I want to find out how many BTU's there are in a candle. My first thought is to weigh a candle then use it to heat one pound of water one degree then extinuish and weigh the candle again. I should then know grams of candle wax per BTU. Will this be fairly accurate?
Tiger93rsl
In thoery that should be right, but how do you figure for the heat that is lost to the air that doesn't warm the water.
On another note, as stated before.....WHY?
On another note, as stated before.....WHY?
Use 10 candles and divide by 10. Since some heat will be lost to the air, the value you get will be the minimum heat output in BTU/hr of a candle.
If the water volume is nearly spherical in shape it will have the minimum heat loss to the air.
Another way is to use the specific heat of a candle flame [equal to that of air?] and its temp [600°-1400°C].
If the water volume is nearly spherical in shape it will have the minimum heat loss to the air.
Another way is to use the specific heat of a candle flame [equal to that of air?] and its temp [600°-1400°C].
there are 252 calories in a btu
it takes 252 calories to raise the temperature of one pound of water at or around its boiling point one degree farenheit in one hour 252 x 60= 15,120------- 15,120 calories per hour x 24 hours = 362,880 calories in a ton of refrigeration
funny it takes 362,880 calories to melt a ton of ice
there is about a thousand calories in a scoop of rocky road ice cream!!!
it takes 252 calories to raise the temperature of one pound of water at or around its boiling point one degree farenheit in one hour 252 x 60= 15,120------- 15,120 calories per hour x 24 hours = 362,880 calories in a ton of refrigeration
funny it takes 362,880 calories to melt a ton of ice
there is about a thousand calories in a scoop of rocky road ice cream!!!
Candlepower
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Jump to: navigation, search
Candlepower (abbreviated as cp) is a now-obsolete unit which was used to express levels of light intensity in terms of the light emitted by a candle of specific size and constituents. In modern usage Candlepower equates directly to the unit known as the candela.
[edit] History
The term candlepower was originally defined in England by the Metropolitan Gas Act 1860 as the light produced by a pure spermaceti candle weighing one sixth of a pound and burning at a rate of 120 grains per hour. Spermaceti is found in the head of sperm whales, and once was used to make high quality candles.
At this time the French standard of light was based upon the illumination from a Carcel Burner. The unit was defined as that illumination emanating from a lamp burning pure colza oil (obtained from the seed of the plant Brassica campestris) at a defined rate. It was accepted that ten Standard Candles were about equal to one Carcel burner.
In 1909 a meeting took place to come up with an international standard. It was attended by representatives of the Laboratoire Central de l’Electricité (France), the National Physical Laboratory (UK), the Bureau of Standards (United States) and the Physikalische Technische Reichsanstalt (Germany). The majority redefined the candle in term of an electric lamp with a carbon filament. The Germans, however, dissented and decided to use a definition equal to 9⁄10ths of the output of a Hefner lamp.
In 1921, the Commission Internationale de l’Eclairage (International Commission for Illumination, commonly referred to as the CIE) redefined the international candle again in terms of a carbon filament incandescent lamp.
In 1937, the international candle was redefined again against the luminous intensity of a blackbody at the freezing point of liquid platinum which was to be 58.9 international candles per square centimeter.
Since 1948 the term candlepower was replaced by the international unit (SI) known as the candela. One old candlepower unit is about 0.981 candela. Less scientifically, modern candlepower now equates directly (1:1) to the number of candelas[1] — an implicit increase from its old value.
[edit] Calibration of lamps
The candlepower of a lamp was measured by judging by eye the relative brightness of adjacent surfaces, one illuminated only by a standard lamp (or candle) and the other only by the lamp under test. The distance of one of the lamps was adjusted until the two were judged to give equal brightness. The candlepower of the lamp under test could then be calculated from the two distances and the inverse square law
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Candlepower (abbreviated as cp) is a now-obsolete unit which was used to express levels of light intensity in terms of the light emitted by a candle of specific size and constituents. In modern usage Candlepower equates directly to the unit known as the candela.
[edit] History
The term candlepower was originally defined in England by the Metropolitan Gas Act 1860 as the light produced by a pure spermaceti candle weighing one sixth of a pound and burning at a rate of 120 grains per hour. Spermaceti is found in the head of sperm whales, and once was used to make high quality candles.
At this time the French standard of light was based upon the illumination from a Carcel Burner. The unit was defined as that illumination emanating from a lamp burning pure colza oil (obtained from the seed of the plant Brassica campestris) at a defined rate. It was accepted that ten Standard Candles were about equal to one Carcel burner.
In 1909 a meeting took place to come up with an international standard. It was attended by representatives of the Laboratoire Central de l’Electricité (France), the National Physical Laboratory (UK), the Bureau of Standards (United States) and the Physikalische Technische Reichsanstalt (Germany). The majority redefined the candle in term of an electric lamp with a carbon filament. The Germans, however, dissented and decided to use a definition equal to 9⁄10ths of the output of a Hefner lamp.
