Specifications

Instruction 0011-9026Page 16
As a rule of thumb, background gases/vapors may be present in con centrations up to
1/2% by volume (5000 ppm) before they present a signifi cant interference problem to
the CO
2
or O
2
FYRITE (20/21% ranges).
An exception exists with the action of ammonia on Oxygen FYRITE Fluid. Ammonia
neutralizes the acidic solution of chromous chloride, and therefore use of the O
2
FY-
RITE with even trace amounts of ammonia in the backgrounds is not advised unless
suitable fi lters are used.
Inert gases, even in concentrations approaching 100% by volume, do not interfere with
either the CO
2
or O
2
FYRITE. In general, interferences can be of a chemical (chemical
reaction initiated) or a mechanical nature, with resultant error, but are also given up
by the solution when the sample no longer contains the interfering substance. They
can therefore be compensated for by saturating the FYRITE solution with samples
containing the mechanical interferant as long as the background stays reasonably
constant. Usually 3 or 4 tests are suffi cient to saturate FYRITE solution with the
mechanical interferant in question.
TYPICAL TYPE OF APPROXIMATE
INTERFERENCE INTERFERENCE EFFECT
(CO
2
FYRITE)
All Acid Gases Chemical 1:1
(SO
2
, H
2
S, Hydro-
cynanic Acid,
Cyanogen, etc.).
TYPICAL TYPE OF APPROXIMATE
INTERFERENCE INTERFERENCE EFFECT
(O
2
FYRITE)
Acetone Chemical 1:1
Acetylene Chemical 1:1
and other
unsaturated
hydrocarbons
CO
2
Mechanical, 20% CO
2
Can be zeroed out up
background can be to approximately 30%
zeroed out in 3 to 4 CO
2
background.
tests if background
remains constant.
Ammonia Chemical Ammonia neutralizes
O
2
FYRITE solution
and instrument use on
this background is not
advised unless suit-
able fi lters are used.
Nitrous Oxide (N
2
O) Mechanical - - -