On Tuesday, 23 November 2021 at 02:59:47 UTC, bill....@ieee.org wrote:
 
> lists polytetrafluorethane as perfectly resistance to 100% hydrogen peroxide. 
> 
> What's your evidence that it isn't? My memory is that it resists anything short of molten sodium. 
> 

There are some etchants like Tetra-etch which is an organo-sodium compound.
Also, sodium dissolved in liquid ammonia attacks ptfe.
John

On Tuesday, November 23, 2021 at 11:53:17 AM UTC+11, Robert Baer wrote:
> Jeff Layman wrote: 
> > On 21/11/2021 05:12, Robert Baer wrote: 
> > 
> >>     Strange, HOOH is the most corrosive substance on the planet there is. 
> >>     The more pure, the more corrosive. 
> > 
> > Not even close: 
> > <https://en.wikipedia.org/wiki/Fluoroantimonic_acid> 
> >
> HOOH reacts with PTFE and "pure" HOOH will decompose it.

https://www.calpaclab.com/teflon-ptfe-compatibility/

lists polytetrafluorethane as perfectly resistance to 100% hydrogen peroxide.

What's your evidence that it isn't? My memory is that it resists anything short of molten sodium.

-- 
Bill Sloman, Sydney

Jeff Layman wrote:
> On 21/11/2021 05:12, Robert Baer wrote:
> 
>>     Strange, HOOH is the most corrosive substance on the planet there is.
>>     The more pure, the more corrosive.
> 
> Not even close:
> <https://en.wikipedia.org/wiki/Fluoroantimonic_acid>
> 
   HOOH reacts with PTFE and "pure" HOOH will decompose it.


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On 11/21/2021 10:25 AM, Cydrome Leader wrote:
> Ralph Mowery <rmowery42@charter.net> wrote:
>> In article <sncdm8$lc4$2@reader1.panix.com>, presence@MUNGEpanix.com
>> says...
>>>   
>>>> Sort of like me.  Around 1972 I thought I wanted to get a job working on
>>>> 2 way radios.  Took the test for that and for one dollar more got to
>>>> take the test to work on the radio and TV stations.  I had never seen a
>>>> radio or TV transmitter but passed the test to work on them.
>>>
>>> Was it called an "FM License" or something along those lines?
>>>
>>>
>>
>> At that time it was a Second Class Radiotelephone to work on the 2 way
>> radios and after you passed that you could take the First Class
>> radiotelephong license to work on the radio and TV stations
>>
>> About 1980 or so they changed it all to the General Radiotelephone
>> license.  I don't think one has even been needed for about the last 20
>> years by the FCC.
> 
> It seems like most of the weird permits were dropped. Does anyone know if
> pilots (air to air, air to ground on VHF) in the US ever needed
> radiotelephone permits, like in other countries?
>

IIRC, yes permits were needed. No test of any kind and it was just an 
operator's permit, no station license. Just fill out a form.

Ralph Mowery <rmowery42@charter.net> wrote:
> In article <sncdm8$lc4$2@reader1.panix.com>, presence@MUNGEpanix.com 
> says...
>>  
>> > Sort of like me.  Around 1972 I thought I wanted to get a job working on 
>> > 2 way radios.  Took the test for that and for one dollar more got to 
>> > take the test to work on the radio and TV stations.  I had never seen a 
>> > radio or TV transmitter but passed the test to work on them.
>> 
>> Was it called an "FM License" or something along those lines?
>> 
>> 
> 
> At that time it was a Second Class Radiotelephone to work on the 2 way 
> radios and after you passed that you could take the First Class 
> radiotelephong license to work on the radio and TV stations
> 
> About 1980 or so they changed it all to the General Radiotelephone 
> license.  I don't think one has even been needed for about the last 20 
> years by the FCC.

It seems like most of the weird permits were dropped. Does anyone know if 
pilots (air to air, air to ground on VHF) in the US ever needed 
radiotelephone permits, like in other countries?

On 21/11/2021 05:12, Robert Baer wrote:

>     Strange, HOOH is the most corrosive substance on the planet there is.
>     The more pure, the more corrosive.

