The dial thermometer can be removed and put back after loading, if it is
more convenient. For precise measurement, be sure thermometer sensing
element directly contacts a shelf or sample.
Distribute the load evenly in the chamber, at least 1-inch away from
chamber walls and resting directly on the shelves or best results.
The following are directions for operating the oven in a vacuum mode:
1. Apply a high-quality vacuum grease to the door gasket, load the oven,
and close the door.
2. Close the vacuum release valve (on the topside, right) and open the
vacuum valve (topside left).
3. Turn the vacuum pump on and note the vacuum gauge dial (graduated
in inches of mercury). Just as the gauge needle reaches the desired
setting, close the vacuum control valve completely and turn off pump.
4. If there is greater vacuum than desired in the chamber, open the
vacuum release valve slightly until the correct reading is obtained, then
close it.
5. After a period of several hours, the vacuum level is likely to decrease an
inch or so. Re-establish the original level by repeating Steps 2 and 3.
Some applications call for replacing the vacuum with an inert gas while the
bake continues. Use only noncorrosive, nonflammable gases, such as
nitrogen and CO2 for purging.
1. Connect 1/4-inch ID tubing to the vacuum release port (right side).
Connect the other end of the tubing to the regulator on a gas cylinder
or bottle.
2. Start the gas flowing at no more than 5 psi. Open the vacuum release
valve and observe the vacuum gauge. The vacuum level will fall as the
chamber approaches atmospheric pressure.
3. Turn off the gas when vacuum gauge reads zero. Turn vacuum release
valve to the CLOSED position. Disconnect hose from barbed fitting.
Caution
Do not pressurize the oven chamber to a level higher than
atmospheric pressure. When the vacuum gauge reads zero, turn off the gas.
The oven is designed to retain a vacuum, not to withstand any positive
internal pressure. Any positive internal pressure may damage component
parts and/or result in injury. The oven does not require very much gas to
fill the chamber - approximately 0.4 cubic feet.
s
6-2
Small Vacuum Oven
VWR Collection
Section 6
Operation
Loading the Oven
Vacuum Control
Purging the Chamber
with Inert Gas
