ABSTRACT

Before proceeding, it may be of use to define some basic terms to be used in this section. The term transfer hatch is often applied, in conversation, to methods of isolator input and output, particularly referring to lockchambers, but also to other types. This is a vague term and it is proposed that it be abandoned in favour of one blanket term to refer to all methods of input/ output, with clearly defined names for each type of method. The terms chosen for this book are intended to convey clear and logical meaning, but they are at variance with some existing definitions (see the Glossary). The suggested blanket term is transfer port. The terms used for each type of transfer port are given in the rest of this section; however, mention should perhaps be made at this stage of the classification of transfer ports given in the Yellow Guide (Lee and Midcalf 1994). This system grades transfer ports on a scale from A through F, according to the quality of transfer, in terms of the intermixing of the isolator environment with the room environment, given by each type of port in operation. Thus, simple doors on isolators are classified “A,” since there is free exchange of air between the room and the isolator interior when the door is used. In the midrange of the scale, there are various types of lockchambers with different degrees of air exchange in use. Toward the end of the scale, docking devices and direct connection of the isolator to equipment, such as an autoclave, are classified “E,” since they allow little intermixing. The principal purpose of the scale is to help in

defining the room environment required to house any particular isolator, as described in Chapter 5. The reader may find reference to the scale in product literature where, for instance, a particular isolator may be described as having type D lockchambers fitted. New devices are under constant development, designed to address particular problems, but the main types are described below.