Not even close:
<https://en.wikipedia.org/wiki/Fluoroantimonic_acid>

-- 

Jeff

Sylvia Else wrote:
> On 18-Jan-21 7:50 am, Piotr Wyderski wrote:
>> Dear fellow terrorists,
>>
>> Per the European regulation 2019/1148, available here, page 16:
>>
>> https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32019R1148&from=pl 
>>
>>
>> "List  of  substances  which  are  not  to  be  made  available  to,  
>> or   introduced,  possessed  or  used  by,  members  of  the  general 
>> public,  whether  on  their  own  or  in  mixtures  or  substances  
>> that   include those substances, unless the concentration is equal to 
>> or lower than the limit values set out in column 2, and for which 
>> suspicious transactions and significant disappearances and thefts  are 
>> to  be  reported  within  24  hours"
>>
>> HNO3 in concentrations above 3% (old news)
>> H2SO4 in concentrations above 15%.
>>
>> And, further:
>>
>> "List  of  substances  on  their  own  or  in  mixtures  or  in 
>> substances  for  which  suspicious  transactions  and  significant 
>> disappearances  and  thefts  are  to  be  reported  within  24  hours"
>>
>> *Acetone*, Potassium Nitrate, Sodium Nitrate, Calcium Nitrate.
>>
>> The regulation will have been effective by February.
>>
>>      Best regards, Piotr
>>
>>
>>
>>
>>
> 
> Stupid policy. Since there are ways to make concentrated sulphuric acid, 
> it won't prevent terrorists from getting it. But it will encourage 
> non-criminals who need it for other purposes to engage in dangerous 
> processes that wouldn't otherwise be required.
> 
> What next - ban Nitrogen? Let's see how well that would work out.
> 
> Sylvia.
   Strange, HOOH is the most corrosive substance on the planet there is.
   The more pure, the more corrosive.

In article <sncdm8$lc4$2@reader1.panix.com>, presence@MUNGEpanix.com 
says...
>  
> > Sort of like me.  Around 1972 I thought I wanted to get a job working on 
> > 2 way radios.  Took the test for that and for one dollar more got to 
> > take the test to work on the radio and TV stations.  I had never seen a 
> > radio or TV transmitter but passed the test to work on them.
> 
> Was it called an "FM License" or something along those lines?
> 
> 

At that time it was a Second Class Radiotelephone to work on the 2 way 
radios and after you passed that you could take the First Class 
radiotelephong license to work on the radio and TV stations

About 1980 or so they changed it all to the General Radiotelephone 
license.  I don't think one has even been needed for about the last 20 
years by the FCC.

Ralph Mowery <rmowery42@charter.net> wrote:
> In article <18c9fd10-417a-4bb2-b5e4-5c5939a10ebcn@googlegroups.com>, 
> soar2morrow@yahoo.com says...
>> 
>> In our state a friend of mine was forced to change the name of his small business because it contained the word "engineering" in it and he wasn't a licensed professional engineer. But you can do that if you have a PE on staff (which may be a part-time consultant). He replaced "engineering" with "designs," and that was acceptable. 
> It is also interesting that you can become a professional engineer here without an engineering degree.
>> 
>> 
>> 
> 
> I have only  known one PE and how he got that I would like to know.  
> Maybe good at taking tests, but he did not show me or anyone else at 
> work much.  We were always doing his work and all he did was carry our 
> work to the blue print office for them to print out .
> 
> Sort of like me.  Around 1972 I thought I wanted to get a job working on 
> 2 way radios.  Took the test for that and for one dollar more got to 
> take the test to work on the radio and TV stations.  I had never seen a 
> radio or TV transmitter but passed the test to work on them.

Was it called an "FM License" or something along those lines?

On 20/11/21 3:29 am, jlarkin@highlandsniptechnology.com wrote:
> On Fri, 19 Nov 2021 10:21:02 -0500, Ralph Mowery
> <rmowery42@charter.net> wrote:
>> I let a car battery go dead because the car was not driven enough.  My
>> best charger would not let the battery start to charge.  I have an older
>> very simple charge that is only a transformer, diode and meter that I
>> hooked to the battery for about half an hour and then I could use the
>> better automatic charger.

> I once had to use 120 VAC and a diode and a hair drier ballast
> resistor to bootstrap charging a car.
> 
> Some devices with a 2-step dimmer have the necessary diode inside.

A friend was stuck with a flat battery at his cousin's place.
He used an old halogen lighting transformer to get going :)
They have called him McGyver ever since...

CH