The dry dewar is employed to transport target materials at LN2 temperature (77K). In practice, the dewar doesn't contain LN2 directly; rather, it employs an absorbent to saturate and maintain the LN2, thus preserving the target material at LN2 temperature. Prior to usage, some prerequisites should be observed: check for vacuum integrity, inspect for leaks, invert the dewar to ensure no LN2 flow, and fully charge the dry shipper with LN2 until no LN2 escapes. 

To verify if the dewar is fully charged:

  • Check the weight:
    • Empty Dry Shipper: 11.7 lbs (absorbent without LN2)
    • Full Dry Shipper: 19 lbs (absorbent with LN2)
  • The calculation is as follows:
    • 1 liter of LN2 = 1.782 lbs
    • 4 liters of LN2 (absorbent holds 4.1L) = 7.30 lbs

So, the total dewar weight is the sum of the empty Dry Shipper weight (11.7 lbs) and the absorbent holding 4.1L of LN2 (7.30 lbs), resulting in a total of 19 lbs.

Here are some important information that we used to write up the document for dry shipper to ship CH2/CD2 and NH3/ND3. 

Documentation from Vendors:

We received documentation from Vendors to prepare dry shipper. K SERIES Cryostorage System.pdf 

W.E. Sanders letter of Compliance:  

We received W.E.Sander letter of Compliance for dry dewar. UVa dry Dewar compliance evaluation 13sep2023.docx 

UVA training material:

    

Dry Shipper and Dry Box: 

  1. Dry Shipper (https://www.mitegen.com/product/cryo-express-dry-shipper-cx100/) 
    1. Dry Shipper specs are listed on the weblink. 
  2. Shipping Case (https://www.mitegen.com/product/cryo-express-dry-shipper-cx100-with-case/)
    1. Shipping Case specs are listed on the weblink. 

DOT code compliance and exceptions:

  1. 49 CFR § 173.320 - Cryogenic liquids; exceptions (https://www.law.cornell.edu/cfr/text/49/173.320#:~:text=(a)%20Atmospheric%20gases%20and%20helium,temperature%20conditions%20during%20transportation%20are) 

  2. Liquid Nitrogen Dry Shippers Preparation and Shipping Requirements by Environmental Health & Safety (https://ehs.weill.cornell.edu/announcements/liquid-nitrogen-dry-shippers-preparation-and-shipping-requirements)

Misc Resources: 

  1. Shipping Cryogenic Liquids Safely (https://www.lion.com/lion-news/june-2014/shipping-cryogenic-liquids-safely)
  2. Care of dry shippers (https://www.diamond.ac.uk/Instruments/Mx/Common/Common-Manual/Shipping-Samples/Care-of-dry-shippers.html)
  3.  Cryogenic Shipping Dewar Testing and Shipping (https://smb.slac.stanford.edu/facilities/hardware/cryotools/shipping-dewar-testing.html) 
  4. Conversions Charts Data (http://www.cts-my.com/conversion.html) 

Drop test for the shipper at UVA  

These pictures were taken during the drop test of the shipper case at UVA. The dewar shipper and plastic box were dropped from a height of 1.8 meters

one time from every direction with LN2 absorbed in the dewar.  No damage to either the box or the dewar was found.  A weight test was performed with

the equivalent weight of 10 ft of the same package stacked on top of the dewar box.  The required weight is 130 lbs so six 25 lbs lead bricks were used for

a total of 150 lbs.  The weight was left on top of the box for 24 hours with no damage to the external box or filled dewar inside.


Pictures after the weight test  

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