Vaseline

wrote:
Harold Rothgar wrote:

Don't use it on pump washers. This can lead to an explosion, which
usually wrecks the pump or its hose.

Wow. Seriously? This sounds like urban legend/myth to me.
Someone with just (not) enough science knowledge thinks,
"hmmm... petroleum based jelly... high pressures in a bike
pump... friction... PV = RT ... all "petroleum" products are
combustable... ergo, petroleum jelly as a pump lube will EXPLODE!!!
Danger Will Robinson, DANGER!!!"

I know the guy who wrote this in Real Life (TM), and he's a reliable
source (he's also a career scientist):

http://yacf.co.uk/forum/index.php?to...8249#msg128249

That doesn't make him immune to MAS (Male Answer Syndrome) even if he
doesn't know the answer. You'll find the "pump leathers" are
traditionally lubricated with oil of one kind or another, most of it
motor oil. It's the "faintly credible" part that makes BS so
dangerous.

oooh, this is so delicious!!! absolutely /so/ yes jobst, that is
/completely/ you.


How about a warning label from someones pump advising
against such an explosive mixture.

when you sign your posts - that is an uniquely propitious "bs" warning
label.

On Oct 3, 2:31*pm, Zog The Undeniable wrote:
KC wrote:
Zog The Undeniable wrote:
Don't use it on pump washers. *This can lead to an explosion, which
usually wrecks the pump or its hose.

Wow. *Seriously? *This sounds like urban legend/myth to me. *Someone
with just (not) enough science knowledge thinks, "hmmm... petroleum
based jelly... high pressures in a bike pump... friction... PV = RT ....
all "petroleum" products are combustable... ergo, petroleum jelly as a
pump lube will EXPLODE!!! Danger Will Robinson, DANGER!!!"

I know the guy who wrote this in Real Life (TM), and he's a reliable
source (he's also a career scientist):

http://yacf.co.uk/forum/index.php?to...8249#msg128249

As a chemist, I think that it's fairly unlikely that the pressures
involved are enough to cause combustion.

I do not think that the link supports the contention.

E.P.

Ed Pirrero wrote:
On Oct 3, 2:31�pm, Zog The Undeniable wrote:
KC wrote:
Zog The Undeniable wrote:
Don't use it on pump washers. �This can lead to an explosion, which
usually wrecks the pump or its hose.
Wow. �Seriously? �This sounds like urban legend/myth to me. �Someone
with just (not) enough science knowledge thinks, "hmmm... petroleum
based jelly... high pressures in a bike pump... friction... PV = RT ...
all "petroleum" products are combustable... ergo, petroleum jelly as a
pump lube will EXPLODE!!! Danger Will Robinson, DANGER!!!"
I know the guy who wrote this in Real Life (TM), and he's a reliable
source (he's also a career scientist):

http://yacf.co.uk/forum/index.php?to...8249#msg128249

As a chemist, I think that it's fairly unlikely that the pressures
involved are enough to cause combustion.

"T" is in that equation too dude.




I do not think that the link supports the contention.

E.P.

wrote:
Karl Clutz wrote:

Don't use it on pump washers. This can lead to an explosion,
which usually wrecks the pump or its hose.

Wow. Seriously? This sounds like urban legend/myth to me.
Someone with just (not) enough science knowledge thinks,
"hmmm... petroleum based jelly... high pressures in a bike
pump... friction... PV = RT ... all "petroleum" products are
combustable... ergo, petroleum jelly as a pump lube will
EXPLODE!!! Danger Will Robinson, DANGER!!!"

I know the guy who wrote this in Real Life (TM), and he's a
reliable source (he's also a career scientist):

http://yacf.co.uk/forum/index.php?to...8249#msg128249

I'm not saying your friend didn't witness a pump explode. But I do
not believe his explanation. Even if he used gasoline for a
lubricant, I doubt that combustion of the vapors could be caused
simply by pumping. Keep in mind that he claims the pump cylinder is
what exploded. The pump cylinder gets new fresh, cool, and free of
vapor air every stroke.

So vapor concentration in the pump cylinder is very low (mixing of
air in the tube & hose with pump cylinder air against a pressure
gradient would be minimal, I think). Combustion is, IMO, highly
unlikely.

I call BS. But I'm interested in the idea... if I'm wrong and it is
possible, someone explain it.

Don't dodge and weave like that. It is BS solid and complete, and
don't pump with Nitroglycerin in the pump.

I just assumed that was humor.
An engine, whose piston is sealed more thoroughly in the cylinder, with
a high compression ratio of 10:1 (more than a hand pump can muster) will
not 'explode' even with properly vaporized gasoline, not vasoline.
That was a hyperbolic attempt at humor.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971
** Posted from http://www.teranews.com **

wrote:
On Fri, 03 Oct 2008 22:31:25 +0100, Zog The Undeniable
wrote:

KC wrote:
Zog The Undeniable wrote:
Don't use it on pump washers. This can lead to an explosion, which
usually wrecks the pump or its hose.

Wow. Seriously? This sounds like urban legend/myth to me. Someone
with just (not) enough science knowledge thinks, "hmmm... petroleum
based jelly... high pressures in a bike pump... friction... PV = RT ...
all "petroleum" products are combustable... ergo, petroleum jelly as a
pump lube will EXPLODE!!! Danger Will Robinson, DANGER!!!"
I know the guy who wrote this in Real Life (TM), and he's a reliable
source (he's also a career scientist):

http://yacf.co.uk/forum/index.php?to...8249#msg128249

Dear Zog,

"On LEJOG some years ago one of our party had done just this, and
blowing up his tyre outside Ironbridge the pump exploded, leaving
about 6" of the barrel behind."

I'm puzzled, but willing to learn more.

