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Compressed Air Dryers - I Need One

Pete Deal

Stainless
Joined
Apr 10, 2007
Location
Morgantown, WV
I really need to install a dryer on my compressed air system. My compressor is a 7.5hp IR- about 25 cfm rated. I have the whole shop piped with hard pipe that slopes away from the compressor, the main is 1" black iron with T's looking up for couplings and all my take-offs come off these T's. I have a moisture trap at the end of the main. I drain the compressor every day but still get too much water in the system. I'd really like to put a better aftercooler between the pump and tank but this is not real cheap either and it still won't lower the dew point of the air below room temp.

Anyway, I think I am about to order a Hankison HPR 25 dryer. 25cfm rating. It has a copper heat exchanger. It appears I can get it for $1100 or so.

Another idea that I think I will do at some point is to put the compressor on 8" or so legs and put a moisture trap at the end of the drain. This would at least allow the water to accumulate outside the tank.

I know there are a lot of compressor posts but not much on dryers. So I post this to see if there is any additional insight on the subject.
 
I would suggest the following

ingersoll rand D41ECA100 dryer

With filters before and after the dryer.

ingersoll rand FA40IG filter ( 2 qty)

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I'd really like to put a better aftercooler between the pump and tank but this is not real cheap either and it still won't lower the dew point of the air below room temp.

Nobody says that the pump has to go directly into the tank. Just run through a coil of copper, or
a zig zag up the wall or something. Cool it down a bit before it gets to the tank, and then you
could even put a trap before the air goes into the tank.

Cool it as much as possible, and remove as much moisture as possible so that your
dryer has to work as little as possible.

Also, on the tank, instead of *you* draining it every day, put one of those automatic
blow offs on there, either one that blows off when the trap is full, or you can get
timed ones.

Then you don't have to drain the tank everyday, and more importantly, don't have to
spend the money to fill it all back up the next morning. Air is EXPENSIVE.
 
I've been down this road and I have an IR dryer. I'm at elevation and in the winter it's cold, and at the moment my air dryer isn't exactly worthless but it's not efficient either. Min dew point realistically is about 40 degrees F (4 degrees C if you prefer) I follow up with a desiccant drier that takes 5 lbs of desiccant. This time of year the silica gel isn't second line of defense it's first line of defense.

Actually not quite true, first line of defense is the combined gas laws we learned in 7th grade chem. Store at as high a pressure as possible, and as low a temp as possible. Keep the condensate drained...... and then use air at as low a pressure as practical.
 
I have a larger ( used on a 50 hp Kaeser) Kaeser refrig. air dryer with a leaking heat exchanger that I'd sell for 250.00 if that's of any interest to you.
 
ingersoll rand D41ECA100 dryer

Looks like that guy is out of production. It is out of my budget anyway. It's a cycling dryer. I've read that these are more $. My air dommand is generally pretty constant through the day so I don't know that the cycling dryer is worth the extra for me.

Bobw- I don't drain air out of the tank. My current protocol is to shut the system air valve and the compressor off at the end of the day. Then in the morning I just crack the drain valve a little to blow the water out, then turn it all back on. The auto valve would be nice but not much of a time saver. Probably ought to start cracking the drain valve at the end of the day too but still I am already at the compressor shutting it down. I shut the phase converter down at the same time.

Regarding the pump aftercooler, this is definitely a good idea to get rid of moisture before the tank. It is on the list. It still just gets the air temp down to ambient and so still the air in the tank will be saturated (with water) so I still need a refrigerated dryer to get it below ambient dew point at pressure.

Cyclotronguy- I think, need to double check, that the refridgerated dryer that I am looking at delivers a dew point, at pressure of 40 deg. F. My shop is heated so I should never see condensation in the lines at this dew point.
 
Pete

As you know a refrigerated air dryer is never going to source up a dew point less than the freezing point of water. But AFAIK all the commercial ones get within 10 degrees of freezing point at rated flow.

That said the large Milton desiccant dryer is pretty much a bargain. The desiccant is easily recycled, it's cheap on ebay and provides a visual indication of your airline moisture. I follow that up with one of the ubiquitous toilet paper filters, just in case there is any carry over of desiccant. Its been trouble free.
 
