Pipe Size Between Compressor Pump and Tank

[gzig5]

Might be a silly question, but here goes. I'm going to put an after-cooler on my 5hp, 60gal, two-stage compressor to eliminate as much water in the air as I can. This will consist of a Derale 15300 trans cooler with 1/2" tubes and -8AN fittings along with a water separator/filter. These get plumbed inline between the pump output and the tank. This compressor uses a 3/4"OD copper tube between the pump and tank. This seems larger than what I've seen on other compressors. I can run 3/4" pipe/tube for the connections, but I'm concerned that the 1/2 tube on the cooler will be a restriction. But at the same time, I know that a 1/2 tube will flow a large amount of air. I've seen videos of other people doing similar and using 1/2" tube, sometimes very long runs acting as the cooler, with no apparent problems. Am I overthinking it, as I usually do?

 

[steve-l]

Yes, you are over thinking this. You are adding some restriction, but it will not be an issue. However, I don' think your idea will work very at all. The dryer and centrifuge needs to be on the output of the tank, not the compressor. You will be far better off investing in an automatic tank drain system.

 

[gzig5]

Yes, you are over thinking this. You are adding some restriction, but it will not be an issue. However, I don' think your idea will work very at all. The dryer and centrifuge needs to be on the output of the tank, not the compressor. You will be far better off investing in an automatic tank drain system.

I've looked at several variations of this and all seem to be pretty effective at cooling the air and getting the moisture out before it goes into the tank. I've got a tank drain already.
How To Remove Moisture From Your Compressed Air - YouTube

 

[pavt]

I think you should use the same size throughout -- if the outlet from the pump is 3/4 then use 3/4 all the way to the tank, *including* the inlets and outlets on the cooler. I have worked in places where the cooler is before the tank and the system works well. I was the maintenance guy that installed it. They did have automatic drains on the tank just in case but I never saw it actually fill up enough to drain anything. The refrigerated dryers got all the moisture.

 

[jermfab]

Why go with a trans cooler instead of a dedicated aftercooler for a compressor? Even with the trans cooler on hand, one is designed to force fluid, the other air.

This is the cooler I set up on my Speedaire compressor:

It was cheap on eBay and sized for the compressors CFM. That way you know you’re not adding any restriction.

On my machine you cannot hold the tube from compressor to cooler, but the compressor to tank tube doesn’t get much hotter than ambient.


Be safe



Jeremy

 

[rons]

This was the original 1/2 tubing from pump to tank. Got real hot real fast.



This coil and filter drain collect all the water. A 120 gal tank stays dry. Open the tank drain and no more water.
A 50 foot coil of 7/8" copper. The pump had a 1/2" copper tube that did absolutely nothing. It got hot enough to mount
a platform to warm a cup of tea. Also increased the connection to the tank to 1 1/4". The coil is hot at the top end
and is warm about 2/3 the way down. The black filter was modified so that the down tube has a air distributor to spray
air in all directions and the only path is up through the scrubs. Water condenses in the scrubs and drips down. A Asco
valve is controlled to open at the bottom of the filter at appropriate times.







Final touches. Replaced wood with 1/2" aluminum and decreased the spacing. Each hole is lined with a few turns of black PVC tape.
The height is 24.5 inches.



If you want to use a automatic tank drain that uses a float there is a issue I have with those. Partially filled chambers just below
the trip point for drain action and then left over-night. Or maybe longer. Have to make sure to drain those things every end of work day.
Otherwise with a steel tank there will accumulate rust. In a aluminum bowl the corrosion will look like a bad weld because of no shielding gas.

 

[EPAIII]

The dryer after the tank is the way I have always done it and I have had great, ZERO WATER results in several installations. I like compressor(s) then tank then about 50 foot copper pipe cooler and finally a refrigerated style dryer. The copper pipe cooler would be set up to drain BACKWARDS via gravity into a collection jar at it's input end. Between them, the tank and the copper pipe will get around 90% of the humidity. The dryer only has to contend with the remaining 10%. I put collection jars at almost every point in the set-ups and since my installations had to run 24/7/365.25, I had bypass valves at every point where maintenance had to be performed.

I have re-done several really problematic air installations in really humid locations like New Orleans and south Florida this way and they went from constant water problems to absolutely zero water at the end of the line where the air was used in things like air bearings. And I am talking not a single drop of water in years of use.

Yes, you are over thinking this. You are adding some restriction, but it will not be an issue. However, I don' think your idea will work very at all. The dryer and centrifuge needs to be on the output of the tank, not the compressor. You will be far better off investing in an automatic tank drain system.

