Water separator for small air compressor

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jimNC

New User
Jim
You guys have any decent recommendations for a small water separator to be used with a 6-gallon pancake compressor? Mine is not oiled so I don't need a oil/water separator - not sure if they all do both. Would be nice if I could pick one up at a local store vs. Internet. I see several on Amazon for around $10, wondering if anyone has any experience with them and if there is a local source. Thanks.
 

KenOfCary

Board of Directors, Secretary
Ken
Staff member
Corporate Member
Northern Tool would probably have them and you may find them at Lowes or Home Depot.

- Ken.
 

MrAudio815

New User
Matthew
Got mine for a 6 gallon pancake compressor at Lowes. Kobalt small filter for around $12 or less works great. Using it for my Vacuum chuck....Won't work without it.
 

ehpoole

Administrator
Ethan
Please beware that coalescing filters (the water & oil trap you and others are referring to) ONLY remove condensed water from the air stream. They can not remove water vapor from the compressed air (which is usually the greater problem), as a result you will still get a good deal of condensing water at the point of use on humid days and especially during periods where the compressor has run continuously for more than a minute or two (oilless especially, as they run even hotter and hot air holds more moisture).

This is especially problematic if you use the air to blow/dust your cast iron surfaces or for painting. Even in a dehumidified air-conditioned workshop, sustained dusting or cleaning with a blower attachment will eventially generate enough heat at the compressor and tank that the now hot compressed air will actually begin to produce a continuous, and often times readily visible, stream of condensing water/steam at the outlet of the blower due to the sudden cooling experienced when the compressed air returns to normal atmospheric pressure!

This issue is typically dealt with in one of four ways:

  1. A long run (20+ ft, more is better) of steel/iron or copper piping (NEVER PVC) installed before the water trap, which serves to cool the air before it reaches the water & oil trap. The water condenses in the piping, the air cools which reduces it's moisture holding ability, and allows the coalescing filter to trap far more water greatly reducing the dew point of the compressed air. If the dew point is below the temperature of the cooled compressed air (the air stream cools further at point of use when the pressure is suddenly reduced) then no water will condense in/on your tools. However, you can not count on a water trap to guarantee no water condenses at the point of use.
  2. Installation of an aftercooler for the compressor (essentially a fan-driven radiator) installed between the compressor pump and tank (not practical for a pancake). This performs the same function as the metal piping in solution #1. Again, this greatly reduces the water vapor stored in the compressed air stream and allows for greater capture of the water (in this case at or before the tank), but does not guarantee that no water will condense at the point of use.
  3. Install a coalescing filter wherever you can to trap what liquid water there is, then install a dessicant (silca gel) filter just before the tool or point of use. These work great, but disposables cost money over time and have a limited life before saturation. The more water vapor there is to remove the shorter the disposable's lifespan, so it pays to condense and remove as much water as possible beforehand. More permanent dessicant filter solutions with renewable dessicant (either manually or automatically renewed) are available but fairly costly.
  4. Installation of a refrigerated dryer (essentially a dehumidifier for your compressor). Typically a hot-air dryer is installed between compressor pump and tank, but for a pancake it could also be placed after the tank without issue. This is the absolute best solution for water removal but it is also the most costly. Fortunately, a pancake compressor can get by with the smallest unit available.
HTH
 

jimNC

New User
Jim
Thanks guys. I think even the smallest refrigerated dryer would cost about as much or more as my PC pancake compressor - but I do appreciate that information anyway. I had to dig to find one on Northern's website, a 2-pack for $25 with nonreplaceable filters. Probably would be good enough as I generally don't run my nail guns excessively. I have all bench tools so no cast iron to worry about :) - aluminum as far as the eye can see.

I didn't see one in Lowe's when I was there yesterday but I guess I just missed it.
 

scsmith42

New User
Scott Smith
Please beware that coalescing filters (the water & oil trap you and others are referring to) ONLY remove condensed water from the air stream. They can not remove water vapor from the compressed air (which is usually the greater problem), as a result you will still get a good deal of condensing water at the point of use on humid days and especially during periods where the compressor has run continuously for more than a minute or two (oilless especially, as they run even hotter and hot air holds more moisture).

This is especially problematic if you use the air to blow/dust your cast iron surfaces or for painting. Even in a dehumidified air-conditioned workshop, sustained dusting or cleaning with a blower attachment will eventially generate enough heat at the compressor and tank that the now hot compressed air will actually begin to produce a continuous, and often times readily visible, stream of condensing water/steam at the outlet of the blower due to the sudden cooling experienced when the compressed air returns to normal atmospheric pressure!

This issue is typically dealt with in one of four ways:

  1. A long run (20+ ft, more is better) of steel/iron or copper piping (NEVER PVC) installed before the water trap, which serves to cool the air before it reaches the water & oil trap. The water condenses in the piping, the air cools which reduces it's moisture holding ability, and allows the coalescing filter to trap far more water greatly reducing the dew point of the compressed air. If the dew point is below the temperature of the cooled compressed air (the air stream cools further at point of use when the pressure is suddenly reduced) then no water will condense in/on your tools. However, you can not count on a water trap to guarantee no water condenses at the point of use.
  2. Installation of an aftercooler for the compressor (essentially a fan-driven radiator) installed between the compressor pump and tank (not practical for a pancake). This performs the same function as the metal piping in solution #1. Again, this greatly reduces the water vapor stored in the compressed air stream and allows for greater capture of the water (in this case at or before the tank), but does not guarantee that no water will condense at the point of use.
  3. Install a coalescing filter wherever you can to trap what liquid water there is, then install a dessicant (silca gel) filter just before the tool or point of use. These work great, but disposables cost money over time and have a limited life before saturation. The more water vapor there is to remove the shorter the disposable's lifespan, so it pays to condense and remove as much water as possible beforehand. More permanent dessicant filter solutions with renewable dessicant (either manually or automatically renewed) are available but fairly costly.
  4. Installation of a refrigerated dryer (essentially a dehumidifier for your compressor). Typically a hot-air dryer is installed between compressor pump and tank, but for a pancake it could also be placed after the tank without issue. This is the absolute best solution for water removal but it is also the most costly. Fortunately, a pancake compressor can get by with the smallest unit available.
HTH

An excellent post above!