It depends on how much Hispanic engineering you want to do but there are a few ways to skin this cat. I don't have a refrigerated dryer but do have a system that gets the compressed air below ambient BEFORE going into the tank, with an auto drain moisture trap also before the tank. Since doing this a few years ago I have not had any moisture in my shop air, zero. I have measured the air temp out of my pump at 200f so cooling it down before the tank is just common sense, to me at least.

Here are some photos of my setup. I have a 4hp 2 stage pump that I run about 75% of the time when using my Kitamura for reference. I cool the air out of the pump with 25' of 1/2" copper with a fan on it, then to 50' of 1/2" copper in the water bath, then a moisture trap with a float valve to automatically drain it, otherwise I have to drain it every 2 hours, then to the storage tank. When it is freezing out I bypass the 50' of copper in the tank, even if there is no water as it can freeze up below 25f. The 25' with a fan is good to 70f ambient, above that and I may start seeing water in my shop air. Sure it is a hack job but it does the job and is very reliable. When I am running hard and it's over 100f outside I will put a box fan on the water bath to cool it down a little more. If I put the fan on the water bath first thing in the morning the water doesn't get much over 70f on those hot days. The plywood cover is to keep the deer out, the clear container has clean water for the animals.

Changes I would make are. 10' of copper after the pump would be enough, the same with the copper in the tank. No need for the fancy aluminum spreaders for the pump copper, especially if I only had 10' there.

cooler.jpgC-1.jpgcoil1.jpg
 
I'll take a look at it. The dessicant dryers I am familiar with from my past life all had a way of regenerating the desiccant. These were expensive to operate. We used to maintain -25deg f dew pt.

greggv- that is probably a smoking deal but I really need something that I don't need to work on. I have a bunch of those already. Also shipping would probably be a lot. Thanks anyway.
 
It depends on how much Hispanic engineering you want to do but there are a few ways to skin this cat. I don't have a refrigerated dryer but do have a system that gets the compressed air below ambient BEFORE going into the tank, with an auto drain moisture trap also before the tank. Since doing this a few years ago I have not had any moisture in my shop air, zero. I have measured the air temp out of my pump at 200f so cooling it down before the tank is just common sense, to me at least.

Here are some photos of my setup. I have a 4hp 2 stage pump that I run about 75% of the time when using my Kitamura for reference. I cool the air out of the pump with 25' of 1/2" copper with a fan on it, then to 50' of 1/2" copper in the water bath, then a moisture trap with a float valve to automatically drain it, otherwise I have to drain it every 2 hours, then to the storage tank. When it is freezing out I bypass the 50' of copper in the tank, even if there is no water as it can freeze up below 25f. The 25' with a fan is good to 70f ambient, above that and I may start seeing water in my shop air. Sure it is a hack job but it does the job and is very reliable. When I am running hard and it's over 100f outside I will put a box fan on the water bath to cool it down a little more. If I put the fan on the water bath first thing in the morning the water doesn't get much over 70f on those hot days. The plywood cover is to keep the deer out, the clear container has clean water for the animals.

Changes I would make are. 10' of copper after the pump would be enough, the same with the copper in the tank. No need for the fancy aluminum spreaders for the pump copper, especially if I only had 10' there.

View attachment 278512View attachment 278513View attachment 278514

I like it! You're cheating though- water cooling! Since freezing is an issue here I don't really want anything outside. I have thought of building a shed for it etc but another project. I even thought of digging up an old well I have near the shop and running a pipe down there to get some cooling water. Or get a trencher and ..., the ideas never end. Right now I need to keep machines running so don't have a bunch of time for that.
 
It is common knowledge that cold holds less water than warm air. When the air temp outside is lower than the air temp inside the humidity inside is greater. A friend of mine has a shop with 9 CNC machines that run 24/7. His coolant use is the same in the winter as it is in the summer as he air conditions his shop. No outside doors are left open. That coolant adds a lot of moisture to the air no doubt. He reduced the amount of water in his shop air (by alot) by taking in outside air. Piped suction through wall to compressor. Even though there are coolers/filters on the coolant a lot is lost through evaporation. He had an uninsulated portion of the shop for a period of time and during the winter it actually rained inside as it was only a steel building. Once insulated rain problem solved. Maybe the OP can pipe in outside air for a try.
 
I like it! You're cheating though- water cooling! Since freezing is an issue here I don't really want anything outside. I have thought of building a shed for it etc but another project. I even thought of digging up an old well I have near the shop and running a pipe down there to get some cooling water. Or get a trencher and ..., the ideas never end. Right now I need to keep machines running so don't have a bunch of time for that.
Oh it freezes here too. Low 20s is normal in the winter, even seen 25 below zero.
 
