Homemade silent air compressor

[cmarlow]

It is OK. Reading the comments from you and Hemmjo about these fridge compressors is giving me a fairly good idea of what they can do. I have a couple of small compressors that are good enough for spraying paint or running small tools, nothing big enough for heavier tools or jack hammers. I also have a couple of the small diaphragm type compressors for running airbrushes. Your posts make me think I should assemble a compressor like yours because I have all the pieces in a scrap pile so it would basically be zero cost.
Thank you again for this interesting post.

[Dimitris Polychronis]

Hey hemmjo,

Thank you for the info, they are very helpful! As I wrote above, I have a 6th compressor under construction for-quite some time now; I was worried about longevity too, so I decided to use oil filters for the incoming air since the compressor will be inside my shop (the level of moistrure and dust in the shop is low)

Here is the oil filter


and these are the motors

Embraco aspera NJ6226Z 220V 1Hp


L’UNITE CAJ4517Z 220V 1.5Hp

Now as for protecting the tank from moisture carried from the pressurized air, I have thought to put a carbon filter between the motors outlet and the tank. Anyway these are some thoughts for now, will see how will goes when I'll start working the project again. Thanks again for the ideas!

All the best
Dimitris

[Dimitris Polychronis]

It is OK. Reading the comments from you and Hemmjo about these fridge compressors is giving me a fairly good idea of what they can do. I have a couple of small compressors that are good enough for spraying paint or running small tools, nothing big enough for heavier tools or jack hammers. I also have a couple of the small diaphragm type compressors for running airbrushes. Your posts make me think I should assemble a compressor like yours because I have all the pieces in a scrap pile so it would basically be zero cost.
Thank you again for this interesting post.

I would like to see it when you finish it! It was my pleasure sharing it with all of you!

Best wishes
Dimitris

[Dimitris Polychronis]

Excellent maintenance video, Dimitris and perfect timing for you to display your precision handy work and meticulous attention to detail! Hopefully you can finish your dual compressor one day soon as that would be of interest here also.

Thanks for sharing this timely build with us.

PJ

Thanks for your kind words PJ, I hope the same too! It's my pleasure sharing it with all of you!

Best wishes
Dimitris

[old_toolmaker]

Dimitris Polychronis,

I like your air compressor and would love to make one for my own small shop. My shop is in the basement and I have a small noisy oil-less compressor. Loud annoying sound is not welcome in the house so this would be a nice tool to have.

[Dimitris Polychronis]

Dimitris Polychronis,

I like your air compressor and would love to make one for my own small shop. My shop is in the basement and I have a small noisy oil-less compressor. Loud annoying sound is not welcome in the house so this would be a nice tool to have.

Hey Dick,

Thank you very much, glad to hear that you like my compressor! I think that every shop needs to have a silent compressor; first the low noise is the big advantage especially if you have your shop in home and second for all the jobs that not need high volume of air. I would like to see your silent compressor when you finish it!

Cheers
Dimitris

[DIYer]

Thanks Dimitris Polychronis! We've added your Silent Air Compressor to our Air Compressors category,
as well as to your builder page: Dimitris Polychronis's Homemade Tools. Your receipt:

Silent Air Compressor by Dimitris Polychronis

tags: air compressor

[justinsane]

This concept is pretty good in that the compressor is really quiet.

However, I watched this entire video to see what all was included.

I am by trade an air compressor service technician (12 years) and DOE Qualified Air Master (10 years) as well as being universal certified refrigeration tech (20 years).

Of the maintenance operations you performed in this video, the only ones I would recommend are the oil check/top off and the filter element change(however certainly not after only 10 hours of operation unless it was contaminated, in which case you've got bigger problems).

The tank should be mounted vertically and a drain of some type placed at the bottom, be it a float drain, an auto drain or just a ball valve that you use to drain the tank after each use.

Also I would increase the size of the tank to store more air and consider using a compressor that is designed for a refrigerant other than 134a so you can increase the tank pressure without over amping. 407c or 404a could give you significant pressure increase if you use a tank, and all the other components(PRV regulator tubing etc) rated for 250 psi you can store more usable compressed air.

Also if you need more than one (substantially different) pressure output I would recommend multiple regulators rather than repeatedly adjusting the single unit.

I would never recommend disassembling a regulator unless it is not working properly(on that note I wouldn't disassemble any of the unit unless it isn't working properly.

Based on the life expectancy of the compressor the other components will likely out live it with no maintenance at all.


All of that said, to which I hope you don't take offence, I like the idea and may some day build one.
If I do I'll most certainly attempt to add oil separation, to both retain the oil in the unit reducing maintenance as well as prevent the oil from contaminating the air system. I would also at least broach the topic of cooling so as to extend the duty cycle and the life expectancy. Though not sure how at this time.

[justinsane]

While it is not gospel consider that a consumer grade single stage lubricated reciprocating compressor will make around 2-2.5 cfm per HP at 100 psi(let's use 2cfm/hp though this type of compressor may do better).

Since this is a positive displacement compressor there will be no gain in CFM by lowering the pressure. Power/Pressure/Flow form a triangle if you lower/raise the pressure but do not change the flow the power will be reduced/increased equal to the amount you changed the pressure, you can save energy by lowering the pressure but you can't get more air. You can however STORE more air in the tank if you raise the pressure, which will use some more energy(honestly energy savings are nearly irrelevant on this because of its size and expected time of use).

If the unit is 1/3 hp you can expect CFM=~(2*.33) or about .66 CFM at +/- 100psi which is not far from where the 134a compressor wants to be on the high side. You can check for a factual number when running the unit but it will likely be over amping not much past 150 psi(remember you're not cooling it like the refrigerant normally would on the suction line coming back at 35deg F).
This is why I would recommend going to a compressor designed for a different refrigerant which is intended to run higher head pressure. That way you can achieve higher tank pressure while not reaching max amps.

In any regard what air compressors make is heat, usable compressed air is a byproduct, about 85% of the energy you put in will become heat, only 15% will become usable compressed air.

[Sleykin]

What could I expect to get with a big outdoor unit that runs 404A? Like a 3 ton A/C . Would there be an advantage to putting the heat exchanger on the input line to cool the input air? I know it would have to run on 220 VAC, A big propane tank at 200PSI would run stuff for a long time before it needed to be filled again.