From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives
Subject: Re: Picric acid safety
Date: 15 Jan 1996 05:07:56 GMT

In article <4dbnde$7ov@zinc.compulink.co.uk>,
mark@murder.compulink.co.uk (Mark de Roussier) says:

>Doesn't sound safe to me. If there are crystals around the lid, there
>are probably cystals *on* the lid ( inside ). You want to 'punch a
>hole ' in the lid and snap pieces off !. Perhaps you meant under
>water, but you didn't say. Picric is sensitive to impact /
>shock/friction . If the stuff hasn't been used in such a long while,
>that suggests its not that important a reagent in your line of work.
>Surely it would be best to arrange for safe disposal and get a fresh
>batch, it's not expensive enough to risk losing a hand or three over..

Nobody in his right mind would recommend applying friction to
a known explosive. In this particular case, there is probably 
little real danger of initiating even very dry picric acid. If
there were a metal lid involved with the possibility of (heavy)
metal picrates, it would be another story entirely.

If the material is no longer of use, the very safest thing to
do would be to blow it up deliberately or have it done. If
it were mine and I had a use for the reagent, I would gently 
ream a hole, break the cap and find a new lid after cleaning
the threads. I'm talking here about what I would do with that
lid, not what others should do. I've handled a lot of sensitive
materials and I do so with patience, caution and enough healthy
fear to back off if the operation doesn't go gently as planned.


What scares me more than opening a stuck jar of explosive
material, which I have often done, is opening bottle of corrosive
volatile liquid such as phosphorus trichloride. The very worst
thing I ever had to open was a stainless steel line in a 
ClF5 plant. The valve on the line froze up with a large
amount of the stuff in a low temperature still for which
the tube was the product outlet. 

We froze the tube above the valve with liquid nitrogen poured 
on a fiberglas wrapping and then cut and flared the tube and 
installed a new valve. The frozen ClF5 seal wasn't a perfect 
fix so a few drops escaped and burst into flame on contact 
with the concrete floor.

BTW, it is nice to be able to talk about ClF5 these days. Back
then it was a classified and otherwise unknown compound which
we called "compound A" in the cloak-and-dagger atmosphere of
those cold war space race years.

I have no idea why they call those "the good old days." Perhaps
its because we got to play with a lot of toys they don't allow any
more. 

Jerry (Ico)

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives,sci.chem
Subject: Re: Picric acid safety
Date: 18 Jan 1996 20:01:06 GMT

In article <4dh1up$m95@news.ox.ac.uk>, mert0236@sable.ox.ac.uk (Thomas
Womack) says:

>Gerald L. Hurst (glhurst@onr.com) wrote:
>
>> We froze the tube above the valve with liquid nitrogen poured 
>> on a fiberglas wrapping and then cut and flared the tube and 
>> installed a new valve. The frozen ClF5 seal wasn't a perfect 
>> fix so a few drops escaped and burst into flame on contact 
>> with the concrete floor.
>>
>> BTW, it is nice to be able to talk about ClF5 these days. Back
>> then it was a classified and otherwise unknown compound which
>> we called "compound A" in the cloak-and-dagger atmosphere of
>> those cold war space race years.
>
>What on earth do you use ClF5 for? I can see it's a good oxidiser and 
>fluorinator (to put it mildly), but I can't see a use for it in the space 
>race. And how did you classify the interhalogen compounds? 'oh, chlorine 
>doesn't react with fluorine, and if you try to perform the reaction the 
>CIA will come and imprison you'? :)

Now I know why we called it "the other place."

Most large rockets are propelled by binary propellants, e.g., a
fuel and an oxidizer such as liquid oxygen and kerosene (kerosine).
About the highest specific impulse is delivered by the combination
of liquid fluorine and liquid hydrogen, both of which are devils 
to handle. ClF5 is a liquid under pressure and chemically 
(energetically) about as close as one can get to liquid fluorine.

