Hi folks. Just a preface before I get into depth with this post. This subject may not be interesting to some, as it is slightly off topic and very technical. It's very much topic-related, though. If you find it boring, please accept my apology in advance.
As you know, one of the issues working on old refrigerators, coolers, and air conditioners is working with refrigerants. Specifically; not wasting expensive refrigerants; nor opening ones self up to legal liability by willfully releasing legally regulated ones into the air.
There are a variety of refrigerant recovery machines which can be purchased from equipment suppliers. These will allow you to remove refrigerant from a system place it into a storage tank. They have their limitations. One significant limitation is the amount of gas lost when you change the recovery machine from one type of refrigerant to another type.
One of the challenges of working with very uncommon (and often one-off) systems is determining how much and what currently-available refrigerant is suitable; as well as what if any modifications will be required to make it work. This may require removing and putting back the charge several times. With some refrigerants, this can get costly in a hurry. Evacuating a full-size recovery tank for a small system won't work well because so much is lost in the recovery system and not returned to the unit afterwards.
As a fun experiment, I built a miniature recovery machine with the intent of maximizing the amount of refrigerant actually transferred into the recovery tank versus lost in the machine.
It's built from mainly salvaged parts. The main part of it is a 50's Tecumseh soft drink cooler compressor. The condenser coil is a part from the scrap heap from a prior fridge repair, and the storage tank is a used torch gas bottle. The gauge manifold came from an antiques shop bargain bin.
It looks pretty silly, but it works. I'm sure there will be more perfecting to be done, and this is "version 1.0" so it is a bit rough around the edges.
I'm hopeful that the video is interesting enough to watch to the end.
If you have wondered how a recovery machine works, this will give you a good understanding. The home-brew machine is all manual, but it follows the same principles as a factory-built recovery unit.
You really are a master of refrigeration it made no sense to me at all as I do not understand how it all works but your video makes it easier to grasp the reasons of what needs to be done to drain systems etc and if you are able to reuse the gas/liquid that has to be good for the environment too.
I take my hat off to you Sir :)
Post# 1169025 , Reply# 2 1/10/2023 at 11:44 (471 days old) by turbokinetic(Northport, Alabama USA)
Thank you Austin. I'm glad it helped explain some things to you. The most basic reasoning for this is summed up as follows. Many of the systems I work on need to be charged, tested, de-charged, modified, charged, and tested again. This has to repeat until the adjustments are finished. One example is changing the length of the capillary tube to match it to a new and slightly different compressor or gas type. This machine will allow me to do that without "wasting" refrigerant every time.
Post# 1169045 , Reply# 3 1/10/2023 at 15:23 (471 days old) by pshbuttoncook(United States )
This is absolutely fascinating to me. My first want was to become a refrigeration tech out of high school, I ended up going to school to become an ME (probably a good move on my part) we touched on basic refrigeration but never got into the down and dirty.
I have self taught my self and repaired several auto A/C systems but always want to know more. I look forward to seeing this progress!
Hi Travis. Thanks for the comment. I appreciate it! It's pretty important to learn the basics of refrigeration, or automotive, or anything technical for that matter. Even if you don't plan to do the work, it helps you avoid getting lied to by unscrupulous service people.
(Lincoln UK) 
Comes to the Rescue!
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