Shop Time w/T.W. Friends. Torque wrench on spark plugs, we need answers so cast your vote now

1900 - 1920's probably, knob and tube wiring and the central heating was added after it was built.

 

Amazing what the occasional oil change will accomplish isn't it.

 

No!

Full points for creativity, but... no!

Basic pressure-vessel test procedure:

1. Disconnect and blank off ALL ports except the highest one which will be the test port.

2. Fit a calibrated gauge to the vessel.

3. Fill the vessel with water to the highest level possible.

4. Connect a proper test pump, and raise the pressure to the required test pressure (usually 1.25-1.5x MAWP) slowly

5. Isolate the pump, and wait five minutes. Pressure should hold within +/- 5%

6. Allow the pressure to bleed down overnight.

The danger of doing it the way you are is that you have a large air space... air compresses and creates a LOT of potential energy. If the tank does fail, you're going to wear it, and it's going to hurt. A LOT! Is the gauge fitted calibrated, and rated for liquid? If not, then you don't know what you're testing, and lastly, the pressure washer provides surge-pressure many times higher than MAWP for that tank, and if it's corroded inside (a very real possibility if it hasn't been maintained), you could wear it.

 

At least he doesn't have far to go to reach that 500k

 

I've seen several different numbers and went with 50% over Working pressure, 150+75 psi. The pressure washer is a cheapo target greenworks 1500psi thing and was super simple to control. Disconnected all accessories except the gauge and plugged the holes. Ran it up to 225psi and let it sit an hour, don't see any leaks but pressure leaked down to 190. I assume it leaked back into the pressure washer. I feel am happy with the result and will put it into service after an oil change. Plan to leave the tank drain open when not using it.

 

*that's a pressure washer wand, not air hose, valve at the top makes sure no air is left inside.

 

Understand it's a pressure-washer, but missed the valve. That does negate the entrapped air issue, but not that of the surge-pressure, and there's no valve (that I can see) to isolate the pressure-washer wand from the tank.

 

Appears to be a well built pump, pressure lube and a head unloader. Who is the manufacturer?

 

Home shop diy. no calibrated gauge, proper inspected test equipment, PPP, etc

 

I don't grasp the necessity of hydro testing a compressor tank. Just keep a clean change of shorts handy if she let's go.

 

It's a Binks unit, pump is a Quincy 210-5. Picked it up on Marketplace for $40, house was being cleared out after owner passed.

 

Shrapnel.

Mostly they just leak - mostly. They can violently fail when the steel tank unzips and you have all that air and everything it kicks up going somewhere fast.

 

Saw one video that happened to a guy, would have died if his son wasnt there to slow bleeding and call 911

 

Score!

Sorry the dude passed obviously...

I have a giant (1200 pound) 1960's Binks branded unit with a Quincy QR-325 powered by a Wisconsin 2 cylinder.

 

True.

Hydro testing the relief valve is much more important. That can be done separate from the tank.

 

I just got a new one when I got new fittings. Like you said, cheap enough. Picked up 3/8 fittings with 1/4 npt threads after watching several videos talking about the difference between the 1/4 "High Flow" fittings vs "proper" 3/8 fittings.

 

RE: Hydro test

I read this years ago and by the magic of my google-fu was able to locate to to re-post here.

Source: https://www.practicalmachinist.com/vb/general/old-compressor-tank-safety-241476/index3.html

Post #47 follows below:

Okay, I'm not an engineer (or a machinist) but I do have a calculator handy.

What would happen if the 80 gallon tank in the center of my garage ruptured catastrophically? Say, one moment the tanks there and happy, then an instant later the tank's just gone and I suddenly have 80 gallons of angry air expanding rapidly in all directions. The compressed air is going to expand and add itself to the air already contained in my garage. My garage isn't air-tight by any means, but for a brief moment before the excess air leaks out, I'll have an excess of pressure in the garage trying to get out.

So, my two car garage is something like 20' by 20' with an 8' ceiling. That's 3200 cubic feet, which is about 24,000 gallons total enclosed space.

The tank holds 80 gallons. Let's say at 120 psi. That's 120 psi above the air pressure outside the tank, which is about 15 psi. So the tank is really at 135 psi (above vacuum), and the air outside the tank is at 15 psi (above vacuum). When that air decompresses fully, it will expand by a factor of 9. (135/15=9) By the time the dust settles those 80 compressed gallons will have expanded to 720 gallons.

Shortly after the tank ruptures, 23,920 gallons (outside the tank) plus the 720 gallons (assuming it expands fully -- it does, almost) from inside the tank makes 24,640 gallons of air squeezed in a 24,000 gallon garage. 24,640/24,000=1.027. The air in in the garage will be over-pressure by 2.7%. Doesn't seem like much. Before the air leaks out of the garage, the pressure inside will be raised by 0.4 psi.

For a brief moment I think I'll have 15.4 psi on the inside, and 15 psi on the outside. That's a pressure differential of 0.4 pounds per square inch, and 57.6 pounds per square foot. If my garage door is 8'x8', that makes a total of 3686 pounds trying to shove it outward. It all depends on how long that force is applied, but I bet if it's there for half a second, I could easily see it bowing out the middle and pulling the rollers out of their tracks and leaving the door laying in the driveway.

I don't think brief exposure to 15.4 psi would do anyone harm. I bet someone in the garage but not near the tank when it blew could emerge unscathed from the pressure wave. I'd be more worried about potential shrapnel.

-Alexander

Edited to disclaim: All the above is my speculation of what might happen. A thought experiment, no more.

 

I get annoyed about these violently rupturing tanks.

They did not rupture because they were rusty or old.

Someone gagged the safety relief and/or
the pressure switch contacts fused closed so the motor could not turn off.

2 safety features failed before that tank let go.

In most cases, rusty tank just leaks, like Russ said.

The safety relief is the part that needs tested more than the tank.

We all love drama, but those violent failure pics were not cased by a weak tank. Other factors were more the cause.

 

The relief valve should be tested on air, not water.

 

My main compressor was built in 1960. I hydro-tested the tank before I put it in service and also bought 3 brand new safety valves.

I like old stuff a lot, and I'm cheap -- but I have no problem spending money when it is the sensible thing to do.