Honda Insight Forum banner

1 - 20 of 43 Posts

·
Registered
Joined
·
4,007 Posts
Nope

--Sam
 

·
Registered
Joined
·
102 Posts
It's a gimmick. I've seen no proof that it's any better. Besides, if a tire gets low, aren't you going to refill with air? If so the "benefit" of nitrogen decreases over time so why bother?
 

·
Registered
Joined
·
1,100 Posts
What benefit would pure nitrogen have over plain air?
It does not expand or contract more or less than air under pressure or temperature changes.

It has less mass - about 2.5 % less than air. A liter of air weighs just above a gram, and there may be some 50 liters of compressed air in a tire so the difference is less than 2 gram per tire.
Hydrogen gas, by contrast, would save you about 50 grams per tire. But hydrogen is volatile; the small molecules may seep out faster than you'd like.

The oxygen might react with the rubber and age it prematurely, I have heard. Oh yeah, but there is a lot of oxygen on the other side of the tire and apparently that holds well enough.
And even if the oxygen does react, it would soon be depleted - there is just some 15 gram of it in the tire. What remains is almost pure nitrogen then; but at no cost!

Air also holds a tiny bit of moisture which is bad for rubber. But again, the outside of the tire will have to hold up against a lot of it.

Finally, who can tell whether the gas bottle holds what it says? If they sell air for nitrogen it would be mostly true, just a 21% lie.
Sure they can order new nitrogen gas every time they run out.
Or they can put the compressor on and replenish it themselves for free, and let you pay for their 79% worth of honesty.
 

·
Registered
Joined
·
831 Posts
Kind of an old thread, but I talked to a guy who fills tires with "nitrogen" at a local tire shop. It's true that 78% of our air is already Nitrogen. What he says they do, is dry the air, take the moisture out... which is what tends to expand and contract the most under influence of heat and cold.

The gist of it... tire pressure doesn't vary quite as much as normal "air" would as tire heats while driving on a hot day and then goes back to cool condition at rest at night.

That's what I found out talking to a tire guy that has a "Nitrogen" system.
 

·
Registered
Joined
·
1,100 Posts
Nobody in the nitrogen business or having nitrogen in the tires is ever going to say that there really is no difference with plain air.
They will always say it is better or they would not be doing it.
They believe it works.

When it comes to the reason why they believe we can go fact checking.
First, they dry it/take the moisture out. Not the oxygen? Then they are basically selling dry air, not pure nitrogen.

But does it even really help to take the water out?
Water is the only component in air that is not a gas by itself under normal temperature and pressure
The water content is usually about 1-2% at sea level though it varies strongly depending on conditions.
It acts just like a gas, so as long as it does not condense it will expand and contract with temperature changes just like the other components.
When the temperature drops the air may become saturated and some water may condense (see Water vapor - Wikipedia, the free encyclopedia). Yet that amounts to just a few % of the whole, at most.

When you drive the tires get warm.
When the tires are warmer than the air was that got pumped in the water is totally vapourised and the air behaves like an ideal gas.

So I think the effect of water in the air is negligible.
Drying the air you put into the tires only makes sense when you fill them during a monsoon expecting to enter a cold area, and even then it will be hard to notice the effect.
Otherwise only your wallet will notice the difference between using air and nitrogen.
 

·
Registered
Joined
·
831 Posts
When you drive the tires get warm.
When the tires are warmer than the air was that got pumped in the water is totally vapourised and the air behaves like an ideal gas.

So I think the effect of water in the air is negligible.
Drying the air you put into the tires only makes sense when you fill them during a monsoon expecting to enter a cold area, and even then it will be hard to notice the effect.
Otherwise only your wallet will notice the difference between using air and nitrogen.
We all definitely need to find an "ideal gas" for our tires!!:)
 

·
Registered
Joined
·
1,725 Posts
But does it even really help to take the water out?
Water is the only component in air that is not a gas by itself under normal temperature and pressure
The water content is usually about 1-2% at sea level though it varies strongly depending on conditions.
It acts just like a gas, so as long as it does not condense it will expand and contract with temperature changes just like the other components.
When the temperature drops the air may become saturated and some water may condense (see Water vapor - Wikipedia, the free encyclopedia). Yet that amounts to just a few % of the whole, at most.

When you drive the tires get warm.
When the tires are warmer than the air was that got pumped in the water is totally vapourised and the air behaves like an ideal gas.

So I think the effect of water in the air is negligible.
The vapor pressure of the water moisture in a tire filled with "air" causes a nonlinear change in air pressure in the tire when it heats up. See this link,

http://www.epicentermotorsports.com/Nitrogen_Inflation_Article_Rev_A.pdf

Also see,
http://www.popularmechanics.com/cars/how-to/repair-questions/4302788]Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

TireRack has a long article about nitrogen in tires.

