How Loud Is A Freeze Dryer

A freeze dryer is not a relatively silent machine like your refrigerator.  There’s a vacuum pump and a compressor that operate continuously during the moisture removal process. Sound levels can vary significantly, depending of manufacturer and model selected, and generally run between 50-70 decibels (dB). 

Typically the vacuum pump is louder than the compressor in a freeze dryer and therefore the pump determines how loud a freeze dryer is. Stay Fresh currently offer two oil vacuum pumps, a standard oil pump, and an industrial pump. The standard oil pump is rated at 65db, while industrial pump 52db.  Most customers find the freeze dryer with the industrial pump quieter than expected.

The formula for calculating how loud something is, is shown in the image here, but it is not necessary to understand that.  Instead, you only need to remember that every 10 dB increase roughly doubles the perceived loudness to the human ear.  For example:

30 dB is a typical library;

40 dB is whispered conversation;

50 dB is a moderate conversation;

60 dB is noisy restaurant conversation;

70 dB would represent a vacuum cleaner;

90 dB would be a gas-powered lawn mower; and so on…

In reality, it is a logarithmic scale where every increment of 10 decibels is actually 10 times more energetic than the previous level.  While 60 dB is loud conversation and 70 dB sounds twice as loud, it has 10 times the energy.  If you doubled 60 dB to 120 dB, it is 10⁷ or ten million times more energetic, like standing next to a jet engine as the airplane is about to take off.  120 dB is enough to produce pain and to cause permanent damage to your hearing.

The great thing about the human ear and brain is that they filter out ambient sounds that aren’t essential.  Until you think about it, a ticking clock in the same room can’t be heard—but as soon as you focus on it, it appears in your perception.  This means that even a noisy Freeze-dryer can vanish into the background after you grow accustomed to it.

Placement

Still, some people are sensitive to sounds so it helps a lot to think about where you’re going to put it.  The usual recommendations are basements, garages or laundry rooms, since these areas are often designed to accommodate additional noise, or are far enough away from the main living space to not affect them.

Surprisingly, another consideration is furniture.  If you place the unit on top of a long workbench-like table, it can act like a sounding board, amplifying the noise, or helping it to conduct sound to walls or floors.  It can then travel much further than you might expect!

One solution is to place rubber sound-insulating feet under the furniture to isolate the noise, or between places where it contacts the walls.  Even a completely different table or surface can be an adequate solution.

Time

The important thing to remember is that the process takes time…  Freeze dryer cycles can run from 20 to 48 hours, depending on the type and amount of food being processed, the machine model, and even environmental factors like humidity and temperature.

You can shorten cycles by pre-freezing food in your deep freezer before introducing it to the freeze-dryer.  Your deep freezer is fairly silent and always runs so you may as well benefit from it.

The Takeaway

People don’t often consider the sound produced by these machines before they buy.  They’re interested in the results they will achieve. 

If you don’t have a good sound insulated space, it’s smart to find a quiet, low dB unit.  Failing that, it is possible to isolate the machine acoustically so that sound only travels by air instead of through the structure of your home.  In that case it attenuates quickly and is manageable.

Buy it quiet; make it quiet; or do both!  Don't forget to check out all available freeze dryer options.