Wow- Interesting- CONVERSION

[Qual7Eng]

how this conversio works ??? +/-14 °C (25 °F) and +/-8 °C (15 °F) as per API

thaks

 

[dgallup]

Multiply by 1.8. These are +/- tolerances so no zero offset.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[djhurayt]

1 Celsius degree = 1.8 Fahrenheit degress
so 14C° X 1.8 ==> 25.2F°
and 8C° x 1.8 ==> 14.4F°

 

[powerhound]

I thought it was multiply by 1.8 and add 32.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II

 

[JNieman]

You only add 32 to get equivalent numbers on a scale, such as 24C being roughly equal to 75F. The offset is to get the numbers based on the same 'zero'.

When you speak of tolerances, they are simply a unit conversion. There is no 'zero' to reference. Merely the difference between Celsius and Fahrenheit graduations.

 

[powerhound]

Aha. I see now. I was misunderstanding the question.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
SSG, U.S. Army
Taji, Iraq OIF II

 

[TheTick]

Where does the "Wow - Interesting" part come in?

 

[dgallup]

Only the OP knows for sure.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[MintJulep]

Perhaps he meant "Wow - inconsistent use of rounding rules to present reference information!"

 

[djhurayt]

That is the only thing I can think of, and honestly did not even notice that unitl your reply MJ, but yes in my world 14.4 rounds to 14 not 15, so maybe that is it, the rounding

OP ???

 

[drawoh]

Qual7Eng,

One of my thermodynamics instructors from college would have re-written your note thus...

How this conversion works ??? [±]14C[°] (25F[°]) and [±]8C[°] (14F[°]) as per API

Note how the letter and the degree symbol are flipped when the temperatures are relative. This affects your math.

--
JHG

 

[djhurayt]

yes drawoh, is correct, technically this tolerance should read:
plus or minus 14 Celcius degrees

so if you have a temperature requirement and tolerance it would be"
x°C ±yC°, which would be read"
x degress Celsius plus or minus y Celcius degrees

 

[dgallup]

Interesting, I don't believe I've ever seen it expressed that way. I just checked both my thermo books and my heat transfer book, all 3 have sections on units and I don't see that. However, none of them specifically address tolerances. Most professors have no concept of tolerances.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[djhurayt]

It seems like this came from a discussion in a thermo class, and while technically it is more correct I don't think it is expressed that way most times, probably because many would be confused.

However you point about academia is well taken. Once had to do a heat transfer on a 2x4 wall, asked the professor what dimension we should use for the 2x4. He looked at me like I had lost my mind, “why, 2” by 4” of course, why do you ask” was his reply. When I told him that today a 2x4 actually measures 1.5” & 3.5” he was flabbergasted.

 

[drawoh]

djhurayt,

I have not done a lot of thermo analysis. My experience has been that if I were to use 4" as the depth of a 2[×]4, that would be the most accurate number in my calculation.

A few years ago, I designed the back steps for my house. I referred to one of my college mechanics of materials text for lumber sizes, and I got 1-5/8 by 3-5/8". You know you are getting old when...

--
JHG

 

[Gilmiril]

The 15°F (excuse me, 15F°) was not converted from 8C°. Considering that API traditionally worked in "US Customary Units", it's the 8C° that was converted from 15F°, and that works (15÷1.8 = 8.3... or 8C°).

 

[Qual7Eng]

Uff...sorry...I took direct(1.8x +32)conversion and misunderstood..btw..fyi api 6a & api 6d gives -/+14degc and +/-13degc respectively for 25degf..

 

[CheckerHater]

Since when it became C° and F°?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[drawoh]

Since when it became C° and F°?

I have not seen this notation in any texts either. My thermo instructor wanted to distinguish between a temperature of 86[°]F and a temperature increase of 16F[°]. This does affect how you do your conversions.

He was British. Does that help?

--
JHG

 

[Qual7Eng]

Always when it is related or relative....correct me if am wrong...