Compressed Air Manifold/Radiator or Aftercooler

[Majeztic]

I am moving into a new shop soon and am planning the compressed air setup and piping.

My current setup in the existing shop utilizes two 60 gallon 3.7hp single-stage Husky air compressors (155 psi; about 11 cfm each). They are installed in a closet with 1/2" copper pipe running about 50' to my finishing area. I have one drop that runs into a filter/regulator then up to a hose reel which we use for a blow gun. I have another drop that runs to a small refrigerated air dryer that is rated for 10cfm at 100psi at 100° inlet temperature. My spray gun, which I run directly off the RAD, is rated for 13.5 cfm.

We sometimes have long painting marathons which uses a lot of air. With two guys, it's an almost constant use of air; we're either spraying paint or using the blow gun from the hose reel to dust off the next piece prior to spraying it. I didn't connect the hose reel to the RAD because I was worried about it being too much demand. The filter to the hose reel seems to be capturing all the water and I don't notice any moisture coming out the blow gun except when I fail to drain it.

I've been using this setup for about 5 years and it has worked really well. I get no moisture out of the gun, the hi-temp warning light has never lit up, and I haven't noticed any issue between the mismatch of cfm ratings between the RAD and the spray gun.

In the new shop I bought a larger RAD which is rated at 25cfm at 100psi at 140° inlet temperature to dry the entire compressed air system, not just the spray gun drop. The RAD will be installed in an equipment room with the same two 60 gallon compressors. I also acquired a 60 gallon tank that I plan on plumbing in after the RAD to use as a dry tank reserve.

I believe that my success with the RAD in the current shop is due to the fact that there is more than 50' of pipe after the compressors. So, to replicate that, my original plan was to install a manifold/radiator (not sure what these things are called) between the compressors and RAD consisting of about 40' of copper pipe either in a left to right or up and down configuration. Similar to these that I found on the web:



However, I recently came across the option to add an aftercooler between the compressor and tank, similar to this (another pic found on the web):



The aftercooler would eliminate the need for the extra copper pipe and would be more compact. I think the difference in cost would be insignificant.

My questions are:

It appears that the aftercoolers are primarily marketed and sold for use on larger two-stage compressors. Are there any issues or concerns with installing aftercoolers on smaller single-stage compressors?

What are the pros and cons of each system and which would offer the best results?

Thanks in advance,

Mike

 

[Citation]

What you are basically looking at is two options, one is an after cooler that goes between pump and tank and has to deal with the flow rate of the pump. The other is a cooler (or heater) that goes after the tank and has to handle the flow rate of your tool. My feeling, with out actually calculating the thermodynamics of the system is the cooler between pump and tank is better for several reasons.

There is no reason why such a cooler wouldn't work on a smaller, single stage compressor. I suspect you normally don't see them on smaller compressors because such systems are typically lower cost (less budget for the cooler) and tools like impact wrenches, air grinders etc are less sensitive to wet air vs painting/blasting.

As for the advantages, the first I see is you capture the water before it goes into your tank. Hot air with high humidity goes into the cooler. In the cooler water condenses out. It gets caught in the inline trap before that air is put into the tank thus less water in the tank. As a side benefit, the air in the tank is closer to room temp so you see less pressure drop due to the air cooling in the tank. Remember the pressure switch now sees cooled air vs the hot air that just came out of the pump. If nothing else, reducing the water that gets into the tank would mean less for an system after the tank to handle. It also means less flow restriction after the tank since that, is what really limits your tool performance.

That said, my answer is based on gut feel and having done pretty well in thermo many years back. Short of doing calculations I'm guessing based on intuition but not experience.