Teledyne 335 - Analog control room monitor for personnel safety - Manual (Page 8)

TELEDYNE ANALYTICAL INSTRUMENTS
2 Operational Theory Model 335
2-2
There is, however, an important difference in the operation of a
battery as compared to the MFC: in the battery, all reactants are stored
within the cell, whereas in the MFC, one of the reactants (oxygen) comes
from outside the device as a constituent of the sample gas being analyzed.
The MFC is therefore a hybrid between a battery and a true fuel cell. (All
of the reactants are stored externally in a true fuel cell.)
2.2.2 Anatomy of a Micro-Fuel Cell
The MFC is a cylinder only 1¼" in diameter and 1¼" thick. It is
made of extremely inert plastic (which can be placed confidently in practi-
cally any environment or sample stream) and is effectively sealed, though
one end is permeable to oxygen in the sample gas. At the permeable end a
screen retains a diffusion membrane through which the oxygen passes into
the cell. At the other end of the cell is a contact plate consisting of two
concentric foil rings. The rings mate with spring-loaded contacts in the
sensor block assembly and provide the electrical connection to the rest of
the analyzer. Figure 2-1 illustrates the external features.
Figure 2-1: Micro-Fuel Cell
Figure 2-2. Cross Section of a Micro-Fuel Cell
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