NITROUS OXIDE ( nos / n2o ) advice forum

As basic as these may seem I believe many nitrous users don't know or fully understand the laws of gases that apply throughout a nitrous system which includes starting at the bottle and going to the injector.

Boyle's Law: The volume and pressure of a mass of gas at a fixed temperature is inversely proportional. If the pressure on a gas increases, its volume will decrease; likewise, if the volume is increased the pressue wil decrease.

The Pressure Law (Charle's Law): The volume of a mass of gas depends on its temperature. The higher the temperature, the greater the volume. If the volume cannot change, the pressure of the gas will. Therefore the pressure and temperature of a gas are also directly related. If you increase one, you also increase the other.

We need to look at this as a liquid more then a gas dont we? I am asking because I thought thats what we did using Trevs design was keeping it as close to a liquid as we can.

There's one problem with that, we're trying not to deal with nitrous as a gas but as a liquid and I think that's where a lot of 'educated' people who know these laws get it wrong. They think of nitrous as a gas and then apply gas laws to their thinking, when in fact they should be thinking of it as a liquid gas.

Now I don't know enough about such laws to say how much they do or do not apply to liquid gases (in particular liquid nitrous) but from what I've seen some people incorrectly claim about liquid nitrous that they've stated is supported by these gas laws, I'd say either they are substantially different or they've applied the laws incorrectly.

I've now seen nitrous in liquid form and gaseous form at room temperature and pressure and I've seen it venting from a bottle at room temperature under vapour pressure. My 'guess' is that from my observations I wouldn't expect the same laws to apply in all instances.

Now I may look to some people like a fool by making these statements but there is a big difference between lacking a specific sector of education and being a fool.

Just out of interest, what similar laws are there that apply to a liquid or a gas in liquid form???

Regards

I see my point has been made in the fact we have 2 intelligent guys with questions rather than answers.

Trev, you are right in the fact that both the laws of liquids and gases need to be adressed and not just one or the other.

The problem we deal with is that nitrous is a GAS by natural definition and is always present along with the it's compressed form of a liquid. Now both liquids and gases share the same category of "fluids" so some of the laws are the same.

Johnny,
My point exactly. We are trying to deal with more liquid nitrous and the fundamentals to achieve this are very often forgotten.

Look at many nitrous products where they promote expansion chambers, therefore converting the liquid.

Now re-read the laws of gases and see where we are losing density by doing so.

I hope I am making sense?

We still have a problem, because liquids at room temp/pressure perform differently to a gas that has been compressed to a liquid at an elevated pressure.

I'm quite certain that unless there are some laws that are intended for compressed gases in liquid form, I doubt any others will do and if anything it's the inappropriate application of gas laws to a liquid gas that's convincing 'educated' nitrous 'experts' that I've got it all wrong.

Like I said I could be wrong about all this, but the better results we get from less nitrous seems to indicate that I've got a better handle on nitrous than most and I've never tried to appply a gas law once.

If I've got it wrong I'd like someone to explain why my systems produce better results than any other from less nitrous.

Regards

Ouch !
Be very wary when applying "the ideal gas laws"
First thing to remember, no gas is actually an ideal gas..........

An ideal gas is one that exactly conforms to the kinetic theory. The kinetic theory, has five key points. These are:

Gases are made of molecules in constant, random movement.
The large portion of the volume of a gas is empty space. The volume of all gas molecules, in comparison, is negligible.
The molecules show no forces of attraction or repulsion.
(Oops, that's not nitrous OXIDE is it ?)
No energy is lost in collision of molecules; the impacts are completely elastic.
The temperature of a gas is the average kinetic energy of all of the molecules.

Non-Ideal Behavior
The Kinetic Theory makes several assumptions about an ideal gas. These cause problems because real gases are not ideal. The main causes of error are related to pressure and temperature.

Pressure
At high pressures, the behavior of real gases changes dramatically from that predicted by the Ideal Gas Law. Under 10 atmospheres of pressure or less, Ideal Gas Law predictions are very close to real amounts and do not generate serious error.

Temperature
When the temperature of a gas is close to its liquefaction point, the behavior is very different from Ideal Gas Law predictions. With increasing temperatures, the Ideal Gas Law predictions become close to real values.

Life becomes MUCH simpler when you treat Nitrous Oxide as a Fluid.
Note I said FLUID, not LIQUID.
The air we breathe and the windows we look through are both FLUIDs, they're only differences are viscosities.
"the gas laws" are useful, but don't think of them as laws. You'll end up sprawled head first on the pavement.

I may just delete this thread as we are having major communication issues.

