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In This Issue :
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Vibration Detector / Vibration Switch
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Technique: Alignment
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Failure Analysis : Lubrication
Vibration Detector VS4, Vibration Switch VS6.pdf
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Laser
Alignment of all rotating equipment,
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Fan /
Rotor Balancing,
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Vibration Analysis
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Condition Monitoring (total site contracts)
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Technical Support and Solutions
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Pruftechnik Laser Alignment Equipment
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Pocket
VibrA Vibration Analyser
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Entry
Level Vibration Meters
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Accelerometers (Various Types)
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ICP
Condition Monitoring Modules
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Multi
Channel Signal Conditioners
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Vibration Monitors / Switches
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Vibration Calibrators
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Stainless Steel Shims
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Training
align@mweb.co.za
+27 12 661 7844
www.alignvib.com
Quote of the month:
“Mechanical
Engineers build weapons, Civil Engineers build
targets”
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Vibration Detector –VS4 and
Vibration Switch -VS6
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Purpose:
The Vibration
Detector VS4 and Vibration Switch V6 are suitable for
machine monitoring in a very simple and economical way.
They measure vibration velocity (often called vibration
severity) at rotating machinery to ISO 10816 as part of
predictive maintenance. |
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A special feature is
there stand-alone design with internal batteries. It
makes cable connections unnecessary. The only
installation work to be done is attaching the VS4 / VS6
to the machine and adjusting the threshold value. Three
flashing LEDs indicate the monitoring status. The status
can be read at a glance during an inspection route which
should be carried out in regular intervals. The VS6 can
also be used as limit switch for other types of
vibration.
Thus the VS4 / VS6 is
perfectly suited for applications with tight budget and
for personnel with little experience in the field of
vibration monitoring. Two selectable gain ranges, two
high pass frequencies and its protection grade IP65 make
the VS4 / VS6 ideal for many applications including, for
example, the monitoring of: Compressors, Pumps, Blower
Fans, Generators, Rail Vehicles, Quality Control,
Transport of Fragile Goods , Doors and Gates. For
more information or quotation please email or phone Sue
on 012 661 7844 /sales@avsrsa.com |
Technique: Alignment
A perfect .000”
alignment can sometimes be the wrong thing to do. Rarely, if
ever, do two machines in a machine train generate the same
temperatures during operation. These factors can cause perfectly
aligned shafts to be misaligned out of tolerance while
operating. Let’s take use the following motor driven pump as an
example of this fact:
To calculate the
amount of expected thermal growth use the following formula:
Thermal Growth = (T
Running - T Non-Running) x h x k
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T
= Casing Temperature in the Plane Of The Feet
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h
= Height from Base plate to Shaft Centerline
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k
= Coefficient of Expansion
In this example the
motor will experience a rise in the front foot of ~2mils and
1.8mils in the rear foot. The pump will experience a greater
amount of growth due to the fact that the fluid cavity will heat
up a greater rate. This calculate out to ~6mils in the back and
~5.5mils in the front.
Assuming that the
shaft centerlines were a perfect .000” prior to operation, they
would be about .002” out during operation. These is right at the
edge of acceptable on most machines, and remember, if we were
just within the tolerance before operation, we would now be
almost .004” out of alignment.
To correct this from
happening, we must intentionally lower each machine to the
amount of thermal growth expected once zero is achieved.
Depending on the method of alignment used these dial indicator
readings can be determined without going through the step of
aligning to zero and then removing the applicable shims.
Failure Analysis :
Lubrication
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Symptoms include
discolored (blue/brown) raceways and balls/rollers.
Restricted lubricant flow
or excessive temperatures that degrade the lubricant's
properties typically cause failures.
Lubricant failure will
lead to excessive wear, overheating and subsequent
bearing failure
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