Questions tagged [safety]

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2
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1answer
53 views

Do pressurised cans still pose a risk to bursting in normal conditions, but after being exposed to heat?

We're planning on shipping some items from the US to Australia as you cannot get them here, that being: https://www.chewy.com/sentry-stop-that-noise-pheromone-dog/dp/56486 I have been in contact ...
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1answer
40 views

Alternatives to sawstop technology

Sawstop table saw braking system works by putting a low voltage on the blade, and when it detects that voltage shorted to ground, the blade is retracted and slammed into an aluminum block. The claim ...
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0answers
14 views

DC Inverter motor AC utilization category

I am looking at specs of an air conditioner unit. It uses DC inverter technology and maximum current listed as 21.5A So are DC inverter motors considered resistive or inductive? What utilization ...
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0answers
10 views

Who was the ANSI certifying authority for Titus CSE ear muffs?

Titus CSE claims to have achieved certain NRR ratings with ANSI for some Titus ear muffs. How can we verify their claims? I looked into this, but I cannot find the ANSI certifying authority for ...
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0answers
10 views

How is “critical service” defined, according to DIN EN 1591-4?

DIN EN 1591-4 specifies how installers for flanged connections ind piping systems "in critical service" are to be trained and certified. The only definition of critical service given in the ...
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2answers
45 views

Pivoting trailer gate on multiple axes

I am currently trying to design a rear gate to retrofit to an existing caged trailer (similar to image 3), with the goal of having a system where the rear gate can pivot down (on its bottom edge) to ...
4
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3answers
104 views

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 ...
1
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1answer
53 views

Reverse vs Drive When Slipping Backwards

I was trying to drive up an icy hill with a front-wheel-drive car (2006 Honda Civic Hybrid) when the front tires lost traction and the car started to slide backwards. The car then easily spun sideways ...
0
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1answer
33 views

What is the actual difference between a control function with Securtiy Integritiy Level (SIL) II and one without?

Consider a simple example: there's a vessel with water and a continuos level sensor (4-20 mW signal) there's a water line with a magnetic valve, feeding the vessel When the water level is below a ...
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3answers
72 views

Mapping of vehicle to its horn sound

From the "meep meep" of the smallest scooter to the "BLLLAAAAAGGGGGHHH" of the largest seagoing container vessel, vehicles seem to have horn sounds that, in an auditory way, seem to indicate their ...
2
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1answer
38 views

What (if any) are the engineering limitations for producing “simulation” exoskeletons

To clarify the title since it cannot be said within the word limit: A "simulation" exoskeleton, is an exoskeleton that doesn't exist to support a disabled user's movement or to help someone carry ...
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0answers
48 views

Origin of barricade tape color combinations (allegedly OSHA)

Various sources (e.g., Wikipedia and WorkSafely) claim that the seven color combinations commonly used for barricade tape (a.k.a. caution tape) and safety markings in North America (yellow and black ...
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3answers
3k views

Is it safe to stand on a toilet bowl?

As most westerners know well, ceramic toilets are designed to be sat on, even by those who are quite overweight. However, since it's customary in Asian countries to squat when using the toilet, some ...
5
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1answer
246 views

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....
0
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1answer
52 views

Can a water pressure switch be used as a low-water cutoff means for a steam boiler?

Steam boilers obviously need to be protected from the catastrophe of running out of water -- you then either get a meltdown if the boiler is fired unwatered for an extended period of time or a boiler ...
7
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2answers
281 views

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 ...
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4answers
183 views

Tubing for explosive gas or hydrogen transfer

Recently, I heard that there is a law/ OSHA/ ASME piece of regulation dictating that hydrogen should be transferred (suppose from a tank of hydrogen to another location) by using specially approved ...
1
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2answers
90 views

Why not use fire-retardant plastics everywhere?

Some plastics will sustain a flame. Others won't. Not spreading a fire is obviously preferable in almost every circumstance. What advantages do combustible plastics have over non-combustible plastics, ...
1
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0answers
48 views

Machine design tip over safety requirement? [closed]

I am designing an automation machine. I remember that I read a document that the machine is stable if some certain amount of force to push on the top corner of the machine and the machine does not ...
2
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3answers
542 views

Difference between seat belts

Today, I was thinking about seat belts. On that note, why do the ones in cars and planes differ? Planes have only belts on the waist, but cars have waist and diagonal. Is there a reason that this is ...
4
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3answers
176 views

CNC milling of large cutouts

I have a part made from 5mm alloy plate and I need to cut a large cutout in the middle of said part: As seen above I intend to use a small cutter to cut through the stock (not necessarily plunging as ...
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3answers
280 views

What would be the adverse effect on the human body travelling at 1000km/h?

