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Thread: making your own fog juice?

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    Quote Originally Posted by cipher0 View Post
    You claim how acrolein can be generated from glycerin, but do you know all the conditions needed for that to occur?
    Yes I do. As would anyone who has taken a 1st year class in organic chemistry. Sugar alcohols break down readily in the presence of HEAT. Admittedly, I had to look up the exact temperature for Glycerin (280 degrees C, by the way), but I knew it was well within the range of the heating element of a fogger.

    Do you know if a fog machine provides those conditions?
    Yes, I do. The temprature switches on my foggers kick OFF at 400 degrees C. How do I know? I own 7 fog machines, and I've had to replace two temperature switches so far. To do that, I had to look up the part number to get the spec. (for what it's worth, Digikey and Mouser both sell them)

    For the record, several other people mentioned thermal decomposition products as well, though admittedly apart from mixedgas and Zorn, I don't think anyone else mentioned Acrolein by name. (then again, it had already been mentioned, so others may have well thought the issue settled.) However, the point still stands that this is something that was talked about back in the first page of posts in this thread. (Something you keep ignoring.)

    And kecked's tests didn't show acrolein or anything hazardous being generated either.
    Show me where Kecked stated that he heated glycol and then measured the resulting decomposition products with a GC head-space analyzer that was calibrated to detect Acrolein. I dare you.

    I'm arguing with you and your friend whose in the business of "bottled tap water" who comes here and scares and disrespects people.
    What the fuck are you talking about? I don't sell bottled tap water, nor do any of my "friends". If you knew anything about me or my past work history, you'd know that I've never been a supporter of the bottled water industry! (Talk about a straw-man!) For crying out loud - I worked in the high-purity water industry (albeit for industry, hospitals, and labs) for 3 years. Why in the HELL would you think I was a fan of bottled water? Sheesh!

    More to the point, you're arguing a point on which it is demonstrably clear that you have zero experience or education in. So please do everyone here a favor: take 15 minutes to educate yourself before you post again.

    So telling people to not use homemade glycerin fluid while being okay with them using commercial fluid is illogical.
    Serious question here: Are you trolling? Because if so, you've won the kewpie doll, and I think it's time to stop.

    If you aren't trolling, then you are completely clueless when it comes to chemistry (as in, flunked out of first-year high school chemistry), and have no business arguing these points.

    A commercial fog fluid will *NEED* stabilizers, preservatives, emulsifiers, and/or chelating agents added to it to prevent exactly the sort of hazardous by-products that we are discussing here. We do not know what they are (though there has been some speculation), nor is there an easy way to discover what they are, not to mention their concentration. This has already been discussed at length in this thread. However, even more important is the fact that HOME-MADE FLUIDS WILL NOT HAVE ANY OF THESE AGENTS.

    If commercial fog fluid was hazardous to use in a fog machine, it would have been taken off the market years ago. The risk is in your assumption that because you can identify one or two key ingredients, you have suddenly solved the whole mystery and can re-create it at home in your kitchen sink with no risks.

    Adam

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    Quote Originally Posted by buffo View Post
    Yes I do.
    So you just googled the temperature of Glycerin and now you think you know all you need to know, and don't need to be a chemist for that. Totally not contradicting yourself.

    For the record, several other people mentioned thermal decomposition products as well, though admittedly apart from mixedgas and Zorn, I don't think anyone else mentioned Acrolein by name. (then again, it had already been mentioned, so others may have well thought the issue settled.) However, the point still stands that this is something that was talked about back in the first page of posts in this thread. (Something you keep ignoring.)
    Oh I'm not ignoring this fact.
    But like someone said here, "In reality if a machine was running hot enough to burn glycerol then it would also probably burn the other glycols". But of course I can't say that because I'll be pretending to be a chemist. Only you're allowed to do that here.

    What the fuck are you talking about? I don't sell bottled tap water, nor do any of my "friends". If you knew anything about me or my past work history, you'd know that I've never been a supporter of the bottled water industry! (Talk about a straw-man!) For crying out loud - I worked in the high-purity water industry (albeit for industry, hospitals, and labs) for 3 years. Why in the HELL would you think I was a fan of bottled water? Sheesh!
    I didn't mean it literally. In a metaphorical way. How stupid can you get? :/

    A commercial fog fluid will *NEED* stabilizers, preservatives, emulsifiers, and/or chelating agents added to it to prevent exactly the sort of hazardous by-products that we are discussing here. We do not know what they are (though there has been some speculation), nor is there an easy way to discover what they are, not to mention their concentration.
    Sure, top secret formulas. Right, right.

