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- Feb 8, 2014
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- 11,145
About a year ago I decided it was time to dry out my water air lines so started looking around for a solution. Up to then a little water in the air didn't bother too much, and we had one pretty dry line, so the air tools got used on that one. But now have 2 CNC machines in the shop that don't like wet air so time to do something.
I finally settled on a Harbor Freight refrigerated air dryer. The reviews were generally good with the primary compliant being the automatic drain valve. It just doesn't work. The specs allude to automatic operation, apparently via pressure switch, but I find no such provision, turn it on and it runs. I'm working on that, I want it to work on air flow, for the moment I'm operating it manually. Not an easy task to design a flow switch that works from just >0 to whatever flow. I think that will be a project for another thread.
https://www.harborfreight.com/compressed-air-dryer-40211.html
I have two 5 HP compressors up in the corner and to date they have not been operational at the same time. A couple years ago a customer gave me the black one because it had a bad motor. Actually pretty low time on it, and it looked like new inside and out. I purchased a 3 phase motor for it and put it up on the shelf beside the red one. Then about 5 months ago the new Baldor motor that I put on the red compressor gave up, so grab the VFD I had been saving for the black one and get it operational. Under some conditions we use quite a bit of air and the air compressor cycles quite a bit, so a 3 phase motor is a much better solution than a single phase because there are no start windings to burn up. The red one is going to get a 3 phase motor also.
The system looks like this, the two tanks are plumbed together with no valve between because the air pressure is sensed only at the red tank so they have to act as one tank. Both tanks are rated at 175 PSI working pressure, but I have the system turned down to 125 PSI
On the right hand side of the right hand picture, if you follow the pipe down the wall, you can just make out the first moisture trap drop, this has a ball valve on it so it's easy to drain, just below the box fan.
The tank drains are easily accessible, just stick the drain line out the door and turn on the valve. This is the first line of defense for keeping water out of the air.
From the tanks the airline goes up the wall and across the roll up door.
And this is one of the places I screwed up the original installation. The pipe is level and should be angled up a bit so the water would flow back toward the air compressors, and the moisture trap drop. Until the last few days everything was hard plumbed in with no unions (another mistake) so too much hassle to fix it.
There used to be a pipe from the elbow above and the tee below, had to cut it out with a Sawzall. I need to do a little re-plumbing up there so I can raise that end of the pipe a bit, the elbow hits the building framework. The other big mistake is that there is no moisture drain at this junction, I will be fixing that. The blue line going to the left goes directly to my front hose reel. When I cut the pipe out, there was quite a bit of moisture in the tee.
Now the blue line from the valve at the top goes to the air drier. Blue line = wet air, Yellow line = dry air.
The Yellow line in the picture below is from the dry air receiver.
This is an overview of the drier system. Air drier on the far left and a 100 gallon receiver tank in the back. This gives me a total air storage capacity of 260 gallons. That is an 8 x 10 mezzanine above the lathe & mill.
Since air compressors seem to be rated by tank size by the marketing types, does this mean that I have a bigger compressor now?
I added the filter/drain after the air drier to try to catch anything that the water trap in the dryer fails to take out. https://www.automationdirect.com/ad...rs,_lubricators)/filters_(af_series)/af-683-a
The 1/4 inch discharge line goes down to the floor
And the plumbing into the receiver. I almost feel like I should be running the air in on one end and out the other, but I can't figure out why that would be any better. The 1/2 inch poly air lines seem to flow plenty of volume for our needs, and If we do need more volume to run a 1 inch drive impact or something we have another access point near the compressors that is not dry air, but is plumbed in 3/4 pipe.
The blue line on the floor is the tank drain, goes down to a valve I'll show later
And another view of the system.
And the guts of the dryer along with the new automatic drain. https://www.amazon.com/gp/product/B00R2110Y0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 This one seems to work correctly, and I see in the reviews that more than one buyer used one of these to replace the automatic drain in the HD dryer. I just installed it today so not much time on it, but it seems to work correctly. The original HF drain is laying on the floor.