The following is in relation to water liquid water boiling to steam. I mention this because it gives and indication that if the internal temperature in the tire rises to 212°+ F (under racing conditions this might be possible) how much the moisture vapor in the tire can affect the pressure. I found this at

Physics Help and Math Help - Physics Forums

"At 212°F, 14.7 psia, liquid water has a specific volume of 0.016716 ft3/lbm and steam has a specfic volume of 26.80 3/lbm, which is a volume ratio of ~1603 : 1 of steam:water."

If your local gas station has liquid water in the air hose you got big trouble if you don't want a big change in tire pressure.

Even if you use dried air you will get an advantage in having a more stable tire pressure. On the other hand, having higher pressure in tires generally will increase the fuel mileage. :)
 

·
Registered
Joined
·
831 Posts
The vapor pressure of the water moisture in a tire filled with "air" causes a nonlinear change in air pressure in the tire when it heats up. See this link,

http://www.epicentermotorsports.com/Nitrogen_Inflation_Article_Rev_A.pdf

Also see,
http://www.popularmechanics.com/cars/how-to/repair-questions/4302788]Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

TireRack has a long article about nitrogen in tires.

The following is in relation to water liquid water boiling to steam. I mention this because it gives and indication that if the internal temperature in the tire rises to 212°+ F (under racing conditions this might be possible) how much the moisture vapor in the tire can affect the pressure. I found this at

Physics Help and Math Help - Physics Forums

"At 212°F, 14.7 psia, liquid water has a specific volume of 0.016716 ft3/lbm and steam has a specfic volume of 26.80 3/lbm, which is a volume ratio of ~1603 : 1 of steam:water."

If your local gas station has liquid water in the air hose you got big trouble if you don't want a big change in tire pressure.

Even if you use dried air you will get an advantage in having a more stable tire pressure. On the other hand, having higher pressure in tires generally will increase the fuel mileage. :)
Think I covered all that in more layman's terms, up above. I tried a "nitrogen"(dehumidified air) fill in my car's tires once to see if it worked as advertised. Noted that the pressure was a little more steady as temperatures varied and overall pressure was maintained about 3 weeks longer than usual before tires needed a refresh. Only did it once out of curiosity to see if it worked.

I check my tire pressure at least every two weeks. More often if we see big temperature changes. One of the best ways to maximize MPG and tire life. I see a lot of under inflated tires on all kinds of vehicles. So easy to resolve.
 

·
Registered
Joined
·
1,100 Posts
The vapor pressure of the water moisture in a tire filled with "air" causes a nonlinear change in air pressure in the tire when it heats up. See this link,

http://www.epicentermotorsports.com/Nitrogen_Inflation_Article_Rev_A.pdf

Also see,
http://www.popularmechanics.com/cars/how-to/repair-questions/4302788]Nitrogen vs Air In Tires - Why Nitrogen in Tires - Popular Mechanics

TireRack has a long article about nitrogen in tires.

The following is in relation to water liquid water boiling to steam. I mention this because it gives and indication that if the internal temperature in the tire rises to 212°+ F (under racing conditions this might be possible) how much the moisture vapor in the tire can affect the pressure. I found this at

Physics Help and Math Help - Physics Forums

"At 212°F, 14.7 psia, liquid water has a specific volume of 0.016716 ft3/lbm and steam has a specfic volume of 26.80 3/lbm, which is a volume ratio of ~1603 : 1 of steam:water."

If your local gas station has liquid water in the air hose you got big trouble if you don't want a big change in tire pressure.

Even if you use dried air you will get an advantage in having a more stable tire pressure. On the other hand, having higher pressure in tires generally will increase the fuel mileage. :)
The graph in the first link shows the pressure development of saturated air; that's what happens if you have excess water (in the condensed form) in the tire. Once the humidity is less than 100% the air acts just like pure nitrogen.
Even when the tires have saturated air the extra pressure increase is minimal until the tires get really warm (according to that graph). That is relevant in motor sports, but less so for everyday moderate use.

The second link is broken, and sorry but steam is something completely different than air.

All I wanted to point out is that dry(ish) air is just as good as nitrogen.

Wet air less so, but imho there should be no reason why there would be any water in an air hose unless someone fiddled with it.
An air compressor will raise the temperature of the air it compresses so even if that air was 100% moist to begin with, it will not condensate within the compressor because the heated up air will keep absorbing it.
 

