Air compressor tank info.?

[John White]

The cut out switch went bad on my air compressor the other day. I went to purchase a new one and the fellow said that the one I had, hadnt been made for years and years. And that I should check the date code on the metal tag welded on my tank He said they were good for only twenty years. Another person said they should be re-tested every 5 years. I had three compressors. Two were built in 1957 and one in 1963. I guess a compressor is something we place in a corner and forget it as long as we get air, we dont worry about it. I've got to admit that the compressor gets less attention and service of any piece of equipement I own. I would like (out of courisoty) to know how old some of your compressors are. I cant believe how many years some of the old compressors run. And any advice on testing the tank. I hate throwing away three good tanks (and probably wont). What happens if one goes bad? Will they explode or just start leaking?

 

[Bedlam]

WOW interesting questions I never gave it much thought.Mine is a sears 5 horse and bought in 1980. Knock on wood only had to rel=lace the belt in all this time.Its inside so . but yes I look forward to the tank testing question.
I have a friend who used the standard water well pump switch to regulate on of his.
My question is is this the switch that has the power cord to it?
If so Id imagine you could just mount another one somewhere on the tank..
i couldn't find anything here but its a good site.
Surplus Center - Air Compressors Cylinders Valves Tanks Pumps

Here is the switch if thats the one you are thinking of.usually has a 1/4 inch thread.Perhaps there are other plugs on the tank to mount one
wow not cheap. I am also wondering if it is indeed that switch, if perhaps the diaphragm is crudded up.It happed allot on the water pump switches. the diaphragm and the nipples get crudded up and interfere with it.

 

[Shmudda]

You guys have to remember that any Pressure Vessel (which a Air Compressor Tank is) typically has a certain life span according to the ASME rules and guidelines. Look at your propane tank on your grill, they are all dated for the end of their life too. MOST people, including me, don't adhere to these and run their compressors until you can't anymore.

As for pressure vessels within industries, they get the vessels inspected on a regular basis from either their certified insurance carrier or a company that has the technical personal certified to inspect and certify pressure vessels. This isnt something that would be worthwhile for an $800.00 compressor because the inspection would be much more the value of the machine.

Pressure vessels are something that really shouldn't be taken lightly, but all homeowners and/or farmers do......me included!

Craig

 

[Renze]

What can happen to a compressor tank ?

It may rot on the lower part because of condensate... then it will start to leak above the waterline where humidity and oxygen are best mixed...

It might start blowing from a pinhole, but explode ? dont think so, never heard nor seen so.
I dont care about the age of my tank, i'll hear it whistle when its time to replace.

 

[CurlyDave]

It might start blowing from a pinhole, but explode ? dont think so, never heard nor seen so.

I have worried about this issue for many years. I am not as convinced that corrosion will show up as a single pinhole leak. The cause of the corrosion is condensate in the tank, and because the air pressure is high in the tank, there is lots of oxygen and corrosion is faster than in a non-pressurized tank.

My belief is that in a horizontal tank the corrosion is going be in two lines, at the water-air interface, and that under the right conditions a tank could split along one of these lines. If the tank is vertical, one of the heads could come off.

Either event can be very destructive.

As an engineer, I have read a lot of reports on corrosion based pipeline failure. The pipes have about the same diameter as a compressor tank, so there is some similarity.

 

[tommu56]

John White

It depends on your state regulations.

In Pa most home air tanks are un regulated
The commercial ones have to be inspected regularly and are registered with state.

At work we have ones over 30 years old but they are inspected regularly
This is physical inspection of the tank and the relief valve if its too old it has to be replaced.

tommu

 

[Bird]

I'm curious as to just what is actually done when an air tank is "inspected". I don't recall ever seeing anything in my compressor manuals about a specific lifespan or needing an "inspection" or whatever after a certain length of time. And this morning, I went through the manual for my current compressor and it has lots of information on maintenance; i.e., draining condensation, changing oil, cleaning the air filter, testing the relief valve, adjusting pulley alignment, adjusting belt tension, etc., etc., but nothing about a tank life or inspection. Of course since mine won't be 3 years old until next month, I figure it ought to last the rest of my lifetime.

 

[ultrarunner]

Aside from the physical inspection, there is a electrical device that measures wall thickness.

The compressor/tanks I've put in at the Hospital are required to be registered and permitted to operate.

All have automatic condensate drain lines which is basically a ball valve that rotates 360 degrees at a set time interval.

Not all tanks can be permitted. I have to specify at purchase that I need the ASTM paper work to certify the tank. It costs about $20 more for a certified tank last time I bought one.

 

[John White]

I think I may have open a whole can of worms. My compressors are two stage and as with all two stages they must be rated for 200 lbs as I unddrstand it. One compressor man told me that they are tested 2 1/2 time the rated preassure, another said 1 1/2, I am amazed how many years some of those old Quinceys, Kellogg, Ingorsoll, compressors will last. One compressor man told me that they will last 10 time longer than the ones you buy at Lowes of some farm store. I guess you should drain them every day but I am luckey if I drain mine once a week or month. (bad bad) I think one of them hadndt been drained for years as when I took the plug out alot of surface rust and chips came out. (I purchased all of them used. Probably came out of gas stations in the 60's.) I THINK two of them are pretty good. I was able to get the large bung (plug) out of one and check it with a light it, looked pretty good. The other two couldnt get it out. ) Just looking at the outside doesnt tell ykou much. And as some one said, paying to have it inspected properly would exceed the value of the tank. So if it just sprouts a pin hole, I wont worry too much and just junk it when it leaks.

 

[rhett]

The cut out switch went bad on my air compressor the other day. I went to purchase a new one and...

