Filling--Adding liquid nitrogen to a warm dewar may cause splashing and will generate a significant volume
of nitrogen gas as old liquid contacts warm dewar surfaces. Add liquid slowly
to minimize these effects. Be sure there is adequate ventilation. Keep your head clear of the heavy volume of vapor that may be produced:
it is extremely cold and could cause personal injury.
Determining Liquid Level--Liquid
level must be checked at regular intervals--refrigeration depends on the presence of liquid nitrogen. The liquid level in the dewar can be determined by measuring with a dipstick. Insert the dipstick straight into the dewar so that it always rests on the canister positioning fixture
in the bottom of the unit. After 5 to 10 seconds, withdraw the dipstick and wave
it back and forth in the air. A frosted section will form representing the depth
of liquid in the dewar.
Never use hollow rods or tubes as dipsticks. When a warm tube is inserted into liquid nitrogen, liquid will spout from the top of the tube and may cause
Inserting or Removing Racks--To prevent the unnecessary
loss of liquid nitrogen refrigerant, the necktube core should remain in the container when the stored material is not being
accessed. When accessing stored material, the necktube core should be removed
as briefly as possible.
When inserting or removing the racks, grasp the rack handle, lift and tilt the rack toward the center
of the dewar and withdraw the rack only far enough to remove the contents. Completely
withdrawing the rack will unnecessarily expose stored material to warm conditions.
Some racks have liquid drain openings; some
do not. If racks are completely removed from the container, liquid nitrogen may
remain in the rack or drain from the bottom. When removing racks, stop briefly
at the necktube to allow the liquid to drain completely, then handle the rack carefully to prevent personal injury.
When room temperature product is added, slowly lower the rack into the dewar to reduce the boiling
of refrigerant and the surge of cold nitrogen gas. When inserting the rack, tilt
the bottom of the rack in the direction of the index ring notch. The numbers
on the index ring notches are a convenient aid to inventory control.
FILLING INSTRUCTIONS FOR
CRYOPRO VAPOR SHIPPERS
THESE HIGH QUALITY VACUUM INSULATED UNITS ARE CONSTRUCTED OF DURABLE MATERIALS, COMPATIBLE WITH THE DIVERGENT TEMPERATURE
EXTREMES AND BROAD APPLICATIONS OF CRYOBIOLOGY. THE MATERIAL USED IN CONSTRUCTION
AFTER 1993 IS HYDROPHOBIC (WILL NOT ABSORB WATER) WHICH UNLIKE CALCIUM SILICATE DOES NOT NEED TO BE PERIODICALLY HEATED TO
REMOVE ABSORBED MOISTURE.
THE CRYOPRO VAPOR SHIPPERS WERE PRIMARILY DESIGNED AS VAPOR SHIPPING CONTAINERS; HOWEVER, THEY CAN BE USED FOR IMMERSION
OFSAMPLES. WHEN USING IN EITHER CONDITION, THE RECOMMEDED FILLING PROCEDURE IS
AS FOLLOWS: FILL THE UNIT TO THE BOTTOM OF THE NECK AND ALLOW THE LIQUID NITROGEN TO ABSORB.
UPON COMPLETE ABSORPTION OF THE FIRST FILL OF LN2, WHICH SHOULD TAKE A MINIMUM OF 12 HOURS, REPEAT WITH ANOTHER FILL. REPEAT AGAIN IF NECESSARY. COMPLETE ABSORPTION
MAY TAKE UP TO 24 HOURS. AFTER COMPLETING THE LAST FILL, JUST PRIOR TO SHIPMENT,
POUR OFF THE EXCESS LIQUID IF THEY ARE INTENDED TO BE USED AS A VAPOR (DRY) SHIPMENT.
