Compressor safety, it always bears repeating

[Plastikosmd]

I’m one of those people that always believes in shutting off the power to the compressor after leaving the shop. I do this every time I leave (apparently mostly every time.)

I was working on the plasma table late last night, and apparently didn’t shut off the compressor. I came into a very loud Shop this morning. thankfully, no overheating, no fire, etc.



Something was missing.

Found it.


Old file as ez-out


So, time to add a timer to the outlet so that doesn’t happen again

(And time to replace all the pop off valves on this one)

 

[PoorUB]

The big reason why I am against a simple switch just for the compressor. People forget, we all do. Tie the compressor to the lights or add a timer so it shuts off after a given time.

I forget to shut off my shop lights once in a while, but I can see the shop window from the house and can see if the lights are still on. The times it happens is when I am working out there, my wife distracts me, and I don't get back to the shop. Once or twice a year I need to run out and shut them off.

Plus, I am very pleased that my wife can still distract me!

 

[Doozer75]

Having your compressor run over night
really won't hurt anything. It might have
wasted 2 or 3 dollars in electricity.
Not worth having to remember to shut it off
your entire life.

--Doozer

 

[Fixr]

I’m one of those people that always believes in shutting off the power to the compressor after leaving the shop. I do this every time I leave (apparently mostly every time.)

I was working on the plasma table late last night, and apparently didn’t shut off the compressor. I came into a very loud Shop this morning. thankfully, no overheating, no fire, etc.



Something was missing.

Found it.


Old file as ez-out


So, time to add a timer to the outlet so that doesn’t happen again

(And time to replace all the pop off valves on this one)

Stuff like that is why I put mine on a bathroom timer. Twist the knob for about as many hours as I expect to be using air. I don't have to remember to turn it off, which is a good thing considering how easily I get distrac - hey look, a squirrel!

 

[rlitman]

Having your compressor run over night
really won't hurt anything. It might have
wasted 2 or 3 dollars in electricity.
Not worth having to remember to shut it off
your entire life.

--Doozer

Most compressors aren't rated for 100% duty cycle. They're most commonly rated for 15 minutes on, followed by 45 minutes to cool down, and thermal overload protection is NOT the norm. So yeah, letting a typical compressor run overnight certainly can damage it and even start fires.

But yes, if you are in the market for a compressor, I would recommend thermal overload protection and 100% duty cycle to go with an ASME rated tank. You pay quite a bit more for these three options, but they're all worth it.

As for me, I have a camera in my garage that emails me any time someone walks past. It's mounted on a spot that shakes when the compressor runs, and that's how I found out about a blown hose years ago (before I added the automatic shutoff valve).

 

[pcmeiners]

Have mine on a timer circuit with a lockout; if it runs for more than the designated time I have to manually reset it. Have a lockout if the oil pressurize drops. I should rig a temperature lockout.

 

[Plastikosmd]

Having your compressor run over night
really won't hurt anything. It might have
wasted 2 or 3 dollars in electricity.
Not worth having to remember to shut it off
your entire life.

--Doozer

I appreciate that but I will still be installing a timer to decrease the risk of overheating, fire, pump or motor failure (all of which have happened on this forum due to runaway conditions)

I would not have expected this type of failure and clearly need to plan better

 

[Doozer75]

Most compressors aren't rated for 100% duty cycle. They're most commonly rated for 15 minutes on, followed by 45 minutes to cool down,

At full load.
Free air is not drawing anything but idle current.

If the motor overheats from just pumping free air
and not compressing anything, it is a giant piece of ****.


-Doozer

 

[Walkers]

Having your compressor run over night
really won't hurt anything. It might have
wasted 2 or 3 dollars in electricity.
Not worth having to remember to shut it off
your entire life.

--Doozer

I see you don’t know much about compressors.

 

[ArcReactorKC]

It is over complicated but before moving from my shop in Oklahoma I had the compressor tied into the rest of the shop automation. It would turn on when the occupancy sensor sensed a person in the shop, and there was a "compressor overrun" variable that monitored the contactor state, if the compressor had been running for 15 minutes and the occupancy sensor was inactive it would shut off power to the compressor and had to be re-enabled manually with the reset pushbutton.

I created that routine from a very similar to scenario where one of the hose reels burst during the afternoon where I was outside the shop and using air but not inside to notice the reason the compressor was running nonstop.

It was a pain to implement but only a few months later I had a fitting break on the air cooler and the automation shut the compressor off, when it didn't turn on automatically the next morning for me I knew something was wrong and found the issue in a few minutes.

 

[johnre]

My compressor's on / off control switch, installed for exactly the reason you cited. It's DPDT and rated 250 V / 20A, so it's good for a lot of mid-range 240 V compressors:

 

[PCustoms]

My compressor's on / off control switch, installed for exactly the reason you cited. It's DPDT and rated 250 V / 20A, so it's good for a lot of mid-range 240 V compressors:

That switch you posted is only rated for 120v 1hp.

