On 2004 May 19 , at 9:15 PM, Bill Potts wrote (responding to a msg from Euric):
You're close enough for most purposes. The BTU is 5.435% larger than the
kilojoule (i.e., 1 BTU = 1.054 350 kJ).
That's not the only possible conversion factor for converting the BTU to kilojules.
The problem here is that there are a variety of slightly different units that are all called the BTU (British Thermal Unit). The value 1.055 kJ = 1 BTU is close enough to all of them, I believe. This is the only value given in a table of conversions of a popular college physics text. That physics text gives the definition of a BTU to be "the amount of heat that would raise the temperature of 1 lb of water from 63 �F to 64 �F." It doesn't specify which of the various BTU's this definition applies to.
Here is the value for one specific BTU, the so called "International Table BTU":
1 BTU = 1.055056 kJ
This is from a table on page 22 of the USMA publication "Guide to the Use of the Metric system (SI Version)". A footnote to this value says:
"There are many types of Btu's, with different values. See ASTM E380 or ANSI/IEEE 268."
As is so often the case, confusion that arises over the relation between an SI unit and an Olde English unit is caused by complications with the Olde English unit, not by any difficulty with the metric unit.
Regards, Bill Hooper Fernandina Beach, Florida, USA <><><><><><><><><><><><> Make it simple; Make it Metric <><><><><><><><><><><><>
