Questions tagged [safety]
The safety tag has no usage guidance.
73
questions
16
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4answers
5k views
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 ...
3
votes
2answers
70 views
Why do pneumatic valves need both a Safety Relay and an Air Dump to be safe?
If air dumps safely release pneumatic pressure from an industrial machine when an E-Stop is pressed, why is it also standard practice to cut electrical control power from the valves with a safety ...
0
votes
1answer
34 views
Is there any way to quantify the rate at which pressure is relieved in a reactor?
If a pressure relief valve is open, is it somehow possible to quantify the rate at which the pressure in the reactor will decrease?
0
votes
2answers
112 views
What is the purpose of these "safety" ledges on this Asian skyscraper?
While watching a video of a crazy person jumping around on buildings in some Asian country in a death-defying manner, I noticed these odd "safety" ledges outside, with nothing preventing you ...
0
votes
1answer
57 views
Lightning strike and metal structures in garden
I am worried about metal posts (support structures for plants) placed in garden and danger from lighting strikes. Posts are 3 meter long rebars and they are about 1,5 m driven into ground. Around ...
3
votes
2answers
192 views
Disposition of the generators on the shipwrecked Costa Concordia
Recently I have been reading about the shipwreck of the Costa Concordia, unfortunately what I read is not online, so I have no links, but it raised a lot of questions.
A rock hit by the ship tore a 50-...
1
vote
0answers
46 views
How to approach potential hazards that may result from user misuse, in a product design phase? [closed]
I am researching guidelines and considerations with respect to user safety when designing commercially sold products that contain user-operated machinery and moving parts (I.e. motors, pulleys, ...
1
vote
2answers
69 views
Why would an oxygen concentrator warrant an "Oxygen in Use" warning for firefighters?
I needed to use a medical oxygen concentrator for a short period, and I found it strange that it came with a warning label I was supposed to put in the window so firefighters would know it was there. ...
3
votes
1answer
159 views
Does electricity go through non-metal materials or not?
Ever since I was a little boy, I've always had this idea that electricity can only go through metal materials. For example, if I put a 100% metal screwdriver into the socket in the wall, I'm going to ...
0
votes
1answer
29 views
Safely Measuring Voltage from Solar Panels in an Experimental Research Field
I'm installing solar panels (not connected to the grid) in units out in a field for research we're doing that looks like this (this is an outdated image, but I can't find the updated one unfortunately)...
0
votes
1answer
21 views
Should we split a building containing a factory and a storage according to (NFPA 13) code?
I asking for a building that contains a desalination plant and a storage of water bottles (in carton boxes).
Should we split the factory and the storage or not (according to NFPA 13)?
And which ...
4
votes
1answer
1k views
What is this locking pin for a hinge called?
The following is a picture of a locking pin for a tubular hinge which specifies Maritime use. I assume it has something to do with railings but I'm thinking of fabricating my own similar hinges. "...
0
votes
0answers
71 views
Need advice on how to detect an object in the way of a closing door
I have a system design with a 149oz-in stepper motor for opening/closing a drawer style door. My cross sectional dimensions of the door opening are 20" width by 15" height. The motor ...
3
votes
1answer
154 views
Gas kitchen stove in skyscrapers
I have watched a property tour around an apartment in the Steinway Tower (NY) on YouTube and I noticed one detail that bugs me, namely gas stoves.
In Poland it is very uncommon for new blocks of flats ...
0
votes
2answers
86 views
How to manage two control loops as safety when BPCS is shared?
I am trying to wrap my head around some excerpts from:
CCPS Layer of Protection Analysis
CCPS Guidelines for Independent Protection Layers and Initiating Events
IEC 61511
I am trying to understand ...
0
votes
2answers
45 views
How is fire risk reduced in dense contemporary timber neighbourhoods?
In the Middle Ages most buildings were made from timber. After large fires timber was restricted or outlawed altogether and brick and stone became the preferred building materials, e.g. in London ...
0
votes
4answers
264 views
Can I safely cook on High temperature paint?
Like a million others, I have a set of enameled cookware that has seen enough use that the enamel has boiled, burned, or chipped off down to the cast iron substrate. Surprisingly, the outer painted ...
2
votes
4answers
146 views
Swing safety: maximum load of beam (supported at one end, free with load on the other)
My husband and his dad built a fort for our two boys. Coming off of one side of the fort is a 4x6 wooden beam with a tire swing attached at the end. It is supported on one side by the fort, but not ...
3
votes
2answers
43 views
H2 Sensor in N2 environment
We develop a test station where we might have H2 leakage.
To prevent explosion we are considering intertisation using N2 gas (primary explosion protection).
However we also want to detect leakage ...
1
vote
0answers
512 views
Is surgical and medical mask based on static electricity?
Is surgical and medical mask based on static electricity? By static electricity I mean like 3M N95 mask with at least two different layers of positive and negative static electrical layer. I googled ...
1
vote
0answers
26 views
Standards for safety car seatbelts locking condition
Is there an (international) standard which determines the condition when a car seat belt locks? Which standard is it? Does the standard determines a speed in m/s of the belt, such that it locks if ...
2
votes
0answers
31 views
What is the test procedures for a flame arrester?
A flame arrester is basically a heat exchanger in front of the tubulure. It conducts the heat of flame to some other place (to the liquid and/or the container especially if the container is built from ...
-2
votes
1answer
44 views
Public data re possible estimate of baghouse efficiency. Plus characteristics of chromium emissions. Thanks!
I'm doing an article on a company whose Title V Operating Permit is currently under review by state regulators. (See biographical note below.) See also my specific questions, numbered below. Most ...
0
votes
4answers
99 views
How is it possible that it took until the 1950s or even longer before they started using car belts and neck-supported seats?
I've spent a large amount of my life thinking back on past times, both long ago and "recently", meaning ~1950s to me.
A lot of things make sense, but some things just fundamentally baffle me. One of ...
0
votes
1answer
294 views
How exactly do respirators seal out pathogens?
A "respirator with a rating of P100, has been tested to be proof against oil, and tested to filter 99.97% of all particles 0.3 microns in diameter or larger.'
As you know, an atom is 99.9999% empty ...
3
votes
2answers
1k views
How to remove protective valve cap from CO2 cylinder?
I have received a CO2 cylinder from an online seller fitted with a protective cap over the valve:
I understand these should unscrew, but this one appears to be stuck very firmly. Is there a standard ...
2
votes
1answer
94 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 ...
0
votes
1answer
111 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 ...
1
vote
0answers
31 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 ...
2
votes
3answers
347 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 ...
6
votes
3answers
125 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
vote
1answer
735 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
votes
1answer
40 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 ...
1
vote
3answers
81 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
votes
1answer
68 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 ...
1
vote
0answers
63 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 ...
0
votes
5answers
7k 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 ...
7
votes
2answers
429 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
votes
1answer
80 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
votes
2answers
516 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 ...
1
vote
4answers
598 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
vote
2answers
99 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
vote
0answers
53 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
votes
3answers
589 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
votes
3answers
267 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 ...
-1
votes
3answers
495 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?
1
vote
2answers
2k 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
votes
2answers
220 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
votes
1answer
209 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 ...
20
votes
7answers
9k 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 ...
