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Dewar Flasks for Liquid Nitrogen
Dewar Flask, Small
A safe means of transporting, storing, handling and dispensing liquid nitrogen. Wide
mouth opening allows for easy filling and dispensing. Manufactured from borosilicate
glass, these flasks are very heavily insulated and wrapped with an exterior
aluminum metal housing that extends nearly to the top rim of the flask adding extra
safety protection. All flasks have a special vented, polypropylene stopper to minimize
evaporation. Smaller flask may be used with a vacuum trap apparatus for cooling
purposes. See page 510 for vacuum trap apparatus.
See free video at flinnsci.com.
Catalog No. Description
Outside
Diameter
Inside
Diameter
Inside
Depth Capacity Price/Each
AP1490 Dewar Flask,
Small
33/8" 2 3/4" 117/8" 1000 mL $186.00
AP1491 57/8" 4 1/4" 71/2" 1900 mL 415.00
Dewar Flask, Large
These lightweight Dewar flasks are recommended when required storage time
exceeds 24 hours. Aluminum construction allows storage of liquid nitrogen for several
weeks! Handles make dispensing a simple task.
See free video at flinnsci.com.
Catalog No. Description
Expiration
Rate
Outside
Diameter
Overall
Height Capacity Price/Each
AP8560 Dewar Flask,
Large
0.40 L/day 75/8" 165/8" 4 L $ 940.00
AP8562 0.22 L/day 113/8" 21" 10 L 1015.00
Regenerate Desiccants
Used and exhausted Drierite® and calcium chloride desiccants can easily be
regenerated. Spread the desiccant, one granule deep, in a shallow dish. Heat
for one hour in an oven at 205 °C. Place the regenerated desiccant, while still
hot, back into the original container. Tightly seal the container.
A temperature of less than 205 °C will not be sufficient to dehydrate the
desiccant completely, even if you leave the desiccant in the oven longer
than one hour.
The color of indicating desiccants tends to fade after several regenerations.
Dewar Flask, Small
AP1490, etc.
Dewar Flask,
Large
AP8560
Petri Dish, Borosilicate Glass
These dishes will remain clear after repeated wet or dry sterilization. Tops and
bottoms are marked with different colored enamels for quick identification.
Catalog No. Description Price/Pkg.
GP3019 Petri Dish, Borosilicate Glass, 100 x 15 mm $47.25/6
GP3020 88.35/12
Questions Most Commonly Asked About Liquid Nitrogen
How is liquid nitrogen made? Liquid nitrogen is made by cooling and compressing
air until it liquifies. The liquid air is allowed to warm up, and the nitrogen boils off first
and is collected, leaving the oxygen and argon as liquids. The collected nitrogen gas is
then compressed and cooled back into a liquid. It is quite easy to produce and relatively
inexpensive.
How long can liquid nitrogen be stored in a Dewar flask? Our best estimate is that a
good 1000-mL Dewar flask will lose approximately 500 mL for every 24-hour period stored.
The larger the Dewar flask, the slower the rate of loss.
Where can I purchase liquid nitrogen? We have had our best success purchasing liquid
nitrogen from local welding supply firms. Also look in the Yellow Pages under “Gas.”
How much does liquid nitrogen cost? Cost vary widely. Most outlets charge a minimum
fee of $10.00. You may pay as little as $1.00 per liter to more than $3.00 per liter.
How can you safely transport liquid nitrogen in your car? Place the specially vented
polypropylene stopper into the flask to minimize evaporation. Find a good-size cardboard
carton that will be stable in your car. Place the Dewar flask in the center of the carton and
stuff crumpled newspaper into the carton to tightly hold your flask. Place the carton with
your flask in the car and transport it directly to your school. Do not store your Dewar flask
in your car for an extended period of time. Transport the Dewar flask as far from the driver
Dewar Flask,
Large
AP8562
and passengers as possible to avoid any exposure from accidental spillage. Drive with the
windows slightly vented, not tightly sealed.
Can I use a regular Thermos® bottle to hold liquid nitrogen? No, do not use a regular
Thermos bottle! Why? Every Thermos-type vessel differs. The one you select to use could
have a plastic exterior that would crack and break from the temperature of the N2(l). An
unsafe situation would result. You might be tempted to use such a container and unknowingly
place the screw cap on the Thermos. As the N2(l) warms, gas pressure will develop
in the bottle and an explosion will result. Choose the safer option of using a dedicated and
safer laboratory Dewar flask.
Is liquid nitrogen safe? Liquid nitrogen should never be stored or transported in a tightly
sealed container. The expanded gas may cause the container to explode. Liquid nitrogen
can cause frostbite on contact with skin. Wear protective
clothing! If you accidentally spill
liquid nitrogen on clothing, do not let the soaked clothing remain in contact with the skin.
Always use liquid nitrogen in a well-ventilated area. Protective eyewear should be worn by
the demonstrator and the demonstration participants.
How can I dispose of excess liquid nitrogen? As N2(l) warms in an open container, it
simply returns to its natural gaseous state. The simple method of disposal is exposure to
air at room temperature. Avoid doing this in a poorly ventilated area.
Dishes
Crystallizing Dishes
Borosillicate glass dishes used for heating and cooling baths, crystallization, disposal
by evaporation and sand baths for microscale experiments. Available in two sizes.
Catalog No. Description Size Price/Each
GP9171 Crystallizing Dishes 80 x 40 mm $16.30
GP9172 150 x 75 mm 57.00
DISHES continued on next page.
Crystallizing Dishes
GP9171, etc.
Petri Dish, Disposable
Polystyrene. Sterile. Package of 20.
Catalog No. Description Size (mm) Price/Each Price/25 or More
AB1470 Petri Dish, Disposable,
Pkg. of 20
50 x 15 $7.50 $6.15
AP8170 90 x 15 6.45 5.42
Petri Dish, Borosilicate Glass
GP3019, etc.
Petri Dish,
Disposable,
AB1470, etc. and
AB1471, etc.
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