The clear/blue drain line goes down to the floor also.
The drain lines follow the leg of the pallet rack down to the floor, the floor has a steep slope in this area and the water will just run out under the roll up door. I wanted them here so I can see if the auto drains are working and how much water I'm removing.
The tank drain is exhausted outside. The small valve center frame.
Had another little problem when we were trying to sandblast. My poor old, 17 year old VFD, that was not designed for single phase input, was overheating and shutting the compressor down on continuous operation. But this only occured above 70° F, below that it was fine and we had one rather chilly day to finish up the sandblasting. Anyway the old VFD got replaced by a new Huan Yang 7.5KW that is rated for single phase input. https://www.amazon.com/Variable-Frequency-Controller-Converter-HUANYANG/dp/B077KSN4C5/ref=sr_1_3?keywords=7.5+KW+VFD&qid=1561881720&refinements=p_85:2470955011&rnid=2470954011&rps=1&s=gateway&sr=8-3
Seems to work OK once I got all of the parameters set correctly. I do have to say the manual was very readable and a good translation. My biggest complaint is they sell the VFD as 7.5 KW (10 HP) but use the same wiring terminals as a 0.75 KW model. Rather a PITA to get that #10 wire into those little terminals, especially given where I have it mounted. This is mounted on an aluminum plate on the wall behind the compressor and above the door. I'm pretty much out of room anywhere around the breaker panel so this was the only place left to mount it.
The whole system is enabled by a programmable electronic timer switch, https://www.homedepot.com/p/Intermatic-15-Amp-Digital-In-Wall-Timer-White-IW505K/205478790 It is programmed to only manually turn on, but is programmed to turn off at 10:00 PM
As I stated above the pressure switch is set at 125 PSI, along with a safety switch that is set at 150 PSI and if that fails, the pop off valves on the tanks open at 185. Also if the pressure goes too high, the VFD will go over current and kick it's self out. So hopefully one of those safety system will work correctly in the event of a failure.
This is a work in progress and the next step is to get proper air lines run to the machines so we can have our hose reels back, right now we just string airlines across the floor.
I'll update this thread once I've had a chance to evaluate the system for a while.
I finally settled on a Harbor Freight refrigerated air dryer. The reviews were generally good with the primary compliant being the automatic drain valve. It just doesn't work. The specs allude to automatic operation, apparently via pressure switch, but I find no such provision, turn it on and it runs. I'm working on that, I want it to work on air flow, for the moment I'm operating it manually. Not an easy task to design a flow switch that works from just >0 to whatever flow. I think that will be a project for another thread.
https://www.harborfreight.com/compressed-air-dryer-40211.html
I have two 5 HP compressors up in the corner and to date they have not been operational at the same time. A couple years ago a customer gave me the black one because it had a bad motor. Actually pretty low time on it, and it looked like new inside and out. I purchased a 3 phase motor for it and put it up on the shelf beside the red one. Then about 5 months ago the new Baldor motor that I put on the red compressor gave up, so grab the VFD I had been saving for the black one and get it operational. Under some conditions we use quite a bit of air and the air compressor cycles quite a bit, so a 3 phase motor is a much better solution than a single phase because there are no start windings to burn up. The red one is going to get a 3 phase motor also.
The system looks like this, the two tanks are plumbed together with no valve between because the air pressure is sensed only at the red tank so they have to act as one tank. Both tanks are rated at 175 PSI working pressure, but I have the system turned down to 125 PSI
On the right hand side of the right hand picture, if you follow the pipe down the wall, you can just make out the first moisture trap drop, this has a ball valve on it so it's easy to drain, just below the box fan.
The tank drains are easily accessible, just stick the drain line out the door and turn on the valve. This is the first line of defense for keeping water out of the air.
From the tanks the airline goes up the wall and across the roll up door.
And this is one of the places I screwed up the original installation. The pipe is level and should be angled up a bit so the water would flow back toward the air compressors, and the moisture trap drop. Until the last few days everything was hard plumbed in with no unions (another mistake) so too much hassle to fix it.