I'd expect that an explosion would break the fellow's arm. The pump
piston would be blown back upward much more easily than the sides of
the pump housing would be blown apart.

I'd expect any explosion to burst the pump at the bottom, not six
inches up, where compression has fallen off dramatically.

I'd expect that an awfully high pressure would be needed to cause
combustion, higher than a roadside bicycle pump produces. Maybe
vaseline vapor is more easily ignited?

Even if the vapor ignited, it's hard to imagine enough vapor to match
the power of an ordinary firecracker, which is not likely to burst a
pump six inches up or leave the fellow's arm undamaged.

A different explanation is that there was no explosion, just a
defective or damaged pump housing that burst.

When a defective housing bursts, the piston isn't blow back, so no
one's arm is broken.

The housing can fail six inches up the barrel, where the defect or
damage is.

And there's no need to produce enough temperature by sheer compression
to ignite whatever faint vapor is available from a little vaseline.

Maybe you could look into whether they considered such things?

Cheers,

Carl Fogel

If such an event actually occurred, it's my guess that the pump must
have been a plastic-barreled high pressure pump like a Zefal I have.

To achieve high gas temperatures from compression, the pump surfaces
should have low thermal conductivity -- plastic does, that's why it
feels "warmer" in your hand.

My Zefal has bore diameter of ~0.75", so (theoretically) it can produce
225 psi with 100lb of force. My calculations show that ~165 psi would
achieve the self-ignition temperature of Vaseline (vapor).

As for the failure "six inches up the barrel", the end of the Zefal is
reinforced with a grip/sleeve for about the first 5.5". I'd guess that
there isn't a whole lot of excess burst strength in the un-sleeved upper
section of the barrel, so I'd expect it to fail at about 6" from the
end. I'd test it with a firecracker, but hey those are illegal here and
besides, I spent $12 for this pump.

The pressure seal of the Zefal is of the plastic cup type, so there's
plastic-to-plastic contact that probably achieves high frictional loads
as the cup skirt spreads under high gas pressure.

Plastic pump? Hot day? Muscular guy pumping very fast & hard? Sticking
presta valve? I wouldn't say this myth is busted yet.

Of historical interest:

http://blog.modernmechanix.com/2008/...or-the-smoker/

On Sat, 04 Oct 2008 10:15:46 +0100, Zog The Undeniable
wrote:

My track pump will manage 160psi, as will a decent hand pump like a
Truflo hpX. The last time I compression-tested a car, the compression
was about 140psi at cranking speed, so it's in the same range.
Admittedly that was a petrol car, but old carburetted cars used to
suffer from run-on (dieselling) after switching off (hence "gulp
valves", fuel cut-off solenoids and other measures).

What was called "dieselling" was not true compression ignition, but
rather ignition brought about by red-hot carbon deposits in the
cylinder heads.

Peter Cole wrote:

Plastic pump? Hot day? Muscular guy pumping very fast & hard? Sticking
presta valve? I wouldn't say this myth is busted yet.

Of historical interest:

http://blog.modernmechanix.com/2008/...or-the-smoker/


If you search Youtube for "fire piston" you'll see many examples of more
modern versions.

Joel Mayes wrote:
Don't use it on pump washers. This can lead to an explosion, which
usually wrecks the pump or its hose.

Wow. Seriously? This sounds like urban legend/myth to me. Someone
with just (not) enough science knowledge thinks, "hmmm... petroleum
based jelly... high pressures in a bike pump... friction... PV = RT ...
all "petroleum" products are combustable... ergo, petroleum jelly as a
pump lube will EXPLODE!!! Danger Will Robinson, DANGER!!!"

But, it's the first I've heard of it, so I dunno, could be true. But
seems somewhat implausible to me.
-KC
Seems perfectly sound to me - the engine in my car works on the same
compression-ignition principle, and that will run on a variety of
fuels.
In fact, the bicycle pump is remarkably similar to the apparatus used
to demonstrate the process for educational purposes - the only major
difference is that the demonstration equipment is transparent.

The flash point of Vaseline is around 204 Celsius, I've never seen a
pump get hot enough to be uncomfortable to the touch, let alone boil
camphor.



Flash point has nothing to do with it. It's the auto-ignition temp that
matters, which for petrolatum is about 290C, or 554F. Pretty hot.

BTW, everyone is saying that the compression ratio of a bike pump is too
low. If a pump can handle P150psi, then isn't the compression ratio
greater than 10:1? The pump draws in air at 1atm, and pumps it up to
10atm (150psi). That sounds like 10:1 to me.

-KC

Peter Cole wrote:

Plastic pump? Hot day? Muscular guy pumping very fast & hard? Sticking
Presta valve? I wouldn't say this myth is busted yet.

Of historical interest:

http://blog.modernmechanix.com/2008/...or-the-smoker/

If you search YouTube for "fire piston" you'll see many examples of
more modern versions.

BS just the same. I have had several pressure gauges broken on my
double acting floor pump by riders trying to inflate a tire trough a
Presta valve that was still screwed shut. That makes pressure exceed
the 200 psi range on the gauge. The HP leather piston is lubricated
with 30W motor oil and caused no combustion... only a gauge that would
no longer register zero nor the correct pressure.

Jobst Brandt

wrote in message
...

BS just the same. I have had several pressure gauges broken on my
double acting floor pump by riders trying to inflate a tire trough a
Presta valve that was still screwed shut. That makes pressure exceed
the 200 psi range on the gauge. The HP leather piston is lubricated
with 30W motor oil and caused no combustion... only a gauge that would
no longer register zero nor the correct pressure.

Jobst Brandt

I find it hard to believe that you would allow riders that don't know enough
to unscrew the Presta valve to use your pump. Especially more than once.