Financial planning, compressor
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I have heard this often and it doesn't actually make a lick of sense. The filter sees what gets past the separators. Once you compress the air the water is squeezed out based on the pressure of the air. The separators will have more water to deal with and will have to be drained more often but in all cases the air will be saturated when it gets to the filter. The absolute grains of water will be dependent on the temperature and pressure of that compressed air. This assumes your separator is working as it should so you aren't actually pushing liquid water down the lines. My point is that the humidity of the air going in isn't what the filter sees, only the moisture that is left after the separators remove it from the condensed air. The temperature in which the compressor operates has a strong effect on the temperature of the heads and the delivered gas and that will affect the filters but not the humidity of the intake air.
I operate my compressor in conditioned space. The air is cool and dry. My separators create a lot of water. That water immediately starts to evaporate back into the space when I drain the separators. It is a very large amount. What the filters handle is a small amount.
Then why are filters rated for temperature and humidity? I'm not saying you're wrong, you have YEARS more experience then me. I'm just curious. Here is the listing for my filter;
So you're saying that temperature has a much larger effect than humidity?
Curious_George
Green water guy
Hey @rob.mwpropane I believe that note is just saying that the amount of humidity in the air that reaches the filter effects the filter life, not the humidity in the ambient air. In other words, running a lower pressure in the PMV will increase the humidity and decrease the life.
I only know that because I stayed at holiday inn last night.
I only know that because I stayed at holiday inn last night.
From 2010
how temperature and humidity affects a compressor filter
This thread states the reality pretty clearly.
Think about the physics of it. This is beyond the psychrometric chart but it's the same concept. Air holds what air holds. As the temperature rises air can hold more water molecules. As it is compressed, the molecules are forced closer together and they condense out. As they cool they condense out further. The coalescer separates out the liquid water and the water vapor remaining, which is based on pressure and temperature goes on to the desiccant in the filter. You should then be at less than -90f dew point, at least in the air I pump.
I run my compressor indoors not because the air it breathes is cooler but because the compressor itself is cooler. I also blow a fan across the coils to help cool it a bit more. This results in measured lower head temperatures and obviously lower air output from the compressor which means greater separation and removal before the filter ever sees it.
how temperature and humidity affects a compressor filter
This thread states the reality pretty clearly.
Think about the physics of it. This is beyond the psychrometric chart but it's the same concept. Air holds what air holds. As the temperature rises air can hold more water molecules. As it is compressed, the molecules are forced closer together and they condense out. As they cool they condense out further. The coalescer separates out the liquid water and the water vapor remaining, which is based on pressure and temperature goes on to the desiccant in the filter. You should then be at less than -90f dew point, at least in the air I pump.
I run my compressor indoors not because the air it breathes is cooler but because the compressor itself is cooler. I also blow a fan across the coils to help cool it a bit more. This results in measured lower head temperatures and obviously lower air output from the compressor which means greater separation and removal before the filter ever sees it.
Good read. I had read that the gas entering the filter is 100% humidity, but I guess it just didn't click. Definitely learning more each day, so thank you.
My plan, even though I didn't fully understand the physics, was to run my compressor either late or early to beat any high temps. As it stands, our next cool day will be Thurs or Fri, so the plan was to wait until then.
Great conversation (for me at least), so again thank you.
I actually did a pretty poor job of explaining the water holding capacity of air. I'll try again but may fail so google may be your friend.
Water molecules in air bounce around and sometimes they stick to surfaces. They collide with each other and they have vibrational energy. As they heat up they are actually just vibrating faster along with the air molecules around them. More excited molecules can crowd closer together in the same volume of air. The number of molecules in the air stays the same if the pressure and temperature stay the same. Some of the molecules will stick temporarily to surrounding surfaces or bounce off of them. They will rest and relaunch into the air based on their energy. As the air cools the molecules lose their energy and they get tired. They stay adhered to surfaces in greater numbers. As the temperature reaches the dew point of the air and surfaces, the molecules build to the point where they undergo a phase shift called condensation and this requires a realignment of the molecules which requires energy called the heat of condensation. This happens in the cooling coil of your air conditioner (and also in the cooling coils of your compressor) and the energy required for this phase change is your latent load as opposed to your sensible load which is the actual absorption of sensible heat. The latent load can be substantial in a humid climate in a leaky house.
So the water molecules are held in the air by the energy of their vibration which allows them to crowd together with the air molecules. Temperature is what determines the ability of air to hold water molecules. If the temperature of the air is lowered from 70 degrees to 50 degrees its ability to hold water vapor is cut in half so temperature matters BUT..... If we compress air to half its volume the relative humidity doubles as we force more molecules into the same space. Our compressors compress the air by 200-300 times. The amount of water that is squeezed out of it is similar to dropping the temperature to something like -60 so the pressures we use have a far greater impact on the water holding capacity than the temperature or absolute humidity of the ambient air.