ClF5 was, I assume, discovered during work under a government 
contract, I would guess at Rocketdyne. It was classified by the 
simple expedient of only disclosing its existence to people who 
had an appropriate security clearance. Such individuals had 
signed an agreement not to divulge classified information, often 
for 12 years, until automatic declassification.

In the case of ClF5, it was unlikely anyone would stumble onto
it in the lab, because, in typical fashion, many theoretical
chemists knew good reasons why it couldn't exist as a stable
molecule. Also, the conditions required to synthesize the 
material were rather extreme considering the nastiness of the
starting materials, and thus it was not too likely anyone would
stumble onto the compound.  Of course, it was known to all that
chlorine reacted with fluorine to give ClF and ClF3. BrF5 was
known, but was often justified in chemists minds by the larger 
bromine atom.

I believe there were two pilot plant scale methods of
manufacture: The batch process which I developed at Aero-Jet 
General, and a continuous process developed at Rocketdyne. I do 
not know how successful the latter was, but I can imagine they 
had their difficulties along the way:) My plant made a total 
of about four tons of the substance before we finished the
contract and shut that juggernaut down.

If the stability of ClF5 appears obvious today, that obviousness
is probably augumented by a few temporal diopters.

Jerry (Ico)

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: rec.pyrotechnics,sci.chem,alt.engr.explosives
Subject: Re: Lye/Aluminum reactor?
Date: 14 Feb 1997 08:09:09 GMT

In article <5e11vv$6v4@crl13.crl.com>, gherbert@crl.com (George Herbert) says:

>You can use water as fuel with ClF5 oxidizer, but nobody does... hydrazine
>is much higher specific impulse.  There is a ClF5-hyd motor and associated
>upper stage that were recently developed by the DOD for high performance
>transfer stage usage.

It is good to hear that the early work on ClF5 has born some fruit.
I designed, built and managed the Aerojet-General pilot plant which
churned out 8,000 lbs of ClF5 for experimental purposes back in 1966.

In those days, ClF5 was unknown in the open literature.  Perhaps the
happiest day of my life was the day the program was completed and
I was finally able to shut down that monster plant which had been
running around the clock in a perpetual fog of evaporating liquid
nitrogen.

It seemed that whenever the plant blew, there was rain to ignite 
the ClF5 gas escaping from the various ruptured high and low pressure 
lines. The dripping cold liquid also put on a pretty pyrotechnic
display as it burst into white flame on contact with the concrete
plant floor.

As a reward for working 20 hours a day, seven days a week for months 
the division V.P. offered me a sincere apology for the tiny Christmas 
bonus (based solely on a low seniority level). As a consolation prize I 
was given a standing ovation (attaboy with clapping) by the fully 
assembled Aerojet V.P.s and handed an extra week's vacation.  Later, 
the V.P. of my division said to me, "You B******, you used that week 
to find another job."  He was right.  I got a super raise and a night
of unlimited banana cows by joining the new Explosives Corporation of 
America (EXCOA) as their Chief Scientist. Working with ultra-sensitive 
explosives was like a vacation after dodging hot ClF5 at at obscene
pressures.

Despite my abrupt departure from Aerojet, I really did like that
company and I understood that the boss' hands were tied by inflexible
company policy. After all, I had volunteered to take over the then 
unproductive plant after being forewarned by the previous manager 
(a once sane PhD engineer) whom I met babbling to himself in the 
hallway about needing an exorcist.  

Besides, I learned the valuable lesson that no good deed goes 
unrewarded at best or unpunished at worst :)

Frankly, I miss those early days of both the aerospace race and the
entrepreneurial explosives research nurtured by the Viet Nam problems.
Both of these situations created incredible R&D environments where 
the only limitation was the imagination. In those days science was
actually a respected occupation.  Don't get me wrong though. I 
wouldn't do it again for any amount of money.  It took an undeserved
lot of pure luck to survive the learning curve.

Jerry (Ico)