What I am trying to say is not coming across properly and I have spoken to both Trev and Johnny in person and cleared things up.

I guess this is where the internet may not work as a learning tool as many times you need a person to person talk otherwise you will just end up with a lot of typing that no one will read.

For instance Loopy a window is not a fluid but a gas is considering a fuid is defined by matter that "can't" hold it's own shape. Now we can easily spend a page sorting through just this tidbit of details. Kinda misses my point of keeping things basic so people WILL read and learn.

Now if I worded my initial post above by stating "these are basic laws people should understand that take place inside the nitrous cylinder and throughout the plumbing and that's why we address the details of eliminating expansion chambers throughtout, would this make more sense?

I also initially posted this in the "general" forum as I believe many basic users know pressure drop occurs but not fully undertand why. Again would I make more sense now?

Well i hate to tell you this, but window glass is a fluid.
If you don't count window glass then when do you count something as a fluid ?
Grease ?
Mollasses ?
Treacle ?
Syrup ?
Oil ?
Water ?
Air ?

Starting with the basic laws is one way to confuse people, because sooner or later you end up contradicting yourself.
It's a fact of life, they don't fit and can't be made to fit.
Using basic laws to help explain why specific things happen or are is usually a better method of getting through to people.

How is it that galss is a fluid? Maybe it possibly is but I cant see how? In it's phase of becoming a "solid" object; yes, but in it's final phase as we know it how is it a fluid?

The rest are fluids as they can't hold a shape of their own.

There are gray areas yes but you can't dsimiss all laws and say they don't fit. Do you mean every law has no place?

I love the glass argument, it can go on all night.
Even the experts don't agree
Supercooled liquid or amorphous solid ?

As for the laws, they can apply yet at the same time can't.
It really does depend on what you try to do with them.
Use them as a guide, but keep your eyes open.

The real explanations are more often found in the fluid dynamics department because thats what the dominant force is during use.
(behaves more like a fluid with a viscosity than an ideal gas, but then gasses also have viscosity)
Life would be easier if we didn't hold our "gas" in the form we do.

I think this is a good thread and it's in the right section.

For those that want it simple they can just read your first post and for those that want a better understanding they can read the whole thread.

Regards

Denny, you & Loopy are way above my head here. The following 2 "laws" seem in contradiction?



Coming back to something simpler, that I might understand. I've seen some state phase change occurrs at 1025 PSI. And to NOT go above that bottle pressure because of it.
Well, I've ran my nitous systems at 1050 PSI for years - due to the high heat conditions we race under during our racing season. For instance, we ran 2 races this year, at a sunny @103ºF - so keeping bottle pressure down in the staging lanes, becomes almost impossible when the inside car temp is 140-150F.

It seems to me, that Boyles law cannot be accurate here, because in every instance (up to 1100psi) the more bottle pressure available, the more nitrous was used during a pass and the tune-up definately became leaner. I know of 1 good hard/running car that always runs @ 1150psi bottle pressure. My question is, can phase change be a constant? Is it temperature and/or pressure sensitive? Is it entirely due to "the plumbing"? Or is it some, or ALL these things?

As a personal aside here regarding liquid/fluid nitrous delivery: I put a double set of Trev's Pulsoids on my car (to replace one of the existing nos systems.) I remember receiving the Pulsoids & looking at that very little 4mm OD stainless line coming out of the nitrous Pulsoids, and thought to myself - I don't care what he says, that little line means these things will never make any horsepower! Well, I was wrong (again).

I do NOW appreciate that keeping nitrous liquid, must be darn important. I thought I "understood" the principle of that, but didn't "appreciate" what it REALLY meant. I kinda' thought Trev might be a little crazy, when he initially told me to start running with 3 additonal lbs of fuel pressure, above what I normally ran (I ended up running 2+lbs more.) Even though the system made more power than the one it replaced, nitrous consumption actually went Down 25+%. To someone who has tuned 2 & 3 nitrous systems for years, this indicated a BIG change/difference. In otherwords, less nitrous ended up being more. I'm still kinda' thinking about that one.

Dixie >
It may be of some help to you to understand what's going on with the nitrous when you run it at temperatures above 97.556 F creating pressures over 1037 psi guage .
Essentially you no longer have liquid, nor gas in your bottle.
The densities of the liquid and gas have become the same, whether you call it high density gas or low density liquid is entirely up to you.

It's called the "supercritical point" and beyond this any extra heat simply increases pressure as it would if you heated any sealed container.
Of course as soon as you start drawing that "stuff" it starts to cool, and as it cools it reaches the point of "sub criticality" becomes a definate liquid / gas again and if you're drawing the liquid your nitrous density suddenly shoots through the roof.

