filter setup for air distribution

[sgtriggs]

I am in the process of running copper for air distribution. I have a Porter Cable C7550 that delivers 15.2 SCFM at 175 PSI. This is a somewhat temporary copper installation, so I'm just running 1/2". I've attached an image to illustrate the basic idea of the plumbing.

I am installing a Harbor Freight desiccant dryer with about 30' of copper pipe between it and the compressor, just before the copper begins to branch off to feed the tool drops. I will install a Norgren "general purpose" filter just after the desiccant dryer, because the dryer's instructions say you must do so in case any debris (I assume desiccant dust) makes it out of the dryer. Also, I intend for this to be the last filter in the system, and to just have a regulator at each tool drop, rather than a filter and a regulator.

I am considering installing another general pupose filter (not pictured) just before the dryer, to remove any liquid water before getting to the dryer. I'm wondering though, since I have a copper drain leg just before the dryer, if this may be overkill. To be clear, the pipe from the compressor goes up to a high point, runs down hill (1" in 8') for about 30', and then runs straight down to the floor for a ball valve drain. Immediately before it turns down to the floor, a tee takes off from the top and then feeds the desicant dryer (basically, the way you would take off for a tool drop).

Also, if I'm going through a desicant dryer, is there any need to have drains dropping below the tool drops?

Your thoughts?

Thanks,
Steven

 

[sgtriggs]

I'm planning to work on this tomorrow, so I'm hoping to get some advice before then.

Thanks.

 

[lawfarm]

Regarding the filter before your dessicant filter, is it necessary? No, probably not. On the other hand, assuming you use a filter with adequate capacity, it shouldn't hurt anything, either. Were I in your shoes, I probably would not worry about that issue too much.

As for the drops at each tool, yes, I would install those. With the system you're building, they're unlikely to be necessary, but they will have a minimal expense, and will offer just a bit more protection for your system in the unlikely event of huge temperature swings, etc. I think that's a worthwhile investment.

 

[pierre]

I'm putting the harbor freight desiccant in my system as well - 3 of them in parallel.

It is best you put a coalescing filter before desiccant. You want to keep oil vapor out of the desiccant. The world won't end if you don't, however they may not last as long and they will stink if you regenerate them in the oven.

Couple of things about them - the endcap male & female threads have a crapload of paint on them - I had to burn mine off with a torch and wire brush. It prevented the caps from being fully tightened and getting a good seal. The endcap threads are crummy - I tried teflon pipe dope but I read about rectorseal 5 on here and it's my newfound go-to dope. If your going to use a torch - remove the nylon seals in the endcaps first and let everything cool before reinstalling.

Also the input and output holes - for whatever reason the holes drilled behind the bungs are small. I drilled them out with a 1/2" bit. Could of probably went bigger before hitting the threads.

Clean out the inside, looks like they put a spoon or two of oil in there when they shipped them to avoid rust. After drilling the holes out I sprayed the inside liberally with brake cleaner and ran a jumbled up rag (lint free) through it.

 

[sgtriggs]

...but they will have a minimal expense, and will offer just a bit more protection for your system...

good point, I think I'll go ahead and install them

I'm putting the harbor freight desiccant in my system as well - 3 of them in parallel

Just curious, what are your plans that will need so much air flow? Or are they rated at a very low flow and I missed it? Or, do you feel that you need to increase the drying capacity by "slowing" the flow through each of them?

It is best you put a coalescing filter before desiccant. You want to keep oil vapor out of the desiccant. The world won't end if you don't, however they may not last as long and they will stink if you regenerate them in the oven.

I didn't think about that, but good to know, and I will keep it in mind.

On a side note, would you agree the dryer looks like a pipe bomb? I think Harbor Freight is buying "government seized" materials to make them.

 

[bluesman2a]

I am installing a Harbor Freight desiccant dryer with about 30' of copper pipe between it and the compressor, just before the copper begins to branch off to feed the tool drops. I will install a Norgren "general purpose" filter just after the desiccant dryer, because the dryer's instructions say you must do so in case any debris (I assume desiccant dust) makes it out of the dryer. Also, I intend for this to be the last filter in the system, and to just have a regulator at each tool drop, rather than a filter and a regulator.

Which HF dessicant are you using?
Is it this one: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94733

They are awefully small (single in-line tool use). I have one for use with my paint gun, but I wouldn't feed an entire system through one.

I'm interested in your setup as I'd like to find a reasonable dessicant dryer to plumb into my system as well. If anybody has recommendations on a decent one for a reasonable price, I'm all ears.

 

[pierre]

We are talking about this desiccant dryer. That is the reason I chose these - way more cost effective then others. Don't forget the 20% coupon - I printed out three, and just went back and forth to my car three times.

For the cost, I figured why not 3? Was actually planning on 4. When I called they said they had 4, but when I got there the next day they were down to 3.

They are rated 17cfm. My compressor is right about that, but I chose to add more in parallel for better flow. I hadn't thought about it having better filtering capabilities or not, was just thinking in terms of flow. Also for capacity - each tube holds 2.2lb desiccant - I was previously using a sharpe system that held 5lb, so I wanted something to last as long without having to change the desiccant.

That's my second major gripe (first being the thread/paint issue I mentioned above) - there is no site glass to see whether the desiccant is used up or not. Maybe I'll add one the next time I take them apart to regenerate the desiccant. The pipes are fairly thick - I wonder if I can get away with just drilling a hole and tapping it instead of welding/brazing/soldering in a bung.

$40 each, $32 after the 20% coupon, + maybe $50 in black pipe tee's, union's & other misc fittings - still much ahead in price for equal capacity name brand. I was even thinking of getting my own pipe and rigging my own, but it's not worth the hassle for $32 each. The key pieces are the screens inside (part #3 in the manual) - but it wouldn't be terribly hard to make these either if you really wanted to.

 

[nate379]

Are you doing a lot of painting or running equipment that needs really clean air?

I have never needed a filter on my stuff. I had one for a while and in 2 years I never got even a drop of water in it. It started leaking one day (-30* and the bowl was plastic) so I took it off and never replaced it.

Only painting I do is farm/implement paint in a $30 gun so I don't think I'd even notice a little bit of moisture.

 

[pierre]

From what I've read, those plastic bowls crack because certain compressor oils (synthetic?) attack the plastic.

-30? At that ambient even a small length of hardline or the tank itself will drop the moisture out of the air. Typical desiccant has a -40F dew point, some of the fancier ones are lower then that. Try a continuous (5+ minute) compressor run at 90F without any desiccant or refrigerated dryers and lets see how your paint looks

I don't paint, but I do have a plasma. Current setup is an after cooler between the pump and tank with it's own drip leg, then a water separator after the tank then a motorguard filter. On most days this suffices, but I was still having problems with moisture at the tool but not the drop's drip legs. This much desiccant should do the trick.

 

[sgtriggs]

Yeah, the lack of a sight windows *****, but like you said, hard to beat $32.

Yes, my concern regarding moisture stems from painting. I am currently prepping my brother's car to paint it, and have become really concious of how much water I'm getting, which is what lead me to finally put in a copper distribution system. I'm going to use ball valves and a couple of tees to make it where I can choose between using or bypassing the desiccant dryer, so that I can just use it when doing moisture sensitive work, such as painting his car.

 

[OccupantRJ]

As far as a filter regulator goes, I also use a portable one I made by adding a male quick disconnect to the inlet side of a pair, and a female diconnect to the outlet side. A 3/8" eyebolt was opened up into a hook, then welded to the 1-1/2" long pipe ****** connecting the R/F together. This creates a portable unit with a hook on it so that I can just hang it onto any wall disconnect when not in use, and grap it and snap it into any wall disconnect as I need it, to provide protection at the nearest point of use.

RJ