Questions tagged [safety]
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57
questions
3
votes
2answers
40 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
238 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
23 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
30 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
38 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
73 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
217 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
80 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
78 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
55 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
18 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 ...
0
votes
0answers
12 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 ...
0
votes
0answers
11 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 ...
1
vote
2answers
104 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
votes
3answers
108 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
130 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
34 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
73 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
45 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
51 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
4answers
4k 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 ...
6
votes
1answer
300 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
56 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
342 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
288 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
95 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
51 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
572 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
207 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
323 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
213 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
202 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 ...
19
votes
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
votes
1answer
285 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
votes
2answers
175 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
votes
3answers
348 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
votes
1answer
341 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
votes
1answer
472 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
votes
2answers
174 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 ...
23
votes
2answers
5k 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 ...
77
votes
8answers
33k 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. ...
8
votes
2answers
10k 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
votes
1answer
175 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
votes
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
votes
2answers
105 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
votes
1answer
485 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
votes
1answer
743 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
vote
1answer
128 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
votes
1answer
76 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 ...
