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Selecting the correct operating parameters for Büchi Rotary Evaporators
is an important part of your application. Many variables must be considered,
i.e. choosing the appropriate bath temperature, vacuum pressure, rate
of evaporation, and accessory chiller—so it's no surprise to find
more vapors collecting in the lab environment than in the receiving flask!
For a complete guide for optimizing your Büchi Rotary Evaporator
application, click here.
1–3 L Rotary
Evaporators and Vacuum Accessories |
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| Can a Büchi SafetyVap®
Model R-200 or R-205 Basic be upgraded to an Advanced or Professional model?
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Yes –The Basic Model Rotary Evaporator has a built in power cable.
Please order the following accessories
| Description |
Catalog No. |
V-800 Vacuum Controller 115 V
or
V-805 Vacuum Controller 115 V
|
015680709
015680636 |
| Vacuum Valve with woulff bottle |
015535008 |
| Communication Cable with slotted cover |
015680661 |
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| Can a Model R-200 be upgraded to an R-205? |
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Yes – Please order the Display Module catalog number 015680598
and follow the instructions in the operation manual.
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| Can I control the vacuum pressure of more
than one Rotary Evaporator with my Büchi Vacuum Controller Models V-800,
V-805, or B-721? |
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Yes - Multiple Rotary Evaporators can be connected to one Vacuum Controller;
however, the nominal vacuum pressure must be the same for all of the
Rotary Evaporators. If you would like to maintain the vacuum of each
SafetyVap at different nominal pressures, then an additional Vacuum
Controller and Vacuum Valve are needed for each SafetyVap.
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| When I turn the coupling to secure the
evaporation flask adapter, the whole drive unit turns and I cannot tighten
the coupling. How can I prevent this from happening? |
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Press the button beneath the drive unit in order to lock the motor
mechanism from turning. (Models R-200, R-205, R-114, R-124, R-134, R-144)
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| The solvent vapors are not condensing.
Why? |
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The leading cause of this problem is not using a vacuum controller.
Most likely the maximum vacuum of your vacuum pump is too low, and consequently
the vapor pressure temperature (Vp) is lower than the condenser temperature.
Consider the following example:
| Solvent |
Methanol |
| Boiling point (°C) |
65 |
| Maximum vacuum of Büchi Vacuum
Pump Model V-500 |
10 mBar |
| Vapor pressure temp. at 10 mBar
(°C) |
–25 |
| Condenser temperature with tap water
cooling (°C) |
22 |
In this example the condenser temperature is higher than the (Vp)
of Methanol, therefore the vapors will not condense. The condenser should
be 20°C below the (Vp). You can either buy a Büchi Vacuum Controller
Model V-800 or V-805 or change the glassware to a "C" assembly
(cold-trap condenser).
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| Do I need a vapor trap to prevent vapors
from entering the lab environment or being aspirated into my vacuum pump?
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The risk of vapors escaping the rotary evaporator and entering the
lab environment is a valid concern, especially if a Vacuum Controller
is not being used. A vapor trap is not needed if you are working in
a fume hood with a chemically-resistant Büchi Vacuum Pump Model
V-500 with PTFE diaphragm. The Büchi Stainless Steel Dry Ice Trap
— catalog number 015509759 — is recommended for any use outside
of a fume hood or when using either an oil pump or water aspirator.
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| I just purchased a Büchi Vacuum Controller
Model V-800, V-805 or B-721 and when I press "run" the vacuum
remains at atmospheric pressure and does not reach the nominal pressure.
What is the cause of this problem? |
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Büchi Vacuum Pumps and Accessories: Valve Unit
| Fig 1
Cat. No. 015535008 |
or |
Fig 2
Cat. No. 015652101 |
A vacuum valve must be connected to the Vacuum Controller in order
to control vacuum. Contrary to popular belief, the vacuum valve is not
built into the controller, and it may need to be purchased separately.
The vacuum controller opens and closes the vacuum valve in order to
maintain the set vacuum pressure. The controller and valve work together
to maintain the vacuum pressure of the system regardless of the vacuum
source, whether it is a house vacuum system, water aspirator, Büchi
Vacuum Pump or another manufacturer's vacuum pump.
Brinkmann currently offers two types of vacuum valves that can be used
with Büchi Vacuum Controllers. The first type illustrated in figure
1 has a wolffe bottle and has the necessary hose connections built-in.
