Does your nitrogen... smell?

[marru]

Im building my first unit and im using nitrogen to purge. The problem is im not happy with the results. Even though i use it, the copper pipes still oxidize a little on the inside. I use about 1.5-2 bars pressure and i find a thin layer of brown power on the inside of the brazed pipe.

Another thing that got my attention was the fact that the nitrogen had a smell. I know that we couldnt smell it since its 78% of the air. Could it be that they put a substance in it so people can sense it and not get intoxicated with it?

What do you think?

[Exahertz]

if you can smell something in the nitrogen, its not pure.

who puts scents in nitrogen?? and furthermore, what does it smell like?

[Shadowmage]

The LN2 I used had no smell

[Brettbeck]

Yea it's probably not pure, although my oxygen smells and it's from BOC. I think it might just be something on the inside of the bottle or the regulator that adds the smell. Although in saying that, i've used a full size dry nitrogen tank at a refrigeration shop and that didn't smell at all.

Where did you get your nitrogen from?

[n00b 0f l337]

Not pure, nor should it be chemically signatured for a smell.

[Athanatos]

i've noticed a weird smell when i installed a few lennox a-coils that they use to keep pressure inside

[Ssilencer]

My nitrogen only smells when I'd being eating too much beans and I need to blame something else.

[BenchZowner]

My nitrogen only smells when I'd being eating too much beans and I need to blame something else.

LOL.

No smelly LN2 here as well ( and yes, my nose is fine :p: )

[1badhabit]

My nitrogen only smells when I'd being eating too much beans and I need to blame something else.


heh, good one.

But yeah, I use a Self Generating Nitrogen Cart (SGNC) at work, 99.8% pure, and there's no smell.

[Ssilencer]

heh, good one.

But yeah, I use a Self Generating Nitrogen Cart (SGNC) at work, 99.8% pure, and there's no smell.

Hey, look what I got out of my nitrogen cylinder!

http://img522.imageshack.us/img522/6364/dscn0737rr6.jpg

Looks like your front panel grill for your soon to be released MCT 2007 model unit
:rofl:

[1badhabit]

Hey, look what I got out of my nitrogen cylinder!

http://img522.imageshack.us/img522/6364/dscn0737rr6.jpg

Looks like your front panel grill for your soon to be released MCT 2007 model unit
:rofl:



Woot, cant wait!!

[tim-]

nitrogen doesn't smell, then it's something else you're using. if isn't clean on the inside you got oxygen in the pipes while brazing.

those days oxygen normally has added aroma for security reason. Aga call it odorox. Maybe other suppliers call it something else but i don't think they use any other word.

if you're using nitrogen while purge you use specific flow, not pressure.

I would recommend argon/mison gases for purge as it's made for that.

[wdrzal]

did you buy a bottle of compressed air???????????????

[ineedaname]

Like you said they probably added in a smell so you know if you have a leak.

The fact that ur copper is oxidizing means that its not pure anyway.

I'd definitely try 2 get some nitrogen somewhere else.

[{.bLanK} GoD]

if you're using nitrogen while purge you use specific flow, not pressure.

Wow, 12 posts before somebody mentioned that.
You measure how much gas to to while purging in "Liters per hour" which is flow.
Depending on how big the pipe is and how many open ends you have, you only want somewhere around 1 - 5 liters per hour for our size systems.

This is what a flow meter looks like.
http://justchillin.co.nz/pics/2007%20x3%20Build/THUMB_Flow%20meter.jpg (http://justchillin.co.nz/pics/2007%20x3%20Build/Flow%20meter.jpg)

Alternatively, you could bro one up with a length of cap tube connected to your nitrogen regulator on very low pressure. <30 psi.

And yeah, nitrogen has no smell to it. When purging, you can sometimes smell a tiny something, but thats being picked up from inside the system. (moisture, traces of refrigerant vapor etc) barley even noticeable tho.

[mytekcontrols]

Just wanted to add one more possibility for the non-clean copper after purging. If the connection points where you are purging are not air tight, and/or you have very large openings up stream of where you are brazing, there is a chance that you are drawing in air along with the nitrogen (like an aspirator... see example below... imagine what is shown as air in the diagram is your nitrogen purge, and the water represents the outside air). This is also why it is important to start brazing close to the purge entrance, and then braze each joint that follows along the path of the purge.