If you're handling supercritcal nitrous on a weekly basis and succeeding then you have my admiration, that stuff will have most people in the nut house very quickly

L

Thanks Loopy! I belive I understand. (That is as long as you don't start calling glass a liquid & such. LOL.) Athough I'm still considering the implications of 97.556 F - since it would be a real rarity when that temp could actually be achieved in race conditions.

I just looked at my recorded bottle pressures for several runs. Based on what you stated above, they somewhat surprised me. On the pass I'm currently looking at for instance, the car was staged up - and launched with 1049 lbs bottle pressure showing. However at just 0.037 sec into the run, the bottle presure was 1037 and at 0.049 seconds, it was down to 1009 - and if the thing stays on the track to make a full pass with 2 systems, it will normally be between 890 & 900 lbs (almost without fail) at the 8th mile finish line.

I may have it slightly beyond the supercritical point when the car stages, but it appears that it has already fallen well below this point at just .05 secs into the run. Perhaps this is the reason I've always gotten away with it. But I wouldn't want to bet my life on that assumption, either. LOL

Heck, realistically my gauges in the car and the computer could all be off more than the 13 PSI we are talking about here. Perhaps when my gauges and the computer say it is 1050lbs, it's really 1000lbs and that could explain the whole thing.
Regards.

I think the above statements warrant a second look!!!!

Regards

Loopy,

I recently had my faith in the data sheets for nitrous severely shook when I discovered that you could collect and store LIQUID nitrous in a plastic cup at room temperatures and pressures, without it instantly turning to a gas.

I've always questioned this critical point aspect of nitrous, because I've had similar but even more extreme examples as James has just described. I've heated nitrous to 1,400psi and still seen liquid nitrous at the outlet when the pressure in the bottle was sustained above the critical point by a jet space heater (I believe), although I didn't have a gauge on the system at the time.

Now I don't question that the data sheets etc. state what you've said to be the case BUT do you have any experience or anything other than these sources of info to call on, because after seeing liquid nitrous stay as a liquid at room temp and pressure, I'm now even more inclined to doubt what the spec sheets tell me until someone can explain to me how what I believed was impossible happened.

Maybe it's just the circumstances under which such things happen that I need more info on or maybe we think we understand something we may not.

Any help on this would be greatly appreciated.

Regards

Dixie >
Yep, you get it.
Of course, what do your guages and transducers measure in ?
Guage pressure or absolute ?

Sorry to go metric on you here, but this may help show you what a few degrees can do around the supercritical point.

20oC 50.60 BAR Abs - liquid density 786.6 Gas density 158.1
30oC 63.15 BAR Abs - liquid density 688.0 Gas density 236.7
35oC 70.33 BAR Abs - liquid density 589.4 Gas density 330.4
>>>>>>>>>Critical point<<<<<<<<<<<<
36.42oC 72.51 BAR Abs - liquid density 452 Gas density 452

Drop your launch Temperature a few degrees and you could be in for a nasty suprise, although the pressure generally drops slightly faster which would help compensate.

Nitrous is "simple", but you can see how people trip up !

Trev >
The spec sheets are right, but depend on certain constants.
Getting say 11lb of liquid nitrous upto its Tcrit takes AGES !
The bloody stuff just won't transfer heat...........

When you heat a bottle you only really heat a layer of liquid, and it's that that makes all the visible changes.

I don't say use a STABILISED bottle for fun you know
I really need to finish that little project of mine...........

Both measure in "line Pressure" - which I always 'thought' had to be the same as 'bottle pressure'.


Drop your launch Temperature a few degrees and you could be in for a nasty suprise, although the pressure generally drops slightly faster which would help compensate. [/quote]

Loopy, are you meaning if the pressure were lowered, liquid nitrous output would increase and then lean the system out? It's been my experience that with lower bottle pressures the systems simply fatten up and performance decreases - especially on the top end because the bottle pressure gets lower yet..

Absolute pressure is pressure above zero.
Guage pressure is pressure above atmospheric pressure.

Basically, i'll bet your guage is measuring pressure above atmospheric but your transducer measures pressure above zero.

I'm meaning if your temperature was lower the nitrous would be denser and would have more "effect"
Temperature and pressure are not as linked as they appear.
If you purged down from 1050psi then i wouldn't be supprised it dropped pressure faster and you went slower.
The temperature / density doesn't change that fast and only the pressure would affect the run
If you heated upto 1000psi then i'd be supprised if you weren't leaner to start with even if the pressure drop was higher.

Ever felt that Nitrogen boosting made a lot of sense ?