Just Better Keeping the life of your pump - Manual (Page 7)

Flexible Coupler
Flexible couplers are a three part assembly: 2 metal hubs that look like gears
and a fl exible middle section. The one hub is attached to the shaft of the motor
and the other is attached to the shaft of the cartridge. NOTE: The color of the
fl exible middle section can be either black or yellow.
1 1/2” 7/8”
1 5/8” 2 1/4”
2 1/8” 2 3/4”
PR-208
PR-6
PR-53
Middle section of PR-208 only can
be ordered seperatley PR-308
Breaking Vacuum
Breaking vacuum prior to shut down is important on larger cfm pumps. This
procedure relieves the stress on the fl exible coupler on the next start up. When a
pump is shut down without breaking vacuum, the oil in the cover is pulled back
into the cartridge and intake chamber of the pump trying to fi ll the vacuum there.
Upon the next start up the pump has to clear the oil outof these areas and all the
stress is on the fl exible part of the coupler, especially if the oil is cold. You can
see this occuring by shutting down the pump and watching the sight glass. The
oil will start to drop down and appears as if you are low on oil. Then when you
restart the pump the oil level returns to normal.
To break vaccum on the Platinum pumps, simply close the isolation valve with
the pump still running and open the gas ballast valve all the way and allow the
pump to run 2-3 seconds with the gas ballast valve opened and then shut pump
off and close the valve.
To break vacuum on the Eliminator pumps. After blanking off at the manifold
or an external isolation valve, if used, crack open the un-used intake port on the
pump and allow to run 2-3 seconds and shut pump off.
As the system is being evacuated and the micron level is dropping down through
the increments of the gauge’s display, the gauge will re-sample ambient tem-
perature about every 60 seconds. When this function is taking place, the gauge’s
display will show “auto-cal” (older gauges may see that the display freeze prior
to the re-sampling). The re-sampling lasts for about 15 seconds after which
the micron level that the system is at will then be displayed. For instance, the
system is at a micron level of 5500, the re-sampling begins, the “auto-cal” will
be displayed until the re-sampling is done, then the micron level at which the
system is at will be displayed.
There is also instability inside the system being evacuated. Liquids (moisture)
are being turned into gasses and molecules are moving at different rates of col-
lision with other molecules at different areas of the system at different times
between the high and low sides. The deeper the vacuum, the further apart these
molecules get and the less rubbing together. This decrease in friction changes
the temperature around those molecules and the DV-22N is registering those
changes by way of temperature changes at the sensor’s fi lament. The environ-
ment inside a system being evacuated has more instability at higher micron
levels (9000 to 1000) than at lower micron levels (700 to 50). This is evidenced
when testing the DV-22N at the different ranges on a secured system. When
in the range of 4000 microns, the DV-22N’s display will show 4000 microns,
then jump to 4350, then regress to 3875, then jump back to 4000. After being
blanked-off at this level for a period of time, the changing back and forth will
level out to changing from the incremental display of 4000 microns and the next
incremental display up or down of either 4125 or 3875. But, when in a deeper
vacuum like 350 microns, the changes in display on increments may be from
350 to 357 and back down to 350 or even 329 as the environment inside the
system becomes more stable and the time period of these changes will be less as
most of the out gassing has been done.
Information on Digital Micron Gauges Continued Won’t Hold a Vacuum: The sensors on JB’s DV-22 digital gauges are brass
with the sensor components sealed like a light bulb. The area where the hook
shaped wire and the fi lament attach to the sensor’s body is sealed with a glass
like epoxy. The chances of this leaking are next to impossible. The rise in
pressure experienced in the use of vacuum gauges on systems is discussed on
the previous pages under “Information on Testing a Vacuum Pump’s Isolation
Valve”.
On an analog gauge, at a micron
level of vacuum of 4000, the distance
between 4000 and 4350 is between
2T and 5T. This is a distance of about
1/16th of an inch. This distance on
other gauges may vary. Fluctuations
of the needle as the out-gassing is
happening are barely noticeable. The
downside of the analog gauge is that
magnifi cation of the needle is needed
in order to see it move between
the two increments at this range or
vacuum level (4000-4350 or 2T-5T).
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