Just get a replacement that matches Voltage, Cut-In / Cut-Off PSI, fittings can always be adapted to fit.

And any advice on testing the tank.

Not needed, see response made to "Bird"

What happens if one goes bad? Will they explode or just start leaking?

A Steel Low Pressure Vessel containing air, it will just start leaking.

I'm curious as to just what is actually done when an air tank is "inspected".

A Pressure Vessel is filled with water which is not compressible, then placed in a larger water filled container (safety), then a Pressure Test is performed using test values dictated by OSHA for a vessels specifications. Water is used because the only built up back pressure will be between the Pump and Tank.

High Pressure Vessels require these inspections, some Low Pressure Vessels may require certification depending on intended contents.

 

[Charlesaf3]

manuals on mine all say throw them away after 15-20 years.

I wouldn't mind if they went slow, but a pressure tank explosion sending shrapnel through the barn is not something I need.

I really wonder how often it happens?

 

[rhett]

...
but a pressure tank explosion sending shrapnel through the barn is not something I need.

I really wonder how often it happens?

A small air compressor under 200 psi, the most dangerous scenario I can perceive is a busted air hose whipping around slapping you in the head. The weakest point will always fail first, the steel tank is definitely not the weakest point on a shop air compressor.

A Steam Vessel allowed to over pressurize is another story, H2O is breaking down to its elements, Hydrogen Gas is explosive when ignited. Also a steam vessel will contain a substantial amount of water, if a rupture occurs below the water line the escaping water at pressure will have substantial force escaping, possibly launching the vessel. An example of Hydrogen danger would be welding in water in a small enclosed space, Hydrogen Gas will build up, ignite and cause an explosion. Commercial divers are warned of this occupational hazard.

Has anyone ever shot a full rattle can with a BB gun to see what happens, I have and no explosion, just a small hole with a mess.

If the Air Compressor Pressure Switch and Pressure Relief Valve fail and the pump is capable to build up enough pressure for a violent tank failure, I see a problem. But this would be as dangerous, if not more having a brand new tank.

Sheesh, light duty PVC pipe is rated for pressures under 200 psi. Steel is not going to rip apart violently at normal working pressure. Even a loose fitting will not have much velocity at low pressures, unless something like an air cannon was in place allowing pressure to build velocity of the mass propelling it greater distances.

Basically, if an air compressor tank rusts through, the air will escape and the pump will run and run and run, sorry no explosion! Just need to patch or buy a replacement.

 

[Charlesaf3]

Thats the thing - I can see the case for a pinhole leak, but I've also been around hydraulics that let go suddenly, and that was very impressive. Granted a lot more than th 140 psi or so a compressor runs.

 

[rhett]

Ok, here is a link of a Air Compressor Explosion. Cause = Oil in tank ignited

Alerts

and here

Air receiver on a compressor explodes - WorkSafe Victoria

 

[Egon]

Don't most of the small air compressor tanks have a nozzle on one end that they could be inspected internally from?

 

[ampsucker]

isn't the answer to this simply to make sure the overpressure relief valve is working and properly set? if mean if it pops off at 150 psi, then it's very unlikely that you'll have a serious explosion even if your tank rusts through, right?

our compressor is pretty old, probably circa 70s or 80s. keep the oil changed in the crank and drain the condensate out periodically and that's about all we do.

one dangerous condition i have noticed is a plug of ice freezing in the inlet pipe to the tank. (our tank is outside the shop for safety and space reasons). the compressor will run for a minute or so, then you'll hear a pop as the ice is ejected from the pipe and it bounces off the inside wall of the tank, then the pressure gauage on the tank starts to build like normal. this happens even when the bottom of the tank is drained and i think is due to the design of the inlet pipe allowing just a small amount of moisture to leak down from the pump plumbing. it only happens once or twice a year when the weather conditions are just right. i always keep an eye on it when i turn the pump on the first time in subfreezing temps.

amp

 

[dfkrug]

Basically, if an air compressor tank rusts through, the air will escape and the pump will run and run and run, sorry no explosion! Just need to patch or buy a replacement.

I agree, no explosion. We are not talking 2000-3000psi welding gas or
SCUBA tanks here. Steel is very tough and the failure mode for
a tank with under 200psi in it is not dramatic. I notice that my gas supplier
does not do any pressure tests for my acetylene tank (but he does for
my Ar, Ar/CO2, and O2 tanks) cuz of the low working pressure it is rated
for (a few hundred psi).

My compressor tank is pushing 30 and I have had to replace the pressure
switch once so far.

 

[Charlesaf3]

question is what happens (and I'm not disagreeing with anyone here, just displaying my ignorance) when the relief is at 150 but there is a rusty place in the steel that goes at 125? I'd guess that's the worst case scenario

 

[orezok]

Reminds me of a friend of mine who was a mechanic in Louisiana back in the 50's. They had this old compressor that had the old style tanks that had a inspection plate bolted to the end of it. It was located next to the toilet room in an old tin building. Well, the pressure shut off switch was broken, so they would just turn in on for a while to build pressure in the large tank and then shut it off.

Needless to say, one of the workers went to the can and forgot to shut the compressor off. It kept building pressure until it blew off the end plate of the tank. It went through the wall of the toilet, took the toilet out from under the worker, went through the outside wall and buried itself in a large oak tree.

He said it didn't even scratch the worker, but it sure gave him a wake up call.

He said that the plate and toilet were buried so deep in the tree that they never did get it out!

 

[ampsucker]

i guess i agree with the others that it wouldn't likely be a catastrophic failure at those low pressures. it might make a pretty loud hiss, but i don't think you'd see any shrapnel.

amp