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Dry air tanks in attic of shop?

macds

Hot Rolled
Joined
Jul 24, 2008
Location
Milverton, Ontario, Canada
Since I'm going to be installing a screw compressor here shortly, Im trying to think of air reciever placement.

Curious what the thoughts are regarding placing my air tanks in the attic of my shop?

Air will be dry (refrigerated dryer) and filtered before hitting the tanks, but should I be concerned about moisture buildup in the tanks (from temp changes)?

I like the idea of saving wall\floorspace in my small shop.
I would also much prefer the safety idea of the tanks being stored out of the work envelope.

I could run the air coming back into the shop through another dryer\filter if necessary.

It freezes here for extended periods in the winter.
 
Just take the low point of the tank drain plug out, and replace it with a hose,
leading down to the shop with a valve so you can easily (as in weekly) drain the tank for moisture.
 
Just take the low point of the tank drain plug out, and replace it with a hose,
leading down to the shop with a valve so you can easily (as in weekly) drain the tank for moisture.

Unless you heat trace this line it will freeze at some point. At least in our winters this would not work.


Sent from my iPhone using Tapatalk
 
I don't have any problems with water in my downstream receivers, I have one upstairs and one down on the shop floor.

I put shutoff valves on every receiver so I can isolate the sections. Each night I close them off so I can start in the morning without waiting for the air to come up.

So that's the only issue I would have with an attic install, more of a PITA to get to...
 
My hope is, that by drying the air before it hits the tanks, I shouldnt have any moisture in the tanks.
I know dewpoint plays a role in all of this.

I just dont want to go through the process of drying before storage, and end up with moisture in the tanks anyways (and freezing up in the winter, splitting a tank).

I suppose if need be, I could always put a heat jacket and insulation on the tanks.
 
Unless you heat trace this line it will freeze at some point. At least in our winters this would not work.


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Who cares where your from ?

code says every tank must have a drain.

If, it's a big IF, any moisture condenses in the tank, you need to drain it.

Make it easy on yourself so it will get done.

I'll bet some heat will leak UP, into the attic, and keep it somewhat warm.
If you drain it, and nothing comes out, you then know you have:
1. water
2. it's frozen

So then, put a heat trace on it, BIG deal.

If your whole shop goes unheated at night, what would you doo if the tank
was IN the shop ?
 
Well I guess if that was a real concern, you could get by with just some heat tape on the hose where it is still in the cold confines.
Wouldn't need to heat the whole tank.


I Shirley don't see it splitting the tank tho.
Plugging the drain would be about the worst that I would expect.

???


------------------

Think Snow Eh!
Ox
 
With a real refrigerated drier, before the tank, there will be no water in the tank

The temp of the tank won't define moisture, more the temp/humidity of the air going into the compressor
 
With a real refrigerated drier, before the tank, there will be no water in the tank

The temp of the tank won't define moisture, more the temp/humidity of the air going into the compressor


I don't know where "The Peoples Republic" is, so I have to ask:
(China? Texas? Other?)

Have you ever been outside on a crystal clear night at -30*C? (it doesn't need to be that cold, but...)
Nothing but stars - maybe even so many that you can't even see constelations b/c it is so clear and there are just too many stars visible?
The lakes froze so tight that the ice-breakers will have to werk for at least a week to get the first ore freighter through in the spring?
(no lake effect tonight)
So (wintery) dry that your skin wants to crack? (I have)

.. and yet the cold temp of the night is wringing out some snowflakes?

They didn't come from any cloud.....


-----------------

Think Snow Eh!
Ox
 
I mounted a 50 gallon water heater tank in the rafters of my pole barn many years ago when I had a smaller compressor and wanted to have reserve of compressed air. It never was a problem and was probably there for about ten years until I bought a larger compressor and didn't need the reserve air.
 
With a real refrigerated drier, before the tank, there will be no water in the tank

The temp of the tank won't define moisture, more the temp/humidity of the air going into the compressor

Have you ever been outside on a crystal clear night at -30*C? (it doesn't need to be that cold, but...)
Nothing but stars - maybe even so many that you can't even see constelations b/c it is so clear and there are just too many stars visible? (I have)

.. and yet the cold temp of the night is wringing out some snowflakes?

They didn't come from any cloud.....


-----------------

Think Snow Eh!
Ox
Yup, I was going to point out that refidge dryers cool the air down to some temp.

What is that temp ?

If you send that air up to the tank, and it's colder, you'll drop out more condensation.
 