1221-PLR

www.leviton.com

 

[Wrench97]

We always left the shop compressor on, there was usually a mechanic there 20 hrs a day except weekends and holidays, still left the compressor on since there was a air hose outside the shop in case a driver wanted to air up a tire or blow the dirt out of the cab.
We came in one Tuesday morning after a holiday weekend to find compressor parts all over the floor looked like a rod let loose and broke the cylinder/barrel and head right off the block burnt the belt off and the motor kept on running.
It had to be over 30 years old at the time, took 3 days to approval to buy a replacement compressor head in that time we spent 4 times the price of the compressor on vendor road calls to come and change/remove/install tires in the shop.............................

 

[johnre]

That switch you posted is only rated for 120v 1hp.

1221-PLR

www.leviton.com

There are several variants. I have 1222-7PR, which is 277 V rated. Brochure here.

 

[PCustoms]

There are several variants. I have 1222-7PR, which is 277 V rated. Brochure here.

Still only rated 120v 1hp!

Your link didn't work, look at the technical information:

1222-7PR

www.leviton.com

 

[johnre]

Still only rated 120v 1hp!

Brochure, page 9, bottom.

 

[PCustoms]

Brochure, page 9, bottom.

Doesn't say a darn thing about the HP rating!

 

[yelchevelle]

I put a relay in that is powered by the lights to allow power to the motor starter. I do as the above poster and make sure the lights are out when I lock up at night.

 

[u2slow]

There are HP-rated motor starting toggle switches. They cost a little more.

MS303-DS

www.leviton.com

 

[whateg01]

At full load.
Free air is not drawing anything but idle current.

If the motor overheats from just pumping free air
and not compressing anything, it is a giant piece of ****.


-Doozer

If you've never had to make do with giant pieces of **** for tools or machines, I think that's called garage privilege!

 

[johnre]

Doesn't say a darn thing about the HP rating!

OK, I see it on the spec sheet now. You're correct.

I would say that I am switching it on with no air pressure built up in the tank, and I switch it off with the unit not running. So while I technically am outside the specs, it's not a lot of abuse to this switch, only to the pressure-actuated switch on the compressor. And the latter is built for this.

There are HP-rated motor starting toggle switches. They cost a little more.

Here's the single phase equivalent, MS302-DS, which actually is about the same cost as the 1222-7PR that I linked. Except it lacks the red pilot light when "on" feature, but that could be separately added.

 

[cosmokenney]

Oh snap!

 

[micromind]

I've got you jokers all beat.....I hooked up a system that includes a relay, photocell, a solenoid, some mechanical linkage, a hammer and some wire.

If the compressor runs more than 10 minutes after dark and I'm in bed, a hammer will bonk me on the head.

So far, I've needed this system only once..........

 

[Lorydr]

Our shop compressor is tied in with the alarm system. If the alarm is on, the contacts are programmed to be open for the 2 wires going to the compressor trigger inputs. Every morning when when we shut off the alarm, the compressor fires right up. That way it won't cycle thru out the night. We don't exactly have a super air-tight plumbing system. Just some small leaks, but no one want's to spend 5 minutes to fix them.

One night I forgot to turn off my torpedo heater in my garage. The next morning I heard it come on. The garage was toasty. And the tank was about empty.

 

[pancho400cid]

My wife called me at work once and said "Honey, the compressor has been running for three hours... is that OK?" Ummm... no.

I told her how to turn it off, which is scary to the uninitiated since the reason it was running was that the relief valve popped open for no real reason. Motor was running and air was blowing like hell.

The garage was still kinda smelly and smokey when I got home. Leaving a compressor on and unattended is inviting potentially serious issues in my book.

Mine worked fine after replacing the releif valve but there is no doubt it got hot as hell and probably shortened its remaining life. I try to remember to shut mine off when I'm done in the garage for the day but I've forgotten more than once. Mine leaks enough that it will cycle in the night and I get up and shut it off.

...

 

[Doozer75]

I see you don’t know much about compressors.

I see you can not entertain a view on a subject that is different from your own without being insulting.

-Doozer

 

[PoorUB]

Having your compressor run over night
really won't hurt anything. It might have
wasted 2 or 3 dollars in electricity.
Not worth having to remember to shut it off
your entire life.

--Doozer

Leaving turned on isn't the issue. Having turned on and have some sort of failure is the issue.
I had a pressure switch fail on and the compressor ran for quite a while with the relief valve popped.

Also had an air hose blow and the compressor sat and ran.

Both times the motor was scorching hot and the compressor pump was smoking. It couldn't have been good for the longevity.

Similar situations have happened at a couple shops I worked at. Something failed and the compressor ran for anyone's guess how long.

