Date: Thu Sep 27 09:03:00 2007

Author: Bernard Cleyet

Subject: Re: fire extinguisher cart

Post:
Depends *, It worked fine in the hall beginning at the main lecture room
and adjoining the small room where I taught Concept. Phys. many years
ago, well about >20 years ago, at San Francisco CC. [Competing w/ Paul
was impossible! :-) ] The outlet has a partial plug, so if the valve is
"accidentally" opened, it won't rocket off **. This didn't keep it from
propelling me half way down that rather long hall where some students
would "catch" me. I think I turned it around once when I went too
fast. I remember being sl. frightened; now in my present aged state I
wouldn't do it.


* Someone else must answer, as I've only used that SCUBA tank and not
yet viewed the vid. clip to compare. Can you borrow one from a dive
shop? I note you aren't a thousand miles from the Pacific Ocean.
** Sometime about the 40's early 50's a UCB lab was totally destroyed by
a bottle falling and the valve broken off.

bc admits DJ is not the only complainer of his cryptic writing, and in
his aged state has paper thin skin and capillaries, but not hyper
sensitivity. So he does apologize. [Cal. Poly can't afford a better
server?]

p.s. I used bud Bridges cart, the difference being he threw small sand
bags. Certainly a better demo. for the demonstrator, because its
kinaesthetic, the best teacher in addition to humour.

Douglas Johnson wrote:

>
> BC,
> I do read most of them, but can't always figure out what you are
> saying or thinking about. Please don't take offense to that. It is
> definitely my internal slow server that keeps that from happening(no
> hope for future upgrades on that one).
> So, how does the compressed air compare to the CO2 and would it be
> worth the trouble to switch?
>
> ...Doug J.
>
>
>
>> I add you (D.J.) to the list of people who don't read my posts.
>>
>> bc, can't apologize in the case DJ has a slow server.
>>
>> Douglas Johnson wrote:
>>
>>>
>>> Has anyone ever used or seen used a SCUBA tank of compressed air to
>>> propel a cart, in place of using the CO2? Just curious.... I
>>> imagine it wouldn't work as well but might be easier to refill and
>>> store.
>>>
>>> ....Doug J.
>>>
>>>> I purchased a SCUBA tank because UC Santa Cruz teaches that * and
>>>> filled the tank free. Then I found the fire dept would also w/
>>>> air (SCBA). Maybe CO2 also, but should be considerably more
>>>> expensive, I've forgotten.
>>>> I think the old H2SO4 + baking soda in water type would work even
>>>> better EXCEPT unacceptably messy. No need to modify the hose and
>>>> nozzle, either.
>>>>
>>>>
>>>> * Initially I borrowed the tank to verify it'd work well.
>>>>
>>>> bc, thinks CO2 would make a poor wielding gas, also thinks filling
>>>> tanks w/ a different gas is illegal.
>>>> David Tam wrote:
>>>>
>>>>> Wayne,
>>>>>
>>>>> Wait, aren't those connected in series, i.e. cylinder, tube,
>>>>> diffusing horn? Or did I not understand your terminology?
>>>>>
>>>>> Also, couldn't I also use a pressurized cylinder of CO2, such as
>>>>> those for welding?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> David
>>>>>
>>>>> On 9/25/07, Wayne Easterling
>>>>> wrote:
>>>>>
>>>>> Hi David,
>>>>>
>>>>> What you see is not steam, but water vapor condensing
>>>>> out of the air because of the low temperature of the CO2 being
>>>>> expelled. To do this demo you need to modify a CO2 type fire
>>>>> extinguisher by first removing the discharge tube/horn and then
>>>>> cutting off the diffuser.
>>>>>
>>>>>
>>>>> Wayne
>>>>>
>>>>>
>>>>> From:
>>>>> tap-l-owner@lists.ncsu.edu
>>>>> [mailto:
>>>>> tap-l-owner@lists.ncsu.edu] On Behalf Of David Tam
>>>>> Sent: Tuesday, September 25, 2007 12:37 PM
>>>>> To: tap-l@lists.ncsu.edu
>>>>> Subject: [tap-l] fire extinguisher cart
>>>>>
>>>>>
>>>>>
>>>>> Hi everyone,
>>>>>
>>>>> I'm stumped as regards the demo where a person sits on a cart and
>>>>> a fire extinguisher propels him/her. What did you do to the fire
>>>>> extinguisher to make it propel a jet of steam? Mine either puff a
>>>>> cloud of powder or shoot a focused stream of water.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> David Tam
>>>>
>
>
>

From tap-l-owner@lists.ncsu.edu Thu Sep 27 09:03:00 2007
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