Simply Constructed Freeze Drying Apparatus

[lugh]

From Science 92 611-2 (1940); modifications will probably bee necessary to adjust for currently available items and metric equivalents  

Specially prepared calcium sulfate, "Drierite," has been suggested' as an economical desiccant for drying biological materials in vacuo from the frozen state. A simple, inexpensive apparatus has been devised for application of this principle to the preservation of virus and serum proteins.

The apparatus, shown in Fig. 1, is constructed about the large size (25 quart) National Canner Retort, 2 (A), which serves as the desiccant chamber. This retort can be purchased at low cost and most of the associated parts can be assembled in the laboratory. The retort comes equipped with a rubber gasket and an inside wire rack. In the cover are 4 fittings with 1/8 inch standard pipe threads. The fittings are removed and 2 holes closed with standard plugs. A third opening is used as a vacuum release through the attached calcium chloride bottle (B). The fourth opening is rebored and threaded for a 3/8 inch pipe elbow for the vacuum lead (C) (1/2 inch pressure tubing). In the center of the cover an additional hole is drilled and tapped with a 1/2 inch pipe thread; into it is screwed an 8 inch length of 3/4 inch O.D. brass tubing (D) for connection with the manifold (E). Into the lower end of (D) is sweated another brass tube (F) which extends within the retort to 1/2 to 1 inch of the bottom. The manifold (E) is 1 1/4 inch O.D. brass tubing 16 inches long. The 16 outlets (G) are 5/16 inch O.D. brass tubing 1 1/4 inches long placed 1 7/8 inches apart at an angle of 60° from vertical. All brass to brass joints and manifold caps are soldered or brazed and he threaded joints in the cover are sealed with "Apiezon." Short lengths of 1/4 inch pressure tubing (H) are used to connect the freezing and drying containers (I) to the manifold outlets. Construction and mounting of supports and of 2 sheet copper trays (J) for holding freezing mixture are evident. Castor oil may be used on the bevelled rubber gasket for sealing the retort.
The "Drierite" is held in 3 circular baskets (K) of hardware cloth, 3 1/2 inches high by 11 inches in diameter, constructed with a tubular central opening through which passes the pipe extension (F). The 3 baskets are stacked in the wire rack supplied with the retort and may be removed separately or as a unit for regeneration of the desiccant. Details of the regeneration procedure are given by Flosdorf and Mudd in Jour Immunol 34 469 (1938) and for this a cheap gas oven is applicable.
The desiccant chamber holds 25 pounds of "Drierite," the total capacity of which is 400 cc without regeneration. The single run capacity is 125 to'150 cc and a Cenco Hyvac pump has proven adequate. Either preliminary freezing with a Dry-Ice-alcohol mixture or the degassing-self-freezing procedures may be used, though the former method is recommended. Standard freezing and drying containers and connections obtainable on the market are used. The apparatus shown may be constructed for approximately $35.00 or less and has been flexible and reliable in practice. It occupies only 4 square feet of table space.

[sYnThOmAtIc]

I'm glad you posted that. I just found myself needing one last week to preserve some cultures I've got growing.