My first 'grown-up' compressor

[David Kenagy]

Just bought a DeWalt DXCM603 (60 gal, 5 HP) compressor. Its main job is to supply continuous purge air to a spindle, and sometimes to blow dust out of tool motors or the cyclone filter. (Won't be used for air tools or painting). The spindle requires ~3.5 cubic feet per minute, but over very long periods. So the compressor was chosen for its ability to deliver more than 3 times that volume at 90 psi. The idea is to run no more than 33% of the time but deliver air 100% of the time.

Max pressure is 175 psi, and they advertise the CFM at 40 psi and 90 psi. But (naive question) it doesn't seem to have a means for me to limit the air that it releases. So I guess it just compresses until it gets to that 175 psi, and it just delivers whatever it's got?

Downstream I have a Festo filter/regulator, but its intake capacity is 9 bar (130 psi), and output can be regulated down to 4 bar (60 psi) before the solenoid/valve that operates between 0.5 and 4 bar. The filter/regulator are secured outside the control box, but the air valve is inside and wired to open when the spindle receives power.

1. Do I need another regulator? Does the quality among makers vary? I assume it goes as close to the compressor as possible, so the stress on everything that follows is reduced, right?
2. It's a basement shop, so the air line to the spindle runs ~40 feet through the ceiling joists, after going up 2ft from the compressor port to the line, then down 5 feet to the Festo regulator. I'll replace the tank drain valve (underside of tank) with a ball valve on a flexible hose, intending to drain the tank at the end of each day. Do I need more traps or drains? Where?
3. What other obvious things am I overlooking?

DeWalt.jpg Festo.jpg

[Bill Dufour]

For your use I would reduce the max pressure to 130 and put a larger pulley on the motor for more useful air flow.
BilL D

[George Yetka]

20240612_082437.jpg

Compressed air is easy to modify so I would pipe it out and adjust as needed.
Friends of mine owned a Haas CNC and ran blast cabinets so they were running constant air to the cnc and high volume to the blast cabinets when being used. They quickly had issues with moisture. They researched and came up with a system like the one I have in this picture to eliminate the water. It is far cheaper than a chiller. This one has 4 manual drains at the bottom of each loop. after an hour of running you can pull a gallon or 2 out of them, more depending on humidity. Each of the 4 lines can have a check added and all 4 added to an auto drain on a timer.

An auto drain for the tank is also a huge time saver.
https://a.co/d/3aV2M7d

[Kevin Jenness]

For your use I would reduce the max pressure to 130 and put a larger pulley on the motor for more useful air flow.
BilL D

Why would you want to run the pump faster? David already has sufficient capacity and units like these typically are running pretty fast as built. If any change were to be made a lower pump speed would give a longer pump life. I agree with lowering the pressure for the same reason.

Anything you can do to remove water from the system is good. If you pitch that 40' run down to a trap and drain it off regularly it will help out the coalescing filter. Automatic drains and chillers are available. Clean dry air is not cheap.

[stephen thomas]

I wondered why the air delivery seemed a little low for a 5HP 175 psi compressor so googled it.
It seems astonishing that it is single stage? The motor is not really 5HP. So the pump is ideal for pressures up to about 90PSI above which it becomes inefficient.
I'm not even sure how they are getting 175PSI out of single stage except by small pistons?

Be that as it may, do what Bill D recommended and dial down the cutoff pressure. (125 - 135 range). Whatever you can get with the cut-in pressure set to whatever minimum you can accept. (90 - 100?)
Even if you have to work with 150 cut-off, it will help save your pump and electricity costs over the losses going all the way up to 175 on single stage, and then back down.
IOW, letting the motor run maybe a little more often to deliver the same air at the reduced pressure, will be better for the pump and less costly for electric, than having it pump air all the way up to 175 and then shutting off for a little longer before starting up again at a higher pressure.

To answer your actual question, yes, get another regulator to put on the outlet of the compressor, where it will feed your distribution to other machines.
Most other machines will accept 90 psi, which is regulated again at point of delivery if they are "complex" machines. Air tools will probably take 90PSI direct in most cases (read the tool label) though you mention that is not a factor.

If you dial the cut-off pressure down to 130PSI and your complex machines have integral regulators, then you can install (just as a "for instance") a Y that leads one leg to a regulator set for 90 - 100 for airtools, and a separate bypass leg to feed the complex machines directly. Unless the machine says "input air 90PSI" Then you need to regulate it down to whatever that actual spec is.

Be aware that setting (example 90 PSI) at the compressor won't yield 90 at a distant tool or machine, depending on the losses in your lines to get there. A gage might read 90 at the tool, but as soon as you trigger it, the pressure will drop, sometimes considerably. So take that into consideration when setting the regulator at the pump for discharge. Most shops plumb a compressor direct to an air dryer with drain, that has a regulator after, and a manifold with outletss to the various machines or portable airhoses. There may be more than one regulator if the air is going to multiple machines with widely different air input requirements.

[Bill Dufour]

Long runs of big pipe can be cheaper then adding a larger tank for the same storage effect. A loop clear around the building helps flow rates.
Bill D

[Brian Holcombe]

I would bring the pressure down at the compressor to 130psi, then drop form from there with the Festo regulator. Festo makes nice equipment, I use them and Norgren and both are excellent. Anymore I just use Festo since I like to standardize.

Keep in mind, machinery typically needs clean, dry air and sometimes needs oil added. I add oil at everything which has air driven movable parts.

I would put a cooler/drier into the system, the water separators alone may not be enough to separate out water.

I have run air line in two shops now with copper, I prefer it. It generally squishes when damaged rather burst like plastic.

[Bill Dufour]

PVC Pipe is not allowed for compressed air service.
Bill D

[Brian Holcombe]

As Bill warns, do NOT use PVC under any circumstance, it can and eventually will explode.

There are other plastic types of tubing which are rated for air and used in industrial application. I prefer copper for spanning a shop. I figure if I bang into a copper tube it won’t burst, but a plastic line can be more easily severed by a board.

Outside of the main run, for branches after the regulator and where flexible connections are needed I use polyurethane rubber which is rated to 170psi (working pressure). Off the compressor line if I need a flexible connection I use nylon plastic which is rated to 250 psi.

Both of these tubing types are rated for use with air. Thats very important that they be rated for air.

[Tom Bender]

If there are any components rated lower than 175 psi you should protect them with a relief valve set for the lower pressure. This should be purchased preset. Do this even if you reduce the compressor max to a lower number, it's still capable of 175.