A few years ago, one of our consultants
was working with a plant and located an
accumulator labeled "Danger: Compressed
Air," as shown in Figure 5. This was discov-
ered only two days after an inspection of the
plant by the Occupational Safety and Health
Administration (OSHA). Why would anyone
put this sign on an accumulator? Could it be
because many people have a well at their
homes with an accumulator that is
pre-charged with air? The person who placed
this sticker on the accumulator most likely
thought that the Schrader valve used to refill
with nitrogen looked very much like the accu-
mulator in his well system, bicycle or car tire.
Also, notice that the actual warning
sticker applied by the accumulator manu-
facturer is covered up by the piece of wood
underneath the chain clamp. Fortunately,
compressed air had never actually been
used in the accumulator. If someone had
ever filled it with compressed air, as the
sticker suggests, the bladder could have
ruptured, and the result would have been an
explosion or possibly a fire at this plant.
Needless to say, our consultant had this
sticker removed immediately.
Mounting and Removal
An accumulator should be properly
clamped to the mounting fixture. Figure 6
shows a breakdown of the accumulator minus
the bladder. When assembling the accumu-
lator after bladder replacement, the retainer
ring is fitted around the outside of the poppet
valve, and both are inserted into the accumu-
lator shell. If the accumulator shell is not
properly clamped, then failure of the retainer
ring can cause the poppet valve to disconnect
from the accumulator. This can result in the
shell taking off like a rocket. Figure 7 shows a
properly clamped accumulator.
Prior to removing and storing an accumu-
lator, the nitrogen pressure should be
released and the protective cap installed
over the Schrader valve. One plant only had
a single accumulator. Every time the accumu-
lator needed pre-charging, it was removed,
placed in a pickup truck and driven to the
nearest shop. If the Schrader valve had
broken off or the retaining ring failed during
transport, the accumulator could have acted
as an unguided missile.
Most workers are not aware of the
dangers of accumulators. Don't wait until
someone is injured or killed in your plant to
educate your personnel.
Figure 6
Figure 6. A breakdown of the accumulator minus the bladder
Figure 7. A properly clamped
accumulator
www.machinerylubrication.com
|
November - December 2015
|
29
