Plumbing air compressor, help needed

[seanstrx276]

I know nothing about pipe fitting so any advice is appreciated. This setup will be used primarily for sand blasting and potentially painting down the road. I purchased an aftercooler from a local warehouse and need some advice plumbing it in. Please see attached pictures and diagram for further clarification. My plan is to come out of the 2nd stage cylinder and pipe into the top of the after cooler. Then out of the bottom of the after cooler pipe to an auto drain air filter before enter into the tank. I am also putting an auto drain valve at the bottom of the air compressor tank. Before the air enters the lines to the shop it will pass through a manual drain air fiter. My hope is there will be no water/condensate beyond this point.

Note: I could easily add more air filters at the point of use if needed.

Questions-
1. The fitting in the second stage head is a ½” male npt that 90’s into what I believe is a 5/8” female compression fitting. Can I get a T that has 5/8” male compression fitting to two 3/8” female npt? one female port will be the inlet to the aftercooler and the second would be a low point drain to prevent any moisture from entering the second stage cylinder.
2. Should I use NPT pipe and fittings to plumb the system or go with copper tubing and compression fittings? At some point I have to connect to the aftercooler that has 1” unions.
3. The 1” unions on the after cooler have a copper lining (where the end of the unions meet one another) Can I connect a steel union to the pre existing copper lined union?
4. Can NPT threads be cut into pipe? If using pipe to connect everything I would have to cut the pipe to length then have the threads cut.
5. Installing the auto drain for the tank, do I need any special plumbing? I have heard people speaking of special valves (strainer) that prevent debris coming from the tank from blocking the auto drain valve.

Thank you,
Sean

 

[stonesfan68]

I would leave the 2nd stage discharge installed as-is and then plumb from the tank to the after cooler. The tank will act as a moisture separator and also cool the air. Install an auto-drain valve on the tank.

Downstream of the after-cooler install a moisture separator followed by a coalescing filter, both with drains installed (most will have a float trap inside of the housing). If you buy industrial grade components (Hankison, IR, Zeks) then there will only be a small amount of water left in the air going to the process.

You aren't ever going to get rid of all of the water without installing an air dryer, but with the setup I've described you'll be way better than most.

 

[AndyA]

Yes, you can cut pipe threads, but the tools are expensive.
The handle will cost you from $75 to $100 depending on the style and where you buy it.
EACH die will cost you another $75 to $100.
The threading machines are several thousand $$$$.

There are chinese dies. I bought a set of these before I gave up and bought the rigid ones. You *can* get buy with the chinese dies, but be ready for poorly cut threads and leaks. It's one of those cases where cheap tools don't save you money.

A better bet would be to rent, or have someone cut the threads for you. My local big box store has a threading machine. I don't know what the price per cut/thread is, but it's probably cheaper than buying the tool.

Renting may be a little more expensive, but would be a better choice IMO. If you get your threading done at the store, you're going to have to have EVERY length pre-planned, and probably make multiple trips to the store for each 'oops'. If you rent you can do everything on-site. Have an 'oops' and you just recut and rethread on the spot.

I did threaded pipe for the air distribution in my shop. The material cost was cheaper than copper pipe. Knowing now what a pain it is to install, I think I'd go with copper pipe and silver braze it with an O/A torch if I did it again.

If you go with threaded pipe, remember to use LOTS of unions. If you have to repair a section of pipe you'll have to untwist it to remove it. Without unions, this means disassembling large portions of your piping. I also like to install a ball valve directly upstream from any union. That way you can turn off the valve, disconnect the union, but still use the remaining part of the system.

Your compressor is almost identical to mine. Mine is the 2475FP which has the factory aftercooler. It has two safety relief valves. It's probably a good idea to duplicate that in your system. One before and one after the aftercooler. I assume the one before the aftercooler is incase there is a blockage. I don't know that you'll need a drain between the compressor and the aftercooler (even though it's running uphill). The output pipe from my compressor is way to hot to touch (probably several hundred degrees) so I doubt you'd get much condensed water there. With your aftercooler plumbed input at top and output at bottom and a downhill run to the tank, I'd probably be happy with the first water trap being the tank. If the air out of the aftercooler is near room temp, the tank should catch most of the water. I have an auto drain on the tank, and the first water trap on the output of the tank. I only get water in that trap under very heavy use (sandblasting) when the temperature on the tank rises.