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Old 11-15-2020, 10:35 PM
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Default Compressed Air

I saved this photo from a member here.



Can this loop with the drains be done in pex and still be effective?
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Old 11-15-2020, 11:18 PM
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My own thoughts. The system done in a composite will work on the principle of gravity separating a portion of the moisture from the air, however the ability to radiate heat from the air that is heated as it goes through the mechanical compression will be much less. Two ways that air releases moisture contained within it's mixture are gravity and cooling. We see how this works in our bathroom daily as the cool mirrors remove the moisture from the heated, water laden air.

While the copper is much more expensive to be used in the water trap section, the composite will never be as effective in cooling the air, and releasing the moisture from the air. The balance of the system would make little difference whether it is constructed of composite, or metal, the water trap portion should be constructed of copper to be efficient, IMO.

Example would be that any heat exchanging device is constructed of aluminum, or a copper alloy to be efficient......

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Old 11-16-2020, 03:56 AM
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^^^ I would definitely second that opinion. In fact one of the advantages of PEX for home plumbing would work against you in this application. PEX to some degree insulates the cold/hot water in your home from the air ... keeping it colder or warmer ... exactly the opposite of what you want in an air dryer.

The copper in my opinion would work WAY better, specially if you are talking about longer run times such as painting a vehicle. The copper will dissipate the heat way faster than PEX, thus producing more of a condensing effect in the dryer.

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Old 11-16-2020, 09:52 AM
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I used iron pipe for my setup. Not as fancy as that but would definitely go with metal, some for durability but mainly for heat it's dissipation qualities.

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Old 11-16-2020, 10:40 AM
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That's an impressive rig you've got there. I've got iron pipe too and wish I'd done that with it.

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Old 11-16-2020, 11:19 AM
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Copper dissipates heat significantly better than iron.

Don

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Old 11-16-2020, 12:01 PM
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While the copper would work better as explained above you could still use the PEX and make more loops to eventually get the same overall effect. But then you have to also figure the footage with the cost per foot for each. May not be any monetary gain either way.

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Old 11-16-2020, 12:30 PM
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I only went with iron because it dissipated less of my money at the time.

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Old 11-16-2020, 01:33 PM
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I have 2 separate air lines. 1 in copper I ran years ago, and the newest (about 10 yrs old) I did in black iron. I have ball valves at the drops to eliminate moisture, and a good dryer in line, I also use a good regulator and dryer right before my spray gun. I have never had moisture problems. I did see someone did something similar to the OP but instead of all of the loops ran a couple of copper baseboard heat lines with the fins, I thought that was a pretty good idea as well. My electrician has told me that any plastic piping he gets is priced on the day he buys it because it is so volatile right now, so copper may not be out of line price wise.

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Old 11-16-2020, 04:08 PM
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Hot water baseboard is a good idea .... it's basically a heat exchanger, just what you want.

A coil of Pex in a barrel of water would work.

I opted for an aftercooler on the compressor, removes about 80% of the water before it gets to the tank, then three separator/filters and a cartridge filter.

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Old 11-16-2020, 09:11 PM
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Thank you for the replies.

I will make the loop shown above in copper and then pex for the distribution.

I am going to put in a series of valves where the air can be routed through a plug in dryer.

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Old 11-16-2020, 09:44 PM
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Installing the copper loop between the pump and air receiver works better than after the air tank.

I built a copper loop from a 25' coil of copper. Expensive, but works very well and I get zero water at my air tools.

Info here: http://forums.maxperformanceinc.com/...d.php?t=596325

Also, very important! When soldering copper joints for compressed air, do not use regular pipe solder. The soldered joint is the weakest part of the system and heat and pressure limit the safe working pressure. For compressed air 95%/5% tin/antimony solder should be used.

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Old 11-16-2020, 10:01 PM
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Quote:
Originally Posted by dataway View Post
I opted for an aftercooler on the compressor, removes about 80% of the water before it gets to the tank, then three separator/filters and a cartridge filter.
Is there a drain after the intercooler? Not understanding where the 80% of the water goes.

Don

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Old 11-16-2020, 11:14 PM
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Not to divert from OP's original question but has anyone ever used a commercial brazed-plate heat exchanger/separator instead of all this plumbing?

Here's an example:

Link to Website for SWEP BPHE / Separator



I don't have experience with these things but looks like an interesting way to get the air cooled and condensed water drained out in a small footprint. You'd need to have water running through it but that doesn't sound too difficult.
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Old 11-17-2020, 01:44 AM
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Quote:
Originally Posted by dhutton View Post
Is there a drain after the intercooler? Not understanding where the 80% of the water goes.

Don
I built the setup shown below. A large transmission cooler, cooled by a 120v fan wire to one leg of the 240v so it comes on when the compressor does.

