Georgia Tech Biomaterials & Tissue Engineering Lab

Vacuum Oven Operation

If liquid/solid is present at bottom of vacuum trap, remove trap from clamp. Disassemble trap by gently pulling lower portion of trap (body) away from upper portion of trap (stopper). If the body and stopper do not easily separate DO NOT FORCE APART. Try gentle heating or ask for help from someone with more experience.
Reassemble vacuum trap after emptying; re-secure trap in clamp.
Turn on green power button located on oven control panel.
After panel display stops changing, confirm that temperature set-point (value displayed in green and labeled "SP") is at 20-30 °C.
Close vacuum, gas, and vent valves by turning all 3 knobs at top of oven fully clockwise.
Locate 1900 ml dewar flask and determine whether liquid nitrogen (LN) or dry ice and isopropyl alcohol (CO2/i-PrOH) should be used for the vacuum trap. (If you are not sure, consult a more experienced lab member.)
Place dewar under vacuum trap, adjusting vacuum trap height as appropriate using clamp.
Fill dewar flask: (Promptly turn on vacuum pump once this step is completed. A cold-immersed trap that is not under vacuum is a serious safety hazard and could result in a dangerous explosion.)
1. If LN will be used, fill dewar with LN, being careful not to spill.
2. If CO2/i-PrOH will be used, fill dewar with dry ice and then slowly pour i-PrOH into dewar, being careful not to overfill or fill too rapidly.
Promptly turn on the vacuum pump. Listen for and troubleshoot any rapid leaks in the system.
Wrap towels/insulation around top of dewar and vacuum trap to minimize air currents and heat exchange.
Place samples in vacuum oven chamber if not already moved. Close door as tightly as possible.
While pushing on glass portion of door to help establish a seal, turn vacuum valve counterclockwise until needle on vacuum gauge begins to move. If sample/specimen is pressure-sensitive, rapidly close vacuum valve once needle begins moving. Settle valve so that dot is at top of valve handle, about 1/6 turn counterclockwise from fully closed position.
Set temperature set-point to desired value. (Temperature set-point is currently programmed to change at a rate of 1 °C / minute. Consult lab member responsible for vacuum oven if a different rate is desired. If sample/specimen is time-sensitive (needs to be at specific temperature for specific amount of time), it is important to note that temperature set-point may be reached hours after sample/specimen is placed in vacuum oven.)
Periodically check absolute pressure using vacuum gauge in-line with hose leading to vacuum pump.
For sample/specimen removal, begin by returning temperature set-point to ambient value (20-30 °C).
Fully close vacuum valve by turning it clockwise and open vent valve by turning it counterclockwise. If sample/specimen is pressure-sensitive, settle vent valve so that the "1" in "1/4" is vertical, about 1/6 turn counterclockwise from fully closed position.
Once needle shows that chamber gauge pressure is 0 (atmospheric pressure), open oven door and remove sample/specimen.
Lift clamp and vacuum trap out of dewar and set behind dewar. Promptly turn off vacuum pump.
Recycle dewar contents as possible:
1. If LN was used, empty remaining LN into original container, being careful not to spill.
2. If CO2/i-PrOH was used, place foam and towels over top of dewar as insulation in case next vacuum oven user will employ same trap type.
If oven is hot enough to burn someone, cool by fully opening door. Inform other lab members working in the area that the vacuum oven could burn them. Power may be left on to show temperature present value (value displayed in red and labeled "PV") on display panel as safety precaution.
Turn off green power button.