How much water are you pumping into your PCP?

[Buldawg76]

Taso
That is my next thing to do is add a bleed off valve on the inlet side of the high pressure filter and mount it in a vertical position with the bleed off at the bottom. I have the high side filter laying flat now below the level of the shoebox. I am waiting for the cheap Chinese compressor to arrive before I remount the high side filter and am going to get a bigger low side water separator as well.

Hopefully that will be a good setup to capture as much water as possible from the air especially in the summer saunas we have here in the southeast. You can just about set your clock by the afternoon rain showers here every day.

Mike

[AlanMcD]

Mike,

You are clearly doing the right thing with the drier you have on the output side of the Shoebox - passing the air through a desiccant at the highest pressures is clearly the best possible way of drying the air.  Of course with a Shoebox, that comes at the high "cost" of time to pressurize the filter, and that is wasted air too.  But it certainly is dry air!

You are doing everything right in feeding the Shoebox, although I am not sure what you mean by a water separator - does that have a desiccant in it? I use a big Wilkerson dryer that holds about a pound and a half of desiccant on mine (the dryer is rated to dry to a dewpoint of -45 F at a flow rate of over 10 cfm, and a Shoebox is under 0.25 cfm).

When you say you see "water vapor" blowing out when venting your Shoebox, you may be seeing condensed water blowing out.  If that is the case, the HPA drier will clearly take care of it.  I have not seen that with my set up (I too run a compressor in my garage, and plumbed the air into my workshop so it cools all the way down too, and I have water traps along the way).

I have run about 750 cubic feet of air through my drier/Shoebox, and my desiccant shows no signs of needing dried or replaced yet.  I will probably just replace it with Molecular sieve when it needs to be dried  and then my air will be even drier.  One thing I do though that helps is that I have ball valves in my air path into the desiccant filter to stop any air from getting to the desiccant when not in use - desiccants will pull moisture out of ambient air and become saturated when just sitting there (like with safe driers).  I highly recommend this.

[Buldawg76]

Mike,

You are clearly doing the right thing with the drier you have on the output side of the Shoebox - passing the air through a desiccant at the highest pressures is clearly the best possible way of drying the air.  Of course with a Shoebox, that comes at the high "cost" of time to pressurize the filter, and that is wasted air too.  But it certainly is dry air!

You are doing everything right in feeding the Shoebox, although I am not sure what you mean by a water separator - does that have a desiccant in it? I use a big Wilkerson dryer that holds about a pound and a half of desiccant on mine (the dryer is rated to dry to a dewpoint of -45 F at a flow rate of over 10 cfm, and a Shoebox is under 0.25 cfm).

When you say you see "water vapor" blowing out when venting your Shoebox, you may be seeing condensed water blowing out.  If that is the case, the HPA drier will clearly take care of it.  I have not seen that with my set up (I too run a compressor in my garage, and plumbed the air into my workshop so it cools all the way down too, and I have water traps along the way).

I have run about 750 cubic feet of air through my drier/Shoebox, and my desiccant shows no signs of needing dried or replaced yet.  I will probably just replace it with Molecular sieve when it needs to be dried  and then my air will be even drier.  One thing I do though that helps is that I have ball valves in my air path into the desiccant filter to stop any air from getting to the desiccant when not in use - desiccants will pull moisture out of ambient air and become saturated when just sitting there (like with safe driers).  I highly recommend this.

Alan
Yes it does take time to pressurize the high side filter and is why I have a shutoff valve on the output side of the HPA filter so I can allow the shoebox to build pressure in the line and filter before I start to fill my tanks or guns. I also shutoff the pressure in the filter before I bleed off the pressure at the tanks so I only have to pressurize the filter once per filling session. Doing it that way I only waste the air after all tanks are full and then I let the shoebox run with the HPA side open to help any leftover moisture in the lines be pushed out before I close the HPA shutoff valve.

My "water separator " is a desiccant filled filter with a sintered rock filter on the output side to help prevent any desiccant powder from being forced into the lines themselves. It is not near as big as yours and holds about a cup of the 13X sieve beads but plan to add another one in the LPA side to double up on the filters.

