Questions tagged [specifications]

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4 answers
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Product idea then specification, or specification then product?

I am trying to write a requirements specification for a new product but I am confused about where I should start. Do you start with the product like "A new kettle" and proceed from there, or ...
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2 answers
51 views

What's the process with requirements and design?

What is the usual way which requirements are managed and made sure to be fulfilled in designs? Sorry if the question is vauge and overly general but i'm just looking for a crude description. Thanks
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2 answers
34 views

How to select the right power supply for a stepper motor?

When choosing a power supply for a stepper motor, e.g. this one below: Amazon Link NEMA 23 This one has: Rated Current: 4.0A Operating Voltage: 24-50VDC The Stepper Driver I will be using is: Stepper ...
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-2 votes
2 answers
66 views

Is this a rifle or a shotgun? [closed]

According to a Meta Post I found this is the right place to ask this kind of question. I apparently can't find the post anymore but it pointed towards this subsite. Yesterday I had an argument (for ...
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0 votes
1 answer
65 views

Why are thermocouples documented by couple type (or by pair) and not by material (single) and compatibility

I just found out on Wikipedia (also here and there) that the voltage in a thermocouple in not generated by the both the cold & hot junction, but by the temperature gradient in the wires which ...
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-1 votes
2 answers
157 views

What is the difference between requirements and design specifications?

Working while employed at large companies, I was at times confused as to what was considered to be a requirement and how a specification differs from it. Upon reading more about it, I have discovered ...
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2 votes
0 answers
290 views

What is meant by "accuracy within factor of 2" in sensors?

I've spent quite some time googling the meaning of "factor of (number)" in sensor accuracy but could not find any document explaining the meaning of this expression used to describe sensor accuracy. ...
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1 vote
0 answers
10 views

Are there any specifications that address the environmental conditions items traveling though international post should be able to tolerate?

In terms of temperature extremes, air pressure, humidity, shock, ... In determining what ranges to design for in a device are there any standards or at least guidelines either by postal services or ...
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  • 285
1 vote
1 answer
48 views

buying a mounted bearing determining radial vs axial load it can bear

Can anyone tell if these bearings load ratings are for a radial load or an axial load ? Bearing designed for an axial load is (sometimes?) called a "thrust bearing". Based on its mounting, I guess ...
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1 vote
0 answers
13 views

How to specify plumbing fixtures so models are not immediately out of date

Rock-solid guide specifications are the ultimate pipe-dream of consulting engineers because they minimize the amount of time that needs to be repeatedly spent on the minutiae of tiny details from ...
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  • 561
0 votes
1 answer
63 views

Potentially fatal near miss: Due diligence in tool selection

I recently outfitted a crew to build scaffold in preparation for an upcoming turnaround at our plant. Among the tools requested were canvas buckets for manually hauling material and tools up and down ...
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  • 205
1 vote
0 answers
17 views

External Static Pressure on Open Gallery Fan

I routinely work on building designs that incorporate rooftop upblast fans over large industrial spaces such as this one: When selecting these fans, as with every other fan, you need to determine the ...
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  • 561
3 votes
2 answers
641 views

Specification of linear speed dampers

I'm looking at linear compression dampers and finding them most commonly specified only with a "Max Force" – e.g., 270 lbs. However, since the damping mechanism is provided by hydraulic or pneumatic ...
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4 votes
2 answers
216 views

Inert gas use during HVAC line installation

When brazing HVAC linesets, the correct method is to flow an inert gas through the line in order to prevent interior oxidation of the copper and brazing products. However, as a specifier, I can say ...
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  • 561
1 vote
1 answer
54 views

Comparing 2 shock scenarios with different magnitudes and times

For example, How does one compare 100 g's for 6 milliseconds to 45 g's for 11 milliseconds. These are two different shock scenarios with different magnitudes and times, so how can I compare them? If I ...
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2 votes
0 answers
78 views

Moment Of Inertia Specifications AISC

Is there some regulatory body/inspection that verifies the AISC specified Moment(s) of Inertia for steel I-Beams? So for example, if a mill produces a W8x21 and says hey, it meets the specs, it's 8 ...
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6 votes
2 answers
3k views

Tube Steel - ASTM A1085 vs. A500

Recently, tube steel manufacturers in the US have begun using the new ASTM A1085 specification for forming tube steel (a.k.a. hollow structural section or HSS) shapes, as opposed to the existing A500 ...
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3 votes
1 answer
146 views

Industry standard for AC wall electrical box space

Are there any industry standards (Engineering Specifications) for the minimum / maximum space required for the electrical box that holds a regular AC wall plug? The problem I am trying to solve is ...
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