5
2.3 Process Gas
The R 5 series pumps are designed to pump air and are
not intended for use when water vapor is being
pumped. In some applications, when the quantity of the
water vapor is moderate, R 5 pumps have been used
with good results. On these occasions, the pump is run
until it is up to operating temperature before it is allowed
to pump the process gas. The pump is also operated
for a period of time off process and on air (to clear it of
process gas) before it is shut down. This operating
technique prevents the vapor from condensing in the
pump. Before attempting to pump a gas laden with
water vapor, contact Busch Engineering for advice.
2.4 Stopping Pump
To stop the pump, turn off the power. The pump has a
built-in, anti-suck-back valve (Ref. 251 thru 255) to pre-
vent the pump from rotating backwards when it is shut
off.
Install an automatic operated valve (such as a check
valve) in front of the pump, if more than one pump is
pumping on the same line or if there is a sufficient vol-
ume of vacuum in the system to cause the pump oil to
be drawn into the piping when that pump is shut down.
All R 5 Series pumps are vented internally to atmos-
pheric pressure through venting holes that are next to
the exhaust valve assembly.
2.5 Water-Cooled Pumps (optional)
Water-cooled pumps are cooled by circulating the oil
through a shell-and-tube type heat exchanger. The cir-
culation of the pump oil through the shell is created by
vacuum in the pump, but the circulation of the cooling
water through the tubes is thermostatically controlled.
The flow rate of the cooling water is controlled by a ther-
mostatically activated valve (see Fig. 2) that senses,
through a capillary bulb mounted in the exhaust box,
the pump's oil temperature as it is discharged from the
compression chamber. The valve will open at its set
point and close at approximately 3°F to 5°F below the
set point. The valve set point is adjustable as follows:
(a) Rotate the valve adjustment screw counterclock-
wise to cause the valve to open at a higher tempera-
ture. This makes the pump run hotter.
(b) Rotate the valve adjustment screw clockwise to
make the valve open at a lower temperature. This
makes the pump run cooler.
The thermostatic valve can be manually opened by
inserting a screwdriver under each side of the spring
guide and prying the spring and guide upward away
from the valve body.
The water cooling option can be used to cool pumps
operating in high ambient temperatures, or it can be
used to maintain a pump at elevated temperatures to
prevent condensation inside the pump in wet applica-
tions. Contact Busch Engineering in for details.
2.6 Oxygen Service Pumps
Oxygen service pumps must be used in oxygen
enriched applications that are defined as any applica-
tion which has a process gas that is 25% or more oxy-
gen. If this pump is contaminated by organic com-
pounds, do not attempt to use it on oxygen service until
it has been decontaminated.
These pumps have been manufactured, solvent
washed (to remove organic contaminants) and assem-
bled according to the latest technical standards and
safety regulations. If this pump is not installed properly
or not used as directed, a dangerous situation or dam-
age might occur. It is mandatory that these operating
instructions be read and understood prior to vacuum
pump installation and start-up!
CAUTION: Do not use the anti-suck-back
valve as a system check valve for your vac-
uum system. Do not depend on the anti-
suck-back valve to prevent pump oil from
migrating through the inlet into the system
when the pump is shut down.
Fig. 2 - Water-cooled Pump
Thermostatic
valve
WARNING: This pump is filled with a special
operating fluid. Do not use any other type
of fluid, oil and/or grease. Use one of the
following:
• Fomblin LC 250
• Tyreno Fluid 12/25V (perfluorinated polyether)
• KRYTOX ® Vacuum pump fluid by Du Pont
Company
If you have any questions, please phone our
Customer Service Department for more information.
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