How long can Pope Dewars hold liquid Nitrogen?

Pope Low Form Dewars can hold Liquid Nitrogen for approximately 1 to 2 hours at the most depending on use.

The Cylindrical Lab Grade Dewars can hold liquid Nitrogen for approximately 2 to 8 hours depending on size and use.

The Spherical Dewars can hold liquid Nitrogen for approximately 1 – 2days depending on size and use.

Why does my Dewar get frost on the outside?

If your Dewar is getting frost on the outside, typically it is caused by a scratch or it may have lost the vacuum seal. If your Dewar is getting frost it has become defective in use.

How do you properly pre-chill or pre-warm a Dewar?

It is highly advisable to chill /warm any vacuum-insulated glass vessel before filling with extremely hot or cold liquids. This is easily accomplished by rinsing the vessel with a small amount of lukewarm liquid, warm liquid or cool liquid (depending on the temperature of the final liquid you are using), or liquid gas, in advance of filing.

Can I transport liquid nitrogen in your Dewars?

Pope Dewars are not meant for travel/transportation. The portability referred to is in regards to moving the Dewars within your facility. They are not DOT. And they are not meant for shipping.

Are Pope Dewars safe for food and beverage use?

No. Pope Dewars are not meant for food or beverage use.

What materials are OK to be used in a Dewar?

Any organic solvent or glass compatible material is ok to be used in a Dewar.  Never put hydrogen fluoride in the Dewar as it etches glass.

Please note:  Drastic changes to the temperature (thermal shocking) can cause damage to the Dewar.  Use caution against thermal shocking where you expose the Dewar to a temperature that is much greater than the temperature it currently is. It will cause damage to your Dewar and is unsafe.