What Temperature is BTU Measured At?
Based on the provided reference, the definition of a British Thermal Unit (BTU) describes the energy required to change the temperature of water by one degree Fahrenheit, rather than being measured at a single, specific temperature point.
The reference states the original definition of a BTU:
A Btu was originally defined as the amount of heat required to raise the temperature of one pound of liquid water by one degree Fahrenheit at a constant pressure of one atmospheric unit.
This definition specifies the conditions and substance involved in the energy transfer that defines a BTU:
- Energy Amount: One British Thermal Unit (1 BTU).
- Substance: One pound (lb) of liquid water.
- Temperature Effect: The process raises the temperature of this water by one degree Fahrenheit (1°F).
- Pressure: The process occurs at a constant pressure of one atmospheric unit.
Temperature Change vs. Specific Temperature Point
The question asks "What temperature is BTU measured at?". However, the definition provided explains the amount of energy needed to cause a temperature change of 1°F in a specific amount of water. It defines the BTU based on this temperature difference (1°F), not as a measurement taken at a particular fixed temperature point on the Fahrenheit scale (like 32°F or 212°F).
Therefore, the provided definition focuses on the energy needed to change the temperature of water by 1°F, not on a specific starting temperature for that change. The exact initial temperature for this 1°F rise is not specified within this general definition.
Key Components from the Definition
Here is a summary of the elements involved in the definition of a BTU according to the reference:
- Unit Defined: BTU
- Energy Action: Heat required to raise temperature
- Substance Amount: One pound
- Substance Type: Liquid water
- Temperature Effect: By one degree Fahrenheit
- Environmental Condition: At a constant pressure of one atmospheric unit
- Specific Temperature Point: Not specified in this definition
In conclusion, the provided definition relates a BTU to the energy needed to achieve a 1°F temperature increase in water, rather than defining it as being measured at a single specific temperature.