09 February, 2022

The last touches on the compressed air system.

So my last few bits and pieces, some 3/8" MPT x 1/2" Push to connect unions came in today, and I already installed them. I have narrowed down what I have used in my system, and worked out a full parts list for anyone wanting to do an install like mine without making the mistakes I made along the way.

So let's go!

As a refresher, I have a dual compressor system, both Central Pnuematic oil lubricated, 2HP models, one 29 gallon, and one 8 gallon. They are ganged together in a custom manifold that uses a Central Pnuematic 3/8 filter / regulator, FRL connection bracket, and a Central Pnuematic filter / dessicant dryer. 

Harbor Freight is changing lines from Central Pnuematic to Merlin, and I can find no FRL bracket advertised as compatible with the Merlin setup, so if you want to go with Merlin instead of selecting one on say Amazon, just use a 3/8" close nipple.

I went with the dual compressor setup to be able to delivery just over 14cfm at 40psi, which is more than enough to drive anything I am likely to run in my shop, or around my house. Yes a big industrial compressor would be awsome, but that would require a dedicated 30 amp 220v circuit, and a LOT more space neither of which I have or have any interest in adding to my garage workshop.

Now with that being said, let's go through what we have and how we configured it shall we?

Dual compressor input, regulator / filter / dryer / manifold assembly.

I run the dual compressor setup with one compressor, the 29 gallon, plumbed via the piping sytem to the manifold, and the other via a quick connect to the manifold. These connect through 1/4" NPT one way check valves preventing backpressure or leakage in the system or between the comrpessors. These are in turn assembled to 3/8" x 1/4" NPT bushings, and in turn assembled to a 3/8" FxFxM tee. This tee feeds into my Central Pnuematic 3/8" filter regulator, this in turn is connected via an FRL bracket to a Central Pnuematic 3/8" filter / dessicant dryer.  The first filter does particulates, the second filter removes oil etc...  These each are auto draining. On the output side, another 3/8 FxFxM tee, and from here we connect with the first 3/8" MPT x 1/2" push to connect union to get into the piping system, and on the other output, I use for now am using a Central Pnuematic industrial coupler with a 3/8 x 1/4" bushing. I will be upgrading to a Milton 3/8" MPT unit soonest possible.

My regulator / filter / dryer manifold assembly. The main
components are now discontinued and replaced with the Merlin
brand at Harbor Freight.

So here is the shopping list, and I am aiming for having some spares with best per unit price so adjust as necessary.

  1. First the brass tees. Yes I am linking a 5 pack even though I used 3. These are useful, and, well, it is cheaper this way per unit by a lot. GASHER 5PCS Metals Brass Pipe Fitting Barstock Male Branch Tee T Adapter 3/8" NPT Female x 3/8" NPT Female x 3/8" NPT Male 5pk. https://amzn.to/35RDzsl
  2. Milton S-217 1/4" NPT V Style Coupler and Plug Kit - 6 Piece. This will cover 2 hoses, and the secondary input should you opt to not run it in using the push to connect tubing and keep it mobile, https://amzn.to/3uATpSM
  3. Control Devices P2525-1WA Brass Ball Check Valve, 1/4" NPT Female x NPT Male. You will need 2 of these, 1 for each compressor input. These will require bushings. https://amzn.to/3B3PGyd
  4. T TANYA HARDWARE 1/4" x 3/8" Brass Hex Bushing, Female Pipe x Male Pipe, NPT, Pack of 10. https://amzn.to/3rBRLOU
  5. I used the now discontinued Central Pnuematic, now they have the Merlin 3/8" air filter with regulator. https://www.harborfreight.com/38-in-...tor-58178.html
  6. Again Central Pneumatic, the Merlin equivalent is.... 3/8" NPT (F) Dessicant Dryer filter. https://www.harborfreight.com/38-in-...ter-58180.html

Unlike the Central Pnuematic, the Merlin does not appear to have an FRL connection bracket available. If you can find a compatible unit, use it, if not, just connect them with a brass 3/8" close nipple. The FRL mount brackets were really nice on the Central Pnuematics....

The regulator / filter / dryer assembly can be had in a single coordinated assembly on Amazon for a few bucks more than the Harbor Freight units, but and this is goign to sound funny, this is one area that I know Harbor Freight makes a quality unit, I think you would be better off with theirs. But if you insist on going amazon, here is the lowest cost comaprable unit.... https://amzn.to/35Nk8Rs

Now that we are out of the manifold assembly...

