Shop Projects #3: Air compressor upgrade - drainage whip

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Blog entry by William Shelley posted 05-30-2016 12:43 AM 1618 reads 2 times favorited 6 comments Add to Favorites Watch
« Part 2: Clamp rack / organization Part 3 of Shop Projects series no next part

I’m sure draining an air compressor of any accumulated water is possibly one of the least-fun maintenance activities out there. I’m assuming also that most compressors have virtually no room to fit a bucket underneath the drainage port at the bottom of the tank, so you end up having to tilt the unit to drain, which means not all the water gets out.

I used a short piece of air hose (4’), a pair of 3/8 barb x 1/4” NPT fittings, a 1/4 NPT x 1/4 NPT close elbow, and a small 1/4” valve, and a couple hose clamps, assembled them, and added this “whip” to the bottom of the compressor, to replace the factory default drainage valve. This took about 20-30 minutes tops.

The result is that the air pressure in the tank will force all the water out and through the hose (even “uphill”), and it is now trivial to simply drain the tank into a bucket without rusty water splashing all over the floor.

Indeed, the ease of draining the tank now means I will do it more frequently (as I should have been doing all along), which should improve the life of my compressor.

-- Woodworking from an engineer's perspective

6 comments so far

View JCinVA's profile


232 posts in 1718 days

#1 posted 05-30-2016 02:11 AM

Perfect. I was going to copy a friend who used one of the cheap coiled 1/4” air hoses to reach outside his garage and purge into the grass, but this is a neater solution and fits my garage.

View GreaseMonkey2275's profile


183 posts in 2041 days

#2 posted 05-31-2016 02:17 AM

Cool setup; I simply put a 90 degree street elbow in place of the stock valve on my tank with a 6 inch extension and a gate valve to drain the water out of the tank. Yours definitely gives you more options thought!

-- Jake

View William Shelley's profile

William Shelley

609 posts in 2357 days

#3 posted 05-31-2016 02:46 AM

Thanks. I thought about doing just an elbow and extension, but that still left the issue of how to get the water into a bucket. I also at some point plan on adding an electric solenoid valve, connected to a timer, which would automatically vent the water for several seconds, every day, or week depending on need. So having the whip means I can simply add that on later.

There is one improvement I’m going to make which is to add a 1ft piece of hosing with some sort of sock on the end to the existing barb. Right now the water rockets out like a firehose and is still quite messy.

-- Woodworking from an engineer's perspective

View JoeinGa's profile


7741 posts in 2895 days

#4 posted 05-31-2016 12:17 PM

I did the same basic thing on my dual-tank setup. I clip the drain tubes up to keep bugs from crawling up them and plugging the tubes.


-- Perform A Random Act Of Kindness Today ... Pay It Forward

View dannyfixit's profile


17 posts in 3523 days

#5 posted 07-29-2016 02:40 PM

I just finished configuring a used 5hp 60gal upright unit into my small shop and had seen similar ideas online. Decided it was something that I too had to install as part of this config. I’ve always hated the flimsy valves and mini valves the manufacturers put on even the expensive units. They rust or the stamped out wing handles bust off. My hands are not super large, but those valves are PITA.

Now that all is in place and plumbed up with a nice reachable ball valve, I will be more inclined to remember and actually drain the tank frequently. I expect this compressor to last me for my duration.

Doing this is probably the smartest mod for a compressor. Nice job…

-- - Follow your passion...

View NewbieInWV's profile


20 posts in 1477 days

#6 posted 01-24-2017 07:30 AM

This is a neat idea. I was wondering about the power-spray, but your sock idea makes sense.

Any concern about having the hose under pressure 24/7?

I don’t know anything about compressors, just curious.

-- Mike H, Elkins WV

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