As for the smell; I sometimes notice almost a mothball like odor when I first purge a freshly opened piece of copper tubing. This I believe has something to do with the process or chemicals used in the dehydration process. Is this the type of smell you are noticing?

[wdrzal]

nitrogen is colorless,tasteless,odorless, but MOST people think nitrogen is a Inert gas which it is not.

[n00b 0f l337]

Your right walt, its not, but its cheap, the industrial standard, and DRY!

[- Feedback]

nitrogen is colorless,tasteless,odorless, but MOST people think nitrogen is a Inert gas which it is not.

O2 + N2 + (1600+°C) = NOx :smoke:

[marru]

who puts scents in nitrogen?? and furthermore, what does it smell like?

Its hard to make out the smell and im not an expert, it has a weird... metalic smell. It also reminds me a little of the gas stove, which made me think they put scents in it.


Where did you get your nitrogen from?

Well im from Romania so i dont think it matters to you guys. I filled the nitrogent tank the same place i bought it. Definitely i wont use their services again.

Wow, 12 posts before somebody mentioned that.
You measure how much gas to to while purging in "Liters per hour" which is flow.
Depending on how big the pipe is and how many open ends you have, you only want somewhere around 1 - 5 liters per hour for our size systems.


I said pressure because thats what my regulator shows :p:

did you buy a bottle of compressed air???????????????

Definitely not :)


Ill be changing the nitrogen monday at another place. Thanks guys.

[mytekcontrols]

As a follow up to wdrzal's statement:
nitrogen is colorless,tasteless,odorless, but MOST people think nitrogen is a Inert gas which it is not

I quote the following from the Universal Industrial Gases site:
Nitrogen (N2) is a colorless, odorless and tasteless gas that makes up 78.09% (by volume) of the air we breathe. It is nonflammable and it will not support combustion. It is colorless, odorless and tasteless.

Nitrogen gas is slightly lighter than air and slightly soluble in water. It is commonly thought of and used as an inert gas; but it is not truly inert. It forms nitric oxide and nitrogen dioxide with oxygen, ammonia with hydrogen, and nitrogen sulfide with sulfur. Nitrogen compounds are formed naturally through biological activity. Compounds are also formed at high temperature or at moderate temperature with the aid of catalysts. At high temperatures, nitrogen will combine with active metals, such as lithium, magnesium and titanium to form nitrides. Nitrogen is necessary for various biological processes, and is used as a fertilizer, usually in the form of ammonia or ammonia-based compounds. Compounds formed with halogens and certain organic compounds can be explosive.

Nitrogen condenses at its boiling point, -195.8o C (-320.4o F), to a colorless liquid that is lighter than water.

Gaseous nitrogen is valued for inertness. It is used to shield potentially reactive materials from contact with oxygen.

The inert properties of nitrogen make it a good blanketing gas in many applications. Nitrogen blanketing is used to protect flammable or explosive solids and liquids from contact with air. Certain chemicals, surfaces of solids, and stored food products have properties that must be protected from degradation by the effects of atmospheric oxygen and moisture. Protection is achieved by keeping these items in (under) a nitrogen atmosphere. "Inerting" or "padding" are other terms used to describe displacement of air and nitrogen blanketing.

marru said... Its hard to make out the smell and im not an expert, it has a weird... metalic smell.

Actually that is a very good description. I have also smelled something like this at times, and assuming we are smelling the same thing, it probably can be attributed to the materials you are purging with the N2. If it were a scent that had been intentionally added to the gas cylinder, it would not simply smell "metallic", and instead be something very revolting that would definitely catch your attention.

If the smell originates directly from the gas cylinder, then I have no reasonable explanation :shrug:

[tim-]

if you're using inert gas you have to flush it with pretty high flow before brazing and then stepp down to the recommended 5-6L/min.

I don't know what flow you should have when using nitrogen, proberbly a bit higher 'cause it's not an inert gas a mention before.

[wdrzal]

NOx is nitrates of oxide while not needed in residential combustion tests, is is part of all industrial power plants for large buildings or fossil fueled power plants. mostly tested for & used in the combustion of fossil fuels world, and chemical engineering world.