TO ENSURE THAT THE VAPOR SHIPPERS HAVE ABSORBED THEIR FULL CAPACITY OF LIQUID, IT IS ADVISABLE TO WEIGH THEM. TO COMPLETELY FILL THE ABSORBENT, THE SUGGESTED ABSORBED WEIGHT OF THE UNITS (WITHOUT
CANISTERS INSIDE) AS LISTED BELOW SHOULD BE REACHED. THIS WILL ALLOW THE CONTAINERS
TO HOLD THE MAXIMUM NUMBER OF DAYS IN THE VAPOR PHASE.
WEIGHT FULL (SUGGESTED)
STATIC HOLD TIME (DAYS)
DURING THE INITIAL FILL, OR AFTER THE UNIT IS ALLOWED TO WARM, THE AMOUNT OF LN2 NEEDED
TO FILL THE ABSORBENT WILL BE GREATER. THE TIME NEEDED FOR THIS FILLING PROCEDURE
WILL ALSO BE GREATER.
INSTRUCTIONS FOR TESTING CRYOPRO VAPOR UNITS PRIOR TO EACH SHIPPING
THESE HIGH QUALITY VACUUM INSULATED UNITS ARE CONSTRUCTED OF DURABLE MATERIALS
COMPATIBLE WITH THE WIDE RANGE OF TEMPERATURE EXTREMES COMMONLY EXPERIENCED IN CRYOBIOLOGICAL PROCESSES. ALTHOUGH EVERY CRYOPRO UNIT HAS BEEN FACTORY TESTED, IT IS RECOMMENDED THAT THE DEWARS BE TESTED AGAIN
PRIOR TO SHIPPING TO END USER TO ENSURE THE VIABILITY AND SAFETY OF YOUR STORED MEDIA.
ITEMS SUCH AS FREIGHT DAMAGE DO NOT ALWAYS APPEAR OBVIOUS AND THIS TEST PROCEDURE MAY PREVENT POSSIBLE PRODUCT &
TO ENSURE MAXIMUM PERFORMANCE FROM YOUR CRYOPRO DEWAR SIMPLY FOLLOW LISTED STEPS JUST PRIOR TO SHIPING TO FINAL DESTINATION:
1. OPEN BOX THAT
DEWAR IS IN & REMOVE FROM CARTON
OPEN LID & REMOVE CORK/COVER (do not twist)
3. FILL UNIT TO APPROXIMATELY ¾
A. Follow established safety practices & procedures for transferring LN2
B. Transfer using LN2 hose with
phase separator or pouring container & approved funnel
C. Canisters are to remain inside dewar
4. REPLACE CORK/COVER
& LET UNIT STAND FOR 24 HOURS (cooling down unit).
5. WEIGH UNIT (first weight)
6. ALLOW UNIT
TO SIT FOR ANOTHER 24 HOURS
WEIGH SECOND TIME (second weight)
8. CALCULATE EVAPORATION RATE. THE DIFFERENCE BETWEEN THE FIRST WEIGHT AND THE SECOND WEIGHT IS THE EVAPORATION RATE
IN LBS. THIS CAN BE CONVERTED TO LITERS BY MULTIPLYING LBS. X .5606. THIS FIGURE ROUGHLY SIGNIFIES THE N.E.R.=(first weight – second weight) X .5606 is liter/day
A. Also during this time take note of any uncommon occurrences such as excess frosting or
along outside of dewar. Take note of excess nitrogen boil off especially after
LN2 should settle (cease boiling) after an hour.
How to take care of your liquid nitrogen refrigerator or dewar while taking care of
Protect yourself and others. Read and understand this section.
Keep it available for reference at all times. You can get additional copies through your supplier.
Use only liquid
nitrogen or liquid argon in Liquid Nitrogen Refrigerators and Dewars. Do not use liquid air or liquid oxygen, both of which
may present a combustion hazard with some materials used in the construction of these units, or materials stored in them.
safe handling and use of liquid nitrogen in cryogenic refrigerators and dewar flasks is largely a matter of knowing the potential
hazards and using common-sense procedures based on that knowledge. There are two important properties of liquid nitrogen that
present potential hazards:
It is extremely cold. At atmospheric pressure, liquid nitrogen boils at -320 F
2. Very small amounts of liquid vaporize into large amounts of gas. One liter of liquid nitrogen becomes
24.6 cu. ft. (0.7 m3) of gas.