·
Registered
Joined
·
4,007 Posts
All this talk coming down to moisture in the air... so even the nitrogen advocates agree that it's no better than filling from an air compressor with a line dryer on it?
 

·
Registered
Joined
·
831 Posts
All this talk coming down to moisture in the air... so even the nitrogen advocates agree that it's no better than filling from an air compressor with a line dryer on it?
Pretty much sums it!
 

·
Registered
Joined
·
1,725 Posts
All I wanted to point out is that dry(ish) air is just as good as nitrogen.

Yes but with all due respect, you also said, "The water content is usually about 1-2% at sea level though it varies strongly depending on conditions.
It acts just like a gas, so as long as it does not condense it will expand and contract with temperature changes just like the other components."

Yes initially, but from, Humidity - Wikipedia, the free encyclopedia

"Air density and volume
Main articles: Volume (thermodynamics) and Density of air

Humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature. Therefore, when applying more pressure to a gas saturated with water, all components will initially decrease in volume approximately according to the ideal gas law. However, some of the water will condense until returning to almost the same humidity as before, giving the resulting total volume deviating from what the ideal gas law predicted. Conversely, decreasing temperature would also make some water condense, again making the final volume deviate from predicted by the ideal gas law.".

[I added emphasis.]


Wet air less so, but imho there should be no reason why there would be any water in an air hose unless someone fiddled with it.

I'll try to keep that in mind if I try to paint a car on a hot summer day [again] with my compressor (with the water trap not full) and water comes out of the gun. :)

Part of that may be caused by the reduced air temperature as the compressed air expands in use (dew point). But whatever the cause, we can get water spraying out of the hose if a real air drier is not used.


An air compressor will raise the temperature of the air it compresses so even if that air was 100% moist to begin with, it will not condensate within the compressor because the heated up air will keep absorbing it.
Take into consideration that we have subtropical conditions in South Fla. Right now the temperature is 77° F and the humidity is 90% and that isn't considered excessively high humidity here. In summer we can have daily humidity up to 98% and daytime temperatures 92 to 104° F. So we start off with a lot of moisture.

Generally the air in the storage tank will be at a lower temperature than the compressed air mixture being placed into the tank. Which can cause water to accumulate in my storage tank and the water trap.

I can get enough condensed water to almost fill my water trap in a heavy days use. And I have to drain the air tank to clear the water out of it too.

It's rare to see a true air drier on home compressors. Most home users don't even know about a water trap.
 

·
Registered
Joined
·
831 Posts
Pretty much sums it!
Oof! I should have added "if the compressor actually somehow removed moisture from the air it was compressing". I somehow blanked out on that!

Garbage in... garbage out. What a dope! My bad.:(
 

·
Registered
Joined
·
1,100 Posts
Hey ho. A compressor does not remove moisture, but it heats up the air so that can contain more. if it was saturated is isn't any more after the compressor.

A spray gun has a compressor and a 'decompressor', the trigger valve.
While the compressor heats up the air by compressing it, the decompression at the valve does the opposite.
Of course the air will lose some of its heat on its way from the compressor to the valve, so when it passes the valve it will be colder than ambient, over saturated and lose water.
That's why your spray gun will have a small tank to collect that condensation.

The air hose in the filling station will not have that; it is just a compressor.
If I fill the tires the nozzle is warmer than ambient, not colder.
 

·
Registered
Joined
·
1,725 Posts
Hey ho.

I believe at this point we are just sparing with each other.

A spray gun has a compressor and a 'decompressor', the trigger valve.

Could you post a link that shows the compressor in the air gun? Are you referring to the nozzle where the paint is mixed with the air?

All my valve does is restrict the air flow depending upon how much the trigger is pulled or not. Eventually the air has to expand to pull the paint into the air stream and blow it out the nozzle.


While the compressor heats up the air by compressing it, the decompression at the valve does the opposite.

Yep. And the pressure goes down in the hose and storage tank too. If not the air wouldn't flow. And as the pressure goes down ......... water etc ............

Of course the air will lose some of its heat on its way from the compressor to the valve, so when it passes the valve it will be colder than ambient, over saturated and lose water.

I'm glad to see that you [now] agree that it doesn't take a fiddled air hose to do that. :p

That's why your spray gun will have a small tank to collect that ondensation.

My spray gun is over 70 years old and it does not have a tank on it to collect water. It can spray water out whenever it has the urge to do so.

Where the water condenses isn't important. The fact is that it is a natural occurrence for water to condense in the system and even more so when the air is used and cools off due to pressure drop.


The air hose in the filling station will not have that; it is just a compressor.

It depends on the gas station. But they might have an ineffective water trap other than the storage tank.

