PT  - JOURNAL ARTICLE
AU  - Waltrich, P. F.
TI  - System Evacuation Rate and Leak Rate Determination in Freeze Dryers
DP  - 1986 Mar 01
TA  - PDA Journal of Pharmaceutical Science and Technology
PG  - 66--69
VI  - 40
IP  - 2
4099  - http://journal.pda.org/content/40/2/66.short
4100  - http://journal.pda.org/content/40/2/66.full
SO  - PDA J Pharm Sci Technol1986 Mar 01; 40
AB  - Freeze drying of parenteral products is becoming more prevalent in the pharmaceutical industry. An integral part of the freeze-drying process is the vacuum system. Proper operation of a freeze dryer requires some basic knowledge of the design considerations as well as the operation and maintenance of the vacuum system. This paper explains the basic parameters and calculation methods used in determining the evacuation rate of a vacuum chamber. It includes the theoretical methods for dealing with vacuum piping conductance and with gas loads imposed during an evacuation. There is also a brief discussion of actual times in a production unit with a product load. Leak rate determination is an important part of the overall maintenance program for a freeze dryer. Excessive air inleakage can limit the attainable vacuum level and possibly jeopardize the product during the drying cycle. There is also the possibility of the introduction of bacterial contamination should the leak(s) be great enough. This paper deals with some simple methods of evaluating the vacuum integrity of a freeze dryer. It deals with the concept of a system “leak-up rate” as a means of evaluating the magnitude and type of vacuum leaks in the system.