I would add a 5th option, and that is to increase your storage capacity. Increased air storage results in less compressor cycling, and it has been my experience that this reduces the overall temperature inside the tank, especially when you can work off of the cool air already stored in your tanks at the beginning of the day.

You can make your own add-on tank by converting one of the tanks that Northern sells for filling up tires. As I recall they are around 30 bucks. You will also need a couple of quick disconnect fittings to make it easy to plug the tank in as well as remove it from your compressor. I use these with two different pancake compressors with good results.
 

MrAudio815

New User
Matthew
An excellent post above!

I would add a 5th option, and that is to increase your storage capacity. Increased air storage results in less compressor cycling, and it has been my experience that this reduces the overall temperature inside the tank, especially when you can work off of the cool air already stored in your tanks at the beginning of the day.

You can make your own add-on tank by converting one of the tanks that Northern sells for filling up tires. As I recall they are around 30 bucks. You will also need a couple of quick disconnect fittings to make it easy to plug the tank in as well as remove it from your compressor. I use these with two different pancake compressors with good results.


Scott,

Can we get a picture of what you are talking about. Would love to do this for my pancake compressor.

Thanks for all the replies, I love learning from this site~!
 

ehpoole

Administrator
Ethan
Probably would be good enough as I generally don't run my nail guns excessively. I have all bench tools so no cast iron to worry about :) - aluminum as far as the eye can see.
If all you will be using your pancake compressor for is nailing then you should not have major water issues (just oil your tools regularly, unless your guns are oilless) as the compressor should not be cycling very frequently. Infrequent cycling keeps the tank itself much cooler and allows much of the water time to condense inside the tank. You might need a dessicant drier if you operate the compressor in extreme humidity, but I never had any captured water in a coalescing filter with my pancake while nailing. It might be an issue with a framing nailer (which I don't have) but not with 16-23ga nailers/pinners we typically use in woodworking and trim applications.

The auxiliary tank suggestion is doable provided the auxiliary tank has seperate and distinct ports for incoming and outgoing air. If it shares a single tank port for both then during heavy use (such as dusting) the hot wet air from the compressor tank will just flow straight through the inlet hose and out the exhaust hose bypassing the auxiliary tank. An appropriate (dual port) auxiliary tank provides some additional cooling by offering added surface area to cool the incoming air. Just don't forget to drain the auxiliary tank regularly (just like the pancake's tank). Also, keep in mind that nearly all the auxiliary tanks on the market are only rated at 125PSI (some are even less) and many pancakes can generate up to 150PSI, so take care not to adjust your pressure regulator above 125PSI.
 

jimNC

New User
Jim
Thanks Ethan, really good info. What's prompted all this is the recent purchase of a DeWalt 2-gallon compressor for those little jobs - and for me, most of the jobs I do I would consider 'little'. This little compressor is great but if you do more than 20 nails it is going to cycle. And since I will probably tend to use it more and more even for medium jobs, I figured I would look into separators.

I put a couple drops of oil in each nail gun regardless of how much I will be using it that day. I do have a framing nailer I use sometimes, but I would likely use the pancake compressor for that. I just figured an inline water separator, even a disposable type, would be good insurance to have. To be honest, for my applications I don't think it would make a huge difference but the little desiccant filters seem to be a good compromise.
 

scsmith42

New User
Scott Smith
Scott,

Can we get a picture of what you are talking about. Would love to do this for my pancake compressor.

Thanks for all the replies, I love learning from this site~!

Sure Matt, here is a photo of one of my setups that utilize the auxilliary air tank. This particular one is mounted on a portable shop trailer that I use here on the farm, and it's a bit dusty from being under the shed. There is an water drain coming off of the bottom of the tank that is not shown in this photo.

 

dstrbd488

New User
Chris
I don't know exactly what you plan to do with you compressor or what you intentions are, but at a buddys shop we were doing s lot of paint and body work and fixed a "bucket" up for when we were spraying paint. Basically what we did was take some copper tubing and make a coil to fit in the bucket with one end of the tubing connected to the intake side of the air line and the other end connected to a cheap seperator followed by a filter type seperator and the the outlet hose is connected. When we were just working around the shop we would just fill the bucket with water to help chill the line. when spraying finishes however we would put a couple bags of ice in to chill the water and allow the seperator work more efectivly.
 

MrAudio815

New User
Matthew
Sure Matt, here is a photo of one of my setups that utilize the auxilliary air tank. This particular one is mounted on a portable shop trailer that I use here on the farm, and it's a bit dusty from being under the shed. There is an water drain coming off of the bottom of the tank that is not shown in this photo.


Thanks Scott,


What brand is the external tank? I have seen a 10 gallon Task force tank at lowes rated at 125psi no more and an 11 gallon external tank at Harbor Freight rated at 125psi. Both look like they get filled up and used to fill tires as it has a tire filler attachment.

Can I use one of these tanks mentioned and just set my compressor to 125psi as it will go to 150psi and just buy the quick connect/disconnect fitting for the tank and attach it with thread sealant? then attach mu 50 ft hoses to that?

Thanks :icon_thum,

Matthew
 
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