If I fill the tires the nozzle is warmer than ambient, not colder.
So? My air hose & nozzle is in the garage until I use it. The air will still expand and get cooler.

I think we've beat this subject to death by now. I'm going to go out and put some moisture loaded air in my tires. :D
 

·
Registered
Joined
·
1,100 Posts
Spray gun vs. compressor:
No need to post that link.
The gun has no compressor itself, but it needs pressurized air to work, either immediately or stored in a pressure tank.

All your air gun valve does is create the big pressure drop that causes condensation. There may be condensation in other parts of the system too due to the gradual drop in pressure esp. when using pressurized air that has cooled down, like when you use a pressure tank without keeping the pressure stable with a compressor.

But an air gun is not the same as the air pump in a filling station, that has no valve, no pressure drop in the system, no condensation.
Why would an air pump need a water trap? Never heard of that.
But of course if you can show me a link of an air pump with a water trap then I will look at it.

I maintain that for everyday use and under non-extreme conditions there is no saturation in tires and no reason to use nitrogen or even predried air.
Nitrogen can be handy in an air gun though, it would solve the water problems that occur with that.

If you still want really dry air in your tires you can get it on the cheap, if you have access to where the pump draws air from.
Then draw the air through a bucket of fresh ice cubes. Moisture in the air will condensate on the cubes; the remaining air will be almost completely free of water.
You need to be sure there is no water in the bucket; sucking that up would be the complete opposite of what you'd like to achieve.
 

·
Registered
Joined
·
1,725 Posts
Spray gun vs. compressor:
No need to post that link.
The gun has no compressor itself, but it needs pressurized air to work, either immediately or stored in a pressure tank.

At this point I'm sure you are pulling my leg but .............

All your air gun valve does is create the big pressure drop that causes condensation. There may be condensation in other parts of the system too due to the gradual drop in pressure esp. when using pressurized air that has cooled down, like when you use a pressure tank without keeping the pressure stable with a compressor.

Yes I pointed that out in the previous posts. Again I'm glad that you now agree.

But an air gun is not the same as the air pump in a filling station, that has no valve, no pressure drop in the system, no condensation.

You have some strange air pumps in your town. They can pump air into the storage tank, defy the Wikipedia information and then release it through the outlet pipes etc with no pressure drop in the system. Or you have a really high local pressure gradient in your town.

According to the Wikipedia article you can get condensation in the tank with NO air being used. And it only gets worse when you release the air in the tank no matter how you choose to do it.


Why would an air pump need a water trap?

To trap some of the condensed water would be my guess.

Never heard of that.

Oy vey. It's worse than I thought. I already mentioned that in an earlier post. You have to do some of the homework too.

But of course if you can show me a link of an air pump with a water trap then I will look at it.

No problemo. A quick Goggle image search for, "air compressor water trap" found a few links.

https://www.google.com/search?q=air+compressor+water+trap&client=firefox-a&rls=org.mozilla:en-US:eek:fficial&channel=fflb&gbv=2&source=lnms&tbm=isch&sa=X&ei=tnQ3U8SGA7TKsQSlqoGgDA&ved=0CAkQ_AUoAg

I maintain that for everyday use and under non-extreme conditions there is no saturation in tires and no reason to use nitrogen or even predried air.

A lot of people in the goggle search seem to disagree. But most of the new home type compressors I've seen don't come with water traps. You have to buy them separately.

But as President Reagan said, "There you go again, [changing the conditions of the discussion]." We started out with "no condensation in the compressed air", "no water in the hose unless someone fiddled with it" and now, "no saturation (with no defining limits) in tires". Again, in S. Fla I've let air out of tires and it smelled like very smelly warm moist air.


Nitrogen can be handy in an air gun though, it would solve the water problems that occur with that.

I've never heard of anyone using pure nitrogen to paint a car though. If you can post a link I'd be glad to look at it. I want to see the size of the tank it takes to paint a semi truck and trailer. :p

If you still want really dry air in your tires you can get it on the cheap, if you have access to where the pump draws air from.
Then draw the air through a bucket of fresh ice cubes. Moisture in the air will condensate on the cubes; the remaining air will be almost completely free of water.
You need to be sure there is no water in the bucket; sucking that up would be the complete opposite of what you'd like to achieve.
How many cubic feet per minute do you imagine a bucket of ice would allow you to draw air through it without melting to be "completely free of water [moisture]".? Under some conditions ice can turn directly to vapor without melting.

The Water Cycle: Sublimation, from USGS Water-Science School

:deadhorse:

And now back to our normal forum programs. :p
 

·
Registered
Joined
·
831 Posts
I second and third that motion!!:)
 
1 - 20 of 43 Posts
Top