40
Mechanical Technology — August 2013
⎪
Nota bene
⎪
Index to advertisers
Atlas Copco...........................................34
Bearings International.................. OFC, OBC
Bonfiglioli..............................................22
Clyde Bergemann...................................27
Crown Publications................................IBC
Donaldson.............................................16
Engen...................................................33
General Profiling.....................................30
Hansen Transmissions SA........................20
Metso Minerals......................................21
Robor....................................................26
Tega Industries.......................................13
ThyssenKrupp Materials Handling...........IFC
Wearcheck.............................................25
Weir Minerals...........................................2
Industry diary
September 2013
3
rd
Solar Indaba
2-5 September 2013, Cape Town,
South Africa
Rebecca.Rooke@
greenpowerconferences.co.uk
Schweissen & Schneiden, 2013
16-21 September, Essen, Germany
Morgana van Niekerk
+27 11 486 2775
mvanniekerk@germanchamber.
co.za.
en/schweissen
P
umps, fans, compressors and other
motor-driven rotating equipment
are essential to most manufacturing,
commercial and institutional enter-
prises, from fluid handling systems in
petrochemical plants to large air con-
ditioning systems in shopping malls.
Many facilities monitor this type of
equipment on a regular basis, because
a simple problem like lubrication can
often be spotted and fixed inexpensively,
before the entire unit burns out. Such
strategies fall under the general heading
of predictive maintenance (PdM).
Thermal imaging is especially useful
for monitoring rotating equipment, since
many impending failures are accom-
panied by overheating. This predictive
technique uses a handheld thermal
imager to capture two-dimensional im-
ages representing the apparent surface
temperatures of equipment. Thermog-
raphy can also be used together with
other predictive technologies such as
oil analysis, vibration monitoring and
ultrasound.
While in operation and under load,
rotating equipment that is critical to
operations can be monitored. This in-
cludes equipment whose failure would
put at risk people, property or produc-
tion. Thermal imaging can be used to
monitor equipment’s drives – electric
motors, bearings and gearboxes. Also,
on pumps and fans, thermal profiles of
the housings can reveal problems with
bearings or seals, and scans of shaft
couplings, drive belts and sheaves will
also identify areas of excessive friction.
For a compressor, several images may
be necessary to get a thermal profile of
the entire unit.
In general, these imagers are able
to identify hot spots and can make
it easy to compare the differences in
temperature between similar units
operating under similar conditions. If,
for example, a bearing in one fan in a
bank of similar fans is running hotter
than rest, the hotter one may be tending
toward premature failure.
On a pump, a difference in tem-
perature along a seal or gasket is a
‘signature’ of imminent seal failure. A
hot spot on the housing adjacent to a
bearing may signal an impending bear-
ing failure, although the root cause will
probably not be obvious from the ther-
mal image alone. A lubrication problem
or drive misalignment may be to blame.
An overheating bearing on a fan
also signals a problem but, again, the
root cause could be lack of, or incorrect
lubrication, a drive misalignment, or an
imbalance on the fan itself.
Many industrial and most building-
system fans are belt-driven, as are
many pumps. A belt-and-sheave drive
that is designed and installed correctly
generates very little heat, and the belt
moving through the air tends to cool it
to near ambient temperature. Overheat-
ing, detected by thermography, reflects
a problem with the drive’s design or
installation, perhaps mismatched belt
and sheaves, or misalignment. Vibration
analysis and/or an alignment check will
confirm the latter condition.
Since a compressor is a heat gener-
ating machine, a thermal imager can
quite literally ‘see’ the work being done
via the heat produced during the com-
pression cycle. To check the efficiency
of compressors, an imager can be used
to look for belt slippage on cooler fans,
shaft misalignment, bearing problems,
and blocked or leaking valves.
Because pumps, fans and compres-
sors are key to productivity in so many
industries, it is difficult to speak gener-
ally about the cost to a company of a
critical unit failure. A failed pump at
one automotive facility however, cost
more than
€
15 000 to repair, while idle
labour costs totalled
€
600 per minute
and lost production opportunities
amounted to
€
30 000 per minute. Criti-
cal equipment failures in any operation
are very expensive, which makes the
case for investing in a thermal imaging
system easy to justify.
Bauma Africa first for
South Africa
Bauma Africa International trade fair for
construction machinery, building material
machines, mining machines and construction
vehicles is taking place on African soil in Johan-
nesburg at Gallagher Convention Centre, from
18 to 21 September.
“Aside from being the first Bauma Africa
event, the trade show is the first mining and
construction trade show of its size to take place
in Africa. The premier event will feature over
700 local and international exhibitors, and we
are expecting around 15 000 visitors,” says
Elaine Crewe, CEO of MMI South Africa.
Crewe also notes that Bauma Africa will be
the first to offer a matchmaking service, where
attendees are able to contact exhibitors match-
ing their own personal business profile before
the event.
Thermal imagers for pumps, fans and compressors
Since a compressor is a heat generating machine, a
thermal imager can ‘see’ the work being done via the
heat produced during the compression cycle.
Handheld Fluke thermal imagers capture
two-dimensional images representing the
apparent surface temperatures of rotating
equipment.