The water vapor I used to see when bleeding the HPA side is as you say condensed water that is in small drops so it appears as a vapor in the air. Since installing the HPA molecular sieve on the shoebox output I have not seen that condensation when bleeding off the pressure after the HPA filter but still see it when I bleed the HPA line at the shoebox that is before the HPA filter.

I have no clue what volume of air that flows thru the LPA filter and shoebox other than the compressor when at 125 PSI will feed the shoebox for about an hour before it has to come back on to rebuild the pressure back to 125 psi. When its not in use I have the lines into and out of the shoebox and filters plugged so no ambient moisture can be drawn out of the air when dormant between uses.

So with what you have stated and how mine is setup I believe its pretty well capable of trapping all moisture before it gets to my tanks or guns.  Its definitely much better than it was before the HPA filter was added.

Thanks for the info and clarification on how and why you have yours setup like you do.

Mike

[lloyd-ss]

A good discussion of water in PCPs, with a number of good strategies on how to take care of it.  Like Alan said, it can be managed, and managed at various points in the process, from Chris's supplying his compressor with chilled dry air from a fridge, to Mike's high side molecular sieve.

One of the key points seems to be getting the air to linger long enough in the system for its temp to drop so that the water can fall out, or long enough so that some other filtration or absorption method can extract the moisture.  Along that line, I did a few calcs based on claimed output from a Shoebox compressor.  The actual output from a Shoebox at 4500psi is about 3/4 of a cubic inch of compressed air per minute. So if you want the air to linger for 10 minutes before going into the final storage tank, you would need a dryer capable of 4500 psi, and with about 8 cubic inches of volume.  Like wise, if you wanted to catch the water as it left the 125 psi first stage, that air is leaving the compressor tank at about 27 cubic inches per minute.  So you'd need a dryer with about 270 cubic inches of volume to make the air take 10 minutes to pass thru it.  Of course, the rate of flow will vary based on the final output pressure, but you get the idea.  The point is that the actual flow rate of the air is so low that it makes it easier to extract the moisture out of the air stream.

[Buldawg76]

Lloyd
Thanks for the info on air flow and filter volumes to maximize the absorption of moisture from the system before it gets to the tanks ort guns. Very useful info indeed.

I believe my molecular sieve filter is close to or slightly bigger than the 8 ci Lloyd has stated since its close to the size of one of my 22ci air tanks in OD and is just about as long but the ID is a bit smaller since the walls are about 1/4" thick to hold the HPA 4500 psi safely.

My LPA filter is in need of upgrade as far as size goes since its nowhere near 27ci in volume and more like 5ci in volume at best. That may be why I don't see much change or indication of moisture in the 13X medium since the air is passing thru way to fast to absorb the moisture and the fact that the 13X medium works much better at pressure above 1500 psi. I need to add another filter of increased volume in the LPA side to capture more moisture before it gets to the shoebox.

Mike

[Herman Hedning]

Old topic ,  but ...

Does anybody know if this works ?
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F192847696342

Picture .

[Madd Hatter]

I was looking at that too but following Lloyd's chart (?) it comes up all 0s from filling my rifle.

[Herman Hedning]

I was looking at that too but following Lloyd's chart (?) it comes up all 0s from filling my rifle.

Sounds Good , but mine have a lot of water inside every time I open them . 

[Hoosier Daddy]

 Aren't PCP's essentially a loss system like old (vintage) oiled pumpers?
Tom Gaylord had a write up a while back where he intentionally introduced water in a PCP and shot it until the recharge pressure. Then measured to remains.....
Out-come negated all the driers that everyone claims about.
 

[bnowlin]

That filter is very similar to the dryer on the output side of the venturi 4500 amd has a tampon in it and the water falls to the bottom and drain thru the release drain.  Only exception is air is pumped in at bottom and out the top side of the filter/dryer.  Works well on mine.
Bob

[Taso1000]

The device Herman Hedning linked to is a water trap.  Its performance could be maximized with a pressure maintaining valve to raise the pressure in the vessel and force the moisture in the air charge to condense out and be removed with the bleed valve.

Hoosier Daddy, do you have a link to the Tom Gaylord article?

Thank you,

Taso

[Hoosier Daddy]

Taso, the article was in one of the little PA flyers I get in the mail twice a year, I'll see if I can find it.