Questions tagged [unit]

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Strange units with UV water disinfection systems

When retrieving information about UV systems for water disinfection I frequently encounter minimum intensity values. e.g. here: Basics of UV disinfection, page 23 All those I find are given in a unit ...
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-2 votes
3 answers
68 views

Unit of blower speed

I want to know whether the international unit of blower speed is RPM or r/min. I konw ther're the same, but I'm not sure which one is more prevailing internationally. Thanks for answering.
0 votes
2 answers
47 views

units check for horsepower to weight (Hp/W)

is this units breakdown correct: Hp/W= (ftlb/s) / (lbft/s^-2) = s^-1? I think I might made mistake?
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-1 votes
2 answers
41 views

General Units question

so let’s say I worked out a quantity that turned out to be unit less but to work it out I used pounds (lb) and feet (ft) and the units cancelled out But then I used this unit less number later in ...
0 votes
2 answers
55 views

Convert from RPM to per second [closed]

Is this correct please for my conversion from RPM to per second? I've included my working below: (500 / 60) * 2 * π = 500 rpm to just s-1.
0 votes
1 answer
37 views

Reading odd dimensions

I am reading a paper and the dimensions for some electrodes are given, but I was wondering if I was reading it properly: 30 × 15 mm2, is this the same as: (30 × 15)mm2 ? To track the published paper I ...
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4 votes
1 answer
490 views

What does MM prefix mean in MMtoe?

I was reading documents about energy importation and came across the following: The import was of 5,915.87 MMtoe I wonder if MMtoe = $10^6*10^6$ toe = $10^{12}$ toe. First time coming across a ...
  • 271
3 votes
2 answers
784 views

Unit of "cN.m" used on torque wrench

I'm using a torque wrench whose unit is cN.m. I wonder what unit this is, and how to convert N.m (Newton meter) to ...
16 votes
1 answer
2k views

What unit of weight is that?

Recently I was weighting stuff with my dad and as I was playing with one of the old 2 kg weights I felt with my fingers number "5". After cleaning and upon further inspection it turned out ...
0 votes
1 answer
54 views

Thermal conductivity listed in the rather complicated Btu/s-in.²-°F/in - am I converting this right?

I'm currently working through some rather old documentation which gives the thermal conductivity of a material as 9.8 x 10⁻⁶ Btu/s-in.²-°F/in. There are many typical ways to give a thermal ...
1 vote
2 answers
82 views

Inconsistencies with units for thermodynamic identities

I am working out the temperature for an Ideal diesel cycle: Based on the isentropic properties for an ideal gas. $$T_f = T_i * r^{k-1}$$ Where $T_i = 50 ºF = 510ºR$ If I use ºF, then $T_f = 172.9ºF = ...
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0 votes
1 answer
39 views

Half-life Unit Notations

I was looking for some element's half-life, on the following website: http://nucleardata.nuclear.lu.se/toi/listnuc.asp?sql=&A1=214&A2=214&Z=88 For 214,88-Ra, the half-life is shown to be: ...
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0 votes
1 answer
122 views

How can I calculate the density of air?

I major in chemical engineering, and I'm solving a example of unit operations. The textbook is Warren L. McCabe, Unit Operations of Chemical Engineering 7th ed. Here is example 24.1. And this is its ...
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1 vote
1 answer
31 views

Weibull distribution Units - ENGIEQSOL

I am using Engineering Equation Solver, and it has been telling me the units of my distribution are inconsistent. According to a the book I am reading, I think it should be unitless (as it is a ...
  • 271
10 votes
7 answers
3k views

Forgotten time units

As my kids are counting down to Christmas, I came to wonder how did people measure time through history. More precisely I wonder about unit systems for precision time keeping of years past gone. I am ...
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2 votes
6 answers
572 views

What is the accepted way to write units when specifying multiple dimensions?

When writing out dimensions in the form height x width x depth, what should you write for the units? For example, I can think of a few ways to approach this (assuming each dimension is measured in ...
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2 votes
1 answer
140 views

How to set measure display units in Solidworks drawing?

I have already set millimeters in document propertis, nevertheless the display units are meters Why and how to fix?
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-1 votes
2 answers
10k views

Converting flow rate from normal/standard liters per minute to cubic meters per second

I'm really confused about these three units commonly used for measuring airflow: cubic meters per second (m3/s) normal liters per minute (NLPM) standard liters per minute (SLPM) I would appreciate ...
  • 219
1 vote
2 answers
536 views

Questions about newton metre units

I have a few values in Newton metres and I need to make sure each value is an SI unit for calculations. However when I try to search for the units I am given, I can only find similar, but not quite ...
5 votes
6 answers
635 views

Engineering calculations in a tool that will handle units [closed]

I know Mathcad handles units along with numbers which makes it easier to avoid errors by tracking units the way we would by hand. e.g. 250 kW + 500 W I just ...
3 votes
1 answer
102 views

Unit Conversion for Mass Density

I am doing a Finite Element analysis of a continuum. In my problem definition I use these units: mm for length, kPa for applied stress, and MPa for material stifness (Young's modulus). With these ...
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1 vote
1 answer
80 views

US customary units below 1 mil/thou?

I have been asked to provide some of our technical docs in both metric and US units. For the most part, that is easy enough: approx 1cm → approx 1/2" 500μm → 0.02" But then I start getting stuck: ...
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1 vote
4 answers
342 views

What's the current nomenclature for "English" system of units?

Is the term "English units" still in current everyday use? I do hear this term among other engineers I work with but I'm unsure if this is a localized usage or is consistent with the wider ...
4 votes
1 answer
1k views

How do you convert "kps" to Pounds per Square Foot (psf)? [closed]

I'm looking at a soil bearing capacity report, which has a column labeled "kips" and the values are followed by "kps". A "kip" is 1000 pounds, but I'm not sure how to convert from "kps" to psf. The ...
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1 vote
0 answers
104 views

Did the pressure unit "bar" change definitions since the 1930s?

I don't see anything in Wikipedia about it, but (from this question) when I try to reproduce the equations in this 1933 paper, I get values 106 away from the values in the paper. When I reproduce ...
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0 votes
2 answers
196 views

How do I denote someone weight

How do I say my weight? In which SI units? I see people are using Kg as a unit of denoting weight from my childhood. Answer this question "What's your weight?".
1 vote
2 answers
5k views

Darcy to SI permeation units

How can permeation units in Darcy be converted to the SI form. For example, how would 9.0 x 10-6 darcy be converted to SI units of permeation? How would it also be converted to the permeation units: (...
0 votes
1 answer
46 views

I need clarification on how pressure is measured

I have a vessel that has a pressure measuring device. The value it shows as the pressure inside the vessel is 6 inches of water column. Is inches of water column meant to always be used as gauge ...
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0 votes
2 answers
94 views

Units to use in this formula?

Should standard SI units be used in this formula or are other units supposed to be used for the formula for stress in a thin-walled spherical pressure vessel? $$\sigma_{yield}=\frac{P_g r_i}{2t}$$ ...
1 vote
1 answer
291 views

Definitions of strength?

Can tensile strength be the same as yield strength? Can Flexural Yield Strength be related to the yield strength of a material in any way?
0 votes
1 answer
137 views

What is pros of weight density?

I've been studying mechanical simulation with nastran/patran, nowadays. I knew weight density is used in imperial unit system, instead of mass density. I feel using weight density is tedious, ...
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