The safety precautions in this section must be followed to avoid potential injury or damage which could result from
these two characteristics. Do not attempt to handle liquid nitrogen until you read and fully understand the potential hazards,
their consequences, and the related safety precautions. Keep this handy for ready reference and review.
Note: Because argon
is an inert gas whose physical properties are very similar to those of nitrogen, the precautions and safe practices for the
handling and use of liquid argon are the same as those for liquid nitrogen.
Contact of liquid nitrogen or cold gas with the skin or eyes may cause serious freezing
Handle liquid nitrogen carefully.
low temperature can freeze human flesh very rapidly. When spilled on a surface the liquid tends to cover it completely and
intimately, cooling a large area. The gas issuing from the liquid is also extremely cold. Delicate tissue, such as that of
the eyes, can be damaged by an exposure to the cold gas which would be too brief to affect the skin of the hands or face.
Never allow any unprotected part of your body to touch objects cooled by liquid nitrogen.
Such objects may stick fast
to the skin and tear the flesh when you attempt to free yourself. Use tongs to withdraw objects immersed in the liquid, and
handle the object carefully.
Wear protective clothing.
Protect your eyes with a face shield or safety goggles (safety glasses
without side shields do not give adequate protection). Always wear gloves when handling anything that is, or may have been,
in immediate contact with liquid nitrogen. Insulated gloves are recommended, but heavy leather gloves may also be used. The
gloves should fit loosely, so that they can be thrown off quickly if liquid should splash into them. When handling liquid
in open containers, it is advisable to wear high-top shoes. Trousers (which should be cuffless if possible) should be worn
outside the shoes.
Use only containers designed for low-temperature liquids.
Cryogenic containers are
specifically designed and made of materials that can withstand the rapid changes and extreme temperature differences encountered
in working with liquid nitrogen. Even these special containers should be filled SLOWLY
to minimize the internal stresses that occur when any material is cooled. Excessive internal stresses can damage the container.
Do not cover or plug the entrance opening of any liquid nitrogen refrigerator or dewar. Do not use any stopper or other
device that would interfere with venting of gas.
These cryogenic liquid containers are generally designed to operate with
little or no internal pressure. Inadequate venting can result in excessive gas pressure which could damage or burst the container.
Use only the loose-fitting necktube core supplied or one of the approved accessories for closing the necktube. Check the unit
periodically to be sure that venting is not restricted by accumulated ice or frost.
Use proper transfer equipment.
Use a phase separator or special filling funnel to prevent splashing and spilling when transferring liquid nitrogen
into or from a dewar or refrigerator. The top of the funnel should be partly covered to reduce splashing. Use only small,
easily handled dewars for pouring liquid. For the larger, heavier containers, use a cyrogenic liquid withdrawal device to
transfer liquid from one container to another. Be sure to follow instructions supplied with the withdrawal device. When liquid
cylinders or other large storage containers are used for filling, follow the instructions supplied with those units and their
Do not overfill containers.
Filling above the bottom of the necktube (or specified maximum level)
can result in overflow and spillage of liquid when the necktube core or cover is placed in the opening.
Never use hollow rods or
tubes as dipsticks.
When a warm tube is inserted into liquid nitrogen, liquid will spout from the bottom of
the tube due to gasification and rapid expansion of liquid inside the tube. Wooden or solid metal dipsticks are recommended;
avoid using plastics that may become very brittle at cryogenic temperatures.
Gas can cause suffocation without warning.
Store and use liquid nitrogen
only in a well-ventilated place.
As the liquid evaporates, the resulting gas tends to displace the normal air from the area.
In closed areas, excessive amounts of nitrogen gas reduce the concentration of oxygen and can result in asphyxiation. Because
nitrogen gas is colorless, odorless and tasteless, it cannot be detected by the human senses and will be breathed as if it
were air. Breathing an atmosphere that contains less than 18 percent oxygen can cause dizziness and quickly result in unconsciousness
The cloudy vapor that appears when liquid nitrogen is exposed to the air is condensed moisture, not the gas itself. The issuing gas is invisible.