    If commercial fog fluid was hazardous to use in a fog machine, it would have been taken off the market years ago.
    Bingo!
    That's why I'm saying, for the 67th time, that's enough evidence by itself that glycerin fog juice is harmless. Or if it isn't, it's illogical to be against it and be all for glycols, or be against any homemade fluid and be all for commercial ones when they use the same chemicals in them.

    Show me where Kecked stated that he heated glycol and then measured the resulting decomposition products with a GC head-space analyzer that was calibrated to detect Acrolein. I dare you.
    I'll show you what I've said Kecked has done (for the second time that is):
    Quote Originally Posted by kecked View Post
    Ok finished tests at lunch. Using glycerine in a viper fog machine 30% 70% water it made a fog that was kind of boring and more like a smoke. It smelled bad as well. There was no formaldehyde, acetaldehyde, or acrolein measured. I have been collecting the polymers if they exist for about 3 hours. I will do the extraction and nmr after work today. So far nothing is seen but the fog sucks and stinks. A preliminary filter showed nothing but excess glycerin on the filter.
    Last edited by cipher0; 06-12-2014 at 11:33.

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    Cipher-0

    If your willing to bet your own life on a single point scientific test with no peer review, be my guest. The rest of us , who are quite a skilled bunch, prefer to go with the industry accepted norms and not use a outdated solution nor assume there is no risk. We also know that MSDS in the US come with rules allowing trade secrets and not requiring the declaration of certain trace additives, or that companies would evaluate the risk of detection and not declare the additives on the MSDS.

    The industry as a whole has moved off of Glycerin and onto Dihydric and Trihydric Glycols. A 1989 MSDS from ADJ is back when Glycerin would be in use, prior to the development of more modern mixtures.

    Kecked was kind enough to run a single point test, but to use that data point it would need to be verified in a independent lab on a second set of machines, and over a long period of time, to verify a hypothesis. The accepted methodology of the "Scientific Method" requires that result to be validated by more tests. Even if its verified that there is no Acrolein or acceptable amounts of Acrolein present, it is still only verified for one type of fluid and one machine

    You are quite a skilled debater (someone has trained you well in philosophy of debate) but you seem to be untrained in science and engineering. Your use of a single data point argument certainly verifies that fact. Basic engineering ethics requires more then one test and preferably more then one methodology.

    So while you personally are allowed to argue from a single point of data, those of us who have undergone lab safety training, will not accept that as a basis of proof. We're happy that Kecked ran the tests, but we also know that without exposing the same detection machine to a small known dose of Acrolein, Kecked can only say what he did, he detected no Acrolein. He did not mention running a control group to verify the machine. It is a technicality, but for a formal test there must be a control group of samples or a calibration ran. You will find that is a requirement in the published tests for Acrolein.

    Kecked did nothing wrong, part of his job is to rapidly assess many thousands of hazards and possible hazards on a huge campus while remaining within a budget. For that reason he has access to a modest amount of instruments.


    We have three points of data we do know: 1. Most fog machines have heaters in them that operate significantly hotter then the temperature known to 'crack" Glycerin to Acrolein. 2. We know that Acrolein can be formed at ~280'C from the wiki, which has cited peer reviewed sources proven true by scientific method. We know that the ANSI Standard for the fluid mentions that the machine and fluid combination must be designed so as to not produce Acrolein and two other compounds.

    Since those compounds are mentioned in the standard, that means it is fairly easy to make Acrolein in this type of machine, or the standards committee would not be warning systems designers to check their new designs for these byproducts. Buffo's argument that Acrolein production is possible at low temperatures is thus supported by the peer reviewed ANSI standard.

    All ethical manufacturers caution that only their approved fluids are known to be safe in their machine, and now you know why.

    You cannot make the unsupported statement that Glycerin and the Glycols are chemically close enough that they will react the same in in any given machine. You have no peer reviewed proof that this is so.

    By your argument method, I could equally argue that since some MSDS for Water state you can aspirate it into your lungs or submerge yourself in it and drown, such that all quantities of Water are hazardous.

    Case closed.

