Router Forums banner

Status
Not open for further replies.
1 - 20 of 29 Posts

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #1 (Edited)
Well, my $20 Craigslist Special C-H compressor has served me pretty well for the last year (except for the waiting for it to re-pressure and spitting water after it gets warm), so a new one followed me home on Friday.

I've recently been given a small ShopVac which I'll be plan to set up as a sander DC with a new pneumatic ROS sander (as well as my electric), once the rest of my parts (regulator, etc.) arrive. We'll see how well it all works. I'll keep you posted.

Here's a picture of the old and the new.

In the background you can see the 4C/#2 w/Ground SOOW "extension cord" I used to drop a temporary 100A subpanel into this home I'm leasing. It'd make Tim Allen proud!
 

Attachments

·
Registered
Joined
·
515 Posts
Nice choice It will work great we have the same brand at our shop for many years with no problems,
 

·
Registered
Joined
·
10,671 Posts
Nice pick, bigger is sometimes better in such cases as this.
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #5 (Edited)
Adding a aftercooler

OK.. It's been a couple of weeks, so time for me to catch up here. After getting the compressor wired up and a regulator hooked up, I decided to test it out. While today's use will be for sanding and drilling, I want to add a HVLP conversion gun some day and want to make sure I won't have water condensing in the system when I get the gun. To load down the system I ran my 6” pneumatic ROS for an hour straight, using a blowgun concurrently as needed to keep the compressor running continuously. After an hour of continuous operation the 60 gallon tank was noticeably hot and the line connecting the compressor discharge to the tank felt like an oven element. My blowgun nozzle had also started blowing some mist.
A visit to my local AC vendor told me what I’d suspected. The hot discharge air was carrying hot humid air through the line. When the air reached the room and dropped tp room temperature, moisture was dropping out. The solution was a compressor after cooler. This was available as part of a megadollar compressor upgrade when I bought the compressor (no way!) and they sold after market units running more megadollars. Still, no way. Back to the drawing board.
Let’s see.. a Craigslist squirrel-cage fan w/ a 1/12hp motor (400 cfm), 50’ of 5/8” tubing (coiled using a spring-type tubing bender with gallon-size peanut cans as a form) and some plywood and voila!!! I then ran a 2 hour test and the tank was within a couple of degrees of room temp and the air was dry as a bone.

My walk-away for others: If you decide to make your own, 50’ is probably a bit longer than necessary and you can probably use smaller tubing. I used 5/8” cuz my compressor delivers 14.7 cfm at 175psi and it used 1/2” tubing already and 50' cuz that was the length of the coil. Here’s some pictures of the making of the after cooler and finally with it installed. The hot air goes in the top and spirals down while the cool air blows upwards. The cooler is located above the tank and the line sloped so any condensation in the coils drains into the tank. I need to get a couple more tie-downs to get it sloped well.

My neighbors tell me I could pay fr the cooler by using it as a moonshine distillers coil in its spare time! :D
 

Attachments

·
Registered
Joined
·
2,881 Posts
Now that's a SERIOUS compressor! Congrats! I love when tools follow me home. :)
It is very obvious that you are the lady side of the "follow me home" equation. I happen to be on the opposite end. "Followed me home" died as a valid statement some 40 years ago. Cremated, buried, scattered to the wind. Never to be resurrected. Nope, no hope.
 

·
Registered
Joined
·
2,881 Posts
Hi Jim:

The "air cooler" is quite ingenious. Nicely done.

Now, I'm setup differently but, like you, I'm at the mercy of every compressor vendor and their dizzying array of add-ons, each more expensive than the previous. So, I'm hoping you'll help relieve some of the confusion.

I have an air dryer. On the outfeed side. It removes moisture from the compressed air line. It is quite effective. How does your cooler compare to my dryer? Was there a specific reason you didn't go with an air dryer?



In the picture above, you have quite an array of add-ons. Can you list each one and it's purpose please.
 