Will Hyper loop succeed as a means of human transportation? What would be the adverse effect on the human body travelling at 1000km/h?
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2answers
1k views

How do you prevent ignition of the gas-air mixture before it reaches the burner nozzle?

I believed that the flame propagates over the place where fuel contacts the oxygen. If it contacts a fule+O2 mixture, the mixture inflames as well, and so on and on and on until there is no more ...
6
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2answers
208 views

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 ...
2
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1answer
199 views

Equilibrium of rigid bodies

I wanted to evaluate the safety of a walking aid device (walker). For example, if the way it is constructed and whenever I handle it, there are no risk of rotation, around its center of mass, turning ...
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7answers
8k views

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 ...
12
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1answer
248 views

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 ...
7
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2answers
155 views

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, ...
5
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3answers
323 views

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) ...
2
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1answer
286 views

Is an Explosion Proof Circuit Breaker Panel Required at a Gas Station?

Check the attached photo of a gasoline station. The two panel boxes at the center of the photo (in the corner of the station) are standard panels (IP-67), which enclose standard circuit breakers for ...
2
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1answer
371 views

Tornado Safety: Basement or first floor interior room?

Bulding I live in a new (~10 years old) 2 story duplex home in the Eastern United States. We have a completely interior bathroom on the first floor. It is between 2 other (exterior) rooms, the ...
4
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2answers
127 views

Can a dry-pipe or preaction valve be used to create a branch off a wet pipe sprinkler system?

Individual-head (i.e. not deluge) sprinkler systems come in three flavors: Wet-pipe systems have water pressure at the head at all times -- they are the quickest to respond, but can't be subject to ...
22
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2answers
4k views

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 ...
76
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8answers
31k views

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. ...
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2answers
8k views

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 "...
3
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1answer
167 views

Service Life of a Flashback Arrestor

First of all, I would like to know about the service life of a flashback arrestor. In my laboratory, I got three flashback arrestors {WITTgas RF53N(1/4”NPT-F), Brass} from the ex-students who used ...
2
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1answer
71 views

Is there such a thing as a voltage level that is safe for humans in all circumstances? [closed]

My question is naive but I'm having a hard time finding a precise yes/no answer when I ask google. The general advice seems to be "it depends", but are there voltage levels where it really does not ...
0
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2answers
103 views

When backup cooling fails in reactors without passive safety, what is the risk of radioactive contamination?

Most/all nuclear fission reactors require cooling. Due to radioactive decay heat, this is true even when the reactor is switched off. Hence, there are requirements for nuclear plants to have power ...
5
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1answer
466 views

What is the difference between being UL recognized and being UL listed?

A product can be UL recognized or UL listed. I understand that there is some difference between these two things, but I have never had a full and clear explanation of the difference. What is, in fact, ...
0
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1answer
639 views

Exact procedure to mount a blanking spade near a butterfly valve

This is a follow on to my previous question about blanking spades. There's a gas pipeline with a butterfly valve mounted between to flanges. I want to work on one side (call it the inert side) and ...
1
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1answer
127 views

What are best safety practices for visits to waste water treatment plants (WWTP)? [closed]

In my position I'll frequently visit wastewater treatment plants, often when refurbishments work happen. What are best practices I should adopt to avoid accidents?
2
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1answer
75 views

Device to remove condensate, without creating a hazard (EX) zone

I have gas pipeline with biogas, low pressure - approx 40mbar over atmosphere. I want to remove a small amount of condensate, inside a building, without creating an ex-zone. Small amount: I honestly ...
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2answers
2k views

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. ...
3
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2answers
352 views

First glance: structural integrity of this roof

There's a rooftop we recently discovered with a great view, and it's easily accessible for us. Obviously we'd like to go up there a bit more, particularly in summer with a couple of fold up chairs or ...
3
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2answers
2k views

Will lightning strike an aluminum rod in a pot on my balcony?

I have some tomato plants on my balcony (4th floor in a 7 story building). The balcony is a recessed one. The building has lightning protection on top. To support them, I put a 2 m long aluminum rod ...
5
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1answer
147 views

What drives improvements in seismic safety?

I get the impression that a lot of old buildings fail to meet modern earthquake safety norms, and need to be rebuilt or retrofitted. But what has changed in the last few decades that would make a ...
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2answers
139 views

How does one define 'safe' in engineering?

What is safe and what is acceptable in the context of Engineering. Specifically speaking we are in the process of designing a test rig which will pump water. What is a maximum safe temperature for ...
27
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4answers
11k views

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 ...
43
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9answers
6k views

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 ...