    Steve
    Last edited by mixedgas; 06-12-2014 at 13:01.
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    Hey Zorn,

    Download "The Introduction to Modern Atmospheric Effects, Forth Addition" here:

    http://tsp.plasa.org/tsp/documents/published_docs.php

    If you would like some more technical reading, get the two documents titled:

    Theatrical Fog Made with Aqueous Solutions of Di- and Trihydric Alcohols


    Since we last have talked, I have done research and learned a few new things:

    The difference lies in what is considered Smoke and Fog.

    Smoke in this case is the decomposed product of a chemical combustion reaction between one, two, or more chemicals.. Fog in our discussion is the product of completely vaporizing a fluid at a low enough temperature that it does not decompose and break into combustion products. A good FOG fluid does not get burned or cracked into toxic smoke.. Your Fog machine is running at a average chamber temperature close to the temperature where some fluids could or would decompose into smoke. Parts of the chamber are well above the point where decomposition occurs.

    So the chemicals in the fluid are picked for minimum decomposition at a given chamber temperature.

    If you use Glycerin, it breaks down at a much lower temperature (280'C) then PG and the other five legal chemicals. So you want to make Fog, but you do not want to make any hazardous smoke or small droplets of a hazardous byproduct.

    The fog chamber is heated to well above 280'C to store energy in the chamber walls and heating elements when not making Fog. So until the chamber is filled fully with vapor and its temperature is reduced to below 280'C, you can produce Acrolein, when glycerin is present. When the vapor has passed out of the chamber and the machine is heating back up, any residual fluid in the chamber will chemically "crack" or burn with incoming air. So fluids are chosen to have minimal reaction at chamber pressure and when the chamber is empty and very hot.

    That's why pure glycerin is no longer used. Now mixtures of fluids are used that have are tested for safety and optimized for the best droplet distribution. They are chosen for a high optical index of refraction so they scatter more light.

    This whole thread has become one person arguing that there is no byproduct from Glycerin , when in fact one can be easily made.
    What he is probably missing is that tests done in the 1980s and Early 1990s, pre-internet, often never make it on line.

    So if the temperature controller on your fog machine breaks, and stays heating, you end up making some really toxic materials. During operation it makes minimal amounts of these materials if used with the fluid it is designed for.

    Pure Glycerin in water is likely to make at least some small amount of the toxin Acrolein. If the amount is very tiny enough to be diluted by the air in your venue, your safe. So the unknown variable is how much Acrolein is made in a given machine when used with non-standard fluid.

    If a FOG machine malfunctions or runs with the wrong fluid, it will possibly become a SMOKE machine.

    It can be argued that lower boiling point materials remove the stored heat from the chamber walls quickly, the chamber thus drops to a temperature not much higher then , or equal to the boiling point and thus any chemical reaction is slowed or stopped.

    An excellent machine will have thick chamber walls to store residual heat and a very good temperature controller keeping the chamber below the maximum listed in the ANSI standard. A cheap machine will have a red hot coiled heating element and will produce a small amount of burning until the element is cooled below a certain temperature when a burst of FOG is created, Steam trapped in the chamber will delay any burning until all the steam has left the nozzle.

    Hope that helps explain the arguments in a nutshell.

    Steve
    Last edited by mixedgas; 06-12-2014 at 14:04.
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    Quote Originally Posted by cipher0 View Post
    So you just googled the temperature of Glycerin and now you think you know all you need to know, and don't need to be a chemist for that.
    No. I admitted I wasn't a chemist, which is why I had to look up both the decomposition temperature AND the AMRL for Acrolein. But I was aware of the basic cracking process, AND the fact that Acrolein was toxic.

    In case you haven't been paying attention, it's been stated above more than once that I work at a multi-divisional chemical manufacturing plant, and have done so for over 2 decades. I'm no research chemist, but I am quite familiar with basic amines, aldehydes, ketones, aramids, and other volatile organics. In my tenure I've worked with many hazardous chemicals, including benzyl chloride, methyl chloride, cyanuric chloride, sodium mercaptobenzothiazole, tertiary butylamine, trimethyltin (dissolved in pure pentane, no less), para-cresidine, and even methyl isocyanate (which, if you don't know chemistry, you should at least remember from your history lessons of the Bhopal disaster).

    Bottom line: I'm no dumbass when it comes to organic chemistry. It's literally what I work with every day. And even so, there are people here (like Steve Roberts and Mark Rubin) who have knowledge that vastly outpaces my own.

