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Hope so, or at the very least, you are draining the receiver manually a couple of times a day. You see, the fastest and most economical way to get water out of your air system is to drain it at the source, the receiver.
After all, a 250 HP compressor will generate about 80,000 gallons of free water a year. What happens to that water in your compressed air system?
Drain The Receiver
Much of your down-stream air treatment equipment could be either over taxed or rendered useless if the simple and effective action of removing compressor generated water from the compressor receiver isn't performed.
Assuming you've got a receiver with your compressor, put your hand on the receiver / tank after your compressor has been running a while and feel the temperature. If the receiver is warm, and it stays warm or hot all the time you're using air, you are actually generating warm, water-vapor laden air that will ultimately deliver water from the receiver to all the places in your air system you don't want water at!
To make draining the receiver most effective, cool the air at the receiver, as the cooler the air is in there, the more water will drop out of the compressed air in the tank, water which you can eliminate from your system by opening the drain manually or let the your auto-drain void from the tank as it cycles.
Maybe a Larger Receiver
Consider adding a larger receiver as a passive air cooler. The larger receiver means that your compressor will run longer to fill the added reservoir, but it would also mean that you'll have more "dwell time" in the receiver for the air to cool naturally, before the compressor kicks in on demand for higher pressure. If the air can cool enough to reach it's dew point it will condense into free water which can be drained right at the receiver.
If you've high demand on your compressor, consider adding a second receiver tank plumbed quite a distance from the first, to allow the air to cool naturally as it flows to the second tank.
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In fact, if your extra compressor receiver was placed on the other side of the plant, and you ran your main air lines from the first compressor receiver up to the ceiling and around both sides of the plant, you'd have a "ring" supply of compressed air, which is the highest recommended method of plumbing air throughout a plant.
You will have to take into account where and what the demand for your air is and ensure that the added plumbing doesn't "starve" any application. By having that second receiver installed, you can manually drain the first tank daily, auto-drain the second automatically a number of times each day, and remove substantial amounts of water at the receivers rather than later down-stream where the water can cause you problems. If it were us installing two, plant wide receivers, we would install an auto drain in both receivers just so we wouldn't have to worry about the manually drained receiver being forgotten and filling up with condensate.
The second receiver offers an alternate, energy-consumption-free method of naturally cooling air from your compressor.
If your compressed air travels from the first receiver to the second without being used by any appliance, then - immediately after your secondary receiver - and before the air gets to any of your in-plant applications, install a general purpose filter sized for the expected demand of the plant.
Remember, depending on the size and capacity of your receiver, the general purpose filter must have the flow capacity of the total CFM flow demand of your plant, not just what the compressor output is rated for. If it's possible for all air consuming devices in your plant to come on at the same time, that's the flow that will be moving through the first filter.
Space being available, we would install that first general purpose filter right at the tank, and then a second one as far away from my last receiver as we could, to allow air flowing to it from the receiver to naturally cool in the longer flow path, allowing more water to condense and be removed.
There are many additional steps that can be taken to remove water from your compressed air, each one usually more complex and costing more in up-front purchase, and energy consumed to operate them.
The intent here is to give you options that allow you to improve water removal in your system to a level that suits your needs, at the lowest possible cost.
Not everyone needs air that’s dessert dry, and since it costs a small fortune to get larger quantities of compressed air that dry, you will not want to do so if your plant applications don't require it.
We've touched on the use of additional receivers to help in the natural cooling and de-watering of your compressed air, let us now give some consideration to the overall plumbing in your plant and how following some fundamental rules will help in your compressed air treatment.
Overall Plumbing
We know that compressed air cools as it travels, and as it cools it often reaches the dew point, where water vapor condenses into free water in your air lines.
And we all know that gravity works, right?
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When water condenses in your compressed air lines, (it is inevitable that it will) it can be removed from your air lines through sensible plumbing, rather than flowing into your end applications and causing all sorts of problems. Get the water out before it gets to your air tools, your air valves and your cylinder / actuators, and there’s no more problem.
We recommended earlier that as the air exits the receiver, it should flow through an appropriately sized air filter straight up to the ceiling in the plant. Instead of having an elbow from the horizontal line from the receiver to direct the piping upwards, consider installing a ‘T’.
Install the ‘T’ so that the two in-line ports in the ‘T’ fitting are vertical. Plumb your air line from the top port up to the ceiling, and plumb a line from the bottom port to either an electric or float type auto drain.
Plumbed this way, as the compressed air climbs up to the ceiling in the plant, it will start to cool, and, as it does, water will condense. The water will flow back down (gravity works :-} ) to a ‘catchment’ at the bottom of the vertical line. And you guessed it, at the bottom of that drop leg should be a float type or electronic auto-drain.
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But what about all the other drop lines? Won’t the free water in the mains run down all of them?
Not if you take your drop lines off the top of the air mains as shown in the next graphic. Rather than any free water that collects running down the drop leg to the application, water that collects in the mains will only run to the one location at the lowest point in your plant that you want it to, then down that drop leg to be drained regularly by your auto-drain or drop-leg float drain at the bottom.
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Yes, it is extra work and cost to plumb your drop lines as shown in the drawing.
The upside is a reduction in ongoing maintenance at the application and a reduction in machine down-time to perform that maintenance. Over the longer haul, plumbing properly will save money.
Remember that the main air lines at your plant ceiling, if at all possible, should be in a ring, so that any particular drop line can pull air from two directions, hopefully avoiding air starvation at that application.
Each step of your air preparation that we’ve covered so far has been towards systematically removing free water from your air lines that's there through a natural cooling process. The air in your receiver and air mains has been reaching it's dew point, and more and more of the air vapour in your compressed air has been condensed into free water which can be removed as noted.
Here's more information about removing water via aftercoolers and refrigerant dryers.
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