Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [safety]

96 questions
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Why do glass windows still exist? (Why haven't they been replaced by plastics?)

Glass is fragile and impractical to transport, install and repair. Even worse, glass kills and hurts people when it breaks. Falling to the streets like guillotines during earthquakes and bomb raids. During wars people put tape on their windows to…
LocalFluff
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My customer wants to use my products to do something unsafe. What is my ethical obligation?

We sell products that attach to a motor drive's DC bus. We also formerly sold diode kits that let you hook one product up to multiple drives. We stopped selling those diode kits because they were unreliable with modern hardware, and we had better…
Stephen Collings
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Which is Worse: Car vs. Car or Car vs. Wall?

So I got myself questioning what could be worse for the driver... a collision of two identical cars at equal speed (frontal crash) or the same car with the same speed crashing through a wall? The first case I see it would double the impact, but also…
Alessandro Nardinelli
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24
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Why would you launch a large ship by dropping it sideways?

I'm referring to the process shown in this video: https://youtu.be/Quyr5R1Rbfw?t=20 Or this image from Wikipedia: In it, a large warship is launched into the water by essentially dropping it sideways down some ramps and off of a pier. The ship…
aroth
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7 answers

Why would a train automatically derail if a signal is passed at danger?

In a recent incident in London Network Rail said an empty train had travelled past a red signal, which resulted in an automatic derailment. No one was injured. [link] The derailment has caused quite a bit of damage, and a lot of travel disruption…
Gremlin
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Why are train brakes so complicated?

The concept is simple enough: no pressure in the train line has the brakes locked, full pressure is loose, and partial pressure drags accordingly. So if pressure is lost for any reason, the train stops. (or at least it's supposed to; more on that…
AaronD
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Replace mercury with silicone oil in diffusion pump

We have obtained an old mercury-vapor diffusion pump for high vacuum. However, we do not want to operate it with mercury in our lab due to health concerns (which is presumably the reason it was scrapped by the original owner). Instead, we plan to…
dominecf
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Will PVC build up an electric charge and cause a spark?

I'm working on an application in which sparks (specifically from static discharge) present a severe safety hazard. One component in question is a piece of PVC water pipe. It has been proposed to "ground" the pipe to minimize the risk of static…
Carlton
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Under what circumstances would one need or not need an electronic brake for a permanent magnet motor?

My company was asked to design a custom product several years ago. The original requester never bought it, but we've sold several a year through distribution. It's been a small side-line for a while, but we'd like to understand the broader use and…
Stephen Collings
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How are blanking spades entered into gas pipelines?

I often see specifications for refurbishing works on gas pipelines calling for blanking spades, to separate the area worked on from the rest of the gas system. This is in addition to closing valves. Googling showed me some pictures of how blanking…
mart
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Industry standard factor of safety for ballast design

What design standards exist for the design of ballast against uplift forces, and what factor of safety against uplift do these design standards promulgate? I am familiar with a typical FS of roughly 1.5 against sliding forces due to active soil…
Rick
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Why do car-seats have an expiration date?

My wife and I are expecting our first child, and therefore are expecting to purchase a car seats. My wife and I have discovered that car seats have "expiration dates": a car seat, no matter how lightly used, is deemed unsuitable for use after a…
PipperChip
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How are dangerous to build things studied?

How are dangerous to build things studied? Such as, nuclear reactors, jet engines, sawing machines. How do engineers discover, how they ought to be built, while avoiding getting or getting others hurt? Is there perhaps a component of "anticipating…
mavavilj
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Is it safe to drop a bomb?

I realise that "bomb" can refer to all sorts explosives, but I am mainly interested in air-dropped bombs. Ever since reading about the USS Forrestal fire, I wondered about the safety of bombs when stored or transported in general- but in plain…
user7646
5
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3 answers

Questions about the level flight lift equation

In level unaccelerated flight we have relation $$ W=L=\frac{1}{2}\rho\cdot V_{stall}^2\cdot S\cdot C_{l,max} $$ taken from book Daniel P Raymer "Aircraft Design: A Conceptual Approach" equation (5.5) at page 85. The question is: why does this…
d.pensopositivo
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