    Now that all that is on the table, please enlighten us as to your chemistry background. (If any...)

    But like someone said here, "In reality if a machine was running hot enough to burn glycerol then it would also probably burn the other glycols".
    Absent a stabilizing agent, this is 100% true. Although due to the relative lack of free oxygen in the heater, cracking is a bigger concern that true burning. (Even though burning does sometimes still occur, especially if the high-temp cutout on a heater fails.)

    But of course I can't say that because I'll be pretending to be a chemist.
    Do you have any real-world experience in chemistry? Have you had any training in chemistry? Did you take two semesters of organic chemistry in college? Do you work for a chemical company? Are you HAZWOPER trained? If the answer to any of these questions is yes, then I would say you have the right to say something about this topic, regardless of whether you have a degree in chemistry or not.

    But you haven't provided any indication that you fall into any of those groups. In fact, your comments in this thread betray a shocking lack of knowledge when it comes to even BASIC chemistry, let alone organic chemistry. *THAT* is why I accused you of pretending to be a chemist.

    Now, regarding your "bottled water" comments...
    I didn't mean it literally. In a metaphorical way. How stupid can you get? :/
    Not nearly as stupid as you are, apparently. We are discussing matters of FACT, not metaphor. If you want to accuse someone of something, you'd better be able to back it up. Otherwise shut the fuck up already. I've laid my bonifides on the table. I'm still waiting for yours.

    regarding the comment that commercial fluid is safe:
    That's why I'm saying, for the 67th time, that's enough evidence by itself that glycerin fog juice is harmless.
    Wrong. Because you can't reproduce the stabilizing and/or scavenging agents in that commercial fluid that either inhibit acrolein production (by shifting to a more favorable decomposition product) or react with it as it's produced to further oxidize it to something less toxic.

    if it isn't, it's illogical to be against it and be all for glycols,
    Glycols are demonstrably safer than glicerols, even if they still carry some risk. You have a habit of excluding the middle position - a common logical fallacy.

    or be against any homemade fluid and be all for commercial ones when they use the same chemicals in them.
    False dichotomy. The commercial fluids are known to contain at least some buffers and stabilizers. It's foolish to think that they would sell a fluid containing glycerin without addressing the risk that acrolein poses.

    I'll show you what I've said Kecked has done (for the second time that is):
    I have been collecting the polymers if they exist for about 3 hours. I will do the extraction and nmr after work today.
    Did you miss that second part? Where he said he would do the extraction later and run it on the nuclear magnetic resonance instrument? Now, if you had even a thimble-full of knowledge about organic chemistry, you would understand that THIS is the part where he would detect the acrolein. And until we see that data, I remain utterly unconvinced. Because the physical conditions necessary to create it damned sure exist inside every fog machine I own.

    Zorn:

    Your recent questions are well-thought out and asked with care, so please allow me to respond.

    First, even though glycerin may have been used in the past (and/or could still be in use by some bargain fluid companies), there are additives that can mitigate the risk of acrolein production. Off the top of my head, I think just about any thiosulfate salt would work, although this would tend to make the fog smell like a fart! (No, really, I'm serious! Sulfonated organics really stink!) Nitrate salts would probably be a better choice, so long as you could prevent the generation of gaseous NOx. Kecked and I actually kicked this around briefly in an earlier section of this thread. The problem is knowing which one and how much... So while it might be safe in a commercial solution, trying to re-create it at home is much more difficult and time consuming. Could it be done? Eventually, sure. But it's almost certainly not worth the time, or the effort, or the risk if you get it seriously wrong.

    With regard to why they've moved to glycols, I'm sure the decomposition of acrolein is a factor, but there are others to consider. It may well be that a glycol solution produces better fog. (I don't know for sure myself.) Likewise, it's possible that due to changing economies, glycol is now cheaper. (I don't have any hard data on bulk prices for either chemical, so I fully admit that this may not actually be the case. It's just one of many possible explanations.) One reason that seems obvious to me is that - regardless of the decomposition temperature - it's still easier to manage the decomposition products of glycols because they're not as toxic as acrolein or it's esters, which is what you get when glycerin cracks.

