Operator`s manual

344 GAS ANALYZER
PROCEDURES
The PXA Gas Analyzer has four user-replaceable filters. This section describes the filters
and the benefits of checking them on a regular schedule.
• Sample Filter Bowl
• Drain Filter
• Check Valve
• Air Filter
Sample Filter Bowl Elements
The filter bowl assembly contains two filter elements. Each filter should be checked
visually on a daily basis. Generally, after 25 cumulative hours of exhaust gas sampling,
both filters should be replaced. For instance, if the average test lasts 15 minutes, change
the filters after every 100 tests.
Vehicle exhaust enters the lower filter from the inside. It may
not show from the outside how dirty it really may be inside. If
either filter becomes restricted, the gas values may change
slowly or a low-flow condition may occur. It is normal for a
minimal amount of water to be sitting in the filter bowl.
Operating the Gas Analyzer with extremely dirty filters may
cause particles to clog the inside of the measurement cell.
Replacing Filters
Open the hinged panel and slightly tug on the filter bowl
assembly. Do not pull past the point of any resistance. Twist the
top half of the plastic bowl counterclockwise to the lower half.
The bowl may be a tight fit but will loosen after it has been
disassembled a few times.
Replace both filters at the same time. The lower filter is denoted
by a red dot or stripe. The lower filter is a 14-micron particulate
filter. The upper filter is a 10-micron particulate filter. Wash the
bowl with mild soap and water if necessary. Check the location
of the rubber separator between the two filters for proper
seating. Twist the top half clockwise to the lower half to
reconnect the housing.
Perform a Leak Test to assure proper sealing. (See Section Leak Test on page 349.)
NOTE
Change the filter elements at the first sign of discoloration.
CAUTION
CAUTION!
Failure to comply with the maintenance
procedures may void the warranty.
SAMPLE
FILTER BOWL
ASSEMBLY
O-RING
TOP SHELL
OPEN
AFTER-FILTER
ELEMENT
PRE-FILTER
ELEMENT
BOTTOM SHELL
SEPARATOR