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Re: Imperial System

Posted: Wed Mar 06, 2019 9:23 pm
casinterest wrote:
Personally I like jogging a 5k better than a 5 miler

I see what you did there. Well played sir

Re: Imperial System

Posted: Wed Mar 06, 2019 9:48 pm
Tugger wrote:
akiss20 wrote:
This is not true. All base SI units will be based off of exact values of physical constants in the universe (the kilogram and a few others are switching definition on May 20th 2019). The meter is defined off the distance the speed of light travels in a certain amount of time (and the second itself is defined off of the decay of a cesium 133 atom). The Kelvin (from which the Celsius scale is defined) is defined from Boltzmann's constant (and before that it was based on the triple point of water which only exists at a single pressure and temperature). Most imperial units are now defined as exactly some amount of SI units (e.g. since 1959 1 foot has been defined as exactly 0.3048 meters).

SI is much much more useful in scientific applications as unit and it makes unit analysis a lot easier than imperial. I am in aerospace engineering academia in the US. While industry still often uses imperial, much of academia does everything in SI as it is so much easier to use. Whenever we work with data from industry, we do what I call the imperial sandwich. Convert everything to SI, do all the actual analysis and work, and then convert the results back to imperial to present to industry. Even in industry you will find some SI as you move further away from product development and into research. I have also found that the younger generations tend to be much more resistant to imperial than the older.

Yes it is true. We are talking about the metric system, not "SI" per say. And you prove it, the metric measurements are also "variable" and so are fixed to a specific parameter and then matched to a universal constant.

Yes metric has been adopted into SI which also include atomic measurements etc. and everything is now converted to a fixed physical law.

You could do the EXACT same "physical constant value" for Imperial.

Tugg

The metric system is synonymous with SI (https://en.wikipedia.org/wiki/Metric_system). They are one and the same.

You claimed that the meter was based off of some arbitrary physical "meter stick" on which the meter was defined. That is simply not true as I showed. You also claimed that the definition of Celsius was vague and ill-defined, which it isn't. The only SI unit which was based on a physical object in recent history was the kilogram, which was historically based on the international prototype kilogram in Paris (or Le Grand K), but as I said that itself is changing to reflect a physical constant of the universe as the IPK itself is not constant. Basing our units on physical constants of the universe is the most rigorous way we could possibly define units and is not itself "variable" the way defining units off of a physical object is.

Of course you could define base imperial units on physical constants of the universe, but the point is they aren't. They had the same problem as the kilogram did, that there was no constant and consistent basis for their definition. That doesn't even begin to mention that Imperial units are just way more annoying to use. A great example is that of power. In SI there is simply one units for this in all applications (electrical, mechanical, thermal, what have you): watts (which is simply joules per second). In Imperial we routinely see horsepower, BTU/hour, foot-lbf/s.

Re: Imperial System

Posted: Wed Mar 06, 2019 9:49 pm
casinterest wrote:

Tugg,
There are issues though, and metric solves them much better.
Newtons vs Pound-force
1 Liter of water weighs 1 KG

At what pressure and temperature

Re: Imperial System

Posted: Wed Mar 06, 2019 9:59 pm
trpmb6 wrote:
casinterest wrote:

Tugg,
There are issues though, and metric solves them much better.
Newtons vs Pound-force
1 Liter of water weighs 1 KG

At what pressure and temperature

This relationship is not definitionally true anymore, although 1L of water is very close to 1Kg. The kilogram was defined in 1795 as the weight of 1 cubic decimeter of water at the temperature of melting ice [1](I am not sure what pressure, but presumably at standard atmospheric pressure, 101325 Pa). The kilogram has since been re-defined several times so this relationship is no longer definitionally true.

[1] https://en.wikipedia.org/wiki/Litre#cite_note-decree-5

Re: Imperial System

Posted: Wed Mar 06, 2019 10:01 pm
akiss20 wrote:

The metric system is synonymous with SI (https://en.wikipedia.org/wiki/Metric_system). They are one and the same.

You claimed that the meter was based off of some arbitrary physical "meter stick" on which the meter was defined. That is simply not true as I showed. You also claimed that the definition of Celsius was vague and ill-defined, which it isn't. The only SI unit which was based on a physical object in recent history was the kilogram, which was historically based on the international prototype kilogram in Paris (or Le Grand K), but as I said that itself is changing to reflect a physical constant of the universe as the IPK itself is not constant. Basing our units on physical constants of the universe is the most rigorous way we could possibly define units and is not itself "variable" the way defining units off of a physical object is.

Of course you could define base imperial units on physical constants of the universe, but the point is they aren't. They had the same problem as the kilogram did, that there was no constant and consistent basis for their definition. That doesn't even begin to mention that Imperial units are just way more annoying to use. A great example is that of power. In SI there is simply one units for this in all applications (electrical, mechanical, thermal, what have you): watts (which is simply joules per second). In Imperial we routinely see horsepower, BTU/hour, foot-lbf/s.

You're kind of working against yourself at the same time though by referencing the change of the kilogram to reflect a physical constant. What it is being changed to is something that closely matches the existing kilogram. Not the other way around.

By the way, did any of you know that the United States was one of the original 17 countries that helped found the BIPM in Sevres and keeps several of its own official Kilogram balls at the National Institute of Standards and Technology. You wouldn't know it reading this thread.

The nice thing about imperial is that it is indeed reflective of tangible measurements convenient to visualize. Horsepower for instance.

Though, I don't really have a horse in the race. I just run the numbers. Doesn't matter if its PSI or Pascals. It's just a scale factor.

Re: Imperial System

Posted: Wed Mar 06, 2019 10:13 pm
trpmb6 wrote:
By the way, did any of you know that the United States was one of the original 17 countries that helped found the BIPM in Sevres and keeps several of its own official Kilogram balls at the National Institute of Standards and Technology. You wouldn't know it reading this thread.

Unsurprising as most imperial units today have a definition based on metric units and their definition

Re: Imperial System

Posted: Wed Mar 06, 2019 10:38 pm
As a child, we were taught in school that conversion to comprehensive use of the metric system was imminent, and certainly expected to be completed by 1970 (I started elementary school in 1965). Thus, we were taught the metric system concurrently with, and with equal emphasis to, the English units. I was not politically aware at the time, so I don't know what all went into the decision to back away from metric conversion, but there was a period there for a while when quite a few highway speed and distance signs had both miles and kilometers shown. All this was in Texas; I cannot speak for elsewhere.

As a practical matter, of course, conversion to use of the metric system has already happened in many of the most important areas; most precision manufacturing of newly-designed products is conducted in metric units, for example.

I agree that there is no overwhelming and compelling reason to make the switch, but I think it would make sense to do it. For what it is worth, at 60 years old, I do not expect to see it accomplished in my lifetime in the United States. C'est la vie.

Mildly-amusing anecdote: last Christmas, spent a week in Nassau, where many cars are gray-market imports from Japan (they ship the timed-out cars to the Caribbean for further use), with right hand drive, and a lot of US imports with left-hand drive, with some speedometers marked in kilometers and others, MPH. The road signs all match the appearance of the international standard (like in Europe), but speed limits are in miles per hour, not kilometers per hour cognitive dissonance, since European-looking speed limit signs seem like they ought to reference Ks, not MPHs. I found myself wondering whether the bizarre state of driving there was the results of confusion over units, but I rather suspect is just because there are a lot of sketchy drivers there. But, what the heck, with all the Californians moving to Texas, that's a problem we had here as well.

Re: Imperial System

Posted: Thu Mar 07, 2019 12:10 am
There are two kinds of countries: Those that use the metric system and those that have landed men on the Moon.

Re: Imperial System

Posted: Thu Mar 07, 2019 1:06 am
OA940 wrote:
If they go metric what will happen to aviation though? I mean Imperial is a dumb system that was created just so someone could say they did something important, but it plays a huge role in aviation. Like, will we start measuring in meters instead of feet? How expensive will it be to change everything up for aircraft? I'd like to see the world adopt metric, but it's definitely not a walk in the park

The vast majority of the world has adopted metric.

Re: Imperial System

Posted: Thu Mar 07, 2019 1:13 am
Airstud wrote:
There are two kinds of countries: Those that use the metric system and those that have landed men on the Moon.

When did Liberia send men the moon, did Burma help? I can’t recall any UK moon missions either.

Re: Imperial System

Posted: Thu Mar 07, 2019 1:56 am
flyingturtle wrote:
I just had to think about the paper sizes used in Europe and in other places.

Annoyingly, for the longest time Lloyds-TSB (UK bank) sent their printed statements in what I think is US Letter size. Why Lloyds, whyyyyyyy? You can't find a plastic sleeve to stick that thing in a file.

Brick wrote:
There are two types of countries on this planet:

1. Those that use the metric system.
2. Those that have been to the moon.

Dutchy wrote:
The loss of the mars orbiter because Lockheed Martin used the Imperial system and NASA the metric.

Hmmm....

KentB27 wrote:
Fahrenheit measures temperatures in smaller increments than Celsius does. From freezing point to boiling point for water in Fahrenheit is 32F-212F, so you have 180 degrees between freezing point and boiling point with Fahrenheit. With Celsius, you only have a 100 degree difference between the freezing and boiling point of water so 1 degree Celsius is a broader difference in temperature than 1 degree Fahrenheit. Therefore Fahrenheit is slightly more accurate than Celsius is.

It's neither more accurate nor more precise. Fahrenheit has smaller increments, which is meaningless, because you use the decimal system, just like the rest of the world. See how a common system is beneficial?

Re: Imperial System

Posted: Thu Mar 07, 2019 2:02 am
WHat's the problem with learning both systems. I work in healthcare and have to do conversions in my head in a second or less all the time. Seriously, the miles would stay in the USA. Liquid measurement and temperatures could easily been made metric at any time. Someone just has to give to go ahead.

Re: Imperial System

Posted: Thu Mar 07, 2019 2:13 am
I'm surprised no one has mentioned food measurements. I grew up in a country that (at the time) produced all its own food and was fully metric, so didn't give this any thought. Until I moved somewhere that imports a lot of food from the US.

Now I have to read caloric content in hilariously stupid quantities like "1/3 cup" or "one serving (about 2.5 oz)" for irregularly shaped solids. Like broccoli. Take a moment to imagine this. A head of broccoli will not fit in a cup. It has to be cut into smaller pieces. How small? The smaller the pieces, the less air is going to be in the cup, so the more the volume of broccoli.

Now, I see the utility of using standard cups and spoons for baking - I mean, who wants to weigh flour and salt when you're baking? But when it's to determine nutritional details, it's seriously not accurate.

Re: Imperial System

Posted: Thu Mar 07, 2019 2:51 am
Kiwirob wrote:
Airstud wrote:
There are two kinds of countries: Those that use the metric system and those that have landed men on the Moon.

When did Liberia send men the moon, did Burma help? I can’t recall any UK moon missions either.

Around the same time the word "barb" got defined.

Re: Imperial System

Posted: Thu Mar 07, 2019 4:41 am
Airstud wrote:
There are two kinds of countries: Those that use the metric system and those that have landed men on the Moon.

If only it was that easy. But there are more than two kinds of countries, epecially concerning mass and volume.

Take a hundredweight for instance (abbr. "cwt"), it is 8 stone = 112 lb (Libra), therefore the name hundredweight. Well, at some places. At other places a hundredweight is 100 lb, again Libra, which is Latin, but those 100 or 112 lb are, as far as I know, not in Rome. They are also called long and short hundredweight, forgot which one i what. Stone is easier, it is always 14 lb, no short or long stones. Hundredweights of all types can be multiplied by all fingers and toes and become a ton, short and long ton depending on continent. But it can never become a real ton - 1000 kg.

What are you gonna do here? Multiply by 100 or 112 Libra?
https://en.wikipedia.org/wiki/Hundredwe ... Ilkley.jpg

Volume is more complicated. I will need a good night's sleep first.

Re: Imperial System

Posted: Thu Mar 07, 2019 7:51 am
seat64k wrote:

Now, I see the utility of using standard cups and spoons for baking - I mean, who wants to weigh flour and salt when you're baking? But when it's to determine nutritional details, it's seriously not accurate.

I you want to be truly accurate and consistent in your baking, you would certainly use weight vs. volume. All-purpose flour (spooned), for instance is 120 grams per cup.

For the record, I would love it we went over to metric. Easier to move between units and intuitive.

But, I can move easily between the 2 standards, so it's no big deal.

I haven't read through all the replies, but has anyone mentioned that aircraft construction? I know the Airbus aircraft I've worked on use imperial. The drawings and the maintenance manual all use metric with imperial in parenthesis, but the hardware is all imperial.

Re: Imperial System

Posted: Thu Mar 07, 2019 7:59 am
I do love imperial.
Bc a pint of beer is more than a medium one, that's 0,4 lt. But costs the same.

Re: Imperial System

Posted: Thu Mar 07, 2019 8:22 am
KentB27 wrote:
I seriously doubt that the US will ever fully convert to the metric system. It would be very costly and take years to completely convert. One huge hurdle I see is that changing all of the highway markings and signs to kilometers would be a massively time consuming and expensive undertaking that realistically isn't necessary.

In France we just changed our speed limit for undivided highways from 90 to 80 Km/h and the cost to change the signs was a few millions euros, for 11000 of them.

Re: Imperial System

Posted: Thu Mar 07, 2019 8:23 am
fr8mech wrote:
I you want to be truly accurate and consistent in your baking, you would certainly use weight vs. volume. All-purpose flour (spooned), for instance is 120 grams per cup.

Oh I agree. My point is just that with things like powders (flour, sugar, salt, etc) and most liquids, using measuring cups or spoons [*] is close enough for every baking at home.

[*] While the units conveniently map onto things we're familiar with, hilarious things happen when you translate this mess into other languages. For example, in my native tongue, the word for cup and mug is the same. Someone in my family went through their entire lives not knowing that a cup is a specific measurement, and happily using a giant coffee mug, never understanding why the recipes never quite worked out.

fr8mech wrote:
I haven't read through all the replies, but has anyone mentioned that aircraft construction? I know the Airbus aircraft I've worked on use imperial. The drawings and the maintenance manual all use metric with imperial in parenthesis, but the hardware is all imperial.

How weird. Which models was this?

Also, wasn't there a problem with measurements during the A380 development?

Re: Imperial System

Posted: Thu Mar 07, 2019 8:27 am
Since we're on an aviation site, most countries use feet for altitude, nm for distance, kn for speed, be it for planes or boats. Time to go metric !

Re: Imperial System

Posted: Thu Mar 07, 2019 8:44 am
fr8mech wrote:
I haven't read through all the replies, but has anyone mentioned that aircraft construction?

Yes, aircraft design has been mentioned before.

fr8mech wrote:
I know the Airbus aircraft I've worked on use imperial. The drawings and the maintenance manual all use metric with imperial in parenthesis, but the hardware is all imperial.

How can hardware be imperial? Hardware has certain dimensions, but they can be measured and expressed in any system. The only point is that their dimensions might be named with imperial units. But that is no different with my TV screen (it may be named 30", but is measures 75cm) or with all the pipes, tubes and threads for plumbing (I use a 1/2" hose with a 3/4" thread connector to water my lawn, but their actual dimensions slightly differ from that, they are just names).

Gruß, masi1157

Re: Imperial System

Posted: Thu Mar 07, 2019 8:53 am
masi1157 wrote:
How can hardware be imperial? Hardware has certain dimensions, but they can be measured and expressed in any system. The only point is that their dimensions might be named with imperial units. But that is no different with my TV screen (it may be named 30", but is measures 75cm) or with all the pipes, tubes and threads for plumbing (I use a 1/2" hose with a 3/4" thread connector to water my lawn, but their actual dimensions slightly differ from that, they are just names).

Gruß, masi1157

Yes, but my 1/2" wrench fits a nut or bolt that is 1/2" across the flats...or points on a 12pt. My 12mm is too small, and my 13mm is too big. Therefore, the hardware is measured in imperial. That is the standard used.

Re: Imperial System

Posted: Thu Mar 07, 2019 9:18 am
fr8mech wrote:
Yes, but my 1/2" wrench fits a nut or bolt that is 1/2" across the flats...or points on a 12pt. My 12mm is too small, and my 13mm is too big. Therefore, the hardware is measured in imperial. That is the standard used.

Measure your 1/2" wrench, I'm sure it is 12.7mm. Sure, there is no 12.7mm wrench in a european toolbox, they will be 12mm, 13mm and so on. But that is only the one standard, just like the 1/2" wrench is from the other standard.

Our standard M8 thread is called after its principal dimension 8mm, but the standard defines a lot more dimensions of that thread and names it all together M8.

Gruß, masi1157

Re: Imperial System

Posted: Thu Mar 07, 2019 9:21 am
From a defense perspective, the imperial system likely slows down any attempt to steal our designs. If someone tries to replicate something from our drawings, they're going to have to convert EVERYTHING without errors and/or expensively retool themselves.

What's a disadvantage in many industries is an advantage in some.

Re: Imperial System

Posted: Thu Mar 07, 2019 9:26 am
masi1157 wrote:
Measure your 1/2" wrench, I'm sure it is 12.7mm. Sure, there is no 12.7mm wrench in a european toolbox, they will be 12mm, 13mm and so on. But that is only the one standard, just like the 1/2" wrench is from the other standard.

Correct. But your 12mm wrench will be too small for my 12.7mm bolt and your 13mm wrench will be too big. But my 1/2" wrench will fit it just right.

Re: Imperial System

Posted: Thu Mar 07, 2019 9:28 am

Re: Imperial System

Posted: Thu Mar 07, 2019 9:40 am
masi1157 wrote:
fr8mech wrote:
Yes, but my 1/2" wrench fits a nut or bolt that is 1/2" across the flats...or points on a 12pt. My 12mm is too small, and my 13mm is too big. Therefore, the hardware is measured in imperial. That is the standard used.

Measure your 1/2" wrench, I'm sure it is 12.7mm. Sure, there is no 12.7mm wrench in a european toolbox, they will be 12mm, 13mm and so on. But that is only the one standard, just like the 1/2" wrench is from the other standard.

Our standard M8 thread is called after its principal dimension 8mm, but the standard defines a lot more dimensions of that thread and names it all together M8.

Gruß, masi1157

I don't run into metric threads, fortunately. Do you seriously just call it "M8" and not bother with a pitch? Like a common size here is 1/4"-20, and the more specific nomenclature might be 1/4"-20 UNC (coarse thread) 3A, 1/4"-28 would be UNF (fine thread). So it goes nominal diameter-pitch-series-class.

Re: Imperial System

Posted: Thu Mar 07, 2019 9:41 am
Would be great if we all spoke the same language too. Just image how much language difficulties costs us per year! And why not eat the same food everywhere?

Re: Imperial System

Posted: Thu Mar 07, 2019 9:49 am
doug_or wrote:
KentB27 wrote:
Therefore Fahrenheit is slightly more accurate than Celsius is.

I'd say more precise.

I'd say more granular.

Greater granularity; that's what Fahrenheit offers.

More granular.

Re: Imperial System

Posted: Thu Mar 07, 2019 9:56 am
Jouhou wrote:
Do you seriously just call it "M8" and not bother with a pitch?

As I said, the standard defines a lot of other dimensions, also the pitch. M8 has the standard pitch, but there are other pitches in the standard. M8x1.25 is called simply M8, the others are M8x0.75 and M8x1. And there are other standards, which would then not call the thread Mxxx.

Gruß, masi1157

Re: Imperial System

Posted: Thu Mar 07, 2019 10:06 am
masi1157 wrote:
Jouhou wrote:
Do you seriously just call it "M8" and not bother with a pitch?

As I said, the standard defines a lot of other dimensions, also the pitch. M8 has the standard pitch, but there are other pitches in the standard. M8x1.25 is called simply M8, the others are M8x0.75 and M8x1. And there are other standards, which would then not call the thread Mxxx.

Gruß, masi1157

It seems that when it comes to standard threads, we might be a bit more granular and specific in how we describe our everyday threads.

Re: Imperial System

Posted: Thu Mar 07, 2019 10:44 am
Aesma wrote:
Since we're on an aviation site, most countries use feet for altitude, nm for distance, kn for speed, be it for planes or boats. Time to go metric !

that I think is because the planes were invented in the us of a.
anyway you can still hear confusion during plane - atc conversations, when declaring emergencies, about fuel quantity.

also in aviation, in russia (and iirc also in china) altitudes are expressed in meters, not in feet. always iirc, there is a button that transforms the altitude on airbus planes from feet to meters. but I'm not sure of that.

Re: Imperial System

Posted: Thu Mar 07, 2019 10:56 am
Actually, now that I'm thinking about it, in metric drawings do they use the same tolerances for dimensions? Most formal drawings have a tolerance block but when I draw up a part to be made I only write a tolerance range on critical dimensions. Otherwise I will assume the person manufacturing the part understands what I want for a tolerance, with fractional dimensions being ±1/64" and three decimal places being ± .005"

It's occurred to me this would not translate well to metric. Do metric drawings provide a tolerance range as a mandatory detail? The only metric dimensions I ever see use a range.

Re: Imperial System

Posted: Thu Mar 07, 2019 11:49 am
Jouhou wrote:
Actually, now that I'm thinking about it, in metric drawings do they use the same tolerances for dimensions? Most formal drawings have a tolerance block but when I draw up a part to be made I only write a tolerance range on critical dimensions. Otherwise I will assume the person manufacturing the part understands what I want for a tolerance, with fractional dimensions being ±1/64" and three decimal places being ± .005"

It's occurred to me this would not translate well to metric. Do metric drawings provide a tolerance range as a mandatory detail? The only metric dimensions I ever see use a range.

we have tolerances in %.
our products (hdpe boxes) have a ± 7% tolerance.

Re: Imperial System

Posted: Thu Mar 07, 2019 12:01 pm
To really add some spice to the mix, when I graduated nursing school in 1993, we also had to the learn apothecary measurements (grains, drams as certain meds were just traditionally ordered that way by old fossil doctors WHO WERE NOT having that metric change bullshit).

Por ejemplo, pain meds like aspirin/Tylenol/morphine would be routinely ordered as “ACA/APAP gr. V-X, po Q4-6h, prn pain” - roughly (and I *do* mean roughly) corresponding to 1-2 tabs of 325 mg. For morphine it was usually ordered in 1/4 - 1/2 grain. Fascinatingly, the weight of a piece of grain was the official go-to gold standard reference.

Go figure!

Most, if not all of the pills already came in metric anyway, so it was an unnecessary, unsafe practice on the part of those old fossils. And don’t even get me started on minims, ounces and drams for liquids. It was a mess.

It’s so interesting and a bit tragic that people are perfectly fine with using both metric and imperial systems — as if it somehow either doubles one’s knowledge or is some ideological proxy for “don’t you dare tell me what to do.”

I doubt you’d feel the same if Granny got incorrectly dosed due to the some bastard melange of both measurement systems.

Jus’ sayin’.....

Re: Imperial System

Posted: Thu Mar 07, 2019 12:55 pm
Kiwirob wrote:
OA940 wrote:
If they go metric what will happen to aviation though? I mean Imperial is a dumb system that was created just so someone could say they did something important, but it plays a huge role in aviation. Like, will we start measuring in meters instead of feet? How expensive will it be to change everything up for aircraft? I'd like to see the world adopt metric, but it's definitely not a walk in the park

The vast majority of the world has adopted metric.

But not in this age. Anyway America is not very likely to adopt the metric system. They tend to like being unique in a lot of aspects and besides it would cost them a lot.

Re: Imperial System

Posted: Thu Mar 07, 2019 1:15 pm
Bostrom wrote:
falstaff wrote:
Bostrom wrote:
Another good question is, when will the UK settle on one system?

The UK still uses miles. Cars in the UK have mph speedometers.

The UK sort of uses both systems. Speed limits are in mph, road lengths are measured in miles, but their width is measured in metres. Temperatures are Celsius, apart from on headlines during heat waves. And so on. Fruit and vegetables is sold by the kilo, but tap beer by the pint. Makes sense?

falstaff wrote:
Bostrom wrote:
as Burma/Myanmar mostly uses old burmese units and not the imperial system.

I didn't know that. What do they call them and how to they correspond with the imperial or metric system?

Click the link on my post and you'll find out…

But a selection of lenght units are:
လက်သစ်let thit, 1.905 cm
မိုက် maik, 15.24 cm
ထွာ htwa, 22.86 cm
တောင်t taung, 45.72 cm
လံ lan, 1.8288 m
တာ ta, 3.2004 m
ဥသဘ out-thaba, 64.008 m
ကောသ kawtha, 1.28016 km
ဂါ၀ုတ် ga-wout, 5.12064 km

Dutchy wrote:
It seems to cost billions, two sets of measures, products, mistakes being made etc.

And, human health. Conversion errors leading to drug overdoses are a problem in the US health care system.

Medications are written and dosed exclusively in the metric units, most of them in milligrams but some In micrograms, and a few in a grams. Even if they weren’t it wouldn’t matter to 95% of patients. They’re instructed to take “a half pill” or “X number of pills Y times a day.” Liquid formulations are dose in milligrams or grams per milliliter. There is no swapping back and forth, nor is there need to because a 500mg metformin prescription is still 500mg of metformin, and is one pill. Medication errors are most often made in dosages written, not giving it at all, inappropriately administering a taper, misreading instructions, or historically not able to read what was actually written or misinterpreting an abbreviation (dosing schedules are often written as qd, bid, tid, qid, qhs, etc, and over the phone “b” and “t” easily sound the same). Where there could still be a need for conversion is weight-based medications, but now every electronic medical record I’ve used automatically includes weights in kilograms for that purpose.

Re: Imperial System

Posted: Thu Mar 07, 2019 1:19 pm
One of my profs many years ago, when this was more of an issue given the push in 1975 was flailing in the wind a few years later, used to joke “base ten is for slackers that don’t want complicated math”. He was old as hell, he hated metric so much he probably insisted in his Will that he be buried six feet under.

Re: Imperial System

Posted: Thu Mar 07, 2019 1:35 pm
luckyone wrote:
Medications are written and dosed exclusively in the metric units, most of them in milligrams but some In micrograms, and a few in a grams. Even if they weren’t it wouldn’t matter to 95% of patients. They’re instructed to take “a half pill” or “X number of pills Y times a day.” Liquid formulations are dose in milligrams or grams per milliliter. There is no swapping back and forth, nor is there need to because a 500mg metformin prescription is still 500mg of metformin, and is one pill. Medication errors are most often made in dosages written, not giving it at all, inappropriately administering a taper, misreading instructions, or historically not able to read what was actually written or misinterpreting an abbreviation (dosing schedules are often written as qd, bid, tid, qid, qhs, etc, and over the phone “b” and “t” easily sound the same).

There is however a problem, mostly for children, that doses are usually X amount per kg body weight. If the body weight in pounds and kg are mixed up, they might get the wrong dose.

https://www.chihaklaw.com/Articles/Conf ... rors.shtml
https://psnet.ahrq.gov/webmm/case/293
https://www.modernhealthcare.com/articl ... ion-errors

Re: Imperial System

Posted: Thu Mar 07, 2019 1:35 pm
FatCat wrote:
that I think is because the planes were invented in the us of a.

Nah, rather because aviation grew out of shipping. Knots and nautical miles actually are better suited in some circumstances. Like, 1 knot is one nautical mile per hour, and one nautical mile is a minute of arc near the equator.

seat64k wrote:
Annoyingly, for the longest time Lloyds-TSB (UK bank) sent their printed statements in what I think is US Letter size. Why Lloyds, whyyyyyyy? You can't find a plastic sleeve to stick that thing in a file.

Groan. I've had to deal with bank statements that were nearly A4. Just a tad too long to fit the scanner. Maybe as a protection against photocopying/scanning. If the A4 format is off by a bit, then you know the bank statement has not been tampered with.

David

Re: Imperial System

Posted: Thu Mar 07, 2019 1:42 pm
Every Airbus drawing I've seen was dimensioned in metric and the typical drawing tolerances were similar to what you would see on imperial unit parts that are designed for US OEMs. [Note, I suppose there could be some standard parts and Avionics for instance that are developed for standard use across OEMs that would be used] I once worked for a company that did both. It was seriously not an issue for say a machined part. The CNC program handles all the conversions and what not. It doesn't care what unit system you tell it, it's just scaling everything from its initial location anyways. The main hurdle during the machining process would be changing out your bits to get the right radius on your cuts. But for measuring how long of a pass to make - it doesn't really matter its just a number.

It does matter during quality inspections of course. I suppose its a bit of a headache for those folks having to deal with it on both sides. But again, making a mountain out of a mole hill.

A lot of people are talking about the cost associated with changing out road signs for instance. That's probably a drop in the bucket compared to the cost of changing over all of our standard sheet metal sizes, all the testing that would have to be done to requalify metric sheet sizes etc. The impact to industry would be far more reaching than simply changing out road signs. To the point where we would probably ignore such a change and continue building things the way we currently do. That would just make things worse.

DL717 wrote:
One of my profs many years ago, when this was more of an issue given the push in 1975 was flailing in the wind a few years later, used to joke “base ten is for slackers that don’t want complicated math”. He was old as hell, he hated metric so much he probably insisted in his Will that he be buried six feet under.

What is the equivalent expression for being buried in a country using SI units? "Buried 1.8288 meters under"

Re: Imperial System

Posted: Thu Mar 07, 2019 1:55 pm
trpmb6 wrote:
Every Airbus drawing I've seen was dimensioned in metric and the typical drawing tolerances were similar to what you would see on imperial unit parts that are designed for US OEMs. [Note, I suppose there could be some standard parts and Avionics for instance that are developed for standard use across OEMs that would be used] I once worked for a company that did both. It was seriously not an issue for say a machined part. The CNC program handles all the conversions and what not. It doesn't care what unit system you tell it, it's just scaling everything from its initial location anyways. The main hurdle during the machining process would be changing out your bits to get the right radius on your cuts. But for measuring how long of a pass to make - it doesn't really matter its just a number.

It does matter during quality inspections of course. I suppose its a bit of a headache for those folks having to deal with it on both sides. But again, making a mountain out of a mole hill.

A lot of people are talking about the cost associated with changing out road signs for instance. That's probably a drop in the bucket compared to the cost of changing over all of our standard sheet metal sizes, all the testing that would have to be done to requalify metric sheet sizes etc. The impact to industry would be far more reaching than simply changing out road signs. To the point where we would probably ignore such a change and continue building things the way we currently do. That would just make things worse.

DL717 wrote:
One of my profs many years ago, when this was more of an issue given the push in 1975 was flailing in the wind a few years later, used to joke “base ten is for slackers that don’t want complicated math”. He was old as hell, he hated metric so much he probably insisted in his Will that he be buried six feet under.

What is the equivalent expression for being buried in a country using SI units? "Buried 1.8288 meters under"

They take the lazy way out and round it to 2.

Re: Imperial System

Posted: Thu Mar 07, 2019 2:09 pm
Airstud wrote:
There are two kinds of countries: Those that use the metric system and those that have landed men on the Moon.

Hhehehe!

Running on "metric" supervisors/managers/teachers and using metric in the areas that count:
https://www.reddit.com/r/askscience/com ... landed_on/

Re: Imperial System

Posted: Thu Mar 07, 2019 2:24 pm
Honestly, the metric system is easier and more intuitive. It (in general) is the better system. But we aren't switching.

Re: Imperial System

Posted: Thu Mar 07, 2019 2:51 pm
Aesma wrote:
KentB27 wrote:
I seriously doubt that the US will ever fully convert to the metric system. It would be very costly and take years to completely convert. One huge hurdle I see is that changing all of the highway markings and signs to kilometers would be a massively time consuming and expensive undertaking that realistically isn't necessary.

In France we just changed our speed limit for undivided highways from 90 to 80 Km/h and the cost to change the signs was a few millions euros, for 11000 of them.

The United States is about 18x the size of France and our highway networks is eons larger. It's not going to be easy or cheap to convert to kilometers. It would create more trouble than it's worth to convert. Also, changing speed limits is far less disruptive than having different parts of the country in two different measurement systems in the interim period while the conversion to metric is done. If we do ever covert to metric I think we'll still drive in miles per hour like the U.K. does.

Re: Imperial System

Posted: Thu Mar 07, 2019 2:56 pm
Dutchy wrote:
KentB27 wrote:
The irony of the metric system is that its main advantage (the mathematical side) is less and less relevant with modern technology. Technology is readily available and can calculate essentially anything. The days of needing to know how to manually calculate are nearing their end. What people are actually complaining about is conversion. Well, if every country was on the imperial system, we wouldn't have an issue with that either. So it's not a problem of the imperial system. The problem is that there's more than one system.

This is hilarious. I never even wrote this. Somebody manipulated the quotes in the editor and made it seem like I did.

Re: Imperial System

Posted: Thu Mar 07, 2019 2:59 pm
DL717 wrote:
They take the lazy way out and round it to 2.

Or did you take the lazy way out and rounded it up to six feet

Re: Imperial System

Posted: Thu Mar 07, 2019 3:13 pm
I don't think the US is going to change any time soon. It's just way too ingrained in the construction industry. I can't honestly remember the last time I saw a set of plans or submittals that had metric on them.

That being said, in my four years of engineering school, I absolutely dreaded doing calculations in imperial. If I still had to do them by hand, I'd probably be miserable.

Re: Imperial System

Posted: Thu Mar 07, 2019 3:16 pm
einsteinboricua wrote:
Celsius is based off of the freezing and boiling points for water, so to measure temperature of a substance, it makes total sense

Old news I'm afraid. Since the 50's it's been based on absolute zero and the triple point of VSMOW (Vienna Standard Mean Ocean Water). This made and kept it tied directly to it's kelvin equivalent (ie 1K = 1'C).

In another redefinition of the SI units, Kelvin (and celsius along with it) will be defined from the Boltzmann constant from next month.

Originally, 0'C was boiling and 100'c freezing. This was reversed in 1743.

Personally, I switch between different units based on what's being measured and which is more suited to the specific application.

Re: Imperial System

Posted: Thu Mar 07, 2019 3:25 pm
trpmb6 wrote:
A lot of people are talking about the cost associated with changing out road signs for instance. That's probably a drop in the bucket compared to the cost of changing over all of our standard sheet metal sizes, all the testing that would have to be done to requalify metric sheet sizes etc. The impact to industry would be far more reaching than simply changing out road signs. To the point where we would probably ignore such a change and continue building things the way we currently do. That would just make things worse.

Then there are industries that have realized the benefits of SI and converted on their own, like the US car industry.