There used to be a pipe from the elbow above and the tee below, had to cut it out with a Sawzall. I need to do a little re-plumbing up there so I can raise that end of the pipe a bit, the elbow hits the building framework. The other big mistake is that there is no moisture drain at this junction, I will be fixing that. The blue line going to the left goes directly to my front hose reel. When I cut the pipe out, there was quite a bit of moisture in the tee.
Now the blue line from the valve at the top goes to the air drier. Blue line = wet air, Yellow line = dry air.
The Yellow line in the picture below is from the dry air receiver.
This is an overview of the drier system. Air drier on the far left and a 100 gallon receiver tank in the back. This gives me a total air storage capacity of 260 gallons. That is an 8 x 10 mezzanine above the lathe & mill.
Since air compressors seem to be rated by tank size by the marketing types, does this mean that I have a bigger compressor now?
I added the filter/drain after the air drier to try to catch anything that the water trap in the dryer fails to take out. https://www.automationdirect.com/ad...rs,_lubricators)/filters_(af_series)/af-683-a
The 1/4 inch discharge line goes down to the floor
And the plumbing into the receiver. I almost feel like I should be running the air in on one end and out the other, but I can't figure out why that would be any better. The 1/2 inch poly air lines seem to flow plenty of volume for our needs, and If we do need more volume to run a 1 inch drive impact or something we have another access point near the compressors that is not dry air, but is plumbed in 3/4 pipe.
The blue line on the floor is the tank drain, goes down to a valve I'll show later
And another view of the system.
And the guts of the dryer along with the new automatic drain. https://www.amazon.com/gp/product/B00R2110Y0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 This one seems to work correctly, and I see in the reviews that more than one buyer used one of these to replace the automatic drain in the HD dryer. I just installed it today so not much time on it, but it seems to work correctly. The original HF drain is laying on the floor.
The clear/blue drain line goes down to the floor also.
The drain lines follow the leg of the pallet rack down to the floor, the floor has a steep slope in this area and the water will just run out under the roll up door. I wanted them here so I can see if the auto drains are working and how much water I'm removing.
The tank drain is exhausted outside. The small valve center frame.
Had another little problem when we were trying to sandblast. My poor old, 17 year old VFD, that was not designed for single phase input, was overheating and shutting the compressor down on continuous operation. But this only occured above 70° F, below that it was fine and we had one rather chilly day to finish up the sandblasting. Anyway the old VFD got replaced by a new Huan Yang 7.5KW that is rated for single phase input. https://www.amazon.com/Variable-Frequency-Controller-Converter-HUANYANG/dp/B077KSN4C5/ref=sr_1_3?keywords=7.5+KW+VFD&qid=1561881720&refinements=p_85:2470955011&rnid=2470954011&rps=1&s=gateway&sr=8-3
Seems to work OK once I got all of the parameters set correctly. I do have to say the manual was very readable and a good translation. My biggest complaint is they sell the VFD as 7.5 KW (10 HP) but use the same wiring terminals as a 0.75 KW model. Rather a PITA to get that #10 wire into those little terminals, especially given where I have it mounted. This is mounted on an aluminum plate on the wall behind the compressor and above the door. I'm pretty much out of room anywhere around the breaker panel so this was the only place left to mount it.
The whole system is enabled by a programmable electronic timer switch, https://www.homedepot.com/p/Intermatic-15-Amp-Digital-In-Wall-Timer-White-IW505K/205478790 It is programmed to only manually turn on, but is programmed to turn off at 10:00 PM
As I stated above the pressure switch is set at 125 PSI, along with a safety switch that is set at 150 PSI and if that fails, the pop off valves on the tanks open at 185. Also if the pressure goes too high, the VFD will go over current and kick it's self out. So hopefully one of those safety system will work correctly in the event of a failure.
This is a work in progress and the next step is to get proper air lines run to the machines so we can have our hose reels back, right now we just string airlines across the floor.
I'll update this thread once I've had a chance to evaluate the system for a while.
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