Quincy QHD750, Instruction Book

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Instruction book
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8 Problem solving
8.1 Problem solving
Symptom Possible cause Corrective action
Poor dewpoint Free water in compressed air inlet Check the condensate separators and
drains upstream of the dryer if they are
operating correctly
Temperature of compressed air is
too high Clean compressor after-cooler
Working pressure is too low Check outlet pressure of compressor and
check pressure drop over dryer, filters
Poor regeneration Too small purge nozzle for higher working
pressure installed.
Regeneration silencers clogged. Check
the service indicator. The regeneration
pressure should be less than 300 mBar
Check if all other described symptoms are
applicable. Solve them
Poor desiccant Replace desiccant. Check the
maintenance schedule for normal
replacement periods
Damaged desiccant Air flow too high during start-up. Replace
desiccant. Install sonic nozzle to avoid
problems in the future High pressure
difference between vessels when
switching. This indicates that a too small
purge nozzle is installed
Oil vapors adsorbed by desiccant Remove some desiccant from the bottom
part of the vessel. Yellow colored
desiccant indicates oil vapor adsorption
Dryer is stopped Check that the dryer is turned on.
Desiccant has become
oversaturated for a longer period Replace desiccant
Too high purge
consumption Incorrect purge nozzle installed. Compare the actual working pressure with
the ordered optimized purge nozzle.
Higher working pressures result in higher
purge consumption that creates more
noise.
The dryer produces
a lot of noise Incorrect purge nozzle installed. See symptom Too high purge
consumption
Safety valve of silencer is opened See symptom Too high purge
consumption
Check the silencers and their
fixation Replace the silencer if necessary
Incorrect adjustment of
regeneration valve Adjust the opening time of the
regeneration valves with the needle valve
on the actuator