    About that decomposition temperature, I've had difficulty finding much information on it, but from a chemical standpoint it should break down at or near the same temperature as glycerin does. (The molecules are similar in structure and bond arrangement, so there's nothing that stands out as making one far more robust than the other.) I know that the DOW-THERM heating and cooling oil we use at several facilities in the plant where I work has a working temperature limit of around 150 degrees C, which seems an adequate safety margin if the decomposition temperature is close to that of glycerin. However, I seem to recall that most of the glycol esters have much higher decomposition points. I just can find the data...

    This article suggests that mono-propylene glycol (an exceptional case with no other esters present) starts to decompose at 230 degrees C, but I can't back that up with any other data... And again, a mix of ethylene and propylene glycol would likely have a much different decomposition temperature, because once you get to around 250 degrees C, you've got lots of other polymerization reactions going on at the same time. (Long story short - organic chemistry is hard!)

    As for the more basic question of how a fog machine works - it's a lot like cooking in your kitchen. If you put some cooking oil in a pan and turn up the heat, you'll notice the oil starts to smoke as it gets hot. What you are doing is breaking down (decomposing, or "cracking") the oil into other compounds. Usually, the decomposition products will be simpler molecules, but in some special cases you can get a polymerization reaction going that creates longer chains of hydrocarbons (and other molecular groups) yielding some complicated (and quite often toxic) substances.

    In a fog machine, the aim is to atomize, (and possibly very gently crack the fluid - albeit carefully), under a narrow (but high) temperature range, to create small particles (usually in the 20 to 100 micron size range) that are then driven out of the heater by the steam pressure of the water in the fluid that flashes to steam as the mixture is pumped through the heater. Of course, beyond the fog agent (be it a glycol derivative, a glycerin, or some other hydrocarbon) and the water, there are going to be stabilizers, preservatives, and possibly other agents to maintain the mixture in solution. (Things like chelating agents, coagulants, or emulsifiers, for example.) All of these elements can (and will) react with each other at the high temperatures found inside the heating element.

    I hope this helps you to understand the problem.

    Adam
    Last edited by buffo; 06-12-2014 at 14:26.

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    Oh, finally some logic and facts. I like that. Okay, let's discuss:
    Quote Originally Posted by buffo View Post
    No. I admitted I wasn't a chemist, which is why I had to look up both the decomposition temperature AND the AMRL for Acrolein. But I was aware of the basic cracking process, AND the fact that Acrolein was toxic.
    Did I say I wasn't aware of cracking? No, I didn't.
    My point was, which I've repeated several times already, that I don't see a reason to be okay with glycols but say glycerin is harmful.
    The same cracking happens to propylene glycol right? I myself couldn't find the temperature at which it happens, but it's boiling point is lower than glycerin's and like you seem to agree the cracking temperature is also likely to be close to it, not way higher.

    I've also been thought that cracking happens in very high pressures and in presence of catalyst. Has this been discussed in this thread and I've missed it?
    Because up until now I've completely ignored this.

    Now that all that is on the table, please enlighten us as to your chemistry background. (If any...)
    You Seem to know logic. So you know this question is pointless. I don't need to have any chemistry background, because I'm only using the facts you guys mentioned and explain the conclusion reached by using those facts is wrong (to those who are antiglycerin, proglycol when it comes to homemade fluids)

    Not nearly as stupid as you are, apparently. We are discussing matters of FACT, not metaphor. If you want to accuse someone of something, you'd better be able to back it up. Otherwise shut the fuck up already.
    Yeah okay, I can't prove it. Unfortunately. So you work in a chemistry facility, with degree in computer science and ,correct me if I'm wrong, also work as a laser safety officer, and have no gain in this, and I got the completely wrong impression that your initial posts were disrespectful, off-topic and had little facts and buried the posts by others which were giving us facts about what commercial fluids have in them, which I wrongly assumed only someone wanting to hide the truth would do. Okay, I'll shut up and assume that.

    Because you can't reproduce the stabilizing and/or scavenging agents in that commercial fluid that either inhibit acrolein production (by shifting to a more favorable decomposition product) or react with it as it's produced to further oxidize it to something less toxic.
    Okay, good point, and I'll admit I missed it in all this flaming.

    Glycols are demonstrably safer than glicerols, even if they still carry some risk.
    Can you explain how safer they are? We have a person with propylene glycol in his hands right now using it as fog juice.

    Did you miss that second part? Where he said he would do the extraction later and run it on the nuclear magnetic resonance instrument?
    I did see that his experiment was incomplete and that he had said he hadn't found anything *so far*. And I did say I hope to see him continue the experiment. But him being a chemist and reporting no acrolein at that point kind of means that was also "the part where he would detect acrolein".

