Using Vacuum Ovens for Drying Sensitive Substances
Vacuum drying ovens are commonly used for drying samples at the lowest possible temperature to avoid deterioration of the sample. Beyond sample drying, vacuum ovens are used for applications such as curing epoxies, baking-out, degassing liquids, moisture determination, aging tests, and heat treating.
Vacuum pump selection depends on the following:
- The volume of the oven
- The chemistry of the vapors removed from the oven
- The vacuum level needed for the process
- The mass of vapors removed
What to Consider When Selecting Vacuum Pumps for Vacuum Ovens
For many procedures using vacuum ovens, an oil-free, standard duty, WOB-L piston vacuum pump or a chemical duty diaphragm vacuum pump is used. These offer a sufficient vacuum level to do the job, and are compact, lightweight and portable.
Because these vacuum pumps are oil-free, there is no oil contamination of samples, no exhaust smoke, no oil leaks, and best of all, no oil changes. Normally a liquid trap is located in front of the vacuum pump. This prevents any vapor that condenses within the vacuum line from being drawn into the vacuum pump. Supplemental inlet cold traps are recommended for high water vapor loads.
The Most Suitable Vacuum Pumps for Vacuum Ovens
Some applications for vacuum ovens that require sample drying, bake-out, curing, etc. require ultimate vacuum pressure below 0.1 torr (0.13 mbar). In these situations, the key factor in vacuum pump selection is in the ultimate vacuum level achievable by the pumps. Welch Vacuum offers vacuum pump solutions for this high vacuum level in oil-free and oil-sealed vacuum pump technologies. Your individual budget requirements play a key role in deciding what type of pumping technology should be selected.