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A journey into the workshop. #95: Why you don't leave air hoses plugged in and compressors turned on.

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Blog entry by dbhost posted 04-06-2016 04:11 PM 1421 reads 0 times favorited 16 comments Add to Favorites Watch
« Part 94: More shop cleanup, more found tools! Part 95 of A journey into the workshop. series Part 96: Air Compressor dump line, mistakes, home AC fixes and replacement tools... »

So I had to run some errands yesterday due to some medical stuff, I wasn’t out of the house very long. Maybe 2 hours. Well I came back and from the driveway I could hear it…

Air compressor was flailing away and there was a constant FAST hiss coming from the shop.

I know what that sound is!

Go in to the shop as fast as I can, it’s hot in there, I flip the switch on the compressor to shut it down, and disconnect the feed hose to my manifold.

Right where the hose bends to go up to the manifold there is very clearly a 1/4” long tearout in the hose.

Now mind you, all of my hoses except for my Hitachi, came from Harbor Freight. Now before anyone goes bashing Harbor Freight, mind you I have a LOT of experience with compressed air systems, and hoses. The BEST air hoses I have used hands down have been Goodyear, the black ones.

This experience was back when I was a MUCH younger man, and gas stations actually had full service. I managed one for several years, and we averaged a 12 month time to failure on hoses. My home garage workshop use has been, well I need to verify but I believe it has been 26 months since I set up the reel / manifold rig, and I leave it pressureized and connected WAY more than I ever did in the gas station.

Now like I mentioned, I was only out for about 2 hours, and the hose wasn’t blown out when I left, so some time in that 2 hour time frame, the hose blew, the compressor kept running, and it produced enough heat to heat up the shop to over 90 deg F.

This could have possibly led to a shop fire, and considering my shop is attached to the house, this had the potential to be REALLY bad.

Lessons learned?

#1. ALWAYS disconnect the feed whip when done with the system for the day. I am considering a simple ball valve on the feed line to keep things connected, and moist air out of the filter / dryer. #2. Turn the compressor OFF when not likely to be used that day. #3. Drain the compressor tank FAR more often than I do. I never neglected to do this to the big 60+ (Actually a bank of 4 120 gallon compressors) on a daily basis, but their drains were a LOT easier to get to. I will end up extending the drain out with a ball valve so all I have to do is flip a ball valve open instead of reaching way back in and under to get to a petcock valve that instantly spews every bit of shop dust into your face.

Now the question is… How to approach fixing this disaster next?

Step #1. Gather supplies. First I need 2 1/4” full port ball valves.
http://www.harborfreight.com/14-in-full-port-ball-valve-68254.html (I already have one).
Will need one 1/4” NPT male x female brass elbow.
http://www.homedepot.com/p/Sioux-Chief-1-4-in-x-1-4-in-Lead-Free-Brass-90-Degree-MPT-x-FPT-Street-Elbow-930-271001/202254920
Need 10” brass 1/4” NPT nipple. Can’t find a link, but I know my local Lowes has them. That’s where I got mine.
3/8×8 – 15ft air hose remnant. (Useful for whip hoses).
http://www.harborfreight.com/38-in-x-8-ft-15-ft-rubber-air-hose-remnant-60356.html

#2. Disconnect the compressor from power. And pull it out of its cubby hole. #3. Remove the quick connect from the outlet port on the compressor. Treat the threads with pipe dope, and install the first of ball valves, Install the quick connect on the ball valve. #4. Transfer over the quick connect fittings from the blown hose to the new one. #5. Dry out the dessicant beads, seal them up while I finish the rest of the work. #6. Remove the petcock valve from the bottom of the compressor tank. #7. Pipe dope the male of the street elbow, and install it onto the tank insuring the female threads point back toward the wheels. #8. Pipe dope both ends of the 10” nipple, Install the second 1/4” ball valve onto the nipple, install the assembly onto the street elbow.Close all valves, check for tightness. #9. Reconnect to power. Power on and test fittings for leaks. #10. Assuming step #9 passes. Move compressor back into place, replace dessicant in dryer / filter, and reconnect whip hose. Open output valve, Check for leaks. #11. Close output valve, turn compressor off, and open drain valve to bleed tank. #12. Create, print, laminate, and post compressor operation / maintenance procedures on cabinet behind compressor.

Step #12 is for my wife since she may end up having to know how to turn the compressor off in an emergency.

-- My workshop blog can be found at http://daves-workshop.blogspot.com



16 comments so far

View TheGreatJon's profile

TheGreatJon

295 posts in 697 days


#1 posted 04-06-2016 04:26 PM

Thanks Dave!

I need to be better about maintenance on my compressor. It isn’t an every day tool for me, so I probably neglect it a bit. I’ll start emptying the tank regularly.

Also, rule #12 is a fantastic idea. I might do this for several machines.

-- This is not the signature line you are looking for.