·
Registered
Joined
·
23,786 Posts
Hi JIm

Nice job,,,,I have a question for you ,has your cheese slipped off your cracker ?
but I like your over the top air system setup :jester:

Amazon.com: Semi Professional 4 PSI 2 Stage HVLP Finishing System - 54 CFM: Home Improvement

I got one from HF for 55.oo bucks that works very well :)


=====


OK.. It's been a couple of weeks, so time for me to catch up here. After getting the compressor wired up and a regulator hooked up, I decided to test it out. While today's use will be for sanding and drilling, I want to add a HVLP conversion gun some day and want to make sure I won't have water condensing in the system when I get the gun. To load down the system I ran my 6” pneumatic ROS for an hour straight, using a blowgun concurrently as needed to keep the compressor running continuously. After an hour of continuous operation the 60 gallon tank was noticeably hot and the line connecting the compressor discharge to the tank felt like an oven element. My blowgun nozzle had also started blowing some mist.
A visit to my local AC vendor told me what I’d suspected. The hot discharge air was carrying hot humid air through the line. When the air reached the room and dropped tp room temperature, moisture was dropping out. The solution was a compressor after cooler. This was available as part of a megadollar compressor upgrade when I bought the compressor (no way!) and they sold after market units running more megadollars. Still, no way. Back to the drawing board.
Let’s see.. a Craigslist squirrel-cage fan w/ a 1/12hp motor (400 cfm), 50’ of 5/8” tubing (coiled using a spring-type tubing bender with gallon-size peanut cans as a form) and some plywood and voila!!! I then ran a 2 hour test and the tank was within a couple of degrees of room temp and the air was dry as a bone.

My walk-away for others: If you decide to make your own, 50’ is probably a bit longer than necessary and you can probably use smaller tubing. I used 5/8” cuz my compressor delivers 14.7 cfm at 175psi and it used 1/2” tubing already and 50' cuz that was the length of the coil. Here’s some pictures of the making of the after cooler and finally with it installed. The hot air goes in the top and spirals down while the cool air blows upwards. The cooler is located above the tank and the line sloped so any condensation in the coils drains into the tank. I need to get a couple more tie-downs to get it sloped well.

My neighbors tell me I could pay fr the cooler by using it as a moonshine distillers coil in its spare time! :D
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #9
Huh??

It is very obvious that you are the lady side of the "follow me home" equation. I happen to be on the opposite end. "Followed me home" died as a valid statement some 40 years ago. Cremated, buried, scattered to the wind. Never to be resurrected. Nope, no hope.
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #10
Hi JIm

Nice job,,,,I have a question for you ,has your cheese slipped off your cracker ?
but I like your over the top air system setup :jester:
=====
You only saw the cheese?? You missed the salami, pastrami and *especially* the bologna (baloney)!! :->

Thanks. :D

Yea, it's probably "over the top". The minor additional justifications for it are:

* I "get" to swap the summer to winter tires on the 2 cars for my parents, two for my wife's parents, our two cars twice a year and usually one of the parent's friends cars. Inevitably at least one of the cars had the tires last attached by some 16yo tire jockey whose idea of torquing lug nuts is to stretch the studs as far as their big rattle gun (impact wrench) will take them. I use a rattle gun to remove them but a torque wrench to re-apply. I've got a 4' "cheater bar" I often need to use on the end of my breaker bar to bust the nuts loose. When choosing this, I decided "never again"; I'll keep working up the air pressure until the nut comes off or the stud breaks.

* I wanted the capacity for a 6" pneumatic air sander

* I wanted the dry air for a HVLP gun.

* Many here know I'm an engineer but not so many know that I'm an electrical engineer whose focus is designing control and safety shutdown systems for petroleum production in remote (ultra-cold Arctic) Alaska. These systems are permutations of electrical, hydraulic and pneumatic systems whose instrument air must be water-free to -70F (-57C). I've used this personal "science project" to better understand my "book learning" on compressed air treatment.