The wolffe bottle is designed to collect any rogue solvent vapors. The
valve unit is secured by a mounting device or holder, which prevents
damage to the wolffe bottle. This type of vacuum valve is supplied with
the Büchi Vacuum System Models V-502, V-512, V-503 and V-513 as
well as the SafetyVap Models R-200/R-205 Advanced and Professional.
The second type of vacuum valve is illustrated in figure 2. This type
of vacuum valve does not require a special holder; however, it does
not have all the necessary hose connections for installation. An additional
"Y" connector (cat. no. 016005967) is required to connect
the Vacuum Controller and SafetyVap to the valve unit.
The following diagrams illustrate how to connect each type of vacuum
valve. The vacuum valve in both cases has an electronic communication
cable that connects to the v or valve connector port of the vacuum controller.
The hose connections are best understood by referencing the following
diagrams.
Hose connections for Vacuum Valve V-500 (cat. no. 015535008)
Hose Connections for Two-Way Vacuum Valve (cat. no. 016005967)
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| What should I check to eliminate a vacuum
leak? |
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- When was the last time you changed the PTFE vacuum seal? As part
of a routine maintenance schedule, check and replace the vacuum seal
as needed.
- Tighten and inspect the Gl-14 hose connections.
- Inspect all glassware for cracks.
- Use joint grease on the ground glass joints but not on glass/PTFE
joints.
- If you have a cold trap condenser provide a slight pressure on the
cold-trap lid until the vacuum begins to decrease.
- Disconnect the rotary evaporator from the vacuum system to see if
the leak is before the rotary evaporator.
- Make sure the continuous feed valve is closed.
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| My RE XXX vapor duct is jammed. How
can I remove it without breaking it? |
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The steam duct should be periodically removed and cleaned. Gently tap
the cold side of the vapor duct with a book until it is freed.
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| What is the recommended mixture of acetone
and dry ice with the cold trap condensers? |
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50/50 |
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| What is the maximum cooling liquid pressure
that can be applied to the lab-size coil condensers? |
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1 Bar
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| What is the minimum obtainable vacuum
with the lab-size rotary evaporators? |
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1 mBar
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Rotavapor Model
R-220
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Heating Media
Which heating medium can be used in the heating bath? |
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Normal water is the most commonly used medium.
When using distilled water, 2 g of borax should be added. Other options
include most mineral oils or polyethylene glycol. |
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Compatibility to R-153
Which spare parts are interchangeable between Models R-220 and R-153? |
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The evaporating flasks used with Models R-220
and R-153 are identical, and the condensers are compatible. The receiving
flask, when used with the drain valve, is also compatible with both models.
The steam duct has a larger diameter and therefore, the complete sealing
system has been changed. The distribution piece and the vapor duct have
different dimensions and are not interchangeable. The Rotavapor Model
R-153 cannot be updated with a Snap Flange Coupling, but the EasyClamp
is fully compatible with both models. |
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Dimensions
How do the dimensions of the Model R-220 compare to the Model R-153? |
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The dimensions of the new Model R-220 Rotavapor
are slightly larger. The height is identical for the two models, but the
R-220's depth is increased by 5 cm and its width is increased by 20 cm.
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Snap Flange Coupling Adjustment
When I attempt to adjust the Snap Flange Coupling to its maximum diameter,
I have difficulty attaching the evaporating flask. |
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If the dimension of the evaporating flask flange
is not within a certain tolerance, the Snap Flange Coupling cannot be
closed successfully. This may occur when older model flasks or non-Büchi
flasks are used. Please contact us to replace the flask. |
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Removal of the Evaporating Flask Seal
It is difficult to disassemble the evaporation flask seal. What can
I do? |
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The evaporating flask seal is secured by a
silicone ring clip. The tension can be affected by humidity, the age of
the clip, and/or temperature. Applying a small quantity of grease around
the ring should make the seal easier to disassemble. |
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Overpressure
Can I use the Model R-220 under positive pressure? |
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The Model R-220 vacuum seal is designed to work
under vacuum: the lower the vacuum pressure, the better the seal. The
Rotavapor should not be used under ambient pressure and must NEVER be
operated in any conditions over ambient pressure. |
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Power Frequency
Is there any difference between 50 Hz and 60 Hz? |
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No. The Model R-220 does not contain any components that are affected
by frequency.
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