NOX protection

[Jmk88]

For those that like to work outside, like myself, the following will be of use.

In my last post on this I gave a link to a Honeywell filter that provides protection against NOX gases; the below link shows another filter that does the same.

https://en.safetygas.com/co-no-filter-cartridge-xplore

These have an rd40 thread and can be used with rd40 masks. I understand the oxygen content of the localised atmosphere must be a minimum of 17%.

 

[Martijn]

The oxygen content in air is 20.9%. At 17% you should not be there. With or without mask.
First of all, safety is not about getting the best personal protective gear, but about preventing exposure to harmfull substances.
If possible, use a lesser harfmful substance or a safer process.
As a last resort, one should use ppg. Like glasses and gloves. And no bare skin.

A mask with the proper filter can protect you against NO and NO2. I think NOX is a name to describe a combination of NO gases.
But, keep in mind that you don't know what concentration you are working in.
A filter I found protects up to 2500ppm. That is 0.25% by volume or mass in air, but i don't know how thick the brown toxic cloud has to be for such a concentration.
I assume you will add nitric in small increments and will not not consume pounds of metal with nitric. If you keep it small, a mask could work I guess.
I would feel trapped.
And you don't smell it until the filter gets saturated or you are working in a thick brown fog.
Once you smell old diesel engine fumes, change cartridge.
Once the sealing sticker from a cartridge is removed, the lifespan is limited. The filtermedium inside will stop working after being exposed to open air. Resealing with tape might delay this a bit, but not indefinetely.
And be sure you have the right color code on the side. I think it's the brown stripe for NO.

There are other ways of keeping NO fumes away from yourself.

Like a scrubber bubbling flask. Lots of examples here on this awesome forum.
So know what the lifespan of the cartridge is and write the date when you open it on the side. Try not to saturate the thing in one day.
Then still only use it as long as you smell nothing at all while using it.

Be safe. Martijn.

 

[jarlowski1]

The point of the mask is obviously to protect yourself from dangerous gasses, but it may also make you complacent and too bold (making you "ok" with being in that brown cloud). Like martin said there are other ways to keep yourself protected from the brown fumes like a scrubber container. For those that want to spend a little more money then you can buy a reaction vessel with 2 or more necks. 1 neck is used to connect to your scrubbing vessel and the other is used to add reactants when not in use then it has a glass stopper. Remember DO NOT heat a closed system so always allow the gasses to escape either into the scrubbing vessel or to open air. You can also use a box fan to gently push the fumes away. With the mask if you choose to go that way just be aware that if you wear it too long it can deplete your oxygen levels and could cause you to faint. Just my 2 bits worth

 

[FrugalRefiner]

Martijn, I agree with all that you posted.

A mask with the proper filter can protect you against NO and NO2. I think NOX is a name to describe a combination of NO gases.

My understanding of the term NO_x is it represents any compound with one atom of nitrogen and one or more atoms of oxygen. It can represent NO (nitric oxide), NO₂ (nitrogen dioxide), as well as N₂O (nitrous oxide). It doesn't necessarily mean a combination of gasses. It's a catch-all term to include one or more of them without having to specify.

Dave

 

[Jmk88]

Martin,

You are a good man.

Would you be able to share the filter you’ve found?

The data sheet suggests this has been tested against dioxide and monoxide. I was also going to ask for conformation that both are equally as deadly. This is available on the Scott safety pro2000 safety sheet. It’s on their website and others also share on theirs.

I can not even stand the smell of weak nitric acid and it plays on my mind all day. I like to work outside where I can and am spending a lot of time worrying. I’m a “worry-er” (sic). I don’t believe even working outside is advisable without something like this.

Thanks again.

 

[Jmk88]

And to add, sorry, it’s the blue strip on the Scott safety, Honeywell and the Dräger ranges; they are all blue and coded with NO; I understand this represents monoxide’s and dioxides.

