Efficient Plant February 2018 - 30

feature | lubrication strategies
ments, such as a foundry, and every six months
in cleaner environments.

FILLER/BREATHER CAP

Bannister on
Lubrication

Go to the online
version of this article at
efficientplantmag.com to
hear a podcast in which
Ken Bannister provides
more detail about breathers
and how to specify and
maintain them.

Contributing editor
Ken Bannister is coauthor, with Heinz Bloch,
of the book Practical
Lubrication for Industrial
Facilities, 3rd Edition
(The Fairmont Press,
Lilburn, GA). As managing
partner and principal
consultant for Engtech
Industries Inc., Innerkip,
Ontario, he specializes
in the implementation of
lubrication-effectiveness
reviews to ISO 55001
standards, assetmanagement systems,
and training. Contact
him at kbannister@
engtechindustries.com, or
telephone 519-469-9173.

The most common
breather in service is the
combination filler/breather design that allows a
single reservoir opening
to serve two purposes.
The device looks like a
typical fill port with its
screw-on cap and tubular
mesh basket designed to
prevent large debris from
falling into the reservoir
during the filling process
(see image, right). The
difference from a regular
fill port is found in the
combination-unit cap
design, which contains a
filter element to keep out
contaminants. Filters can
be made from different
media based on the filter
size and airflow restriction requirements. For
example, a polyurethane
filter medium is good for
>10-micron particulates
and allows an airflow exchange of 140 gpm (19 cfm),
whereas an impregnated-paper medium will capture
>3 micron particulates and
allow an air exchange of 110
gpm (15 cfm).

DESICCANT
BREATHERS
Desiccant breathers are recent
additions to the breather
family and differ in that they
offer superior air exchange
and condition control and are
designed to visually indicate
to the operator when replacement is required. Dessicant
units are designed with a
see-through polycarbonate
body filled with a silica-gel
absorbent designed to hold
as much as 40% of its weight
in absorbed moisture. The gel
changes from a blue to light
pink color when saturated.
The unit also contains regular
polyester filters designed to
capture particulate as small as
3 micron.
Desiccant breathers use a
see-through polycarbonate
body filled with a silica-gel absorbent that holds as much as
40% of its weight in moisture.
Replace the breather when the
gel turns pink. Photo courtesy
Des-Case Corp., Goodlettsville,
TN, descase.com

STANDARD BREATHERS
Standard breathers look almost identical to the
filler/breather cap and is usually screwed onto a
threaded pipe that provides air exchange through
the top of the reservoir. Other styles can look
similar to an automotive spin-on oil filter.
In environments that experience large shifts

| EFFICIENTPLANTMAG.COM

in ambient and working conditions, or high humidity, breather caps designed with a filter and a
pressure valve can be specified. The pressurerelief and vacuum-breaker capability is designed
to limit air exchange and provide a positive suction head at
the pump inlet.

WORD OF CAUTION

Note that a breather will only
work when it's in place. Breathers taken off to fill reservoirs, or
for checking purposes, must be
replaced or refitted immediately
if the reservoir environment is
to stay protected from outside contamination.
The opening photo on p. 28 shows an example
in which the filler breather cap has not been
refitted correctly, allowing contamination into
the reservoir. Breathers are an important and
integral part of any reservoir-based lubrication
system-and they require their own maintenance
schedule. EP

FEBRUARY 2018

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Table of Contents for the Digital Edition of Efficient Plant February 2018