Who knew! Damnit!

[Ball_Ze]

I'd say at least 78%...

Dammit ? Beat me by3 minutes

Sponsored

 

[salvino]

Brass valve stems can be problematic with aluminum caps. These are brass, not steel.


There are videos out there on this very topic because of dissimilar metals, moisture.

Brass valve stems don't get along well with aluminum. Stainless steel is bad with aluminum but mild steel is ok with aluminum.

Sadly many fancy caps are aluminum and many valve stems are brass. Galvanic corrosion even with only WATER and nothing else.
The aluminum will corrode more because it is more anodic than brass, and will also corrode where it contacts the brass since brass is more cathodic.

steel and aluminum are relatively compatible so if they were steel, then ok - but valve stems are not typically steel - it would rust. And stainless steel and aluminum together is bad.

Brass is incompatible with aluminum, per Mil-STD-889



The caps on my truck are green on the end. They are chrome plated plastic, and not nitrogen filled. Same caps on both of my JTs.

It’s the same as attaching an aluminum hose end to a brass/bronze outdoor spigot. If you leave them connected long enough you will not get them apart.

 

[Nexstar7]

Problem solved:

https://a.co/2wNQZTZ

they stay on great in snow, mud, water crossings... ahem ... well that's what a friend told me

?

 

[PW45]

In Navy, we'd purge pressurize some aircraft electronics with nitrogen to be 100% sure there was no moisture.

Otherwise, Pv=nRT reigns supreme in this conversation.

 

[ShadowsPapa]

Won't your tires get the bends if the tires are nitrogen filled and you emerge from the water too fast?

 

[DJPodratz]

Can someone explain the supposed advantage of nitrogen to me. I am a chemical engineer and most arguments I hear are bunk. Air is 72% nitrogen and ignoring minor components 28% oxygen. Nitrogen (N2) as a molecular weight of 28, Oxygen (O2) is 32. So N2 at 28 v. air, a 72/28 blend of N2/O2 at 29.12. Air is 29.12 / 28 or 4% heavier. Anyoung want to guess what 4% of a tire's gaseous fill weighs? I can calculate it if you want, but your scale will not be able to tell the difference.

Is N2 drier than air? Water has a MW of 18 so is lighter than both O2 and N2 if you think weight is the issue.

Does the O2 on the inside of tire oxidize the rubber quicker? Maybe, but I doubt it. Is there evidence for this why people use N2?

Does the water on inside of tire corrode your wheels? I doubt it. Again, evidence? Most air compressors have a condenser to knock out the water?

I really want to understand why I should fill my tires with nitrogen. Give me a good reason and I will do it in a heartbeat!

 

[ShadowsPapa]

Does the water on inside of tire corrode your wheels? I doubt it. Again, evidence? Most air compressors have a condenser to knock out the water?

That's a minor reason - but it is true in many cases.
No, most air compressors don't have a condenser to knock out the water.
Unless there's a specific water filter inline, there's likely moisture in the compressed air because it draws it from the same air you breathe.
I ran the lines in my shop in a special way to get rid of some of the moisture issue - as the air comes out of the tank it expands into the lines where it is cooled and the water condenses out. I ran the line from the air compressor up high, and branched out from there. Every line up high on the wall has a slight "grade" to it as it goes across the wall. I use Ts to tap into the main lines and the Ts point up, I then use elbows to reverse direction downward. At the bottom end of each "drop" I have a valve. The fittings for my air hoses are a couple of inches above that valve. Every so often I drain the water out of those valves, especially those drops at the end of the run.
I run a water filter in the line that supplies my bead and sand blast cabinets. Water filters are used if I spray paint. Even with the many feet of copper air lines and the special precautions I've taken, including dumping the air from the compressor into a large vertical pipe with a drain at the bottom end. there's still water in the air.
You've never seen rusty steel wheels.? I sure have. Yes, it's an issue with steel wheels. Not a big issue, a small one, but it exists.
I've worked on cars, trucks and tractors for decades and have seen my share of rusty steel wheels. (I checked around my shop - all but one wheel around here currently have tires on them so can't get a good picture)
In Iowa, I can still use my blast cabinets and need to watch when the humidity here is high. Water filter must not be doing a great job.

Nitrogen is supposedly dry, unlike air from some station or shop compressor is one reason I suppose.
The theories vary from "larger molecules so less likely to get through the rubber" to "less variation in pressures in wildly varying temperatures (mine can go from 38 down to 30 pretty easily)
I see sites that talk of the use of nitrogen in aircraft tires.

and yet science sites agree - if the gas is DRY, the pressure changes are the same regardless of the gas for a given temperature change and volume.