Have you ever been outside on a crystal clear night at -30*C? (it doesn't need to be that cold, but...)
Nothing but stars - maybe even so many that you can't even see constelations b/c it is so clear and there are just too many stars visible? (I have)

.. and yet the cold temp of the night is wringing out some snowflakes?

They didn't come from any cloud.....


-----------------

Think Snow Eh!
Ox

I am sure this is true, and when it starts snowing in my air tank, i'll let you know
 
Yup, I was going to point out that refidge dryers cool the air down to some temp.

What is that temp ?

If you send that air up to the tank, and it's colder, you'll drop out more condensation.

My rubber output line frosts on mine.

[edit]

just went, got on my hands and knees and opened the valve, yup, 4 years exactly zero liquid water ever came out the bottom of the 400 gallon tank. Zero water out of the petcock on the shop lines, and I know no one has touched that in years

I am not trying to say there is zero scientific amount of humidity in the air, but that once it goes through a refrigerated drier the level is so low that it won't be able to cause you a problem. My vertical tank has the drain on the bottom and the exit 3 feet up. at 10 below zero I am certain there is the possibility of a little frost, but it would never ice that line
 
My rubber output line frosts on mine.

[edit]

just went, got on my hands and knees and opened the valve, yup, 4 years exactly zero liquid water ever came out the bottom of the 400 gallon tank. Zero water out of the petcock on the shop lines, and I know no one has touched that in years

I am not trying to say there is zero scientific amount of humidity in the air, but that once it goes through a refrigerated drier the level is so low that it won't be able to cause you a problem. My vertical tank has the drain on the bottom and the exit 3 feet up. at 10 below zero I am certain there is the possibility of a little frost, but it would never ice that line

Theory be dammed.

Code must be followed.

You must have a drain.

Period.
 
Yup, I was going to point out that refidge dryers cool the air down to some temp.

What is that temp ?


Sounds like you have yours set pretty low.
Possibly wastefully low?

I don't have much experience with dryers.
I have one and it's hooked up to my big screw, but that unit never sees use, so ....


-------------------

Think Snow Eh!
Ox
 
Yup, I was going to point out that refidge dryers cool the air down to some temp.

What is that temp ?

If you send that air up to the tank, and it's colder, you'll drop out more condensation.

Yup. Typically 33-34 deg. F. Any colder and you risk having the condenser freeze up. So, if you send this air up into the tank in the attic and it is zero degrees, MORE water will condense out. You may not ever find the water over the long run, however. Next summer when the tank is at 90 deg.F, the air will pick up that water and it will 'disappear'.

There is another consideration, however, and it has a lot to do with what the air is going to be used for. We spray paint, and the last thing we need is drops of water condensing at the nozzle. The airflow expanding out of a nozzle has a cooling effect. Refrigerator dryers take this into account, and run the outgoing air through an air-to-air heat exchanger, which pre-cools the incoming air. It also heats the outgoing air well above its dew point, so even when it cools down through expansion, it remains above that dew point. If you store your air at, say, zero degrees in the attic, it will be even colder at the nozzle, and will pull droplets of water out of the surrounding air. Not good, if you are painting, or blowing dust off furniture before applying the finish. For other uses, may not be a problem at all.

Dennis
 
Refrigerated air dryer will get air to a dew point of 38 degrees F or so and generally not better. IF your receiver sees temps below freezing there will be condensation. Drains are cheap and easy and smart.

And yes I've done exactly as you suggest, a refrigerated air dryer after the "wet-receiver" and that feeds 80 gal of air storage in the rafters and another 60gal outside. Drains and drip legs cost nearly nothing to implement
 
I am sure this is true, and when it starts snowing in my air tank, i'll let you know

A refrigerated drier does not take the refrigeration charge below 32F. If it did, the refrigeration coils would freeze up, eventually blocking air flow through the drier.

The effective dew point is what is important. The efffective dewpoint also varies with pressure as does the amount of water vapor to reach saturation. The drier is only going to get you to a 32F dewpoint at best and it is usually higher, closer to 40F.

If the receiver tank is in a heated area so that it does not go below 32F, there is usually no problem however in this case the tank will be in an unheated area so it could go below 32F. If the tank temperature goes below the dew point, then you will get condensation, especially if the tank or system pressure drops over night.

So, a refrigerated drier will only remove so much water at a given temperature/pressure. You need to plan for the outlier conditions meaning adding a tank drain. This is also a good way to monitor the drier performance.

When the drier is developing problems, moisture will start to show up at the drain.
 








 
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