drain Archives

Automatic air compressor drains are fantastic. An automatic drain makes it so easy to keep the condensate to a minimum in tanks that I recommend them to everyone. The only time you can’t rely on one is if it is below freezing and ice may cause the little valve to stick open. For that reason, I switch to a manual ball valve when it gets cold here in Michigan because my shop is unheated. As soon as spring rolls around, I immediately reinstall my trusty Midwest Controls EAD-25 valve made in 2011. There are tons and tons of clones out there that range from $11 upwards.

Now, as reliable and simple as these devices are there are some preventive maintenance and routine troubleshooting that need to be done. Basically, the device has a timer on the top that counts how many minutes until it blows off and then the duration. An electromagnet is tripped, pulls back against a spring and allows air and condensate to flow out the valve. This area can and will get dirty from rust and other debris. This can cause air to leak because of an imperfect seal or even jam the unit open or closed. Fortunately, these are a breeze to work on.

Each spring, before I put the unit back into service, I take it apart and clean it. At the end of the box is a silver hex nut. Simply remove it and the washer. Note how the rubber part of the washer goes to the back. The metal valve assembly will then slide out of the electro-magnet coil.

Next, note the hex nut at the base of the valve assembly. Loosen it to remove the valve from the brass body. If you need to, put the body in a vise to hold it while you loosen it. Personally, I never go crazy tightening mine because there in an O-Ring in there that I do not want to crush so mine can come apart by hand. Be careful that the parts do not fall out of the valve assembly. Do this some place where you can keep track of small parts. There is a tiny double stacked spring in there you do NOT want to lose.

When you turn the valve body upside down, the metal valve itself and the return spring should come out. I clean the parts and wipe everything down with a coat of silicone. Look at all the rust and junk on the towel from inside the tubular body of the valve assembly. Keep track of that little double spring – it is a small spring in a big spring and they will come apart!!

I do the same thing with the brass body as well. You’ll see all the dirt. I blow it out first with compressed air (be sure to wear your safety glasses) and then clean it also. The rubber face of the valve will sit squarely on that elevated nipple you see. Do not oil these parts or use anything that will attract dirt. I tend to use silicone spray myself but use whatever you prefer. Some guys choose not to use anything for fear of causing particles to stick – it’s your call.

Assembly is just the reverse order. One big tip – I install the spring on the valve and keep it horizontal during reassembly. Do not just stick the spring in the valve and drop it all back in the tube vertically. There are good odds the spring will fall out. By keeping it on its side, you can then screw the tube back onto the brass body and everything will then stay together properly because the spring will be held in position. I do not tighten the tube back on very tightly – just firm.

Once it is reassembled, push the Test button. You should hear a very crisp snapping sound as the valve opens and closes. If it does not sound really crisp, or however it normally sounds, then the spring may have fallen out.

Troubleshooting Your Valve

I have really only encountered two types of problems – either there is air leaking out even when the valve should be closed or the valve sticks wide open.

Sometimes you can simply fix this by Pushing the “TEST” button 3-5 times and see if doing so blows the debris free and it closes all the way. If if does not, then disassemble and clean the valve per the above.

If that valve is frozen open due to frozen moisture, you really need to warm it up. You can put a light near by to warm it up, use a pipe heater, etc. My honest recommendation is to switch over to a manual valve. Your risk that your valve may stick open when you are not around and cause the pressure to drop and the compressor turn on over and over causing wear and using electricity for no reason. Some guys will put their valves on lamp timers and only let it run for the time they normally use it – for example from 7am to 7pm. That is what I do but my hours are 6am – 11pm as I have such a crazy schedule but I do turn my compressor off at the breaker box before I leave the shop.

In closing, I really like the automatic air compressor drain valves and I’ve had my Midwest Controls EAD-25 for quite a while now and it is still going strong. The hints above have certainly helped me out over the years and can apply to many of the automatic drains that use the electromagnetic valve approach.

Here are Midwest Controls automatic drains on eBay (may not show any if none are listed):

Here are other brands of automatic drains with very good reviews on Amazon:

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If you are just jumping into this three part post, an inline compressed air filter by itself does not work very well when it comes to removing moisture from compressed air but it definite works good as a third step in a thought out moisture control strategy. If you haven’t read them yet, please read these other posts first:

Now, as a third step, good filters are definitely needed. In line filters remove even more moisture and protect your regulators and equipment from debris such as rust. Filters are a good example of you get what you pay for. Those really cheap air filters aren’t up to demanding tasks. Setting shoddy construction to the side for the moment, you will notice that some do not say how fine their filter is (as measured in microns) or give you any indication of the cubic feet minute (CFM) the filter can handle. You at least need to know the first part.