Man lots of ideas. I didn't think of bringing in outside air. That should not be too bad to try. I would want to undo that for summer because my shop is dryer than the outside air in summer.
 
I follow up with a desiccant drier that takes 5 lbs of desiccant. This time of year the silica gel isn't second line of defense it's first line of defense.

I completely agree with this. I service dental air compressors both lubricated and non lubricated. Almost all the ones manufacturered in the last 20+ years have desiccant dryer systems on them. These things are designed to cycle from 80-100 psi throughout an 8-10 hour work day 5-6 days a week. Some of these compressors are in cold damp basements and some on roof tops. Keeping moisture and oil out while maintaining reliability is a big concern. What makes condensation is the hot air from the compressor head going through the cool pipes, tanks or tubes on the compressor. Most dental compressor manufacturers plumb the outlet tube from the compressor head into some kind of a condensing coil, from the condensing coil into the bottom the desiccant tank. The air flows up the tank (through the desiccant) right into an empty purge tank and into the main compressor tank (install a check valve at this point right on the main tank that follows the flow of air) Since water and moisture is heavier than air it will stay on the bottom of the desiccant tank as the air flows through it. The desiccant beads help trap the moisture inside. Plumb a "T" on the bottom of the desiccant tank and wire in a normally open solenoid valve (same voltage as your compressor). Wire the normally open solenoid valve to the pressure switch on your compressor. When your compressor cycles the solenoid valve is closed so you can build pressure in your main tank. When the compressor stops cycling the valve opens and purges the moisture out of your condensing coil and desiccant tanks. The check valve keeps you from losing the air from your main tank when the solenoid valve opens. Most dental manufacturer's add a 3Rd air tank between the check valve and the desiccant tanks to help purge the moisture out of the desiccant tanks. If it's a lubricated compressor I recommend you install a filter in between your condensing coil and the desiccant tank. Change or clean the filter on a regular bases to keep your desiccant from getting saturated with oil. Install a 2nd filter on the outlet of your main tank and then plumb your air dryer. Your air dryer will last a lot longer if you do this. Depending on how large your compressor is and how much it cycles you might want to consider adding 2 desiccant tanks in series. (Air in on the bottom of the 1st tank and air out on the top. air in on the bottom of the 2nd tank with a check valve (following the flow of air) at the "T". Air out the top of the 2nd tank into your spare purge air tank or your main. Hope this helps

Martin
 
I like it! You're cheating though- water cooling! Since freezing is an issue here I don't really want anything outside. I have thought of building a shed for it etc but another project. I even thought of digging up an old well I have near the shop and running a pipe down there to get some cooling water. Or get a trencher and ..., the ideas never end. Right now I need to keep machines running so don't have a bunch of time for that.
Home made seperators for "harry Homeshop" can be found here Home Page - Projects and Articles on Our Forum! | The Hobby-Machinist
 
Might want to try local auctions. I picked up a large (100cfm capacity, way large for my needs) older Ingersoll unit at auction for $100. Replaced the on/off switch and it's been running awesome for the last year. You do need to really run the air through some sort of aftercooler (ideally before the tank) before it hits the dryer. I also run a HTP Max Dry unit before feeding the CNC. Every 6 months or so I take the beads out and dry them in the oven. You could also use of of the toilet paper style filters.

Max Dry for Plasma Cutters, Welding Parts, Metal Working Accessories, Welder Supplies | USAWeld.com
 
For what's it's worth. about 10 years ago we purchased two three Ingersol rand refrigerated air driers, large units.
16 months later one unit had the fan bracket that was pop riveted to the base brake off and take out the coil.
That same units tempeture control unit failed 4 months after that. One of the other units had a pressure switch fail, we found that when I/R built the unit they never provided a charge valve on the high/low pressure lines, then a few months later the temperature control failed on that one as well. All three had auto drain valve failures, None of theses was covered under warranty. In my option pure JUNK.
I know I will take some heat from the I/R camp and that's o.k. We pulled all the I/R driers and tossed them into our scrap bin.
We installed Keaser drier units 6 years ago with Zero problems since then, at the same time we replaced all our I/R Unigy rotary screw compressors, they were pure junk as well, I/R rep even agreed with me on that. Keaser buyer for life now.
 








 
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