# Homemade Auto compressor drain



## woodchucker (Jul 12, 2017)

A few years ago I wanted an auto compressor drain. But being too cheap to buy one, I adapted some stuff and made one. Today I noticed it wasn't working well, the problem was the filter was clogged. So I removed it, and then realized I should share it with you guys.  So it has some drawbacks, one is that if you leave your compressor on 24x7 it won't work. It works when you shut the compressor off and it leaks air.. So that knocks out a bunch of you that don't have leaks.  I do, I have a lot of plumbing going on. It feeds the wood shops, metal shop and garage. It's very simple and cost almost nothing.

It's HF mini filter and a couple of ball valves. The spring at the bottom of the cup releases when the pressure gets low, letting the water rush out. And when restarting the compressor it will push any remaing water out until pressure re-closes the valve. I've had it in use for 3-5 years...I don't remember how long..
Just thought I would share it with you guys. BTW I don't use wheels on this compressor, it's hardwired and just too big to move around, so I put it on blocks.  It helped with the clearance underneath too.


Here's what I removed from the filter to get it going again. The filter was clogged from rusty water.


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## Bob Korves (Jul 13, 2017)

Automatic drain valves are nice to keep the tank drained.  I know people who have used the ones used on big trucks.  Bendix and others make them.
http://www.plazafleetparts.com/uploads/2/1/9/0/2190100/dv-2_drain_valve_installation.pdf
They are quite robust...


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## RandyM (Jul 13, 2017)

I am a little confused, why the filter?

By the way, I really don't have a need for the auto-drain, so here is the economical way I drain my compressor. You can see how I solved the clearance issue.


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## woodchucker (Jul 13, 2017)

Because the filter has a spring loaded release, so that when the pressure gets low, it opens and lets all the water out. This is why I wanted the filter, because it does it automatically.
I didn't want the water to have to rise to the OCCASION so I didn't do what you did. I used to only have a ball valve like you, but the compressor is in another room, and the switch in one of my shops. So it empties it when it loses pressure on it's own.


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## RandyM (Jul 13, 2017)

woochucker said:


> Because the filter has a spring loaded release, so that when the pressure gets low, it opens and lets all the water out. This is why I wanted the filter, because it does it automatically.
> I didn't want the water to have to rise to the OCCASION so I didn't do what you did. I used to only have a ball valve like you, but the compressor is in another room, and the switch in one of my shops. So it empties it when it loses pressure on it's own.



Got it, using the drain on the filter. Yes, removing the filter element should get you back in business.

You know the water level does not need to as you say "raise to the occasion". I just crack the valve whenever I think of it. Some times there is very little water to empty it does not need to get to the level of the valve.


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## SSage (Jul 13, 2017)

Thats a good idea Randy. I think I'll try that, the HF air filter deal didn't work for me. I tried the auto drain filter without a filter and it didn't last very long, started leaking too much air. Tried a name brand expensive one and it started leaking too. Down here in Alabama you really need a good air dryer, its so humid here. I really need to drain my 80 gallon vertical two stage more often, it does fill up faster than I expected.


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## RandyM (Jul 13, 2017)

SSage said:


> Thats a good idea Randy. I think I'll try that, the HF air filter deal didn't work for me. I tried the auto drain filter without a filter and it didn't last very long, started leaking too much air. *Tried a name brand expensive one and it started leaking too*. Down here in Alabama you really need a good air dryer, its so humid here. I really need to drain my 80 gallon vertical two stage more often, it does fill up faster than I expected.



Yeah, I think the issue is that you are dealing with all the dirt and rust at the bottom of the tank and these filters just aren't made for that kind of contamination. I only had one issue with my set up and it was a defective fitting that needed to be replaced in 20 years.


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## woodchucker (Jul 13, 2017)

I haven't had a problem, hopefully I won't w/o the filter. If I do, I can' work on cleaning up the filter and replacing it, or buy a new unit.
Cheap enough


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## aliva (Jul 13, 2017)

I drain my tank out the side of the building via a hose to open air. No filter,why would you want to filter the drain, get rid of all the garbage that may accumulate in the tank. I have an electric  seloniod on the bottom of the reservoir. I unusually activate the drain weekly, depending on how often I use the compressor and local humidity


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## woodchucker (Jul 13, 2017)

aliva said:


> I drain my tank out the side of the building via a hose to open air. No filter,why would you want to filter the drain, get rid of all the garbage that may accumulate in the tank. I have an electric  seloniod on the bottom of the reservoir. I unusually activate the drain weekly, depending on how often I use the compressor and local humidity


Read post #4.
I would like a solenoid unit that could on a timed (every x hours) release the shmoo.


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## fixit (Jul 14, 2017)

In my other life a a corporate maintenance engineer we had a constant water problem in our compressor operation. Each plant had no less than 3500 (yes 3500) horsepower of compressors on line at all times 24-7-365. I found the best auto drain was a 3/8 " motorized ball valve with a built in timer, they could be set for various schedule of operation & had a test switch for manual operation. On schedule the valve would slowly rotate open & close. At 3/8 inch dia it never plugged up. For smaller air receiver we used a plug with a small orifice to reduce the pressure drop but most of the receivers were 6 ft dia X 15 to 20 ft long. Believe me I tested MANY no fail drains that failed.

fixit


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## tq60 (Jul 14, 2017)

If you have an unloader valve it can be used to operate a sprinkler type of valve where the vented air operates the release.

That is how the automatic ones work in that they operate the tank drain every time the compressor cycles.

Our compressor came with it and there is very little in the way of parts so it cannot cost much to simply buy one.



Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## JPigg55 (Jul 14, 2017)

Here's one from Harbor Freight for $10 with a Youtube video of how a guy installed it.





https://www.harborfreight.com/automatic-compressor-drain-kit-68244.html


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## woodchucker (Jul 14, 2017)

JPigg55 said:


> Here's one from Harbor Freight for $10 with a Youtube video of how a guy installed it.
> 
> 
> 
> ...


That unit does not work with my compressor, or any of the 3 compressors I have. And it is prone to failure. It has an extremely high failure rate if you read the reviews.


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## Bob Korves (Jul 14, 2017)

tq60 said:


> If you have an unloader valve it can be used to operate a sprinkler type of valve where the vented air operates the release.
> 
> That is how the automatic ones work in that they operate the tank drain every time the compressor cycles.
> 
> ...


That is how the big truck ones work.  The unloader initiates the drain cycle, and the tank drains the water.  The cycle interval is related to compressor cycling, that is, it cycles each time the compressor turns off, not some random setting on a clock timer.  Very simple and reliable system, and easily repaired should it ever fail, which they nearly never do.  Some have heaters, but the heaters are 12 or 24 volts.


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## Terrywerm (Jul 14, 2017)

I have one of the drain valves from Harbor Freight, and yes, it does work, but it drains so little water each time that I still have to manually drain the tank on a regular basis, at least during the summer months. During the winter the air is dry enough that I get very little moisture in the tank.


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