* My 19yo son is studying EE in college and will be taking Thermodynamics this next year. Rather than have him approach it from a purely theoretical approach as most students do, I wanted him to have it tied to reality. Working with me on this he got to see the moisture issue, help build the air-to-air heat exchanger, saw the air line cooling and resulting condensation. I hope this will then let him see the real-world value of the class and ground his studies in reality.

Those are the minor justifications.. The major one is just because I wanted it.

Ever buy or build something just because you wanted to do it? <g>
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #11 (Edited)
Hi Jim:

The "air cooler" is quite ingenious. Nicely done.

Now, I'm setup differently but, like you, I'm at the mercy of every compressor vendor and their dizzying array of add-ons, each more expensive than the previous. So, I'm hoping you'll help relieve some of the confusion.

I have an air dryer. On the outfeed side. It removes moisture from the compressed air line. It is quite effective. How does your cooler compare to my dryer? Was there a specific reason you didn't go with an air dryer?



In the picture above, you have quite an array of add-ons. Can you list each one and it's purpose please.
Ron,

Prior to answering your questions, please understand that my cooler isn't in lieu of an air dryer but supplements one. This will be explained below. FWIW, what I'm about to say is my own conclusion formed from many sources of information. These sources have included the typical web articles and reports and discussions with co-workers and vendors. In my last post I explained what I do: engineering. I work for an engineering company with about 100 mechanical, electrical, chemical, petroleum and process engineers. I've been picking the brains on the smartest in each area for the last year or two on this. This summer we've been called on to upgrade two 350hp air compressors and air treatment systems for a large petro processing plant. This has resulted in multiple conversations with the engineers from a couple of compressed air system vendors and I've picked their brains too. While I'm no expert on the topic, I feel I've gathered some pretty good information. Probably not perfect, but pretty good.

You asked about the add-ons. I'll identify them as the air flows (from right to left). They were purchased from www.compressedairstore.com, should you want additional information on any component.

* The first is a particulate filter. Its job is to capture any large particles and large wanter droplets. I have it equipped with a 3 micron (a human hair is about 100 microns wide) filter.

* The second is a coalescing filter. It has a 0.01 micron filter and its main job is to capture any oil carry-over from the compressors oil lubricant but it also catches smaller water particles that form on the filter as the air passes through.

* The third is a desiccant filter that reduces the himidity in the air. It contains hard spherical beads of silica gel. These beads do not absorb the moisture but rather "adsorb" them. Absorbing would be to suck up, like a sponge. Adsorbing is where the water molecules stick to the outside surface of the bead in a "bonding-like" manner. These beads are colored blue and turn pink as the surface capable of adsorbing water gets filled up. As long as only water adsorbs to these beads, they can be recharged in a cool (275*F oven for 30 minutes) and put back to use. Unfortunately these beads also adsorb oil which doesn't bake off, effectively "poisoning" the desiccant. When that happens, you replace it.

* The fourth component (which is optional) is another particulate filter. The desiccant beads are somewhat fragile and break down over time. The desiccant filter has a coarse filter element to remove the largest of the dust. My particulate filter removes the rest of it.

* The fifth component is a filter-regulator. I purchased it for its regulator capability but since once I buy my next house I'll move the regulator way downstream from the compressor I opted for the filter/regulator for a few $$$ more.

After that's just a Tee with two quick-disconnect fittings and a couple of coiled polyurethane air hoses. I originally ordered one hose but they sent me two wrong hoses before sending me the one right one I'd ordered and they told me to just keep the wrong ones for my trouble.

Now, as to why the aftercooler.. (TBC)
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #12
Warm air can hold more moisture than cool air, and hot air even more. Under steady-state conditions the discharge temperature from a 2-stage compressor gets hot; I've read reports of 300*F to 350*F and that's what the radiant heat coming off the old tubing felt like. I didn't touch it. :) This air is then discharged into the tank.

