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Chapter 1: Introduction
cascade type refrigeration so that the collector
temperature can be cooled to below –75°C, or a dry
ice/solvent trap can be used between the collector and
the vacuum pump.
Samples Containing Volatile
Substances
In certain cases the solvent in a sample to be freeze
dried may contain volatile components such as acetic
acid, formic acid or pyridine. In addition to these
substances having an effect on the eutectic temperature,
they may increase the vapor pressure at the surface of
the sample. Also, compared to water, they will require
the absorption of less heat for sublimation to occur.
Hence, freeze drying samples that contain volatile
substances will have a greater tendency to melt,
particularly when placed in flasks or exposed to room
temperature. If a sample containing a volatile
substance tends to melt when placed on a freeze dry
system, dilution of the sample with more water will
help keep the sample frozen. For example, a 0.2M
solution of acetic acid is much easier to freeze dry than
a 0.5M solution.
About This Manual
This manual is designed to help you learn how to
install, use, and maintain your Freeze Dryer.
Instructions for performing routine maintenance and
making minor modifications to your Freeze Dryer are
also included.
Chapter 1: Introduction
provides a brief overview of
the Freeze Dryer, explains the organization of the
manual, and defines the typographical conventions used
in the manual.
Chapter 2: Prerequisites
explains what you need to do
to prepare your site before you install your Freeze
Dryer. Electrical requirements are discussed.
