to measure liquid nitrogen level.
2. Level will be indicated by frost line which develops when dipstick is
removed and waved in a back and forth motion away from the user.
The Dual Shipper contains a solid absorbent which holds liquid nitrogen.
During shipment, there is no "liquid" nitrogen to move around and
potentially spill within the airplane, truck or train. Only absorbed nitrogen
and boil-off from absorbed nitrogen is present to keep samples at cryogenic
temperatures.
A "warm" shipper, one standing at room temperature, should not be
immediately filled with liquid nitrogen. A small amount of liquid nitrogen
should be dispensed into the shipper. The top of the shipper is then closed
and the container allowed to equilibriate for approximately 2 hours. After
this period, the vessel may be filled with liquid nitrogen. It is important
that the level of liquid nitrogen remain below the fiberglass necktube of the
vessel and that it not come in contact with the vacuum port which is
covered with a black plastic cap.
Shortly after filling the vessel, it is important to check for areas of frost or
"sweating." Frost patches and sweating are not normal and may signify a
compromised vacuum. Vacuum leaks will measurably decrease holding
times and may endanger sample integrity. If you suspect a vacuum leak,
call Technical Services. Do not ship precious samples if there is any other
alternative!
In preparation for shipping, the vessel should be allowed to remain full of
liquid nitrogen for 24 hours. At the end of this period, the liquid
remaining in the vessel should be poured off into another vessel. Charging
is now complete and full transfer holding times will be achieved.
It is important that shippers remain in the upright position during transit.
The mushroom-shaped shipping cases provided with the Dual 10, 19, and
28 shippers are especially shaped to prevent the shipper from being
inverted or placed on its side. Holding times are significantly reduced from
the stated values if the containers are not kept upright during shipping.
Thermo Scientific