Just Better Deep Vacuum Principles and Applications - Manual (Page 4)

Preventing
“Hard
Start-Up”
Dispelling The Argument Of
“No Deep Vac On Heat Pumps, Etc.”
The word “sublimation,” the ability of moisture
to go directly from solid ice to vapor without
passing through a liquid state, is commonly used in
vacuum. This phenomenon is observed when the
wash is hung out in the winter and freezes solid.
Still, in time it dries due to sublimation (drying). If
lines are in a cold ambient, it is possible to have
ice in the system. It will be removed during
evacuation. Of course, the addition of heat (heat
gun only) at these cold spots speeds up the job.
READINGS AFTER 5-20 MINUTES
Under
500 Microns
Evacuation Complete
Slow Rise To
1500 Microns
Moisture
Rapid Rise To ATM Leak
Pressure Rise Test
We previously mentioned that the only difference
between deep vacuum and the methods of the past is
that we can measure what we have done. This is called
the Pressure Rise Test.
When the sensor reads between 300 and 400
microns,
DV-29 Method. Blank-off the high and low side ball
valves attached to the system.
General Hookup Method. This includes using
copper tubing or metal hose to the high and low side.
Close blank-off valve on the pump. This will isolate the
gauge from the pump.
Wait for at least 5 to a maximum of 20 minutes to
allow system pressure to equalize. The reading you see
at the end of this test will be very close to what you
actually have in the system. A rapid rise during this test
to atmospheric pressure indicates a leak, while a slower
rise to around 1500 microns indicates moisture is
present.
Printed in U.S.A.
2007 JB Industries Inc.
Evacuation Brings Out The Worst In A System!
vacuum, oil must be clean and mois-
ture free throughout evacuation. Just
take a few minutes during and after
each job to drain, flush and refill. Keep
your pump running at peak perfor-
mance and maintenance free for years
to come.
Always store your vacuum equip-
ment plugged or capped to prevent
contamination due to condensation
and dirt. Because a slight cut or dirt on
the o-ring seals can cause leaks, the
mating flare fitting faces should be
wiped and checked for damage before
hookup. Vacuum pump oil makes a
fine lubricant at these connections.
After closing
the isolation
valve, open
the gas
ballast valve
and shut the
pump off.
There are many evacuation level recommendations
including the statement “evacuate the system to below
200 microns.” This should not be considered. Note we
say “system” because it is possible to evacuate piping or
some component other than the compressor to below
this level. Refrigeration oil has a vapor pressure and by
going below 200 microns, you will degas particles of the
refrigeration oil. By changing the makeup of the oil, it will
no longer be a true lubricating oil.
Remember, hydrofluoric and hydrochloric acids, and their
pal, moisture, do collect in the oil. Having nothing but time
on their hands, they effectively destroy pull down and act
as an abrasive on internal surfaces. If left sitting in an idle
pump, these culprits keep busy by rusting and corroding
internal surfaces. Deep vacuum pumps need a fill or two
for every job.
In order for your pump to pull a near perfect
JB Industries
PO Box 1180
Aurora, IL 60507-1180
www.jbind.com
e-mail: [email protected]
Technical Assistance
800.323.0811