    Okay, lets get back to the point I waited for the most:

    stabilizing and/or scavenging agents in that commercial fluid that either inhibit acrolein production


    So now you say both glycerin and glycols likely can decompose in high temperatures inside fog machines and all fog juice manufacturers add extra chemicals to prevent or reduce that.

    Two issues I see in an answer like this:

    1) How can we know a commercial fluid uses anything like that at all, if they are all top secret formulas?
    Because I didn't feel the nasty smell of acrolein at all when I tested both glycerin and propylene glycol. And I didn't notice any coloring either.
    At this point why should I trust a corporation and government and believe its not simply selling me tap water, because I have no way to know this myself?

    2) I think saying a fogger can reach 400C and glycerin cracks at 280C and say done is a "bit" hasty.
    Acrolein smells really bad from what I know. How come I dont sense it?
    But what if, there's no Acrolein to begin with?
    Adding to what I said previously,
    What if the part of the fogger which reaches those temperatures doesn't contact the fog fluid directly and/or long enough to make it as hot as itself?
    What if the glycerin/glycol is pushed out of the fogger before it has time to reach that temperature? By the way, this is actually what I've been told in real life. Fog juice is mostly (usually) water, it's not just glycerin/glycol, let's not forget that.
    Can anyone answer these? Do you also know exactly how foggers work inside? Please enlighten us.
    Last edited by cipher0; 06-13-2014 at 01:08.

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    If it did make the fluid/fog so hot, wouldn't I burn my hand by just holding it close to the nozzle as the fog is coming out?
    Have you ever held your hand close to the nozzle as the fog is coming out?

    In my experience, very close to the nozzle it is in fact very hot, but given the small droplet size, and passing through the ambient air at speed (and potentially a pressure drop too) they cool very quickly.
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    I thought it fitting, considering the rocky terrain.

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    Quote Originally Posted by cipher0 View Post
    I don't see a reason to be okay with glycols but say glycerin is harmful.
    You are excluding the middle. This is not a binary solution set. Glycol is *less* risky than glycerin, but the risk is not zero. For one, glycol by itself is mildly toxic in it's natural state, where as glycerin is not. Also, absent any stabilizing agents, glycol can still decompose to hazardous substances. It's just that the decomposition products for glycol are not nearly as toxic as acrolein is (which is what you get when glycerin decomposes).

    This doesn't mean anyone is "OK" with glycol, absent a stabilizing agent. There is still some risk involved. It's just a lot *less* risky that glycerin.

    The same cracking happens to propylene glycol right?
    Yes, absent a stabilizing agent. In theory, it should be at or near the same temperature. Like you, I've had difficulty finding hard data on the exact temperature though.

    Another complicating factor is that when you have multiple esters of glycol, they can interact with each other at high temperatures, which can raise or lower the decomposition temperature. (The great thing about organic chemistry is also it's biggest hurdle. You can make *lots* of different things, but sometimes it's hard to make just the compounds you want without anything else competing for the reactants.)

    I've also been thought that cracking happens in very high pressures and in presence of catalyst.
    High temperature is the only ingredient needed to initiate cracking. However, high pressure and the presence of a catalyst can greatly speed up the reaction and also shift the reaction towards specific types of byproducts. For example, the petroleum industry has spent billions researching the optimal cracking conditions for crude oil, to the point that we can now extract upwards of 21 gallons of gasoline from a barrel (42 gallons) of oil, whereas without advanced catalysts the nominal yield for a fractionating tower is around 11 gallons of gasoline for a barrel of crude. (An improvement of nearly 100%.)

    Regarding my previous remarks about your apparent lack of knowledge when it comes to chemistry...
    You Seem to know logic. So you know this question is pointless. I don't need to have any chemistry background, because I'm only using the facts you guys mentioned and explain the conclusion reached by using those facts is wrong
    Here's the problem with your line of thinking: You are drawing conclusions based on your incomplete understanding of chemistry. But this is not binary logic, where something is either true or false. This entire discussion revolves around risk reduction, which is by definition an analog process. Furthermore, you continuously propose false dichotomies (such as "it's illogical to be against glycerin and for glycol", or "You can't be against glycol and glycerin in home-made fluids and for commercial fluid, because they use the same chemicals") without acknowledging the other differences (discussed ad naseum above) with regard to additional elements that are added to commercial fluid.

