04 April, 2014

Running 2 different size air compressors in tandem. Plumbing done!

I have the plumbing for the dual air compressor setup done, based on 3/8" rubber hoses yes, but it is what I have to work with, and I am not ready to solder copper pipe for this yet, or cut and thread black iron... Like I have mentioned previously, if / when I experience a hose failure between the filter, and the reel, THEN I will upgrade to, well most likely copper pipe. 

Each compressor is plumbed via a 3/8" pnuematic hose, the 29 gallon compressor using a 3' 3/8 hose, the 8 gallon using an 8' "Remnant" 3/8" air hose, both are fed via quick disconnect to a 1/4" F NPT check valve, in turn this is attached via a 1/4 to 3/8 M-M reducer, and fed into a 3/8" brass tee, 3/8" brass nipple and then fed into the regulator / filter / water separator is the Central Pnuematic #68232

On the outlet side of the regulator another 3/8" brass nipple is used and a 3/8" tee, then more 3/8 to 1/4 reducers, to quick disconnects. The upper feeds the hose up to the hose reel, the lower is at the ready for connecting a second hose if so desired.

I was unable to find the clamps to secure the hose, however I figure I have a bunch of plastic hanger strap, I will figure SOMETHING out... I will probably have to try a different Home Depot. I was honestly looking for a bag of 1/2" EMT conduit straps to do the holding job, they just happend to be sold out.

I should mention all connections were treated to a generous portion of teflon tape, and I made extra certain that there was no way excess teflon tape could possibly get into the air stream... When I took the outlet side connectors apart it became painfully obvious that I was the cause of my clogged impact gun. 

From what I can tell, it appears I managed to get a couple of extra wraps loose in the air stream after the connection was made, probably just had some extra over the end, being too tired to notice and it worked its way loose, down the hose, and into the gun.. 

I think moving forward I may venture out and get the teflon paste instead of tape to insure I don't do that again...

As you may recall I have 2 Central Pnuematic 2 HP oil lubricated air compressors. A direct drive 8 gallon that I purchased in I guess it was 2009, the model is similar to the current version with the exception that mine has a large plastic handle instead of the steel tube of the newer model. Honestly I don't care either way, both work...

The 8 gallon compressor peeking out from underneath the 
dust collector stand. Not pretty, but very functional!

Specs on it are...

8 gallon storage capacity.
125 Max PSI.
4.4 CFM @ 90 PSI
5.5 CFM @ 40 PSI

The second, and larger model is the belt driven #68127 that is still the same model that I picked up in 2009. I did a LOT of comparison shopping when I was looking for compressors, and this beat out all similar large portable compressors in performance except for the Ingersoll Rand 30 gallon, and that one was priced out of my league.

29 gallon Central Pnuematic 2HP 150 PSI compressor
parked in a niche created for it behind the mortiser.
Those green hoses are stashed away for now.

Specs on it are...

29 gallon storage capacity.
150 Max PSI.
5.9 CFM @ 90 PSI
7.3 CFM @ 40 PSI

While I understand there will be some line losses from running a dual configuration, from what I have been reading, and depending on which engineers you believe, either my gain in airflow will the the additive sum of the CFM ratings of both compressors minus approximately 1% for losses due to line friction. Others put that number at 10%, while others still claim I should only see a 10% gain off of the larger of the two compressors. I have no real way of verifying this, however I would suspect that the truth would be closer to the 10% loss number, not counting storage capacity because, if anything we add extra storage in the hoses, so if we do the math.

Must be regulated to 125 PSI max so as to not exceed the output of the smallest compressor.
10.3 CFM @ 90 PSI - ~10% so say 10 CFM @ 90 PSI
12.8 CFM @ 40 PSI - ~10% say 11.5 CFM @ 40 PSI

If indeed that is the case, then there really isn't anything I am likely to run off of my air system that would come close to challenging this setup.

To test as best I could the rig, I set the big comrpessor's regulator to about 123 - 124 PSI, to kick on just barely before the 125 PSI regulator / max pressure for the 8 gallon compressor. 

BOTH compressors are connected, and on. I held the blow gun wide open, allowing the large compressor to kick on, and then the small one. I allowed them to run until they kicked off, so I know the combined effect at least was able to compensate for the flow of the blow gun..

So all in all, I am happy as I can be with this setup. Aside from needing still to secure the overhead hose, and that will come. Likewise I should have the issues with errant junk in the lines completely solved at this time, so no more jammed up air tools!

Looks like a science experiment, but so far so good!

I am not going to lie, I would LOVE a Maxair C5160V1-MAP 170 PSI 60 gallon 5 HP compressor, and it IS possible I could figure out a way to make it fit, I would have to either narrow down the library cabinet cutting into precious storage space, or move the dust collector somewhere. I am not ruling either out for now. But as it sits, I am honestly not sure what I could possibly want to run pnuematic tool wise that my current rig won't handle.


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