Compressed Air Line Question

[Deere Dude]

A little off topic but related.

Today I brought my small portable air compressor over to a friends place to air up some flat trailer tires on a trailer that has not moved in many years sitting out in the field.

Decided to go 30 psi all around... the first three aired up nicely and all was good.

Went to air up the last one and stopped when it got to 30... a moment after I pulled the hose from the stem I heard a ripping noise and KaBoom... tire exploded sending pieces everywhere... my friend was up at the tongue about 10 feet away and got hit on the cheek with flying tire and my right ear still rings...

Amazing just how much force/energy is in 30 psi!

I was a pipefitter in a factory messing around with an airline. We had a 2-3" sch 40 mains with a few 1" laterals for assembly areas. I shut the air off on the main so I went to remove a 1" plug to install another lateral. I usually remove them slowly and did this time also. What I did was shut the wrong valve off and when I slowly lefty loosyed the plug it took off like a bullet into next week. I don't think we ever found it. That was only with 100 PSI of air on it. Dang it was loud and then I had to listen to it until I lowered the lift and ran over to the correct valve.

Don't underestimate what 100-150 PSI in shop air will do.

 

[Midniteoyl]

A little off topic but related.

Today I brought my small portable air compressor over to a friends place to air up some flat trailer tires on a trailer that has not moved in many years sitting out in the field.

Decided to go 30 psi all around... the first three aired up nicely and all was good.

Went to air up the last one and stopped when it got to 30... a moment after I pulled the hose from the stem I heard a ripping noise and KaBoom... tire exploded sending pieces everywhere... my friend was up at the tongue about 10 feet away and got hit on the cheek with flying tire and my right ear still rings...

Amazing just how much force/energy is in 30 psi!

 

[Industrial Toys]

NICE! I think he smashed his face on the ground! Now he will probably sue, and win!

A friend gave a rotten 8" tire a shot of air on the bench. It exploded and busted the drywall above the bench and ripped open his hand exposing the bone! Good thing, he wasn't leaning over it. He has been working with such things his whole life, and insists he didn't try and over-inflate the tire. Scary!

 

[ultrarunner]

Never had one go before... probably my fault for inflating to 30lbs after sitting in a field for 10 years...

In the future I will maybe go 20lbs and leave it for a few days... I'm always coming across cars that have been sitting for years or decades with my car hobby... few put cars on blocks as was once common.

My ears were ringing all night from the pop... a neighbor down the road thought it was a shot fired.

Thing is I wasn't expecting it in the least... so always something new to learn.

At work we needed to specify certified air tanks and they are inspected and licensed on a regular basis... 60 gallon vertical Speedaire with 125 lbs max.... always makes me think of all those home air compressors that are never inspected

Without the compressor it would have taken a long time to fill with a bicycle pump and probably not as full...

 

[SPYDERLK]

Never had one go before... probably my fault for inflating to 30lbs after sitting in a field for 10 years...

In the future I will maybe go 20lbs and leave it for a few days... I'm always coming across cars that have been sitting for years or decades with my car hobby... few put cars on blocks as was once common.

My ears were ringing all night from the pop... a neighbor down the road thought it was a shot fired.

Thing is I wasn't expecting it in the least... so always something new to learn.

Without the compressor it would have taken a long time to fill with a bicycle pump and probably not as full...

Im glad you werent hurt. Obviously not much fragmentation. -- Bicycle pump would have given exactly the same explosion when fail pressure was reached.

 

[ultrarunner]

I doubt I would have put 30 psi in with a bike pump... just too easy with the compressor.

Rubber Chunks blew 10 to 12 feet.... can only imagine jagged shrapnel.

 

[bigtiller]

I just got around to finish reading my July Popular Mechanics magazine. I couldn't believe it. Beginning on page 108 is a step by step directions with photos on how to build a ping pong cannon out of PVC pipe with your 10 year old kid. Their engineer must have been on vacation that week.

How to Build a Ping Pong Cannon

 

[SPYDERLK]

I doubt I would have put 30 psi in with a bike pump... just too easy with the compressor.

Rubber Chunks blew 10 to 12 feet.... can only imagine jagged shrapnel.

Agreed. Safety by increased difficulty to achieve a mistake is a :confused2: concept.

 

[SPYDERLK]

I just got around to finish reading my July Popular Mechanics magazine. I couldn't believe it. Beginning on page 108 is a step by step directions with photos on how to build a ping pong cannon out of PVC pipe with your 10 year old kid. Their engineer must have been on vacation that week.

How to Build a Ping Pong Cannon

Cautionary details cannot be raised without causing suspicion to some amount of foreknowledge and therefore exposure to responsibility.

 

[dstig1]

I do not have a fluids background, so I am going by what those who do have told me. They said the two main issues with air vs water were that that air is compressible vs water (liquid) not. This one, everyone who knows, knows. The second item was that the forces are not the same as the pressures, as a result of viscosity. So air at 40PSI can cause a lot more trouble than water at 40 PSI, and this was not due to the gas vs liquid issue, it was due to the lower viscosity of the air fluid vs the liquid. I believe these folks as they know this stuff pretty well, but I could not prove it with equations myself. When I blew out my sprinkler I always kept the pressures low for this reason.

I'm not the expert on this, just listened to those who had the fluids background. Feel free to post the equations to show that 40 psi air vs water is not viscosity related, at all. I can learn...