    Put another way, you are trying to take a qualitative analysis of the problem and draw quantitative conclusions from it. With some valid assumptions and a healthy chemistry background, that is possible to an extent, but there's no way the layman should be trying it. As mentioned above, organic chemistry is hard (and very complicated).

    you work in a chemistry facility, with degree in computer science and ,correct me if I'm wrong, also work as a laser safety officer, and have no gain in this
    Correct. Thank you for acknowledging this.

    Regarding stabilizing agents...

    Okay, good point, and I'll admit I missed it in all this flaming.
    Fair enough. I admit that it's easy for me to miss facts when my emotions get the best of me too.

    Regarding the relative safety of glycol compared to glycerin:

    Can you explain how safer they are? We have a person with propylene glycol in his hands right now using it as fog juice.
    We know that glycerin will decompose to acrolein, which is very toxic even in ridiculously low concentrations. So that's something we really want to avoid. We also know that ethylene and propylene glycol will not produce acrolein, so that's a good start.

    However, propylene glycol decomposes to lactic acid, oxalic acid, and formic and acetic acid (vinegar). Ethylene glycol follows a similar decomposition pathway, with the difference that oxalic acid is the main product, and lactic acid is not normally produced.

    Now, oxalic acid isn't wonderful. It's corrosive and toxic. It's also an eye, skin, and respiratory irritant. But that's not as terrible as it sounds. They actually sell it at Wal-mart for cleaning the scum off the hulls of boats. (It's good for cleaning the concrete around your swimming pool as well.) Still, it's still something you need to watch out for. But by adding a weak base to your fog solution, you can tie up these organic acids as they are formed so they don't get into the fog that is sprayed into the air. (Note: you don't want to use a strong base like sodium hydroxide, because that would tend to come out of solution and scale the inside of the heating element.)

    Bottom line: if you had to choose between dealing with oxalic acid or acrolein, you'd want to pick the oxalic acid. For one, it's easier to remove, and in any case it's still far less toxic than acrolein is.

    How can we know a commercial fluid uses anything like that at all, if they are all top secret formulas?
    We don't know the exact chemicals used, but we can infer a lot from how the solution performs. But yes, we are taking a lot of it on faith. The driving force, of course, is corporate liability. If they didn't take precautions, they could be on the hook for tremendous fines (not to mention lawsuit payouts). Absent a detailed list of the ingredients with their formulas and concentrations (which we'll never get), all we have to go on is the generic comments on the label that list "other" as one of the ingredients. That's where your stabilizing agents are.

    I didn't feel the nasty smell of acrolein at all when I tested both glycerin and propylene glycol. And I didn't notice any coloring either.
    You shouldn't see any color change, especially at the concentration levels we're discussing. And there's no way the human nose will detect acrolein (or any other chemical) at 3 parts per billion (which is the AMRL, remember). Bottom line: if you can smell it, you are already WAY over the limit. (By several orders of magnitude)

    At this point why should I trust a corporation and government and believe its not simply selling me tap water, because I have no way to know this myself?
    Perhaps the regulations are different where you live. But in the US, most companies take the approach that it's better to perform the due-diligence up front rather than dealing with the legal fallout later. We are a litigious society, and corporations know that. Furthermore, our government has set rigid standards (some of which are ridiculously complex) for chemical safety. The penalties for non-compliance are steep. Thus, it's better for everyone to play by the rules - especially when you're talking about chemical safety in a consumer product.

    I think saying a fogger can reach 400C and glycerin cracks at 280C and say done is a "bit" hasty.
    The point is that you don't need much cracking to make enough acrolein to be in trouble. (just 7 micrograms per cubic meter of air) Remember this stuff is highly toxic. From a risk-analysis standpoint, this is well into the danger zone.

    Acrolein smells really bad from what I know. How come I dont sense it?
    Because your nose isn't sensitive enough to detect things in the part-per-billion range.

    What if the part of the fogger which reaches those temperatures doesn't contact the fog fluid directly and/or long enough to make it as hot as itself?
    The fluid does contact the heater. Directly. It is absolutely exposed to the maximum heating element temperature. In fact, the inside of the heater is the hottest part. The temperature switch is on the outside. So when the high-temp switch opens, the middle of the heater is probably well above that temperature.

