I've only had one thing I would have quit if forced to work on. We had some new cleaning gear that used ClF3. After the safety lecture and video most of us decided not to work on that project, “no way, no how” after reading this from "Ignition! An Informal History of Liquid Rocket Propulsion". After it was installed a new management team decided to dismantle the entire machine down to the shielded AC power cables.

Chlorine trifluoride, ClF3, or "CTF" as the engineers insist on calling it, is a colorless gas, a greenish liquid, or a white solid. It boils at 12° (so that a trivial pressure will keep it liquid at room temperature) and freezes at a convenient —76°. It also has a nice fat density, about 1.81 at room temperature. It is also quite probably the most vigorous fluorinating agent in existence—much more vigorous than fluorine itself. Gaseous fluorine, of course, is much more dilute than the liquid ClF3, and liquid fluorine is so cold that its activity is very much reduced.

All this sounds fairly academic and innocuous, but when it is translated into the problem of handling the stuff, the results are horrendous. It is, of course, extremely toxic, but that's the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water —with which it reacts explosively. It can be kept in some of the ordinary structural metals — steel, copper, aluminum,

etc. —because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.

And even if you don't have a fire, the results can be devastating enough when chlorine trifluoride gets loose, as the General Chemical Co. discovered when they had a big spill. Their salesmen were awfully coy about discussing the matter, and it wasn't until I threatened to buy my RFNA from Du Pont that one of them would come across with the details.

It happened at their Shreveport, Louisiana, installation, while they were preparing to ship out, for the first time, a one-ton steel cylinder of CTF. The cylinder had been cooled with dry ice to make it easier to load the material into it, and the cold had apparently embrittled the steel. For as they were maneuvering the cylinder onto a dolly, it split and dumped one ton of chlorine trifluoride onto the floor. It chewed its way through twelve inches of concrete and dug a threefoot hole in the gravel underneath, filled the place with fumes which corroded everything in sight, and, in general, made one hell of a mess.

Civil Defense turned out, and started to evacuate the neighborhood, and to put it mildly, there was quite a brouhaha before things quieted down. Miraculously, nobody was killed, but there was one casualty — the man who had been steadying the cylinder when it split. He was found some five hundred feet away, where he had reached Mach 2 and was still picking up speed when he was stopped by a heart attack.

This episode was still in the future when the rocket people started working with CTF, but they nevertheless knew enough to be scared to death, and proceeded with a degree of caution appropriate to dental work on a king cobra. And they never had any reason to regret that caution. The stuff consistently lived up to its reputation. Bert Abramson of Bell Aircraft fired it in the spring of 1948, using hydrazine as the fuel, NACA and North American followed suit the next year, and in 1951 NARTS burned it with both ammonia and hydrazine.

The results were excellent, but the difficulties were infuriating. Ignition was beautiful —so smooth that it was like turning on a hose. Performance was high —very close to theoretical. And the reaction was so fast that you could burn it in a surprisingly small chamber. But. If your hardware was dirty, and there was a smear of oil or grease somewhere inside a feed line, said feed line would ignite and cleverly reduce itself to ashes.

Gaskets and O-rings generally had to be of metal; no organic material could be restrained from ignition. Teflon would stand up under static conditions, but if the CTF flowed over it with any speed at all, it would erode away like so much sugar in hot water, even if it didn't ignite. So joints had to be welded whenever possible, and the welds had to be good. An enclosure of slag in the weld could react and touch off a fire without even trying. So the welds had to be made, and inspected and polished smooth and reinspected, and then all the plumbing had to be cleaned out and passivated before you dared put the CTF into the system.

First there was a water flush, and the lines were blown dry with nitrogen. Then came one with ethylene trichloride to catch any traces of oil or grease, followed by another nitrogen blow-down. Then gaseous CTF was introduced into the system, and left there for some hours to catch anything the flushing might have missed, and then the liquid chlorine trifluoride could be let into the propellant lines.

 

... in 1951 NARTS burned it with both ammonia and hydrazine

When I started reading the article, I thought that CTF and hydrazine were the same thing! ... and your article makes it look far worse than hydrazine! ...

 

When I started reading the article, I thought that CTF and hydrazine were the same thing! ... and your article makes it look far worse than hydrazine! ...

At least its not a greenhouse gas.

 

At least its not a greenhouse gas.

That would garner enough points in some circles to make it common place.

 

That would garner enough points in some circles to make it common place.

Can you point to one of those "circles". I think the members of those anonymous "circles would have to be dumber than the author of your post - which is why I doubt such "circles" exist.

 

Can you point to one of those "circles". I think the members of those anonymous "circles would have to be dumber than the author of your post - which is why I doubt such "circles" exist.

I can name one.

https://www.ncbi.nlm.nih.gov/pubmed/21549502

Environmental and health risks of chlorine trifluoride (ClF3), an alternative to potent greenhouse gases in the semiconductor industry.

The first accident involving chlorine trifluoride (ClF(3)) in the history of semiconductor fabrication processes occurred on 28 July 2006 at Hsinchu (Taiwan), resulting in a large release of the highly reactive material and causing the chemical burn to several workers. ClF(3) is used primarily as an in situ cleaning gas in the manufacture of semiconductor silicon-wafer devices in replacement of perfluorocompounds (PFCs) because they have the high potential to contribute significantly to the global warming.

 

I can name one.

https://www.ncbi.nlm.nih.gov/pubmed/21549502

Environmental and health risks of chlorine trifluoride (ClF3), an alternative to potent greenhouse gases in the semiconductor industry.

But you weren't the student I called on.

 

But you weren't the student I called on.

You seemed to assume his statement was baseless when it fact it was descriptive of the rational for using the dangerous chemical.

 

You seemed to assume his statement was baseless when it fact it was descriptive of the rational for using the dangerous chemical.

There are many types of danger. Toxic substances with longer time constants make a lot of people feel safer. Also, toxins that kill mankind seem safer than toxins that kill just you.

 

This chemical sounds like it should be "soaked into excelsior and ignited by rifle fire". Although I'm not sure I would even want to get close enough to do the soaking part.

 

There are many types of danger. Toxic substances with longer time constants make a lot of people feel safer. Also, toxins that kill mankind seem safer than toxins that kill just you.

I'm a total believer in man-made 'Global Warming' and the need to moderate the use of green-house gasses but 'Kill Mankind' is just BS. Bureaucrats forcing companies to use some of the most Toxic and dangerous chemicals in the world instead of containment/capture controls for industrial CFC PFC applications like we use for most Hazardous Production Material is beyond stupid.

 

When I was in grad school (late 1960's) we all knew about fluorine, but no one used it. Teflon had been invented, but as a reagent, it just wasn't studied in organic chemistry for a reason. We used a lot of other stuff, like N2O4, sodium dissolved in NH3, Na-K alloy (liquid), but not fluorine. Aside from its reactivity, the one thing I learned is that if the mass of an ion in a mass spectrum is < nominal (12C= 12), it probably contains fluorine.

 

I haven't been a formal student since the early 1970s. I have, however, been through the school of hard knocks a number of years. Based on the observation of some fanatical groups, yes, I see them kneeling at the altar of a non-greenhouse chemical no matter what the detrimental properties can produce.

I'm just a cynical old SOB.