 

[ShadowsPapa]

Is N2 drier than air? Water has a MW of 18 so is lighter than both O2 and N2 if you think weight is the issue.

No one is thinking weight is the issue. I was mocking that point when I joked about helium in tires. Even the scale I use to measure the chemicals I use for plating wouldn't see the difference between air - mostly nitrogen, and pure nitrogen.

For a real weight difference, I used to use calcium chloride in the rear tires of one of my tractors for weight. Now that is a weight difference! (and it corrodes the crap out of things)

 

[salvino]

No one is thinking weight is the issue. I was mocking that point when I joked about helium in tires. Even the scale I use to measure the chemicals I use for plating wouldn't see the difference between air - mostly nitrogen, and pure nitrogen.

For a real weight difference, I used to use calcium chloride in the rear tires of one of my tractors for weight. Now that is a weight difference! (and it corrodes the crap out of things)

If we used nitrous oxide we could have some laughs while airing down.

 

[ShadowsPapa]

If we used nitrous oxide we could have some laughs while airing down.

Good one!

 

[DJPodratz]

No one is thinking weight is the issue. I was mocking that point when I joked about helium in tires. Even the scale I use to measure the chemicals I use for plating wouldn't see the difference between air - mostly nitrogen, and pure nitrogen.

For a real weight difference, I used to use calcium chloride in the rear tires of one of my tractors for weight. Now that is a weight difference! (and it corrodes the crap out of things)

Water and antifreeze would be just as easy and less corrosive. Perhaps more toxic if a tire leaked.

 

[DJPodratz]

Water and antifreeze would be just as easy and less corrosive. Perhaps more toxic if a tire leaked.

So at the end of the day, why nitrogen?

 

[DJPodratz]

That's a minor reason - but it is true in many cases.
No, most air compressors don't have a condenser to knock out the water.
Unless there's a specific water filter inline, there's likely moisture in the compressed air because it draws it from the same air you breathe.
I ran the lines in my shop in a special way to get rid of some of the moisture issue - as the air comes out of the tank it expands into the lines where it is cooled and the water condenses out. I ran the line from the air compressor up high, and branched out from there. Every line up high on the wall has a slight "grade" to it as it goes across the wall. I use Ts to tap into the main lines and the Ts point up, I then use elbows to reverse direction downward. At the bottom end of each "drop" I have a valve. The fittings for my air hoses are a couple of inches above that valve. Every so often I drain the water out of those valves, especially those drops at the end of the run.
I run a water filter in the line that supplies my bead and sand blast cabinets. Water filters are used if I spray paint. Even with the many feet of copper air lines and the special precautions I've taken, including dumping the air from the compressor into a large vertical pipe with a drain at the bottom end. there's still water in the air.
You've never seen rusty steel wheels.? I sure have. Yes, it's an issue with steel wheels. Not a big issue, a small one, but it exists.
I've worked on cars, trucks and tractors for decades and have seen my share of rusty steel wheels. (I checked around my shop - all but one wheel around here currently have tires on them so can't get a good picture)
In Iowa, I can still use my blast cabinets and need to watch when the humidity here is high. Water filter must not be doing a great job.

Nitrogen is supposedly dry, unlike air from some station or shop compressor is one reason I suppose.
The theories vary from "larger molecules so less likely to get through the rubber" to "less variation in pressures in wildly varying temperatures (mine can go from 38 down to 30 pretty easily)
I see sites that talk of the use of nitrogen in aircraft tires.

and yet science sites agree - if the gas is DRY, the pressure changes are the same regardless of the gas for a given temperature change and volume.

Thank you! I did not know rusting steel wheels from the inside was a real issue. Good to know!

 

[redfish]

Guess i need to replace my snazzy Method valve caps

 

[ShadowsPapa]

Water and antifreeze would be just as easy and less corrosive. Perhaps more toxic if a tire leaked.

I'm sure there were reasons to go that way - today it seems beet juice is a possible substitute.
Similar in weight to calcium chloride but not as freeze resistant - about the same as antifreeze in that respect.
Ethylene glycol is toxic and not cheap. A 50/50 mix would freeze at about 35 below or so, 70/30 is only a little better. And pure ethylene glycol is even worse for freezing. (not to mention expensive and kills whatever drinks it)
Calcium chloride won't freeze in the lower 49 states - good to more than 50 below.
Weighs somewhere around 11 pounds/gallon? (parts of Alaska mayget colder than that at times so I left them out. )

Sponsored