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Units Converters

05/19/2017 2:12 PM

We all know how crazy converting pressure units from obscure systems of measurement can be, along with other units of measure, some of which are actually engineering type of units.

There are any number on calculators, and converters online, including the ones in the "engineering toolbox". If you know how to navigate "the engineering toolbox" from its home page, then you truly are an engineer.

For the many varied pressure units I have come across in my career at these local power plants, and other places I have called on while servicing water treatment accounts, I finally came up with a spreadsheet, and it has one main page, and one conversion factor table page.

The converter is set up in such a manner that I type in yellow boxes the input value and UOM (as suggested by text possibilities) (it should have been made into a drop-down menu), then you type in the UOM for the output measurement, and the adjacent cell gives you the conversion factor to multiply the input by.

The result window updates as soon as you hit enter.

I also made a simple entry for the barometric equation, for pressure change (assuming nothing about any lapse rate of temperature for the air column above), to gauge how much correction to apply to flow measurements when corrected back to sea level measurement, and if the pressure and temperature were different from STP as measured.

Anyone who wants the spreadsheet is more than welcome to it. The conversion factors either came directly from one of the later editions of CRC Handbook of Chemistry and Physics, or were derived from published conversion factors there. By the way, I did find errors in their conversion factor tables, and these were corrected in my factor matrix.

I have found it to be a worthwhile thing to have around, from time to time. Hint: yes we should all be using standard MKS units of measurement for pressure by now, but no not all of us do.

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#1

Re: Units converters

05/19/2017 2:53 PM
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#2

Re: Units converters

05/19/2017 3:01 PM

I have an air pump that you can set to psi or kg/cm2 . The latter gets on my nerves whenever I see it. kg ain't force!

...and the adjacent cell gives you the conversion factor to multiply the input by.

Instead of outputting the multiplication factor, it might be more convenient for your spreadsheet to do the multiplication and just give the answer. Just a nit.

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#6
In reply to #2

Re: Units converters

05/19/2017 3:58 PM

Oh, it already does output the number down below, but you have a lot of data to convert, you can just put the factor into the formulae.

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#21
In reply to #2

Re: Units converters

05/21/2017 4:55 PM

I'm not sure how psi (pounds per square inch) differs from Kg/cm2 here. Neither pounds nor kilograms are units of force.

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#22
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Re: Units converters

05/21/2017 7:08 PM

The pound IS a unit of force. The kilogram is a unit of mass.

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#24
In reply to #21

Re: Units converters

05/21/2017 10:14 PM

kg/cm2 is a bit odd even if kg was a unit of force. I would expect the metric unit to be pascals (Pa).

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#26
In reply to #24

Re: Units converters

05/22/2017 2:59 AM

Strictly speaking it should be kgf/cm^2, where kgf = 9.81N, but we all know what it means. Pa (usualy a multiple of) is the SI unit.

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#34
In reply to #21

Re: Units converters

05/22/2017 9:46 AM

Actually pounds are strictly a unit of force. The unit of mass in the English system is slugs, I think.

A slug is defined as the mass that is accelerated by 1 ft/s2 when a force of one pound (lbf) is exerted on it. One slug has a mass of 32.174049 lbm or14.593903 kg based on standard gravity, the international foot, and the avoirdupois pound.

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#36
In reply to #34

Re: Units converters

05/22/2017 5:44 PM
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#37
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Re: Units converters

05/22/2017 6:46 PM

The difference between force and mass measurements is that a mass measurement does not change with gravity. It must be done with a balance-beam and a set of standard-sized/massed objects or some other device that can work in zero-gravity. If it is done on the moon, the balance will not change. In zero-gravity, it might have to be a centrifuge or something. But, a standard bathroom weight scale only measures the force that gravity exerts on that mass, and will change with gravity. Mass does not change with gravity. If this is a critical factor, then Force/Mass must be specified with the unit(s). But since we very seldom have a different gravity, they are usually interchangeable.

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#3

Re: Units converters

05/19/2017 3:06 PM

I had a program back in the 90's that did a wide range of conversions

I believe it was called Omnicon98.... did a quick web search and did find it.

At the time, it did come in handy.

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#4
In reply to #3

Re: Units converters

05/19/2017 3:34 PM

Even further back there was an App called "Log Tables 1.0".

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#5
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Re: Units converters

05/19/2017 3:40 PM

In college, I had one in the back of my Technical Math book.

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#7
In reply to #4

Re: Units converters

05/19/2017 4:03 PM

before that, we had to memorize the logarithms and the sine and cosine tables, what a bunch of rubbish that was!

Then there was Schlipschtick 2.1, a small circular device for multiplying real numbers and adding logarithms. You had to put your own j or i in front of the imaginaries.

What a lack of imagination!

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#8
In reply to #4

Re: Units converters

05/19/2017 9:21 PM

Yeah, those days were fun, watching all those adders multiplying on our log tables, their shadows dancing on the cave walls in the firelight.

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#9

Re: Units Converters

05/19/2017 10:13 PM

"Hint: yes we should all be using standard MKS units of measurement for pressure by now, but no not all of us do."

And leave the FFF system out in the cold? Perish the thought!

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#28
In reply to #9

Re: Units Converters

05/22/2017 9:26 AM

I don't believe I included any of the factors for cross-conversion between the FFF system, and English or MKS units in my pressure unit conversion spead sheet factor table....hmmm.

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#10

Re: Units Converters

05/20/2017 12:01 AM

After having taught Physics for 32 years, mostly in metric, and most of that in MKS, I retired from teaching. Very soon thereafter, I began working in the aerospace industry, and was appalled to discover that they still use imperial measurements. Now, after 20+ years in aerospace, I've seen no movement toward metric, except on jobs for Roll-Royce.

I assume your spreadsheet is in Excel. Sure - I'd like a copy!

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#11
In reply to #10

Re: Units Converters

05/20/2017 12:10 AM

Nov. 10, 1999: Metric Math Mistake Muffed Mars Meteorology Mission

"The software calculated the force the thrusters needed to exert in pounds of force. A separate piece of software took in the data assuming it was in the metric unit: Newtons."

Oops.

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#12
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Re: Units Converters

05/20/2017 12:28 AM

Yep! I clearly remember that. It was just three years after I entered the aerospace world.

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#30
In reply to #11

Re: Units Converters

05/22/2017 9:38 AM

Yes, that was a total mission failure OOPS!

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#14
In reply to #10

Re: Units Converters

05/20/2017 9:18 AM

I would like to take this opportunity to advertise my very own made-up number system.

Hear me out, I'm serious. Both the metric system and the S.A.E. (Society of American Engineers) system have pros & cons. Metric Pro: easy to do do decimals. Metric Con: hard to do fractions. S.A.E. Pro: easy to do fractions. S.A.E.Con: hard to do decimals.

I've invented a new number system that uses the best of both worlds. Serious.

Both Metric and S.A.E. use the base-ten number system. However, S.A.E. uses measurements with multiples of twelve, making decimal math hard. Metric uses measurements using multiples of ten, making fractional math hard. So, I invented a base-twelve number system where the symbol 10 actually means twelve. this system uses measurements using multiples of both ten & twelve simultaneously, making both decimal & fractional math easier within the same system. The only draw-back would be that you'd now have to remember two more different symbols that represent ten & eleven. For instance:

Base Ten: 0 1 2 3 4 5 6 7 8 9

Base Twelve: 0 1 2 3 4 5 6 7 8 9 (new symbol 1 ) (new symbol 2)

However, I invented twelve new symbols so that they would not be confused with the base-ten number system.

So, maybe I'm not such an old geezer after all.

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#15
In reply to #14

Re: Units Converters

05/20/2017 9:43 AM

Might have been useful before we had computers, or even hand calculators. Nowadays, not so much.

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#17
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Re: Units Converters

05/20/2017 11:17 AM

Anything can happen out in the field. Wouldn't want to get caught up a formula without a solution. How would you be able to paddle back to civilization? Think about the field workers or 3rd-world countries, or even astronauts who can't get back to Earth. Your life could depend on it.

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#19
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Re: Units Converters

05/20/2017 11:40 AM

I don't see how a 12-base would make things any easier than decimal. Maybe if you're on your own and your happier with it, could be OK, but you might have a problem if you had to communicate with others. Just my thought.

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#23
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Re: Units Converters

05/21/2017 9:47 PM

For one thing, fractions/ratios eliminate any repeating decimals. You won't have to memorize Pi to the Nth digit. 1/3 is exact. And multiplying a denominator, by any factor, is easier than finding its decimal equivalent. And switching between fractions and decimals is easier, so everybody can use whichever technique they're best with. If you prefer decimals, no problem. If you prefer fractions, no problem. We both can use the same system, no problem. If you're NOT on your own, and not happy with the way others do it, no problem.

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#25
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Re: Units Converters

05/21/2017 10:24 PM

What does 1/3 have to do with pi? Pi is a transcendental number. Transcendental numbers are irrational and don't have repeating decimals. Numbers with repeating decimals are always rational. As an irrational number pi, by definition, cannot be represented exactly as a fraction, only approximated.

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#32
In reply to #14

Re: Units Converters

05/22/2017 9:43 AM

You have twelve toes and ten fingers?

Why use that system, as it neither fits in with decimal (really?), nor with English strictly speaking, nor does it fit in with octal, binary or with hexadecimal system.

Maybe we should grow up speaking hexadecimal, but I don't recommend it.

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#39
In reply to #32

Re: Units Converters

05/23/2017 10:03 AM

You missed the point. This system will not "fit in" anywhere, but it will include other systems. In other words, the decimal system will not fit into the English system, and the English system will not fit into the decimal system. However, both the decimal and the English systems will fit into this system. No system can "fit into" any of its own sub-systems.

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#29
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Re: Units Converters

05/22/2017 9:30 AM

Let me see if I can squeeze it in here.

That way does not work. I will send it to you as an attached file in PM>

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#38
In reply to #10

Re: Units Converters

05/23/2017 5:28 AM

Rumour has it that the aerospace industry is inching slowly towards the metric system.

Aircraft fly globally at altitudes in feet, though.

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#40
In reply to #38

Re: Units Converters

05/23/2017 10:50 AM

I'd hope so, but haven't seen much evidence of change in our area of work.

Of course it'd be faster if they were metering, instead of inching.

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#13

Re: Units Converters

05/20/2017 4:25 AM

You're not a Mathcad user? With it you can convert between any of a wide range of built-in units, and if it doesn't have what you want you can define your own. Eg my version doesn't have millibar (earlier one didn't have bar if I remember right) so I just define mb = 100Pa and good to go. It would be nice if you could save user-defined units, perhaps you can on later versions.

BTW MKS is usually called SI these days I think, includes K for temperature (not °K!)

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#31
In reply to #13

Re: Units Converters

05/22/2017 9:40 AM

I still think of chemical equilibrium constants as K, although many texts use Q, therefore I continue to include degrees, as degrees still matter.

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#16

Re: Units Converters

05/20/2017 9:59 AM

I have been using convert for the last 15 years. It's pretty good, and allows you to enter your own 'unique' conversion units.

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#18
In reply to #16

Re: Units Converters

05/20/2017 11:25 AM

I use the program called units, readily available for Linux and I believe there is a version for Windows.

$ units

Currency exchange rates from www.timegenie.com on 2014-04-02

2866 units, 109 prefixes, 79 nonlinear units

You have: 22000 ft2

You want: acres

* 0.50505051 / 1.98

You have: tempF(98.6)

You want: tempC

37

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#20
In reply to #18

Re: Units Converters

05/20/2017 4:04 PM

Windows binary and Linux source available at:

https://www.gnu.org/software/units/

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#33
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Re: Units Converters

05/22/2017 9:43 AM

nice.

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#27

Re: Units Converters

05/22/2017 4:28 AM

EngNetTools is my favourite converter, seems to cover most units plus many I've never heard of.

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#35

Re: Units Converters

05/22/2017 4:19 PM

https://joshmadison.com/convert-for-windows/

it is free

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#41

Re: Units Converters

05/24/2017 12:55 PM

I just can't help myself, I gotta share something I hope you find amusing. Shortly after I invented my new number system, I wrote this poem: (I hope you like it)

The Modern Columbus

There comes a time when your thoughts start thinning.
And writer's-block won't let you start by beginning.
So I'll try something new, and by doing some pretending,
I'll trick my brain, and I'll start by ending.
That goal has paid its toll, and now my brain can wander.
Free to explore, I'll go some more, A lllooooonnngg way out yonder.

I don't have to think out-of-the-box, if there is none.
Going to infinity is easy, and might even be fun.
There's no time for common-place pretensions.
So don't tell me there are no unknown dimensions.
I beg your pardon, for not regardin', common practicality.
But it might be cuter, if I take my computer, into criticality.

So now I'll retire, that old beat-up tractor.
Latch the rods, and boot-up the high-tech reactor.
What was known, now has flown, back into the past.
And something grew! All brand new! Now is coming up fast!
Faster than the speed of light, I know it must be best.
To leave all behind, as far as east is from west.

Something new up ahead, and I'm really gaining ground.
Oh! you'll never believe what it is that I have found!
Like the world, Time has curled, into a revolving globe!
What I sent, came back bent. All the data from that probe!

Columbus had an idea, and sailed to prove it true.
He sought something old, but found something new.
But unlike Columbus, all truth be told,
I sought something new, and found something old.
Try as I might to leave from where I departed,
I find myself right back where I started.

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