In the tank the air begins to cool, heating the wall of the tank. After my original hour-straight of running the wall of the tank was (I'm estimating) in the 120*F to 140*F range. With the compression some of the moisture in the humid room dropped out as water in the tank, leaving the air exiting the tank at or near 100% relative humidity (R.H.) at the 120-140*F. The desiccant filter brought the RH way down but as it was exhausted to the room (cooled to room temperature) some moisture still dropped out.

After installing the aftercooler, the air entering the tank was within a couple of degrees of room temperature and exited the tank even nearer room temperature, again at or near 100% R.H.

The particulate and coalescing filter capture any droplets entrained in the air and the desiccant filter brought the RH way down, this time on near room temperature air. When this air was exhausted to the room it was already at or near room temperature so there was no drop-out.

A refridgerated air dryer like you may see in some plants is doing essentially the same thing except it's cooling the air to 40*F or so, so it warms when mixed with the air and the humidity there goes down ratherthan up. The difference is that refridgerated coolers are expensive to buy and operate, bulky and even more over the top than mine.

I also chose desiccant style because that's the technology needed to dry air to moisture-free to -70F (except they use molecular sieve technology, way too expensive for me) like is used in my work.
 

·
Premium Member
Joined
·
6,056 Posts
Y

Ever buy or build something just because you wanted to do it? <g>

naaaaaaaaaa, I know I've never done did that!!!!:dance3::dance3::dance3:

Honestly, I applaud how you promote jr.s education the old fashioned way!! cool!!
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #14
At least one of the pictures I've posted shows where I've added a HEPA filter to a 6-gallon shop vac that was given to me and hooked it up to the discharge chute on my pneumatic sander (also works with my 5" Dewalt). It does a really nice job grabbing the ultra-fines.

During the hour-long test I spent it sanding a scrap of hard maple about 10" square, working through 80, 120, 180, 220 and on to 320 grit, just for fun. While I've read all about the finishing issues resulting from over-sanding, I must say that piece of wood feels smoother than a baby's bottom. After that test I can only *wonder* what it'd feel like if I were to get even finer sandpaper and sand it, like some do, to the 1500 or even 2500 grit!!
 

·
Registered
Joined
·
2,881 Posts
Hi Jim:

Thanks for the answers. When I go to the primary user of compressors, my local mechanic, the air dryer is full of water, the whole thing is squashed into a corner and covered with grease and oil and junk and I bet the tank has never been drained. Then, you come along with this array of what appears to be overkill and it is no wonder that I'm confused. What's worse, I buy a compressor and it barely has an air filter, let alone in-line filters, dryers, regulators and oilers.

However, your explanations below have answered a lot of my questions. That said, given that air is made of up constituent parts that are contaminants in themselves, is it not possible that it would be cheaper just to extract nitrogen or oxygen or other gas and use it rather than compressing air? When my mother was sick we had to install an oxygen generator. The technology exists. Wouldn't that be cleaner at less cost?

For my purposes, I'm thinking your setup as way over the top overkill but my setup is way under the bottom under-kill. What's worse is that I took a look at my compressor manual and it says absolutely nothing but "this is what a few of the parts are called" and "tighten these few bolts." My Makita manual is the only one that suggests I might use an air filter. Any wonder I'm confused?

...please understand that my cooler isn't in lieu of an air dryer but supplements one. ...
In short, you have access to information, gathered it from reliable sources and are passing it on to us. THANK YOU!

You asked about the add-ons. I'll identify them as the air flows (from right to left). They were purchased from www.compressedairstore.com, should you want additional information on any component.
Thank you. I"ve already visited their site.

I have picked up filters, regulators and other unidentified flotsam in garage sales that may or may not be of use. At some point I'll actually identify what I've got.

Ok, all of the above is fully explanatory so I won't comment or question, as is the after cooler part too.

I've gone and downloaded the copper tubing manual and I'm in the process of digging through that. Now, all I have to do is find a source of supply.

How much difference would a single stage compressor make over a two-stage compressor in terms of attracting humidity or retaining contaminants or generating heat. We ran our compressor for about 10 hours per day in about 5 minute cycles pushing a pneumatic hammer while we were cleaning brick and concrete block. It didn't even seem to warm up.

One of the things that bothers me is the size of my air intake filter. Are there after market filters available? Mine is a small foam rubber affair. I was thinking a paper filter like the one used in cars.

I notice that you have your regulator way down at the end of the stream. Mine is at the beginning of the stream. Would you suggest that mine is being exposed to contaminants which may contribute to its inaccuracy or early demise or, leave it where it is, it's fine?

This is going to be the hardest question. Even given that you want to run HVLP components, how much of this is overkill and how much is critical? What would be a bare minimum, an adequate, a "nice" and a "really nice" setup.

I consider your arrangement total luxury. Vendors create products in response to the marketplace. They build in the tolerances needed to meet the requirements of their customers. I've seen HVLP systems run on something akin to a lamb motor (the one in a vacuum cleaner) with something like a furnace filter "cleaning" the air. However, you have taken the time and trouble to assemble an excellent environment so you must have had good reason. Alternatively, is much of what you have installed a mirror of the work you are doing for your customer and deliberate overkill?

I would not normally ask these questions but you have access to information that we do not so I feel privileged to be able to ask.

Thanks for the information, Jim. All of this is much appreciated.

Ron
 

·
Premium Member
Joined
·
3,503 Posts
Discussion Starter #16
Ron,

"That said, given that air is made of up constituent parts that are contaminants in themselves, is it not possible that it would be cheaper just to extract nitrogen or oxygen or other gas and use it rather than compressing air?"

That can be done but the least expensive way to do a volume of it (we do it a lot to get nitrogen in my work) is to compress the air and then run it through a molecular sieve. Once you got the nitorgen or oxygen, you'd still have to compress it.

"For my purposes, I'm thinking your setup as way over the top overkill but my setup is way under the bottom under-kill."

As BJ pointed out, yes, mine is over the top strictly for the service it provides, but I've gotten other benefits (explained earlier).


"I've gone and downloaded the copper tubing manual and I'm in the process of digging through that. Now, all I have to do is find a source of supply."

The copper tubing handbook, available free from www.copper.org has lots of good pressure / temperature and other info on using copper pipe and tubing.

"How much difference would a single stage compressor make over a two-stage compressor in terms of attracting humidity or retaining contaminants or generating heat. We ran our compressor for about 10 hours per day in about 5 minute cycles pushing a pneumatic hammer while we were cleaning brick and concrete block. It didn't even seem to warm up."

The heat generated is a function of the compression ratio (as in an engine), not the number of stages. From atmospheric pressure (14.7 psia) to 175 psi guage (189.7 psia) [12.9:1] is going to generate more heat that atmospheric to 120 psi (134.7 psia) [9.16:1].

"One of the things that bothers me is the size of my air intake filter. Are there after market filters available? Mine is a small foam rubber affair. I was thinking a paper filter like the one used in cars."

I haven't heard of them, though there's no reason you couldn't make one. Seemingly the best way would be to go to a junk yard and buy one for an old carbureted car and tie in where the carb would be. The filters would be available at your nearest auto parts store.

"I notice that you have your regulator way down at the end of the stream. Mine is at the beginning of the stream. Would you suggest that mine is being exposed to contaminants which may contribute to its inaccuracy or early demise or, leave it where it is, it's fine?"

I've seen pre-assembled systems like mine with the filter / regulator at either end, so both surely work. This is one question I had that I was able to learn the least about. For people with an opinion, they recommended putting the regulator downstream either because:

* the higher pressure would be denser (more compact) so would move slower through the filters or

* higher pressure air can hold less water, so its better to get the moisture out at the higher pressure.