View dbhost's profile

dbhost

5605 posts in 2696 days


#2 posted 04-06-2016 04:28 PM

The worst part is. I know better. I have known better for years…

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View Jim Bertelson's profile

Jim Bertelson

3963 posts in 2628 days


#3 posted 04-06-2016 04:32 PM

Interesting story. I have hoses connected to my compressor at all times. But I turn off the compressor at the end of the day. The compressor is located inside of my multipurpose bench, a good solution for noise abatement. I have a switch with a neon indicator when it is on, located on the outside of the bench. But I never thought about a hose blowing, and I am sure that will happen sooner or later. I already replaced one hose.

Thanks for the tip. I just noted an article recently describing an extension to the water release valve, so it was on my mind as well. But turning off the compressor, even if I am gone for a short period of time, sounds like a good idea….....

-- Jim, Anchorage Alaska

View dbhost's profile

dbhost

5605 posts in 2696 days


#4 posted 04-06-2016 04:39 PM

Yeah, I had the compressor pumped up from the weekend when I was using the blow gun and airing up tires.

I think I need to give a serious rethink to my manifold / multi compressor rig. I have been measuring things up. I can just fit the 60 gallon 165 PSI model in the space my 29 gallon compressor is in. AND I have a 30 amp 330v socket available for it. I am not crazy about running dual compressors to get the CFM I need to spray, but that is the only thing I need more CFM for. My sander runs fine on the 29 gallon alone… And even the purple HF HVLP sprays great. Just the Husky HVLP gives me fits running the compressor out of air way too often.

The idea behind the dual compressor rig was I was supposed to drag out the 12 gallon for small jobs. I find that isn’t what is happening though.

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View JoeinGa's profile

JoeinGa

7482 posts in 1471 days


#5 posted 04-06-2016 04:48 PM

I had a similar blowout several years ago and learned the same lesson as you have here. Came home from work and could hear that horrible HISSSSS coming from the garage. Since then I do turn my compressor off when ever I leave the shop for the day, and turn it back on next time I’m out there. Only takes about 5 minutes to get enough built up for most anything I need to do.

I do leave my hose (singular) hooked up all the time because it actually has a VERY TINY leak at the coupler so it acts as a pressure release. I leave mine set for 90psi and if I turn it off at 5pm, the next morning I still have about 40psi showing. It takes almost 2 full days to drain completely.

Oh, and in this shop I built a “lean-to on the side of the building so the compressor (and additional tank) are outside the building. And I added extensions with ball valves to the drains for each tank.
.
.

.

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

View htl's profile

htl

2205 posts in 623 days


#6 posted 04-06-2016 11:51 PM

As others have said thanks for the reminder, I know better but just never think about it.

-- There's a hundred ways to do anything, alot depends on the tools at hand.

View dbhost's profile

dbhost

5605 posts in 2696 days


#7 posted 04-07-2016 04:36 AM

JoeInGa, I LOVE that lean to shed. I am half tempted to put one in around the back of the house. Might be a bit costly to plumb across that distance, but well worth it…

What is the purpose of the additional tank? Do they do anything for improving CFM or just adding run time.

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View USAwoodArt's profile

USAwoodArt

243 posts in 406 days


#8 posted 04-07-2016 02:32 PM

My compressor had a air line crack one time in a rubber flex hose and it did happen when I was in the shop. It scared the hiss out of me because i was quietly hand sanding at the time.

I have used pvc pipes for my air lines for as long as i can remember and they have always worked flawlessly.
The compressor is an 80 gallon tank with a 5 hp motor and installed a ball valve cutoff on the bottom for draining it and ran a drain hose thru the wall and outside.

There is a cutoff ball valve valve right where the air comes out the compressor and I close this valve each evening before closing up shop in addition to turning off the A/C power switch on the compressor motor.

I must admit that I do not drain my tank daily..bu only do it about twice a week. I need to get in the daily habit of dong it since it takes so little effort.
My compressor and dust collector are both located under an enclosed stairway in my shop that is well insulated and really helps to keep the noise at a low level

-- Wood for projects is like a good Fart..."better when you cut it yourself"

View SawyerRob's profile

SawyerRob

33 posts in 302 days


#9 posted 04-07-2016 02:56 PM

Here’s the bigger compressor that I have in my shop, it’s an “honest” five hp compressor,

One time I was standing outside and I could just barely hear a noise coming from my shop, so I walked out to the shop and the pressure switch had went bad and the compressor had been running (I’m guessing) for at least three days straight! OUCH!

I ALWAYS flip the breaker off on it, but not THAT time!!

As for draining the tank… Any more, I leave the valve on the bottom of the tank just “barely” leaking, and let the tank “self drain” that way…

SR

View JoeinGa's profile

JoeinGa

7482 posts in 1471 days


#10 posted 04-07-2016 08:46 PM


What is the purpose of the additional tank? Do they do anything for improving CFM or just adding run time.

- dbhost

The compressor head is one I got when I was a Snap-on Dealer. It’s a 5hp head that is generally on an 80gal tank, but I mounted it on a smaller tank that originally came with a 2.5hp head mounted on it. The extra tank just gives me more volume of air.

The first time I painted a car with it the darn thing kept cycling on and off every couple minutes because my air sander board was using a lot of air volume. So when I was offered the tank (for free) I jumped at it!