Let's move on to the Compressed air piping system.

My piping system is basically a knock off of the Rapidaire, however I looked at the Rapidaire which was considerably more expensive, and itself required lots of parts added to get the kit where I wanted it, not where they want to sell it...  It is a 1/2" OD nylon tubing push to conneect set whcih came with plentiful fittings, 60 feet of tubing which is way more than I will use in my garage, and some just average couplers and plugs. 

I opted for 3/8" MPT unions, and 3/8" MPT couplers to insure I had full flow from the manifold to the hoses. I know I am going to be restricted by the hoses / plugs, but that is something I am just going to have to live with. I wanted no restriction in the path. This also allowed me to eliminate the use of bushings and the added potential point of failure / leakage.

I run the tubing staight up the wall from the manifold, to the ceiling, and make my first bend transitioning to the ceiling. The tubing cut pretty easily with the included cutter, and the push to connect fittings were deemed to be well named by now as they make a good secure connection.

We travel somewhat diagonally accross the ceiling to between the overhead doors, where we tee into the line, and connect to my old Central Pnuematic 3/8" 50 foot self retracting hose reel that is mounted between the overhead door tracks for best coverage of the workshop, and driveway, while taking up minimal headroom. This is an old unit, and the original hose was getting old and started leaking. We replaced the original hose with a Goodyear replacement hose. 

We continued along the ceiling to the front wall, make our second bend to the front wall, and tee down to meet our first outlet block. Both outlet blocks are configured identically. They are Primefit outlet blocks, with the Primefit 3/8" MPT x 1/2" push to connect unions, 1/4" flush pipe plugs, 3/8" MPT Milton couplers, and 3/8" MPT forged ball valves for pressure dump. 

As the tee continues down the front wall to the other side of the overhead door, we make our final bend, to our second outlet block.

Bigatur 1/2" Air Piping System. https://amzn.to/3LgJIyx

Primefit outlet blocks. I used 2. https://amzn.to/3uAdFnd

Glarks 10pc brass 1/4" MPT hex flush pipe plugs. This will close off the unused 1/4" port on the back of the outlet block. https://amzn.to/3GCoNlU

Primefit 1/2" push to connect x 3/8" MPT straight union 4 pack. I used one. https://amzn.to/3oA2Uh3

Antrader 4 pack forged brass 3/8 NPT male x female ball valves 180 degree action. https://amzn.to/3BkAFIB

Milton Industries S-767 HI-Flo V-Style -FeetA,M,V-Feet 3/8-Inch MNPT Brass Body, Single. I used 3. https://amzn.to/3HDwA4u

Central Pnuematic 3/8 x 50ft hose reel. Yes the fittings are 1/4 NPT. So are the hoses. But at least I have full flow up TO it... https://www.harborfreight.com/38-in-...eel-93897.html

NOTE: Harbor Freight appears to be phasing out their pre existing house brands such as Central Pnuematic in favor of their newer lines such as the Merlin Brand, which is reportedly an excellent replacement, but at a higher price point. I am working on a blog post about that move but am not ready to publish it as I am still working out the ideas. The Merlin setup is still less expensive than anything on Amazon though.

Anywhere male pipe threads are, irregardless of factory pipe sealant, recieved several wraps of teflon tape to insure a propoer seal after experiencing multiple failed seal atempts with factory pipe sealed components. 

A spray bottle with soapy water was made up, and once the system was pressurized, EVERY SINGLE JOINT was tested, thoroughly. There are at the time of this writing, ZERO leaks in my compressed air system. 

I still have too many air hoses to think about. both 1/4" and 3/8" ID. The 3/8" ID reinforced polyurethane hoses are far and away my favorites as they are, and stay nice and flexible, are not prone to kinking like hybrid hoses are, and are not super heavy and prone to cracking like rubber hoses are. The disadvantage to the reinforced urethane is that they are not all that abrasion resistant, which is why you never see them in a self retracting hose reel. For use out in the driveway / automotive uses, I pretty strictly use traditional reinforced rubber hoses.

At least in my experience, the hybrid hoses I have tried have simply been the worst of all possible worlds. Poor abrasion resistance, VERY kink prone, very crack prone, the only thing going for them that I can tell is they are lighter than rubber. In my opinion the hybrid air hoses should be avoided at all costs.

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