    Regarding the time factor, what happens when the pump stops? The fluid still in the heater (that hasn't flashed yet) sits in there and cooks. That's when you're most likely to create acrolein. (Absent some mitigating agent, such as a stabilizer, that is.)

    What if the glycerin/glycol is pushed out of the fogger before it has time to reach that temperature?
    See above - the fluid is not in constant motion through the heating element. When the pump is off, the fluid sits there until it boils and/or cooks.

    Fog juice is mostly (usually) water, it's not just glycerin/glycol, let's not forget that.
    The example I used for my calculations assumed just 10% glycerin. Most home-made recipes I've seen on the Internet use more - up to 30%. So yeah, I took that into account.

    Do you also know exactly how foggers work inside?
    Fog machines are incredibly simple devices. You have a heating element (usually with a spiral path in the center for the fog fluid to pass through) that has a restrictive nozzle at the output end. There's a solenoid-driven reciprocating pump (positive displacement) that forces the fluid through the heater, and is capable of overcoming the steam pressure inside the heater as the fluid flashes. There is a temperature switch on the heater that opens when it reaches a set temperature (400 C on my units, others may vary, but I doubt by very much), and another temperature switch that opens on low temp to prevent the pump from running. (If the heater isn't hot enough to flash the fluid to steam, you just spit out hot liquid fog juice, which makes a mess.)

    The heater boils the water, creating steam. The steam pressure forces the fluid through the pinhole nozzle at the output end, which (hopefully) atomizes the heavier glycol molecules into a very fine mist. The goal is to achieve a particle size of between 20 and 100 microns. Unfortunately, because this has to happen in a very short time, the high heat also causes some cracking of the organics in the fog fluid. And in extreme cases, there can be partial or even complete oxidation of those organics. This is what gives you that acrid, smoky smell. (It also clogs the heater with soot.)

    Dream:

    To answer your question, no - the fluid is not heated to the full 400 degrees when the pump is running. It gets well above 100 C, obviously, because it flashes to steam almost instantly, but how much above that temperature it gets is dependent on a number of factors, including how fast the pump is running, how clogged the heater is, and what type of fluid you're using.

    However, when the pump is off, the residual fluid in the heater will eventually reach equilibrium with the maximum heater temperature.

    Adam
    Last edited by buffo; 06-13-2014 at 04:24.

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    Adam, I would disagree that the pump has any bearing on how fast the fluid is moved through the heater, and therefore how long it spends in the tube.
    In my experience, it just affects the volume. I find that the rate and distance the fog is expelled is the same when using slow pump speeds and fast pump speeds, which suggests the fluid in each case is expelled at the same rate due to the expansion, than by any increase in the rate the fluid is going in. Therefore, I don't see that the time spent in the heater block [and hence increased temps] is that variable at all.
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    Quote Originally Posted by norty303 View Post
    Adam, I would disagree that the pump has any bearing on how fast the fluid is moved through the heater, and therefore how long it spends in the tube.
    In my experience, it just affects the volume. I find that the rate and distance the fog is expelled is the same when using slow pump speeds and fast pump speeds, which suggests the fluid in each case is expelled at the same rate due to the expansion, than by any increase in the rate the fluid is going in. Therefore, I don't see that the time spent in the heater block [and hence increased temps] is that variable at all.
    My Chauvet foggers produce high velocity fog when the pump is wide open, and a slow, creeping, low velocity fog when the unit is in continuous mode with the pump running slowly. My large Antari performs similarly, though the difference is less dramatic. (Then again, my Antari is quite old, and the heater is probably partially clogged at this point.)

    That being said, I suspect the fog velocity difference is due to the pressure difference inside the heater. More fluid = more steam = more pressure = faster fog velocity. But this is still related (albeit indirectly) to the pump speed.

    More importantly though, even after the fluid flashes to steam, the particles in the fog are still in contact with the heating element until such time as they are expelled from the nozzle. So the temperature is still rising even after the fluid flashes.

    Quote Originally Posted by dream
    if there's a liquid which remained in the heater and it is continues to be heated beyond vaporization point, why doesn't it turn into vapor and come out of the nozzle from the pressure, like the rest did?
    It does.

    If you watch a fog machine that is just sitting there with the heater on, you will see wisps of fog drifting out of the nozzle from time to time. That's the small amounts of fluid that are left at the input end of the heater dripping into the heating block and being flashed to steam.

    Adam

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