Never dispose of liquid nitrogen in confined
areas or places where others may enter.
Disposal of liquid nitrogen should be done outdoors in a safe place.
Pour the liquid slowly on gravel or bare earth where it can evaporate without causing damage. Do not pour the liquid on the
First Aid Notice
If a person seems to become dizzy or loses consciousness while working
with liquid nitrogen, move to a well-ventilated area immediately. If breathing has stopped, apply artificial respiration.
If breathing is difficult, give oxygen. Call a physician. Keep warm and at rest.
If exposed to liquid or cold gas, restore tissue to normal body temperature 98.6 F (37
C) as rapidly as possible, followed by protection of the injured tissue from further damage and infection. Remove or loosen
clothing that may constrict blood circulation to the frozen area. Call a physician. Rapid warming of the affected part is
best achieved by using water at 108 F (42 C). Under no circumstances should the water be over 112 F (44 C), nor should the
frozen part be rubbed either before or after rewarming. The patient should neither smoke, nor drink alcohol.
Handling Dewars and Refrigerators
Keep unit upright at all times except
when pouring liquid from dewars specifically designed for that purpose.
Tipping the container or laying it on its side can cause spillage of
liquid nitrogen. It may also damage the container and any materials stored in it.
Rough handling can cause serious damage
to dewars and refrigerators.
Dropping the container, allowing it to fall over on its side, or subjecting it to sharp
impact or severe vibration can result in partial or complete loss of vacuum. To protect the vacuum insulation system, handle
containers carefully. Do not "walk", roll or drag these units across a floor. Use a dolly or handcart when moving
containers, especially the larger portable refrigerators. Large units are heavy enough to cause personal injury or damage
to equipment if proper lifting and handling techniques are not used.
Do not attempt to move large stationary-type refrigerators unless they are completely empty.
When transporting a liquid nitrogen container, maintain adequate ventilation and protect the unit from damage.
place these units in closed vehicles where the nitrogen gas that is continuously vented from unit can accumulate. Prevent
spillage of liquids and damage to unit by securing it in the upright position so that it cannot be tipped over. Protect the
unit from severe jolting and impact that could cause damage.
Keep the unit clean and dry.
Do not store it in wet, dirty
areas. Moisture, animal waste, chemicals, strong cleaning agents and other substances which could promote corrosion should
be removed promptly. Use water or mild detergent for cleaning and dry the surface thoroughly. Do not use strong alkaline or
acid cleaners that could damage the finish and corrode the metal shell.
Materials stored in liquid nitrogen refrigerators are protected by the
extremely low temperature of the liquid nitrogen or the gas that issues from the evaporating liquid nitrogen. When all of
the liquid nitrogen has evaporated, the temperature inside the unit will rise slowly to ambient. The rate at which the liquid
nitrogen will evaporate depends upon the pattern of container use and the age and condition of the container. Evaporation
increases as insulation efficiency deteriorates with age and rough handling. Opening and closing to insert and remove materials
and moving the unit will also increase the evaporation rate.
To protect valuable material stored in a liquid nitrogen refrigerator:
Check the liquid level in
unit frequently, at least once each week.
Failure to properly monitor liquid nitrogen level can permit undetected
loss of refrigeration with resulting damage to the material stored in the unit.
Refill the refrigerator as required
to maintain protection of the stored materials.
Always be sure that there is enough liquid nitrogen in the unit to last
until the next scheduled refill. When contents must be kept at liquid temperature, keep the liquid level high enough to cover
the materials. When gas-phase temperatures provide adequate protection, the liquid level can be lower.
Condensed moisture or frost
on the outer shell of a refrigerator and abnormally rapid evaporation of the liquid nitrogen are indications of vacuum loss.
If vacuum loss is evident or suspected, transfer the materials stored in the unit to another refrigerator as soon
as possible and remove the unit from service.