Can someone break down the difference? Probably one for butcher. My understanding is no real difference health wise; dioxide is a decomposed nitrogen which takes place upon heating monoxide and the conversion is result of cooling?

I tend to process about 1 kilo of gold filled material which I obtain; it’s mainly copper and 925. I place a 1 litre Pyrex jug, tall one, within a steel pot which I fill with distilled water. I then place a larger pot upside down, the way nurdrage shows when he is explaining how to make dirty nitric.

I allow the initial reaction to commence and once the majority of nitric has reacted I hear to 65 degrees so to not kill the nitric and allow maximum efficiency.

This is all done in a shed with air changes of about 60l/s. I remotely operate my heat which I pre set before. I generally will wait 20 mins after turning off to remove my set up and repeat.

However, even when my nitric is cold I smell it. This worries me. I appreciate this is generally not considered a worry, as brown fumes are the concern. But I disagree with that opinion. I think, which I’ve developed based on experience, even when filtering small amounts like 300/400 ml of such solution, or AR, something should be worn even when doing such stuff. So back to the monoxide v dioxide. I view both as a concern.

I believe if I had been a younger man trying to learn this, and I had been employed by a professional, I would have been put off if I was told “not to worry”.

Sorry for the long post but I think it’s worth the input!!

Also, whilst on the subject, how does a mask that provides radioactive protection not do the same for NOX? What is the difference? I have zero knowledge of radioactive material and my preference would be that beyond safety implications; that was the case with every human. I would like my technical knowledge of this to stay as it is. But I am confused how something that protects against radioactive material doesn’t for NOX?

I have recently even put my beloved alpina (Bmw) away as since I’ve been refining, I’ve become aware of the awful stench of NOX every time I get out the thing! Another thought. Heartbreaking. I now drive around in a beat up mini. I tell people it’s my “van”. Damn NOX.

 

[Martijn]

Jm88,
Thanks for clarifying the color. That could save lives.
To aswer you question:
"The data sheet suggests this has been tested against dioxide and monoxide. I was also going to ask for conformation that both are equally as deadly. "

That would be the safest assumption.
As much as we like to educate and share our knowledge, i would suggest all (new) members to be self taught and look for known science facts in scientific and literature sources. Learn to fact check and research.
Don't overthink it. Keep it simple.
If you want good answers to questions like that: google name + MSDS.
Or searching google 'NO vs NO2' gave this link:
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.aeroqual.com/meet-the-nitrogen-oxide-family&ved=2ahUKEwiuscblwe_pAhWvM-wKHfpMDL0QFjAAegQIAhAB&usg=AOvVaw3kZ2HzixaNlLs6bJY0ScLM

What i always say: RTM!! With an occasional character added. 'Read the .. manual' 8) which unfortunately is not always practiced when dealing with dangerous substances or applying ppg against them.

Putting H2O2 in the distilled water in the stainless pot will help NO fumes oxidize better to NO2, which can then be better adsorbed in the water, making weak HNO3.
I'm sure i forgot some steps or reactions there. But it helps scrubbing the NO fumes better. Should save you some nasty smells. How much to add i'm not sure. More wont harm, i think. @3%

Now its time to have a day in the 'forest'(300*300m) with my daughter. She want to build a hut. Bushcrafts
Be safe.

 

[Jmk88]

Thanks Martijn, good man.

Enjoy the forest. I’m going to finish some silver.

 

[Martijn]

Jm88, the thing that determines what a filter can handle is the filtermedium. One kind captures only dust, another traps gases. Some do both. And there is not one that gets everything out. Or its very expensive.

When working with filters for radioactive particles i imagine that it first filters out the radioactive dust and then has some lead sheet to protect you from the radiation of the concentrated radioactive dustparticles near your face.
The combination of radioactive parts and NO is not so common, and it will not be comercially interesting to produce.