It orientated so the water runs down the tubes and exits with the compressed air, goes through two water separators, an iron "stand pipe" with drain and then into the tank, the main volume of the water is caught at these two separators. The air exits the tank and goes through a separator/filter, then regulator, then outlet for shop air, then a cartridge filter and exits for "painting air". That way I'm not always using the good filter cartridge for running just air tools.

Anything before the cooler is copper tube (not pipe) with flare fittings, after the cooler you can use anything that will hold the pressure because the air is room temp.

You still have to drain the tank, but it's usually just a mist instead of a stream, and I have manual drains on the separators, complex to explain but automatic drains don't work well on a system like this. I've never gotten a drop of water out of the after tank separator. Since the air going into the tank is pre-cooled it holds very little moisture, and passes pretty much no heat into the tank (warm air can hold more moisture). I think to get any dryer I'd have to install a high end desiccant filter or refrigerated dryer.

The whole unit, compressor, cooler, separators, filters and outlets are all a single unit on heavy duty casters than can be rolled out of the corner for servicing or sold as a unit when the time comes.



Last edited by dataway; 11-17-2020 at 01:53 AM.
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Old 11-17-2020, 11:34 AM
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Quote:
Originally Posted by dataway View Post
I built the setup shown below. A large transmission cooler, cooled by a 120v fan wire to one leg of the 240v so it comes on when the compressor does.

It orientated so the water runs down the tubes and exits with the compressed air, goes through two water separators, an iron "stand pipe" with drain and then into the tank, the main volume of the water is caught at these two separators. The air exits the tank and goes through a separator/filter, then regulator, then outlet for shop air, then a cartridge filter and exits for "painting air". That way I'm not always using the good filter cartridge for running just air tools.

Anything before the cooler is copper tube (not pipe) with flare fittings, after the cooler you can use anything that will hold the pressure because the air is room temp.

You still have to drain the tank, but it's usually just a mist instead of a stream, and I have manual drains on the separators, complex to explain but automatic drains don't work well on a system like this. I've never gotten a drop of water out of the after tank separator. Since the air going into the tank is pre-cooled it holds very little moisture, and passes pretty much no heat into the tank (warm air can hold more moisture). I think to get any dryer I'd have to install a high end desiccant filter or refrigerated dryer.

The whole unit, compressor, cooler, separators, filters and outlets are all a single unit on heavy duty casters than can be rolled out of the corner for servicing or sold as a unit when the time comes.

Awesome!

Don

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Old 11-17-2020, 12:40 PM
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Quote:
Originally Posted by dhutton View Post
Awesome!

Don

Agree that is very clever.

Dataway - to clarify, can you share a photo or more detail of the separators and cast iron collector pipe you described?

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Old 11-17-2020, 02:09 PM
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Let see if this works here are some pics I just took. Rolled that baby right out of the corner for them.

Probably not suitable for professional painting without an additional filter/dryer, but so far with the painting I've done not a single tiny bit of water or oil.

Air deflector on the top directs the air from the fan through the cooler and then onto the small factory intercooler and compressor heads ... in addition to the very lame pulley fan that came on the compressor.

Outlet from tank to the last separator filter is not ideal, shouldn't have the big loop hanging down, should provide a nice incline instead. Spur of the moment thing to get the compressor up and running and I was out of the proper flair fitting adapters.

I should have made the wheels with a bit wider stance, can be a bit tipsy if you build up speed and hit something on the floor.

An added benefit of the aftercooler is better compressor efficiency since you are filling the tank up with cool air at pressure, rather than hot air at pressure that will cool down and lose pressure (energy). The hot setup would be a really good Intercooler (between the stages) this can dramatically increase compressor efficiency as the high pressure stage is fed dense cool air instead of expanded hot air. For some reason the compressor was noticeably quieter when I added the after cooler, I'm guessing the air contracting as it cools absorbs the shock wave coming from the outlet of the high pressure second stage.

It can run for 20 minutes and you can wrap you hand right around the inlet to the tank, haven't felt anything over room temperature yet.


[IMG][/IMG]

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[IMG][/IMG]


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Old 11-17-2020, 10:21 PM
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Great ideas here.
Glad I asked.

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Old 11-17-2020, 11:37 PM
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Nice!

Thanks for taking the time to photograph, label, and post the details.

You put a lot of thought and work into that - bet you are happy with the result!

The trans cooler is a great idea. Most heat exchangers/coolers I see online have a serpentine single-tube fluid loop but yours appears to have multiple tubes in parallel. The parallel paths looks perfect for gravity-collecting condensate into that lower "collector" pipe without water filling up a bend.

My small compressor has a separator right at the tank outlet but it has proven useless. I never see water in it but I remember sandblasting when I first bought it and being frustrated over clogs of mud.

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