 

[Just a Sparky]

This compressor uses a 3/4"OD copper tube between the pump and tank. This seems larger than what I've seen on other compressors.

FWIW my 10 horse single stage has 1-1/2" intake and discharge piping. Roughly 35 CFM. Bigger pipes lend increased volume to help dampen the pulsating surges of air from reciprocating pumps. Less back-pressure on the pistons, lower peak pressures resulting in lower temperatures, cooler valves & cylinder head, greater efficiency, yada yada. No big deal if it's just a garage compressor, but every bit helps if the pump is running long and hard for sand blasting, etc. They get effin' hot when they run nearly non-stop. Hot enough to boil water no problem in my experience. The internets seem to suggest typical compressor discharge temperatures in the 300-350*F range. I'd believe it.

Figuring 20 CFMs through 25 feet of 1/2" pipe, this calculator spit out a pressure drop of 1.39 PSI. VS 0.18 PSI with 3/4" pipe. Probably translates to a degree or three Fahrenheit plus a dozen extra watts to overcome the difference in air resistance.

 

[gzig5]

Why go with a trans cooler instead of a dedicated aftercooler for a compressor? Even with the trans cooler on hand, one is designed to force fluid, the other air.

This is the cooler I set up on my Speedaire compressor:

It was cheap on eBay and sized for the compressors CFM. That way you know you’re not adding any restriction.

On my machine you cannot hold the tube from compressor to cooler, but the compressor to tank tube doesn’t get much hotter than ambient.


Be safe



Jeremy

Do you happen to have a link to that or something similar? Everything that my search came up with regarding purpose built ones are thousands of dollars, which is way beyond budget.

 

[jermfab]

I searched: “air compressor cooler” on the
eBay app and came up with several options. Prices are up, as prices seem to be up on everything, but this one seems like it will fit your bill:

Be safe



Jeremy

 

[gzig5]

Thanks. I tried a again and found some, yours looks like AKG brand. Looks like the dedicated ones tend to be plate style coolers.

 

[tmt]

I used the AKG aftercooler on my setup and it works just fine. From the aftercooler to an autodrain coalescing filter then into a refrigerated cooler and then into the air tank that has a timed drain.

The aftercooler cools the air so that the coalescing filter can remove most of the moisture from the air, but does not completely dry the air. That is why a tank drain is so important for removing any water that accumulates in the tank. I decided on a timer controlled drain so that I wouldn't have to worry about the tank being drained. Depending on your need or how dry you want your air, that's were the refrigerated dryer comes in. I have equipment that requires DRY AIR so hence that is why I have a refrigerated dryer as well.

There are two schools of thought on were to place the refrigerated dry, one is before the storage tank and the other is after the storage tank. Both in my opinion work fine if properly sized. IMO if a refrigerated dryer is placed after the tank the system demand could easily be greater than the rated CFM of the dryer and perhaps introduce moisture to the air supply if it was sized by the CFM of the compressor. With the refrigerated dryer prior to the tank, then the dryer only needs to be sized for the pump capability. and you don't have to worry about that moisture getting into the system. Once you get water in your lines, it is hard to get out.

 

[gzig5]

I'd love to run a refrigerated dryer but my use of the plasma cutter doesn't justify the cost. I'm getting by now and it will only get better with an aftercooler and timed tank purge. I'm returning the 1/2" Derale tube type cooler and will be getting a plate style like the AKG. I think the smaller 10 or 15 row ones should be sufficient for my 5hp Curtis-Toledo. I like the larger outlets and if I can stay away from AN type fittings that saves a bit too.

 

[rons]

This is an air dryer this guy made for his plasma cutter. This is where I got the idea for my setup. I have had it operating periodically for several months.
The coil has reduced the large gush to a trickle when the tank drain is opened.

What I don't like about this design is that everything is welded shut. And the steel inside the chambers will rust. Whatever...

Homemade air dryer and storage upgrade - YouTube

 

[whateg0]

Why go with a trans cooler instead of a dedicated aftercooler for a compressor? Even with the trans cooler on hand, one is designed to force fluid, the other air.

Air is a fluid. My concern would be the pressures present.

 

[steve-l]

The purpose of compressor after cooling, especially between stages, is compressor efficiency, not water removal. I use two tanks for my shop compressor. The first tank is 100 liters and is where the air cools and water condenses. My drain is there. That tank is plumbed to my main 500 liter tank. The air that passes to the main tank is both cool and dry. It really is not rocket science.

I also use a Bauer high pressure 300 Bar compressor. It is a four cylinder progressive design. It uses a tube coil and a condensation bottle between each stage coiled behind the flywheel/fan. The output air is always very dry regardless of the humidity level of ambient air.