ZeroExperience
Aerospace
As title asks.
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Do you want to switch to SI units? 8
- Thread starter ZeroExperience
- Start date
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Not really. On all four federal prison projects I worked with the same architect; on two of the four we had the same prime contractor. Both are very large firms that do a lot of federal work and the people I dealt with were smart, flexible, and handled SI anywhere from competently to expertly. However, as a "practical matter" (I still wonder how practical), most of what the prime contractor and his subs did in the field was in US units, converted from the plans and specs (and much of what was in the plans in specs had originally been converted from US to SI by the design team). Some of the subcontractors were OK with SI, some weren't at all, and none were fully conversant with SI. I think only the contractor's surveyor worked completely in SI units, except for the starting benchmark.
Generally, the only time I saw the construction team using SI units was as the starting point for conversions to US units and in SOME of the submittals. Some submittals were preprinted brochures and if they weren't printed with SI (or at least US+SI), I wasn't going to get SI even if I asked "pretty please". Regardless, this wasn't a hill I wanted to die on. I had better luck with submittals for things like precast concrete vaults that used semi-custom drawings (i.e. standard drawings edits for our project).
The Bureau of Prison's CM staff had little enthusiasm for parcticing SI in the field. Most of them could handle SI competently, but the contractors were mostly using US in the field so the attitude seemed to be "why bother".
The architect for the buildings at the naval air station isn't dumb, but I don't think he's an intellectual heavyweight either. Regardless, both he and the DB contractor failed to completely read the RFP, which is something both and I my project engineer did. That's why they learned of the SI requirement from my project engineer.
This has little to do with intellegence (except the drafter…he's as dumb as a rock and I still can't figure out why my boss hired him…I had the guy figured out in less than a minute). This really has to do with comparative familiarity (US>SI), inertia (US>>SI), and the fact that most products being installed in this type of construction in the US comes in US units and not SI units (US>>SI). However, since SI>>>US, I think we as a country need to get serious about making the change and doing it as "cold turkey" as possible.
==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
Generally, the only time I saw the construction team using SI units was as the starting point for conversions to US units and in SOME of the submittals. Some submittals were preprinted brochures and if they weren't printed with SI (or at least US+SI), I wasn't going to get SI even if I asked "pretty please". Regardless, this wasn't a hill I wanted to die on. I had better luck with submittals for things like precast concrete vaults that used semi-custom drawings (i.e. standard drawings edits for our project).
The Bureau of Prison's CM staff had little enthusiasm for parcticing SI in the field. Most of them could handle SI competently, but the contractors were mostly using US in the field so the attitude seemed to be "why bother".
The architect for the buildings at the naval air station isn't dumb, but I don't think he's an intellectual heavyweight either. Regardless, both he and the DB contractor failed to completely read the RFP, which is something both and I my project engineer did. That's why they learned of the SI requirement from my project engineer.
This has little to do with intellegence (except the drafter…he's as dumb as a rock and I still can't figure out why my boss hired him…I had the guy figured out in less than a minute). This really has to do with comparative familiarity (US>SI), inertia (US>>SI), and the fact that most products being installed in this type of construction in the US comes in US units and not SI units (US>>SI). However, since SI>>>US, I think we as a country need to get serious about making the change and doing it as "cold turkey" as possible.
==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill
patprimmer
New member
Personally when working with materials in both units, I find it a lot easier in the field to convert to SI. A 4' wide sheet of plywood for instance might actually measure 1219mm, but a 1200 sheet might measure 47.24".
My tape will have 1219 marked on it but won't have 47.24. It will have 47 1/4 or 47 5/16 marked on it. It is easier to decide between 1220 and 1219 than it is to decide between 47 1/4 and 47 5/16 unless you have a tape marked in decimals of an inch. even so it's not practical to mark a tape in increments of less than 1/16th or 0.1" where it is practical and common to mark a tape in 1mm increments
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
My tape will have 1219 marked on it but won't have 47.24. It will have 47 1/4 or 47 5/16 marked on it. It is easier to decide between 1220 and 1219 than it is to decide between 47 1/4 and 47 5/16 unless you have a tape marked in decimals of an inch. even so it's not practical to mark a tape in increments of less than 1/16th or 0.1" where it is practical and common to mark a tape in 1mm increments
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
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1
- #123
SomptingGuy
Automotive
Debating the benefits (or not) of inches over mm for construction purposes is completely missing the point. SI is a consistent system for engineering analysis across all domains, not a choice of length units.
- Steve
- Steve
If SI is so great why has the world embraced kgf/cm^2 and bar as pressure units? Could it be that kPa's are too small and MPa's are too big and there isn't a prefix for 10,000 times?
