Thread: How much water in compressor line is acceptable?

Ok, so I know the ideal is none!

My compressor is a Peerless P25. 3 phase, 25cfm.

From the tank I have a temporary 8mm ID hose connected to my 25mm DIA pipe that runs around the shed. That pipe has 2 vertical drain points and 2 regulator/water traps.

I say temporary because it's all I had at the time and I wanted to get it up & running... Because it's never caused me a problem, I've never fixed it!

Up until this weekend it's just had occasional use around the shed, more off time than running time.

This weekend I decided to sand back the deck with my Ingersoll Rand Random Orbital sander. The compressor was running for about 6 hours straight on both days.

Both the water trap behind my take off point and the pipe work drain points collected lots of water (about 400ml in total over the course of each day). Towards the end of each day I started to get water vapor at the sander (about 50m away from the compressor).

The compressor cylinders were too HOT to touch at the end of the day.
Neither of the vertical drain tubes or the water trap were full at any point in the day.

Question:
1. Does that sound about normal for extended running or WAY too much water?

I suspect that my small diameter link hose is probably to blame due to the speed up & slow down of air before it gets into the 3/8 air hose feeding the sander but I'm keen to hear your thoughts.

Any thoughts or suggestions?




Thx
Jon

Is that poly pipe you are using? If so is all your pipe poly? This will hinder water removal.

Dean

Hi Jon
Have you drained the compressor tank?

Roger

Dean, Pipe is all Aluminium.

Roger, tank is drained daily. Maybe get 75-100ml from that.


Thx
Jon

I think the problem is that the compressor and it's reservoir are too small to run an air sander for an extended period.
The compressor was thus running flat chat, the compressed air was so hot that it could hold moisture all the way to the sander where it condensed.
I don't think the size of the delivery line, or the fact that it's Al has much bearing on it.

Remember too that the amount of water in the air is related to the humidity - if you are near the coast or in the tropics there will probably be more water condensing out than if you were in an arid region. As Ian said, if the compressor is hot then the water (in the air) will not come out as easily. Some of hte guys here run a second tank or a heat exchanger to try and knock some of the water out (by virtue of cooling the air)

Michael

One of the issues for water in the lines is the 8mm pipe from the tank because it is so small the air speed through it will be very high compared to the 25mm it goes into. High air speed means that any water in the air stays suspended and can't drop out. Replacing it with 25mm back to the tank might not stop the water problem but at least it should not be as bad. High volume usage will carry the water over a period of time in high humidity conditions and apart from water traps and possibly a refrigerated water extractor there is not a lot to be done. A refrigerated extractor can be made cheaply with a portable air tank and an old fridge. Put the tank in the fridge, hook up the pipes through the fridge walls and attach an external drain. Start the fridge a short time before using the compressor and most if not all the water will be trapped in the tank. A possible advantage to this if you are inclined is stuff like beer can be put in the fridge.

Originally Posted by Chris Parks

One of the issues for water in the lines is the 8mm pipe from the tank because it is so small the air speed through it will be very high compared to the 25mm it goes into. High air speed means that any water in the air stays suspended and can't drop out. Replacing it with 25mm back to the tank might not stop the water problem but at least it should not be as bad.

Not so sure about that. While big pipe all round is good for friction loss, as it stands, where the 8mm pipe connects to the 25mm there will be a pressure drop, which will cause the air temperature to drop, which should cause airborne moisture to condense. If you remove that small pipe, you'll lose the cooling effect of the pressure drop.

Speaking of wet compressors, I was doing some work at a mate's winery and wondered why the air compressor was cycling so often. I opened the drain valve and it started gushing out water. It just kept on coming, so after about a minute I climbed the ladder I was working on took the attached pic. The tank must have been almost full....

I agree with Ian. the compressor is running too hot and either it or the the line or both needs more cooling cooling if you want to use it that way

Originally Posted by Chris Parks

One of the issues for water in the lines is the 8mm pipe from the tank because it is so small the air speed through it will be very high compared to the 25mm it goes into. High air speed means that any water in the air stays suspended and can't drop out. .

99% of the water is not in the form of droplets but gas or vapour so the amount of water that will drop out from this effect is minimal.

When you are talking 50m hose length what is the diameter of that hose?

It won't help your situation but to save you manually venting the comp tank or any point in the line try one or more of these
1 2" 2 Way Automatic Electronic Timed Air Compressor Drain Tank Valve 220V | eBay

Originally Posted by RustyArc

Not so sure about that. While big pipe all round is good for friction loss, as it stands, where the 8mm pipe connects to the 25mm there will be a pressure drop, which will cause the air temperature to drop, which should cause airborne moisture to condense. If you remove that small pipe, you'll lose the cooling effect of the pressure drop.

As explained to me from Pulford compressors when they supplied mine. It is not my theory I am just passing along what the professionals reckon. I am not saying it is the case here but if the air speed is very high then it will tend to carry water more easily or so they reckon.

Originally Posted by Chris Parks

As explained to me from Pulford compressors when they supplied mine. It is not my theory I am just passing along what the professionals reckon. I am not saying it is the case here but if the air speed is very high then it will tend to carry water more easily or so they reckon.

That's an understandable interpretation but it's not what happens.

Most of the liquid water condensation takes place at the walls of the pipe. The water then dribbles down the walls to build up in the bottom of the pipe

In a narrow pipe the air flow is more turbulent and will lift and carry even a thin film of water on the wall of the pipe, in a wide pipe the air flow will be slower so the air will have more time to collide with the walls of the pipe and cool down and condense the water. Slower and more stable air flow will also not lift off as much water from the walls of the pipe as in the narrower pipe This is why more water accumulates in wider pipes.

The effect of cooling from expansion effect of transiting between different diameters pies depends very much on the pressure gradients due to things like path lengths and the presence of other pipe diameter and orifii along the pipe path. A pipe that goes from 8mm to 25 mm then to a working orifice of 5mm will not experience any expansion or pressure drop or cooling across the 8 - 25mm transition because the 5 mm orifice dominates the flow. Any water appearance in the 25 mm pipe is duet the effect described above.

OTOH if the 25 mm vents direct to atmosphere at a full 25 mm opening then there will be considerable cooling from expansion at the 8 to 25 mm transition.

And that is different to what I related, more air speed carries more water.

Originally Posted by Chris Parks

And that is different to what I related, more air speed carries more water.

Now that I re-read what you wrote I guess not. I got the verb "drops" out of the air, confused with adjective "drops" of water.

Thanks guys. An interesting read.

I'm on the coast so humidity is a bit of an issue.

I will change the 8mm hose for a properly sized one and see how I get on. Thankfully this job is only going to be done once in a blue moon so I'm not overly concerned about removing all the water. Having said that I might keep an eye out for an old fridge that could accommodate an old 25L tank I have laying around.

As for your question of hose diameter Bob, I've got about 15m of 25mm ally pipe, 15m of 12.5mm ID and then 15m or 20m of 10mm ID.



Thx
Jon