Demister or Separator Element
The demister, or separator element, is located
inside the receiver tank (fig. 3-55). Replacement of the
demister is indicated by the maintenance indicator
(usually mounted on the receiver tank but also can be
remote-mounted) or any sign of oil in the air at the
service valves. You can reach the demister after
removing the plate on the end of the receiver tank.
As in hydraulic systems, fluid contamination is the
leading cause of malfunctions in pneumatic systems. In
addition to the solid particles of foreign matter that find
their way to enter the system, there is also the problem of
moisture. Most systems are equipped with one or more
devices to remove contamination. These include filters,
water separators, air dehydrators, and chemical dryers.
Most systems contain drain valves at critical low points in
the system. These valves are opened periodically to allow
the escaping gas to purge a large percentage of the
contaminants, both solids and moisture, from the system.
In some systems these valves are automatic, while in
others they must be operated manually.
Removing lines from various components throughout
the system and then attempting to pressurize the system,
causing a high rate of air flow through the system, does
complete purging. The air flow will cause the foreign
matter to be dislodged and blown from the system.
If an excessive amount of foreign matter,
particularly oil, is blown from any one system,
the lines and components should be removed
and cleaned or, in some cases, replaced.
In addition to monitoring the devices installed to
remove contamination, it is your responsibility as a
mechanic to control the contamination. You can do this
by using the following maintenance practices:
Keep all tools and the work area in a clean, dirt-free
Cap or plug all lines and fittings immediately after
Replace all packing and gaskets during
Connect all parts with care to avoid stripping
metal slivers from threaded areas. Install and
torque all fittings and lines according to
applicable technical manuals.
Figure 3-55.Demister (separator element).
All compressed gases are hazardous. Compressed air
and nitrogen are neither poisonous nor flammable, but
should be handled with care. Some pneumatic systems
operate at pressures exceeding 3,000 psi. Lines and
fittings have exploded, injuring personnel and property.
Literally thousands of careless workers have blown dust
or other harmful particles into their eyes by careless
handling of compressed air outlets.
If you ever have to handle nitrogen gas, remember
that it will not support life, and when released in a
confined space, it will cause asphyxia (the loss of
consciousness as a result of too little oxygen and too
much carbon dioxide in the blood). Although compressed
air and nitrogen seem safe in comparison with other
gases, do not let overconfidence lead to personal injury.
To minimize personal injury and equipment
damage when using compressed gases, observe all