 

[rickbb]

"...However, even when my nitric is cold I smell it. This worries me. I appreciate this is generally not considered a worry, as brown fumes are the concern. But I disagree with that opinion. I think, which I’ve developed based on experience, even when filtering small amounts like 300/400 ml of such solution, or AR, something should be worn even when doing such stuff. So back to the monoxide v dioxide. I view both as a concern."....


Yes you should be concerned! If you smell acid fumes, no matter what kind, you are doing damage to your lungs! :shock:

Ventilate that shed, get or build a proper fume hood. With the correct ventilation you will smell little to no acid smell. And you won't need a respirator mask of any kind.

 

[Jmk88]

Thank you Rick.

Completely agree. However when I’ve asked people they’ve said that a smell is nothing to worry about; that smell has been used for centuries by chemists. This made me worry even more.

My shed is ventilated but like I say, even when I’m poring nitric I’m not comfortable.

I have bought the Dräger filter for 50.00£ So when I’m outside filtering or transfer it acids I will wear it. I bought the Scott sari.

I have an airvisor 2 but I don’t think it’s apt for working outside or really with gold. Although I would never get rid of it, obvious reasons.

Thank you Rick.

 

[Jmk88]

I anticipate both products arriving today and will post pics.

I will also scan the data sheets in and post.

I caught a bit of flack from a guy I know in the sense he’s saying I have wasted money. I don’t really care.

 

[Lou]

Ultimately health is your wealth.

Nitric acid is a dangerous chemical, and its reaction products from digesting metals, NO and NO2 (which NO inevitably turns into) are hazardous. My general rule is smelling it is unacceptable and seeing it is Immediately Dangerous to Life and Health.

In the US, non-combustion based sources are kept to <10 lbs per day maximum emission, at which point the source needs to be controlled with a permitted pollution control system (usually a long residence time wet scrubber using reducing basic and/or oxidizing chemistry for the NO component). You can easily build a small scrubber for not much money that will give some peace of mind and improve your air quality. Sodium sulfite/caustic soda is quite effective.

One of the things I have always championed was the use of technology and systems that prevent emissions.

 

[Jmk88]

Thank you Lou.

I also love nature and completely agree with the non emissions.

For me it’s not so much the process of using the nitric, it’s transporting it from containers and filtering etc.

Here is the ppe I’ve bought today which I understand is adequate in the context it’s meant for.

I use a Scott sari mask RD40 which is fitted with the exact filter I posted below. It’s absolutely huge.

 

[Jmk88]

Other pics.

 

[kurtak]

Hmmm - lets see here

According to the link Jmk88 posted the cost of the mask (its self) "starts" a $112 - the cost of the cartridge is $50

The cartridge "duration" time for NO/NO2 is (only) 20 minutes --- in other words after only 20 minutes (plus or minus - depending on concentration) the activated carbon in the cartridge is "loaded" with NO/NO2 & no longer effective in scrubbing the NO/NO2

After 20 minutes (+/-) you may - or NOT smell the gasses - just because you don't smell the gasses - does NOT mean it is still (effectively) scrubbing the fumes --- meaning - does NOT - mean you are working safe :!:

At $50 per cartridge with only 20 minutes use (or less depending on concentration) you are going to "need" to buy a LOT of cartridges --- to STAY SAFE :!:

IMO - if you are going to do this on a regular bases - "BUILD a fume hood & a scrubber" :!:

You can do that for about the cost of the mask & about 8 - 10 cartridges

You are then good to go for the rest of your refining days

For what its worth - those masks are NOT made for regular "working" with --- they are made for "emergence's" - such as an "unexpected" chemical spill that you need to clean up outside of your normal fume control --- as in outside of you fume hood scrubber system

Kurt

 

[kurtak]

To be more clear & add to my last post

Those mask's are made for a ONE TIME ONLY emergency use :!:

They are NOT made for regular on going "re-use" --- & should NOT be relied on for such :!:

The cartridge should/NEEDS to be replaced after each/every time it is used :!:

Again - these mask's are made (& sold) for a "one time" clean up of a spill out side of normal/actual fume control :!:

Thinking you can re-use them on a regular bases is a fools thinking --- they are NOT made for that :!:

If you are "working" with "heavy" fuming reactions - they will NOT completely protect you :!:

That's because in the case of "heavy" fuming - there is NOT enough retention time in the cartridge for activated carbon to scrub all the fumes --- in other words - with "heavy" fuming - some of the fumes are still going to by pass the carbon AND for every minute you breath through the cartridge the carbon becomes more loaded - thereby making the carbon less & less effective at scrubbing the fumes for every minute you breath through it

Also - keep in mind that other fumes/gasses are being scrubbed by the carbon - so that needs to be factored into how much the carbon will work at scrubbing the NO/NO2 --- in other words if "other" acids/chems are involved - the carbon is scrubbing those fumes as well as the nitric fumes - thereby "shortening" the life of the carbon to scrub fumes

In other words- the 20 minute time to scrub NOX applies to cleaning up a spill of nitric ONLY

if you are scrubbing reactions that involve other acid/chem fumes you are shortening the life/time for the carbon to scrub NOX

Bottom line --- these masks are NOT designed for "working" with reactions in the normal process of refining

IMO - they are a "waste" of money - other then having one on hand for emergencies - out side of that -------

BUILD a fume hood & a scrubber :!:

Kurt

 

[Jmk88]

Thanks Kurt - I take this on board.

Having spoken with the manufacturer of the filter, you are correct in that if it is subjected to constant NOX at the levels described, it would last 20 minutes.

I myself do not use this in an unventilated space; it’s mainly for when I’m transferring nitric from a drum to carboys. Also when filtering cemented silver etc.

Thank you for your advice. I think because I’ve worked with small quantities of material a fune hood hasn’t been needed. I think now I’m reaching a point where that’s not the case.

I have bought a cabinet which I intend to convert to a hood. I’m going to attach a bathroom fan to the back wall of the hood which I will feed into a caustic scrubber.

I do not stand in an enclosed space filled with NOX and think this will protect me if that makes sense?

Thanks Kurt.

 

[jarlowski1]

The fume hood is a much better way for you to go in my opinion. My suggestion is that you don't use a bathroom fan. They are not acid vapor resistant or explosion proof. Even if you end up "scrubbing" you fumes in one of the various techniques described on the forum there will still be some fumes that will be in the box from transferring hcl and nitric to the reaction vessel. There are some fans that are real cheap ($30 USD) that are both acid fume resistant and explosion proof and will put out the volume of air needed. Secondly when constructing a fume hood make it a little bigger than you think you will need it. Make sure you can pour your liquids into your filtering flask with no height issues. Your lights are also an issue as they need to be protected. I cut holes in the top of my hood and caulked a piece of glass on the inside of the fume hood this allows the lights to never be exposed to the fumes what so ever. Those are just some thoughts of the top of my head. Hope it helps you plan your build

 

[Jmk88]

Yes the chaps that come and check in on me in person now and then have said the same. They also do not endorse the mask as a full on safety provision. They do feel however it will provide decent protection for the menial tasks I have referenced. They do disagree though with the comments here regarding oxygen; they have advised me that a normal content should be 20% and to drop to 17% which is when the mask does nothing at all.

I am led to understand that a breakthrough value after 20 minutes of 5ppm is excellent In the sense that 5ppm of NOX is a considerable amount. I do not know if this is correct. But they feel the testing is robust and the exposure during such is intense and is in an enclosed space where the atmospheric oxygen content is at 17%. Apparently 5pm exposure to a human for 60 seconds is a fatal risk.

So that ties in with kurts comments really.

I am also aware that with the quantities I plan to process in the future I do not really have an option other than a fume hood. I am toying with the idea of either buying or leasing a workshop.

My preference is to have one commissioned which I’ve been quoted 1200£ for which is circa 1500$. I was told not to bother and that it is a waste of money in the regard that I could build one for a fraction of that price.