Buy quality units from a reputably manufacturer. I like Milton, Parker and PneumaticPlus and they are three of many that are out there. Everything I am going to write about here, I bought with my own money and actually use or have used so this is not some thinly veiled advertisement. I’m recommending the various items because they work for me.

In terms of construction, some have a plastic/polycarbonate bowl and they are rated for lower pressures (usually 125-150 PSI) and others have metal bowls and are rated for higher pressures. For example, my Ingersol Rand 2340 stores the compressed air at 175PSI so I use metal bowls on my filters and drains exposed to that pressure. In downstream areas with lower pressure, I use filters with polycarbonate bowls.

If you are serious about filtering, you need at least a two stage unit. The first stage is a coarse air filter and will range from 5-40 microns in terms of filtering element size. The second stage will be a fine air filter and be remove even smaller particles often down to the 1 to even .01 micron level. You must have the coarse filter in front or you will plug up the fine air filter real fast and negatively impact your CFM.

When you are shopping for filters, there is an ISO standard to be aware of that some reputable filter companies will reference – ISO8573.1. Here is a good blog post if you want to learn more.

With that said, let me show you what I actually use.

My inlet air for the filter is 1/2″ because I wanted to provide a lot of flow. All of my plumbing up to that point is 1/2″ also. After doing a lot of digging, I opted for a PneumaticPlus SAU4030M-N04DG-MEP which is a combination three stage unit with a 10 micron coarse air particulate filter first, then a 0.3 Micron Coalescing Filter followed by a pressure regulator.

In researching the unit, I found that the rated inlet pressure was 250PSI and the outlet was rated at 150PSI — note these are metal bowls hence the higher pressure rating.. I planned on setting the regulator to 90PSI for my tools and found that the maximum flow would be around 38 SCFM (standard cubic feet per minute) @ 90 PSI, which also met my needs. The two filters also have automatic drains so I don’t have to worry about purging them.

You’ll note the black warmer cable in the last photo – that’s because my shop is unheated in the winter. The heated cable is on a thermal switch and only turns on at 32F. This keeps the condensate from freezing in the bowls. You’ll also note the 1/8″ tubing removing routing the condensate to drain where I want it to.

They both still collect moisture – the first filter more than the second. Every day, I can see the condensate coming out of the tank, the moisture separator and to a much lesser extent, these filters. I have been using this set up since August 2016 and really like it. I usually find zero moisture downstream but I still run basic coarse filters just before my various regulators. Attached to my plasma cutter, I still run one of their #128647 1 micron air filters just to play it safe.

Downstream, I still have in-line air filters just in case

As a rule of thumb, it is always a good idea to have an air filter just before a regulatory. Before a couple of my downstream pressure regulators, I run Milton 1018 filters and they are nice. 40 micron coarse filters with 48 SCFM. This one right here has been in use for a few years and predates the elaborate moisture control system I have in place now. Look at the rust in the bowl from when I cleaned it! I still have two of these in daily use and have no complaints.

These inline filters are all bone dry which helps me conclude the upstream moisture control is working pretty well. They are probably 50-75 feet from the tank in terms of how much line the air must flow through before reaching them. The dirty bowls are from the mess I had before the current system. I cleaned them while I was at it hence the above 1018 being disassembled. A nice feature of this model Milton is that it automatically drains when the pressure in the bowls drops to the point that a spring can pop open and let the condensate out. You can also push the rubber nipple sideways to manually drain it while pressurized. They are simple and effective coarse filters.

Now the red and black filter is a Craftsman 16009 and it is pretty low end. When my dad passed away, he left a couple of Sears gift cards that I used to buy three of these filters and some air hose. When I google them now and read on the Sears website, they do not list the microns. I suspect it is a 40-50 micron coarse filter but that lack of a rating should throw up flags. I don’t have the original packaging so I don’t know if it listed it or not. The one unit left in place was inserted a few years ago to protect the one regulator from backflow from the two airlines just before it The Milton’s drain when the pressure in the bowls drops to the point that a spring can pop open and let the condensate out. With the Craftsman, you need to turn that little valve screw on the bottom and manually drain it. Not too bad for casual use but I would not use them again for my stuff. I should point out that on one filter, the pipe hole not straight! Also, guys report bowls cracking and no replacement parts so at least that hasn’t happened to me. I just include them here so you can see what I would not recommend. You can see the angled/not true pipe hole in the second photo especially. These are in my parts bin just in case.

5/2/2019 Update – I have replaced all Craftsmen filters with Milton filters. The PneumaticPlus gear is all still running great.

I hope this three part blog post has given you some ideas on how to reduce moisture in your air lines. I don’t consider myself an expert or anything close, but just wanted to share what worked for me. There are some great resources on the Internet if you want to learn more:

The three blog posts in the series are: