AIR VALVE CLEANING.
5-6.1. To clean the valves, take out the air head cap screws and remove the head and valve
plate from the cylinder. Remove the valves from the valve plate and clean both the valve and
seat by brushing with a stiff bristle brush (not wire). If necessary, use a non-flammable
safety solvent to loosen dirt, oil or carbon deposits. Should it be necessary to scrape, do so
lightly to prevent marring the valve or seating surface.
5-6.2. Handle the valves with care and be careful not to nick or scratch them. When re-
placing a valve, make certain it will lie flat against the seating surface surrounding the port
hole; otherwise, the valves will leak air, resulting in carbonization and reduced compressor
output .
PISTON RING REPLACEMENT.
5-7.1. Piston ring replacement is usually
considered necessary when a compressor
does not meet its normal air delivery or
when its oil consumption is considered to be
too great.. If the compressor's normal air
delivery has dropped off or if the oil con-
sumption of the compressor is considered
to be excessive, it may be an indication of
several possible causes of trouble, one of
which may be that the piston rings could
either be broken or worn., Worn piston
rings can often be a contributing factor in a
decline in performance of a compressor
that has been in service for a long period of
time.
5-7.2. A general rule in determining if a
compressor's oil consumption is excessive
is to consider a good rate of oil consumption to be approximately fifty horse-power-hours per
ounce. This compressor should use no more than one pint of oil in 150 hours of operation.
If it uses more than that, it would be classed as not meeting commercial standards and would
require corrective action, such as replacement of the piston rings. If it has been determined
that replacement of the piston rings is necessary, it is recommended that
a complete new set of rings be installed and that these instruction: be used as a guide for
piston ring replacement.
5-7.3. New replacement piston rings are of the quick-seating-type in that they are distin-
guished by their narrow seating edge where they contact the cylinder wall. Compression
rings are classed as "B" type rings and are single-piece, taper-faced style; they have a slight
taper machined on their outer surface to provide line contact with the cylinder wall for
quicker seating and better oil control. See Figure 5-5.
