1300-87014-1M, REV 2 Cole-Parmer® Page 5 of 7
last depends on room temperature, sample load, humidity, rate of samples being taken
in and out, etc. If the CryoStation is regularly recharged with LN, it can maintain
samples at low temperature indefinitely.
Liquid nitrogen has a boiling point of -195.80 C (-320.4°F) and can freeze skin on contact
with the liquid itself. Metal chilled by LN can be even more dangerous because of its
ability to conduct heat away from the skin. Samples and sample containers can also
cause “freezer burn” if handled with unprotected skin. While very brief contact of LN
with skin may not be harmful in open air if the LN boils away, keeping LN in contact with
skin will cause damage quickly. LN has a remarkable ability to penetrate fabric, the
seams of gloves, etc., so caution must be taken when working with LN. Always wear
protective clothing, cryogloves, and safety glasses.
CHARGING THE CRYOSTATION
Before using the CryoStation, fill it with liquid nitrogen (LN). First place the CryoStation
on a lab bench, and adjust the vent so it is pointed away from people, instrumentation,
or anything that might be damaged by severe cold or water from condensation. If the
CryoStation is overfilled, LN can come out of the vent, but this is rare. The vent directs
nitrogen vapor from boiling nitrogen away from the CryoStation. The smoke-like
appearance of the vapor is due to condensed atmospheric water (fog).
The LN vapor issuing from the vent can chill anything in its path. Once cooled it will
attract condensation. If this is a problem, a tube can be attached to the vent and
directed into a cooler or pail.
The CryoStation can be filled with LN manually through the manual fill port, or through a
hose threaded into the hose fill port. In either case, when LN is first poured into the
CryoStation most of it will boil away, and be purged through the vent. As the body of
the CryoStation cools, the amount of vapor from the vent will be greatly reduced.
As the CryoStation fills with LN, the LN level indicator will rise. The CryoStation is full
when the float in the LN level indicator rises to the top of the tube, or when LN
overflows from either of the fill ports or the vent. If the CryoStation is being filled
through a hose, turn off the LN line valve at the LN tank, then unscrew the connection at
the CryoStation Hose Fill Port. Both fill ports should be capped.
If a digital, thermistor-based thermometer is available; its probe can be placed in the
CryoStation cooling chamber to monitor the temperature there. Whenever the
CryoStation is first being used in a new environment, it is advisable to determine how
long one full charge of LN will keep samples cold in the cooling chamber.