Those answers could be accurate or baloney, I don't know.

"This is going to be the hardest question. Even given that you want to run HVLP components, how much of this is overkill and how much is critical? What would be a bare minimum, an adequate, a "nice" and a "really nice" setup."

The *best* way would be to take what you have and try painting with it. If you have problems, then change things until the problem goes away. I took my approach for a different reason.. cuz I wanted to. <g>

"I consider your arrangement total luxury. Vendors create products in response to the marketplace. They build in the tolerances needed to meet the requirements of their customers. I've seen HVLP systems run on something akin to a lamb motor (the one in a vacuum cleaner) with something like a furnace filter "cleaning" the air. However, you have taken the time and trouble to assemble an excellent environment so you must have had good reason. Alternatively, is much of what you have installed a mirror of the work you are doing for your customer and deliberate overkill?"

I've no doubt that some amount of what I've done is overkill for virtually everyone out there; the amount varies by individual. The only way to determine just how much is to follow the steps above.

Overkill and "over the top" is virtually impossible to define and it varies from person to person. For example, let's look at my $3K Unisaw. Is that overkill for a hobbiest? How does that compare to the person who has a $50K boat or a $150K motorhome they use 10-12 times per year... or the $15,000 for a snow machine.. or the $50,000 for the Chevy Avalanche.. or the Escalade.. How about the home many people live in... Do they *need* that much home?

I dare say that, after 20 years, my Uni will still sell for a higher percentage of new price than the boat, motorhome, snow machine or truck. As for the home, who knows; the people who bought at the peak of the housing boom will have a strong opinion.

BTW, my aftercooler is a shameless copy of the Astrocooler (~$1,000), attached.

{getting down off my soap box and disappearing in the crowd}
 

Attachments

·
Registered
Joined
·
2,881 Posts
Hi Jim:

I'm going through the documents now.

What is:

psig

psia

OK, a heap load big bunch of THANK YOUs from all of us that always wanted to know and didn't know where to look and Google always pointed us to the same pages. the wrong ones.

The Government publication says to monitor and remediate as needed. However, small shop systems like we would use that is almost impossible. However, if you're using compressed air for HVLP and the paint isn't sticking or drying properly, don't blame the paint or the HVLP system, look to moisture in your air first. If your air tools are constantly plugging up or spitting water, clean and dry your air more thoroughly.
 

·
Registered
Joined
·
5 Posts
psig = pounds per square inch - gauge
psia = pounds per square inch - absolute

psig is the number you get when you look at the gauge. When the gauge is not connected to anything, it reads 0 psig, but there still is pressure, atmospheric pressure. At sea level, atmospheric pressure is 14.7 psi. Here in Cheyenne, WY, elevation 6,100 ft, atmospheric pressure is 11.7 psi. The atmospheric pressure varies with elevation. If you really want to be specific, look at the local barometric pressure. It is your current atmospheric pressure.

psia for a closed system (pressure tank and piping for example) is the gauge pressure (psig) + the atmospheric pressure.

What is:

psig

psia

QUOTE]
 

·
Registered
Joined
·
2,881 Posts
psig = pounds per square inch - gauge
psia = pounds per square inch - absolute

psig is the number you get when you look at the gauge. When the gauge is not connected to anything, it reads 0 psig, but there still is pressure, atmospheric pressure. At sea level, atmospheric pressure is 14.7 psi. Here in Cheyenne, WY, elevation 6,100 ft, atmospheric pressure is 11.7 psi. The atmospheric pressure varies with elevation. If you really want to be specific, look at the local barometric pressure. It is your current atmospheric pressure.

psia for a closed system (pressure tank and piping for example) is the gauge pressure (psig) + the atmospheric pressure.

What is:

psig

psia

QUOTE]
Thanks George.

Ron
 
1 - 20 of 29 Posts
Status
Not open for further replies.
Top