GxT Ferret 54 ENGINE DIAGNOSTIC CENTER - Manual (Page 90)

HC-HANGUP
Occasionally, residual hydrocarbons may
linger in the system, causing an HC reading
of over 20 ppm with the probe sampling
ambient air. This is sometimes referred to as
HC-Hangup. If this occurs, and multiple
Purges fail to clear the problem, the source
can be isolated by running the Purge function
with the Sample Hose Assembly
disconnected. If the Purge function passes,
the Sample Hose may need cleaning (see
Cleaning The Sample Hose). If the HC levels
are still high, the filters may be saturated.
The filter bowl contains two filters of different
grades, separated by a sealing Filter Gasket.
These filter the sample that is passed to the
measurement system. Refer to the label on
the Gas Detector for part numbers, and be
careful to install the filters in the proper
locations, separated by the Filter Gasket. If
the Filter Gasket is not in place, the
sample gas will bypass the filters and
enter the Gas Detector directly, causing
possible damage. Make sure the O-ring is
in place, and twist the bowl halves together
so that they lock.
The disposable in-line filter must be replaced
when it is dirty. This prevents contaminants
from entering the drain pump and causing
damage. Be sure that the tubing is clamped
at each end of the filter.
Always perform a Leak Test after changing
filters.
REPLACING THE FILTERS
If the filters appear dirty, or Low Flow
warnings occur frequently, the filters may
need changing. How often filter replacement
is needed will depend upon the amount and
the types of vehicles being tested. To avoid
drawing contamination into the Gas Detector,
make sure the pumps are not running while
changing filters.
8-5
Upper
Filter
Filter
Gasket
Lower
Filter
O-Ring
In-Line Filter
NOTE
T
HE UPPER AND LOWER FILTERS ARE
NOT
INTERCHANGEABLE
. T
HE LOWER FILTER
IS MARKED WITH A RED DOT
.