Chances are if you're a regular user of freeze dryers, you're already familiar with the baseline maintenance procedures. Nevertheless, you may be overlooking some important steps to ensure that your freeze dryer performs to spec for as long as possible.
Below are some guidelines that our in-house freeze dryer specialist has picked up over the years.
Experiencing problems with your freeze dryer? Perhaps our troubleshooting guide will help.
1.) Change your vacuum oil consistently
The importance of regularly changing the oil in your vacuum pump cannot be overstated. Without clean oil your pump won't pull down to its capacity, which can severely inhibit your lyophilization processes.
A good rule of thumb is to monitor the color of the oil on the pump's external gauge. If it's anything other than clear, it's time for a change. However, it's best to simply change the oil on a schedule determined by the severity of your solvent. Sublimating gentler solvents often lets your oil last over 1,000 hours, while harsher solvents can warrant daily changes. Make sure to research your process requirements for the ideal oil change frequency.
2.) Don't use harsh chemicals to clean the door gasket
Unless you're sublimating especially harsh chemicals, you should only clean the door gasket with water or water-based solutions. Water-based cleaning solutions will ensure that your door gasket will remain intact, and thus maintain its vacuum integrity, for longer.
3.) Never turn on the vacuum pump before the condenser drops the chamber to a safe temperature
If you use freeze dryers regularly, you likely know good and well why this guideline exists. But it's worth reiterating: if you start pulling a vacuum before the condenser drops the chamber temperature, the vapors from the evaporated moisture will worm their way back into the vacuum pump and damage its internals, potentially costing you a few thousand dollars down the road.
4.) Always bleed out the freeze dryer's vacuum after a run
Failure to do this will simply result in a mess and wasted vacuum oil. The negative pressure created will suck oil out of the pump and spill it all over the chamber. Sure, it won't cause any damage, but who wants to clean that up?
Most floor freeze dryers have shutoff valves, but many benchtop ones do not. If your lyophilizer does not have a dedicated valve, you can bleed the vacuum by opening one of the ports of the manifold or the drainage port on the front of the unit.
5.) Last but not least: place the freeze dryer a safe distance away from the wall
Condensers are prone to heat damage, so they require proper ventilation to dissipate it effectively. Thus, you should ensure that your freeze dryer is a safe distance away from the wall at all times. Typically 8 inches is sufficient. Anything more than 12 inches is overkill.
Additionally, the ambient room temperature shouldn't be too high. Be sure to consult your lyophilizer's usage manual for safe operating temperatures.
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