On Fri, 5 May 2017 04:56:35 -0000 (UTC), James Waldby
wrote:

On Thu, 04 May 2017 12:39:10 -0700, mike wrote:
On 5/4/2017 9:39 AM, etpm@whidbey... wrote:
On Thu, 04 May 2017 12:16:27 -0400, clare@snyder... wrote:
On Thu, 04 May 2017 08:48:11 -0700, etpm@whidbey... wrote:

All over YouTube are examples of folks using either air conditioner
compressors or refrigerator compressors for vacuum pumps. [... I'm]
thinking of using one for vacuum infusing stuff. Like food. And also
of vacuum storage of dried foods. [...]
So what are the disadvantages of using a
repurposed refrigeration compressor

How are you going to address the lubrication of the compressor? In a
refrigeration system the lubricant circulates with the refrigerant to
circulate through the cyls. When used as a vacuum pump this does not
happen.

Will it work? Sure - for a while. How long? Who knows - but
the pump will deteriorate with use.

Actually, from what I have seen on YouTube, the compressor gets
adequate lube, especially the [reefer] types which actually have the
motor submerged in oil.

Won't you be sucking a lot of moisture? That can't be good.
I'd at least think about the possibility of getting vapors
from the compressor back into your food.

Educate me on the value of high vacuum food preservation.
For bag sealing like seal-a-meal, the purpose of the vacuum is to
EXCLUDE air by forcing the plastic into contact with solid chunks
of food, like chicken breast.
Once contact has been achieved, higher vacuum has no purpose.
I suggest it's a detriment.
The higher the vacuum, the more likely you'll hasten the exit
of water from the food into any voids that exist.
[...] A nitrogen purge might be better than trying to extract the
oxygen directly with a vacuum pump.
...

If the goal is storing frozen foods while avoiding freezer burn,
pulling the air out of aluminized mylar or thick polyethylene
sacks, then heat-sealing, is ok; if that's properly done, foods
keep ok months to years. For storing well-dried non-oily foods
at room temperature for similar times, the same technique works ok.
An oxygen absorber deals with trapped air and allows longer storage.
https://en.wikipedia.org/wiki/Oxygen_scavenger

But long-term storage, eg 30 years, at room-temperature, freeze
drying is about the best approach. The vacuum-freeze-dry process
(see https://en.wikipedia.org/wiki/Freeze-drying) doesn't collapse
food cells as much as heat-drying does, freeze-dried food weighs a
little less than heat-dried, and it rehydrates much more nicely
than heat-dried food.

See eg https://harvestright.com/store/ for some various at-home
freeze-drying models, $2300 to $4100 on sale. Of course most RCMers
could put together something that would work, for much less than that.
But if you are going to make a freeze dryer and run it full time,
several food batches per week, with different temperature and vacuum
vs time profiles for different foods, and depend on the unit making
food that's safe to eat, conveniently and dependably, that may run
the cost up into the same ballpark.

On the "Harvest Right Freeze Dryers" facebook page, water in the
vacuum-pump oil gets mentioned, as well as pump oil going where it
shouldn't be. The company has a recommended oil change schedule.
https://www.freezedryeraccessories.com/ sells a kit with valves
and filters to get water etc out of the pump oil after each batch.
https://harveyfilter.com/buy/ has a lower cost manual filter
system. These companies are in the SLC UT area -- LDS recommends
a three-month short-term food supply, plus a supply of long-lasting
(30 year) foods as well. https://www.lds.org/topics/food-storage

Anyhow, having your own freeze-dryer makes sense if you have a
bountiful garden and access to lots of produce or if you want
to make and store hundreds of servings of almost anything for
future consumption. Otherwise it's less expensive to order freeze
dried foods from companies like Augason Farms in SLC, although
Walmart at https://www.walmart.com/c/kp/freeze-dried-foods often
has the same prices as AF. Eg about $31 for a 25-year-shelf-life
#10 can with 24 servings of Augason chili-mac w/ freeze dried beef,
$23 for 14 servings of Freeze Dried Chicken Fettuccine Alfredo with
best-before date of 1 May 2042, $90-$100 for 307-serving AF 30-Day
All-In-One Emergency Survival Food Supply Kit, etc.
Thanks for all the good info James. There are dietary issues my wife
has but I'll bet most if not all will be addressed with the foods
available now. So much "prepper" and "survivalist" stuff is hyped now
prices on a lot of stuff is way high. The LDS does offer some stuff
and there is a store not too far away from me. I don't know if the
effort to freeze dry myselfwould be worth it except just to say I did
it and could do it again. But that's exactly the kind of thing I like
to do and I would imagine freeze drying a few months worth of food
wouldn't be that big of a deal.
Thanks Again,
Eric