As far as leaving on all the time, as long as nothing fails, no problem! It is the failure that screws it up.

 

[PoorUB]

I see you can not entertain a view on a subject that is different from your own without being insulting.

-Doozer

I believe he is correct.
A compressor running against the relief valve isn't running at "free air". Depending on the relief I have seen them pop the relief, run the tank dowso the relief resets it's self, pumps back up, pops the relief and around we go again.

I have also seen a leak that the compressor could keep up with. There was 160 PSI in the tank and it just sat and ran. Again. Not "free air".

Even if the relief pops and doesn't reset the tank pressure can get to a balance point, sit and run with maybe 50 PSI in the tank.

I have seen it happen.

 

[msharley]

I've got you jokers all beat.....I hooked up a system that includes a relay, photocell, a solenoid, some mechanical linkage, a hammer and some wire.

If the compressor runs more than 10 minuted after dark and I'm in bed, a hammer will bonk me on the head.

So far, I've needed this system only once..........

That? Is fer when the husband comes home early.....finds ya plowin' the "driveway"!

Here we are all these posts...

**** his old lady!

I unplug my compressor when locking up. Seems to work?

 

[cannuck]

I used to have a fantastic compressor on warning system - when we had incandescent lights they would dim every time the compressor started. Damned LEDs screwed that up. Since mine is inside of a sound reducing box (only opened if doing very heavy work such as blast cleaning) it has to be turned off when we close down.

 

[gtae07]

I forgot to turn mine off one time. Came back in the shop a couple days later to it banging away and the shop full of smoke. A leak had started and the piston rings failed and it was burning oil.

 

[ZRX61]

Mine has a service disconnect right next to it & a ball valve on the tank outlet. Set up is about 25 years old, can walk away from the compressor for a month & there's no leak down.

 

[haveissues]

One of the times that I forgot mine on I found the compressor running and the shop filled with an oil smelling smoke. The pressure cut off had welded itself shut after it cycled and it was running against the over pressure safety valve. I hadn't been in the shop for several days or maybe a week so I have no idea how long it was actually running. Could have been several days straight. That was several years ago, still works fine.

 

[Plastikosmd]

I believe he is correct.
A compressor running against the relief valve isn't running at "free air". Depending on the relief I have seen them pop the relief, run the tank dowso the relief resets it's self, pumps back up, pops the relief and around we go again.

I have also seen a leak that the compressor could keep up with. There was 160 PSI in the tank and it just sat and ran. Again. Not "free air".

Even if the relief pops and doesn't reset the tank pressure can get to a balance point, sit and run with maybe 50 PSI in the tank.

I have seen it happen.

It was maintaining 80 psi somehow when I shut it all off, I’m not sure how based on how it seems to be plumbed.

Hope to have it up and running after Amazon delivery.

I think I will also change the oil tomorrow

 

[nadogail]

I once ran a Schram tractor compressor combination that would maintain good pressure with a half inch bleed valve open, this was in 1970.

 

[ybnormal]

I've got you jokers all beat.....I hooked up a system that includes a relay, photocell, a solenoid, some mechanical linkage, a hammer and some wire.

If the compressor runs more than 10 minuted after dark and I'm in bed, a hammer will bonk me on the head.

So far, I've needed this system only once..........

are you one of the 4 Yorkshiremen?

 

[Steve W.]

Interesting to see all of the different alarms and systems used. My compressor remains powered up all the time (unless I am away from home for several days). I do have a ball valve at the output, followed immediately by a regulator. One side of the regulator has a port for a presssure gauge. On the other side I have installed a motorcycle brake pressure switch that is fed power by a 12v wall wart and controls a trailer marker light that is at eye level beside the exit door. If there is more than about 30 psi in the lines, the light is on, so I will go to the compressor closet and turn the ball valve, then go to one of the drops and open the drain valve.

.

 

[micromind]

are you one of the 4 Yorkshiremen?

No, just some crazy dude with a slightly abnormal sense of humor........lol.

 

[CraigStu]

I got a new small compressor 2 years ago and found a twist it for 10-60 minutes run time switch that could handle the amp load. Fairly easy since it runs on 120V. For 240V you could run a contactor controlled by a similar switch. In a previous house I did that to control a remote post at the second drive where the previous own parked his RV. The contactor switched 240V but was controlled by 120V. I love never having to worry about whether I turned the compressor off or not.

 

[Mike65]

I almost ALWAYS shut of the power to the air compressor before leaving the shop, & if I do my wife usually will ask me if I shut off the compressor. Besides the on/off switch on the compressor I have mine plugged into an outlet that has separate on/off switch because the 240V outlet my air compressor plugs into is also for my welder. This way when I have to unplug the air compressor to use the welder the power to the outlet is off so there is no chance of getting a shock from accidently touching one of the prongs of the plug going into or out of the outlet.