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

View dbhost's profile

dbhost

5605 posts in 2696 days


#11 posted 04-07-2016 08:58 PM


What is the purpose of the additional tank? Do they do anything for improving CFM or just adding run time.

- dbhost

The compressor head is one I got when I was a Snap-on Dealer. It s a 5hp head that is generally on an 80gal tank, but I mounted it on a smaller tank that originally came with a 2.5hp head mounted on it. The extra tank just gives me more volume of air.

The first time I painted a car with it the darn thing kept cycling on and off every couple minutes because my air sander board was using a lot of air volume. So when I was offered the tank (for free) I jumped at it!

- JoeinGa

Gotcha,

Yeah, generally speaking these days Snap On isn’t in my budget, but back when I made my living spinning wrenches it was choice #1… Nice stuff, but that price tag hurts!

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View lightweightladylefty's profile

lightweightladylefty

3138 posts in 3176 days


#12 posted 04-08-2016 03:16 AM

No one mentioned that leaving a tank running or not draining it can be even more disastrous when it rusts from the inside out. A number of years back, a family acquaintance blew out the side of his garage because the tank had rusted from the moisture build-up and the rust wasn’t visible to even be aware that there was a problem. He was just blessed that he didn’t happen to be near it when it happened.

Just a warning . . .

L/W

-- Jesus is the ONLY reason for ANY season.

View dbhost's profile

dbhost

5605 posts in 2696 days


#13 posted 04-08-2016 04:18 PM



No one mentioned that leaving a tank running or not draining it can be even more disastrous when it rusts from the inside out. A number of years back, a family acquaintance blew out the side of his garage because the tank had rusted from the moisture build-up and the rust wasn t visible to even be aware that there was a problem. He was just blessed that he didn t happen to be near it when it happened.

Just a warning . . .

L/W

- lightweightladylefty

You are completely correct. I don’t drain as often as I ought and this is something that MUST change. I will be gathering the components to get the fix done this weekend. There will be blog entries, as well as most likely a video of the fix… This MUST be as easy as possible to simply flip a switch, throw a valve lever and dump the tank…

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View Ocelot's profile

Ocelot

1470 posts in 2102 days


#14 posted 04-08-2016 04:38 PM

We had a compressor in a closet at work with distribution via PVC pipe. A pipe blew out when nobody was there and the thing ran until the pistons seized and burned out the motor and tripped the breaker.

At home, I keep my compressor turned off when I’m not using it. Although I power it up no more than once a month, I hate to admit I don’t drain it as I should. It’s a 40-year old unit my Dad bought but never used. Although it looks good, I’m starting to be afraid of it.

-Paul

View dbhost's profile

dbhost

5605 posts in 2696 days


#15 posted 04-08-2016 06:39 PM



We had a compressor in a closet at work with distribution via PVC pipe. A pipe blew out when nobody was there and the thing ran until the pistons seized and burned out the motor and tripped the breaker.

At home, I keep my compressor turned off when I m not using it. Although I power it up no more than once a month, I hate to admit I don t drain it as I should. It s a 40-year old unit my Dad bought but never used. Although it looks good, I m starting to be afraid of it.

-Paul

- Ocelot

Yeah, I gotcha. My compressor, the Central Pnuematic #61489 29 Gallon 2HP 150 PSI Cast Iron Vertical Air Compressor. I have it stowed in a cubby in my shop.My second compressor is the smaller old model 12Gallon 2HP oil lubed compressor. Combined total I am getting around 10.5 SCFM @ 40PSI so it is more than enough to drive my HVLP or my Random Orbit sander, but not for a huge amount of time… I sanded down the hood on my Saturn completely before either compressor cycled.

BOTH compressors have the drain valves at the very bottom / lowest point of the tank, good for drainage, but bad for fat hand access. I already did the elbow / extension on the 12 gallon compressor, I just need to do it to the 29 gallon one now…

IF you are that nervous about the tank on your old compressor, new tanks, depending on the size of course, are a lot less expensive than a complete compressor.

Since you are the second person to mention it here. I probably ought to talk about the PVC pipe for compressed air.

I work with / around engineers all the time, and have actually seen tests on it. Schedule 40 starts to deform under normal air compressor pressures of 150 PSI at 70 deg F. Not enough to cause failure, but it gets weaker the hotter it gets.

I have worked in a shop that had PVC like you did, and it DID fail with people in the shop. Thankfully nobody caught any of the shrapnel. However customer vehicles weren’t so lucky. The lesson to not use PVC pipe for compressed air distribution came at the cost of a condenser, and radiator / trans cooler on a Chevy, and the rental car for the customer while we fixed it. Not free for sure, and that customer was understandably quite upset.

We are all, or at least mostly adults here, and can make our own choices about our safety. For me, and my shop, I will not use any piping that is likely to cause shrapnel in the event of a failure. Cast iron, copper etc… will tear, but PVC, not for me at least.

-- My workshop blog can be found at http://daves-workshop.blogspot.com

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