Why do people who couldn't tell a "foot" from a "shoe" fluently talk about pipe diameter in inches and start counting on their fingers if they have to use DN numbers or mm?
Why are road signs in the UK generally in miles and mph?
Consistent is good, but it falls apart if people can't or won't internalize it.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
Why do people who couldn't tell a "foot" from a "shoe" fluently talk about pipe diameter in inches and start counting on their fingers if they have to use DN numbers or mm?
Why are road signs in the UK generally in miles and mph?
Consistent is good, but it falls apart if people can't or won't internalize it.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
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1
- #125
GregLocock
Automotive
I think the man on the street argument fails horribly when you look at the pond. On the west side a 120 lb man is a shrimp, and on the other side a 26 stone man is an American. (sorry cheap jibe).
My point is that an order of magnitude (14) separates the 'natural' man on the street measures that at least bear some commonality.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
My point is that an order of magnitude (14) separates the 'natural' man on the street measures that at least bear some commonality.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376
SomptingGuy
Automotive
In my little professional bubble of engineering simulation, the only exception we have is rotational speed, which should be SI, but is more commonly rev/min.
Road signs in the UK are miles and mph by (stupid) law. A vehicle without an mph speedometer cannot be sold in the UK (!). I'm surprised our overlords in Brussels haven't outlawed all this.
- Steve
Road signs in the UK are miles and mph by (stupid) law. A vehicle without an mph speedometer cannot be sold in the UK (!). I'm surprised our overlords in Brussels haven't outlawed all this.
- Steve
The guys doing engineering simulations of fluid mechanics tend to also use inches for pipe ID. I see m, kPa, kg, C, kJ (but BTU is not unheard of), and inches. I always chuckle when I see it.
I teach classes all over the world and get to see the range of units that people use up close and personally. Every country (and many regions within countries) has their own way of reporting gas flow rates, and no one is comfortable in the other guy's units (no one outside of Alberta can automatically make sense of E3M3, and you have to be from Queensland to report a volume flow rate in MJ/day). I teach in SCF after first getting an agreement that in any group of 10 engineers from 10 countries there will be at least 11 ways to represent volume flow rate (they all more or less understand SCF). I can work in any of them, but more people get the concepts without the noise if I use SCF. For pressures I use psi, but I use multiples of 14.5 psi=1 bar=100 kPa for the grid lines--it seems to work well. For temperatures I use F, but set the increments in even multiples of C (this doesn't work as well because no one seems to be comfortable going back and forth in temperature).
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
I teach classes all over the world and get to see the range of units that people use up close and personally. Every country (and many regions within countries) has their own way of reporting gas flow rates, and no one is comfortable in the other guy's units (no one outside of Alberta can automatically make sense of E3M3, and you have to be from Queensland to report a volume flow rate in MJ/day). I teach in SCF after first getting an agreement that in any group of 10 engineers from 10 countries there will be at least 11 ways to represent volume flow rate (they all more or less understand SCF). I can work in any of them, but more people get the concepts without the noise if I use SCF. For pressures I use psi, but I use multiples of 14.5 psi=1 bar=100 kPa for the grid lines--it seems to work well. For temperatures I use F, but set the increments in even multiples of C (this doesn't work as well because no one seems to be comfortable going back and forth in temperature).
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
SomptingGuy
Automotive
David,
Our customers like to provide inputs and receive outputs in all sorts of wierd and wonderful units and we have systems to cope with that. Inside the actual simulation codes though, there's no place for furlongs or fathoms.
- Steve
Our customers like to provide inputs and receive outputs in all sorts of wierd and wonderful units and we have systems to cope with that. Inside the actual simulation codes though, there's no place for furlongs or fathoms.
- Steve
SomptingGuy
Automotive
I guess that was a full toss. Well batted!
- Steve
- Steve
patprimmer
New member
Yep. Straight over the grandstand for six
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
patprimmer
New member
I had my money on a horse that accelerated out of the box at a rate that would best be described in furlongs per year^2
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
patprimmer
New member
The 8kph is a direct hangover from 5mph speed limits.
I think no cars have a speedometer that is anywhere near accurate at less than 15 or 20 kph anyway, regardless of readability.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
I think no cars have a speedometer that is anywhere near accurate at less than 15 or 20 kph anyway, regardless of readability.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
""" I had my money on a horse that accelerated out of the box at a rate that would best be described in furlongs per year^2"""
Pat I think you are spelling it wrong, it should be "Furrowlongs" and it sounds like your horse should be pulling the plough.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
patprimmer
New member
Shortly after the start I certainly came to the conclusion it was more Clydesdale than Thoroughbred. This is of course a fictitious story for effect, just in case anyone thought it might be serious.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
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