The temperature of the compressed air when it gets to the filter has a greater effect on the filter capacity and life than the ambient air. This is because the coalescer will remove more water out of the air before it gets to the filter if it cools first. The compressor squeezes out the water but it also heats the air which raises its ability to hold onto its water content. If you compress it and also cool it then you can squeeze and extract most of the water out before the remainder is treated by the desiccant in the filter. The cooling coils of the compressor will do a better job of this if they are in a cool environment.
Don't go crazy trying to figure out how to water cool the coils to maximize this effect. Get it reasonably cool and let the filter do the rest but just visualize why cool air counts but dry ambient air really doesn't. Closed up environments are hell on compressors and filters. I hear of people putting them under their decks or in small closed up sheds to reduce the noise complaints but there is hell to pay in compressor parts and filter replacements.
I hope it makes sense. I tried to condense the discussion on condensation and it really deserves a far more in depth discussion. The water molecule is truly fascinating and I could go on and on about things we have seen all our lives but seldom slow down to understand them. That's for another time.
Water molecules in air bounce around and sometimes they stick to surfaces. They collide with each other and they have vibrational energy. As they heat up they are actually just vibrating faster along with the air molecules around them. More excited molecules can crowd closer together in the same volume of air. The number of molecules in the air stays the same if the pressure and temperature stay the same. Some of the molecules will stick temporarily to surrounding surfaces or bounce off of them. They will rest and relaunch into the air based on their energy. As the air cools the molecules lose their energy and they get tired. They stay adhered to surfaces in greater numbers. As the temperature reaches the dew point of the air and surfaces, the molecules build to the point where they undergo a phase shift called condensation and this requires a realignment of the molecules which requires energy called the heat of condensation. This happens in the cooling coil of your air conditioner (and also in the cooling coils of your compressor) and the energy required for this phase change is your latent load as opposed to your sensible load which is the actual absorption of sensible heat. The latent load can be substantial in a humid climate in a leaky house.
So the water molecules are held in the air by the energy of their vibration which allows them to crowd together with the air molecules. Temperature is what determines the ability of air to hold water molecules. If the temperature of the air is lowered from 70 degrees to 50 degrees its ability to hold water vapor is cut in half so temperature matters BUT..... If we compress air to half its volume the relative humidity doubles as we force more molecules into the same space. Our compressors compress the air by 200-300 times. The amount of water that is squeezed out of it is similar to dropping the temperature to something like -60 so the pressures we use have a far greater impact on the water holding capacity than the temperature or absolute humidity of the ambient air.
The temperature of the compressed air when it gets to the filter has a greater effect on the filter capacity and life than the ambient air. This is because the coalescer will remove more water out of the air before it gets to the filter if it cools first. The compressor squeezes out the water but it also heats the air which raises its ability to hold onto its water content. If you compress it and also cool it then you can squeeze and extract most of the water out before the remainder is treated by the desiccant in the filter. The cooling coils of the compressor will do a better job of this if they are in a cool environment.
Don't go crazy trying to figure out how to water cool the coils to maximize this effect. Get it reasonably cool and let the filter do the rest but just visualize why cool air counts but dry ambient air really doesn't. Closed up environments are hell on compressors and filters. I hear of people putting them under their decks or in small closed up sheds to reduce the noise complaints but there is hell to pay in compressor parts and filter replacements.
I hope it makes sense. I tried to condense the discussion on condensation and it really deserves a far more in depth discussion. The water molecule is truly fascinating and I could go on and on about things we have seen all our lives but seldom slow down to understand them. That's for another time.
1/2 way through reading your post in the back of my mind was water cooler, maybe a nice sprayed mist, or a large fan
.... so I'm glad that was in there! (I do run a large fan blowing into the fan on the compressor for added cooling).I do try to learn and stop and smell the roses by the things that are around me, especially in today's age when it's a "what's next, I need more" type of attitude.
So when the air travels into the coalescer I would assume it's a lot like an expansion valve in an AC system? As it enters it cools and consolidates (not sure if that's the right word?) the moisture droplets and they fall out / get stuck together / trapped on the walls?
Edit: Also wanted to ask; I work in an office upstairs of the shop that is conditioned, would it be better to run the intake for the compressor into the office so it see's conditioned air? I've always planned on filling early / late when things are cooled off, but if conditioned / dry air would make a huge difference then I can do that. The compressor itself would still be on the shop floor though, it would just be the intake hose / solberg filter ran there.
In your configuration, I think you'll need a continuous run compressor to fill the bank bottle. Regrardless, the first question you'll have to ask is about power. You'll likely only have single phase 220 in your house, and you'll need a circuit that has twice the amps of your compressor. In other words, if you buy a single-phase compressor running at 28 amps, you'll need a 60 amp rating for power on the line (for surges). This will limit what you're able to install. Woe be upon you if you have to wire for that or upgrade your house's panel. It isn't cheap.
That's probably going to be your biggest limiter. My guess is you'll have to compromise to a smaller compressor without a bank bottle to get near what you want, but good luck.
OP
I have a 60 Amp welding circuit I can "tie" into
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