Research for a book - light bulb question

WBahn

Joined Mar 31, 2012
29,979
I remove broken light bulbs by jamming the tip of some needle-nose pliers up into the base, then pulling the handles apart so that the tips spread and grab the inside of the base. Then it unscrews quite well. BUT ALWAYS WEAR SAFETY GLASSES when doing this because there are often some glass fragments. AND switch off the power to avoid tripping the circuit breaker or popping a fuse.
And hope that the base and the cord and the circuit are all wired correctly so that, even with the switch off, you don't have a hot lead going to the base of the bulb. Especially the case when the switch is part of the light fixture, like a table lamp (of course, then just unplug the thing -- but people often don't because the outlet is behind some heavy piece of furniture or something).
 

WBahn

Joined Mar 31, 2012
29,979
Yeah I think urinating on it is out. Even if it would do anything, I don't think my character would enjoy it--not really his style. BUT from that other forum you linked to, there's this: "Turn it on and let it warm up for about 5 minutes, then spray alcohol on it. The alcohol will evaporate, cooling the surface of the glass, and causing it to develop tiny cracks through which the gas will leak."

If I have my character experiment with a few failed methods first, I might use this one. Do you think the poster was referring to rubbing alcohol?
The bulb is easily at full temperature after five minutes. Spray a cool liquid on it, such as water or alcohol, and it will explode. Been there, did that as a six year old kid when I thought it would be real cool to shoot the light bulb with my water pistol. Got a face full of glass for my trouble -- very fortunately none in my eyes.
 

SamR

Joined Mar 19, 2019
5,031
Explosive atmospheres are a bit funny. Too little or too much fuel/air and nothing happens. In the right mix BOOM! And it's not just liquid fuel either. We lost a few men where I worked from dust explosions. They go bang and rattle the rafters shaking more dust into the atmosphere and then BOOM the second explosion is huge. The poor guys died of flash burns over 90+ percent of their bodies several days afterwards, not from the concussive shock of the explosion. It was caused by static electric buildup in the dust collector bags of the removal system not being properly grounded and causing an ignition spark.
 

atferrari

Joined Jan 6, 2004
4,764
Explosive atmospheres are a bit funny. Too little or too much fuel/air and nothing happens. In the right mix BOOM! And it's not just liquid fuel either. We lost a few men where I worked from dust explosions. They go bang and rattle the rafters shaking more dust into the atmosphere and then BOOM the second explosion is huge. The poor guys died of flash burns over 90+ percent of their bodies several days afterwards, not from the concussive shock of the explosion. It was caused by static electric buildup in the dust collector bags of the removal system not being properly grounded and causing an ignition spark.
Dust in the right proportion in urea or grain elevators, a frequent reason for explosions.
 

Thread Starter

OrvilleR

Joined May 9, 2019
20
The bulb is easily at full temperature after five minutes. Spray a cool liquid on it, such as water or alcohol, and it will explode. Been there, did that as a six year old kid when I thought it would be real cool to shoot the light bulb with my water pistol. Got a face full of glass for my trouble -- very fortunately none in my eyes.
Thanks for the warning. I was planning on trying this one, glad I waited. Would the bulb explode right away or not until the switch is flipped?
 

WBahn

Joined Mar 31, 2012
29,979
Thanks for the warning. I was planning on trying this one, glad I waited. Would the bulb explode right away or not until the switch is flipped?
If you spray the bulb when it is cool, nothing will happen even as it warms up because it isn't getting shocked. The water will just evaporate (and an oil will just get hot -- it the bulb gets hot enough, the oil might catch fire and burn off).

It's when the bulb is hot and you spray water on it the point of contact with the water cools and contracts rapidly while the nearby parts are still hot and expanded. This results in large stresses that fracture the glass catastrophically. The effect is effectively instantaneous.
 

Thread Starter

OrvilleR

Joined May 9, 2019
20
If you spray the bulb when it is cool, nothing will happen even as it warms up because it isn't getting shocked. The water will just evaporate (and an oil will just get hot -- it the bulb gets hot enough, the oil might catch fire and burn off).

It's when the bulb is hot and you spray water on it the point of contact with the water cools and contracts rapidly while the nearby parts are still hot and expanded. This results in large stresses that fracture the glass catastrophically. The effect is effectively instantaneous.
Gotcha. Thanks!
 
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