Liquid Nitrogen Dewar Repair and Decontamination

When shipping a cryogenic dewar to MVE Chart for repair, the things to remember are:

 

1. All canisters should be taken out

2. Cork and cover must also be taken out

3. As explained by the method below, decontaminate the unit:

 

Chart Aluminum and MVE Dewars Procedure for Sanitizing and Decontaminating

 

The inner of the MVE aluminum cryogenic dewar is constructed with an aluminum that uses a fiberglass neck support. These stainless units are built completely from sheets of stainless steel. The use of any cleaning solution that does not react with aluminum or stainless is used for the sanitation method of these liquid nitrogen dewars, and in most cases a household detergent or mild soap solution is ideal. The cleaners and disinfectants that can be safely engaged in this are bleach, detergents, and mild soaps, hydrogen peroxide, chlorine/water and denatured alcohol.

 

Note: Any petroleum based cleaning solution should never be used. A solution by the name of EXPOR is utilized by U.S. Custom Service for incoming shipments from overseas consist of 9 parts water mixed with sodium chloride & lactic acid.

 

It is very important that the liquid nitrogen dewar’s inner vessel is completely cleaned with water and all cleaner remains are removed. Spraying the solution into the inner vessel is the best but agitation of the solution inside the inner is also tolerable. In the case of cryogenic vapor shippers and Double units, the cleaning mixture must be filled to its full capacity of the inner and then rinse. The cryogenic unit must be dried thoroughly before putting into service. We recommend setting vapor shipper Dewars upturned to drain and dry, but on the other hand, older vapor shipper models made before 1994 are not meant for this process. For cryogenic decontamination using 10% chlorine bleach with 90% water solution is still the best method. But, the agricultural professors at the University of Minnesota and Texas A & M have come to the conclusion that an enlarged mixture of chlorine bleach to 30% and 70% water taking into consideration some of the bovine and swine virus strains we see today and this solution will eradicate all known viruses except BSE.

 

In this disinfecting method, for 30 minutes swathe all inner surfaces of the liquid nitrogen dewar with the solution and then remove. With clean water rinse the decontaminated surfaces and after which remove the rinse water. Before putting into use allow the liquid nitrogen dewar to dry. This means invert the cryogenic vapor shippers and Doble unit Dewars by placing it on end to allowing drying. Note: Vapor shipper Dewars may take longer to renew to 100% capacity, though they are immediately ready after rinsing.