In 1921, the Commission Internationale de l’Eclairage (International Commission for Illumination, commonly referred to as the CIE) redefined the international candle again in terms of a carbon filament incandescent lamp.
In 1937, the international candle was redefined again against the luminous intensity of a blackbody at the freezing point of liquid platinum which was to be 58.9 international candles per square centimeter.
Since 1948 the term candlepower was replaced by the international unit (SI) known as the candela. One old candlepower unit is about 0.981 candela. Less scientifically, modern candlepower now equates directly (1:1) to the number of candelas[1] — an implicit increase from its old value.
[edit] Calibration of lamps
The candlepower of a lamp was measured by judging by eye the relative brightness of adjacent surfaces, one illuminated only by a standard lamp (or candle) and the other only by the lamp under test. The distance of one of the lamps was adjusted until the two were judged to give equal brightness. The candlepower of the lamp under test could then be calculated from the two distances and the inverse square law
The higher the altitude, the lower the boiling temp. Since the pressure is lower.
Same amount of heat, to raise 1 pound of water 1°, weather its from 32 to 33, or 211 to 212.
Key phrase is, pound of water.
If we were talking about a cubic foot of water. Then it would change. And take less BTUs to raise 1 cu ft of water from 211 to 212, then from 32 to 33.
Same amount of heat, to raise 1 pound of water 1°, weather its from 32 to 33, or 211 to 212.
Key phrase is, pound of water.
If we were talking about a cubic foot of water. Then it would change. And take less BTUs to raise 1 cu ft of water from 211 to 212, then from 32 to 33.
Densities and Specific Weight of Water in Imperial Units
Temperature
- t -
(oF) Density
- ρ -
(slugs/ft3) Specific Weight
- γ -
(lb/ft3) (lb/US gallon)
32 1.940 62.42 8.3436
40 1.940 62.43 8.3451
50 1.940 62.41 8.3430
60 1.938 62.37 8.3378
70 1.936 62.30 8.3290
80 1.934 62.22 8.3176
90 1.931 62.11 8.3077
100 1.927 62 8.2877
120 1.918 61.71 8.2498
140 1.908 61.38 8.2048
160 1.896 61 8.1537
180 1.883 60.58 8.0969
200 1.869 60.12 8.0351
212 1.860 59.83 7.9957
Temperature
- t -
(oF) Density
- ρ -
(slugs/ft3) Specific Weight
- γ -
(lb/ft3) (lb/US gallon)
32 1.940 62.42 8.3436
40 1.940 62.43 8.3451
50 1.940 62.41 8.3430
60 1.938 62.37 8.3378
70 1.936 62.30 8.3290
80 1.934 62.22 8.3176
90 1.931 62.11 8.3077
100 1.927 62 8.2877
120 1.918 61.71 8.2498
140 1.908 61.38 8.2048
160 1.896 61 8.1537
180 1.883 60.58 8.0969
200 1.869 60.12 8.0351
212 1.860 59.83 7.9957
In general density can be changed by changing either the pressure or the temperature. Increasing the pressure will always increase the density of a material. Increasing the temperature generally decreases the density, but there are notable exceptions to this generalisation. For example, the density of water increases between its melting point at 0 °C and 4 °C and similar behaviour is observed in silicon at low temperatures.
The effect of pressure and temperature on the densities of liquids and solids is small so that a typical compressibility for a liquid or solid is 10–6 bar–1 (1 bar=0.1 MPa) and a typical thermal expansivity is 10–5 K–1.
In contrast, the density of gases is strongly affected by pressure. Boyle's law says that the density of an ideal gas is given by
where R is the universal gas constant, P is the pressure, M the molar mass, and T the absolute temperature.
This means that a gas at 300 K and 1 bar will have its density doubled by increasing the pressure to 2 bar or by reducing the temperature to 150 K.
Osmium is the densest known substance at standard conditions for temperature and pressure.
[edit] Density of water
See also: Water density
Temp (°C) Density (kg/m3)
100 958.4
80 971.8
60 983.2
40 992.2
30 995.6502
25 997.0479
22 997.7735
20 998.2071
15 999.1026
10 999.7026
4 999.9720
0 999.8395
−10 998.117
−20 993.547
−30 983.854
The effect of pressure and temperature on the densities of liquids and solids is small so that a typical compressibility for a liquid or solid is 10–6 bar–1 (1 bar=0.1 MPa) and a typical thermal expansivity is 10–5 K–1.
In contrast, the density of gases is strongly affected by pressure. Boyle's law says that the density of an ideal gas is given by
where R is the universal gas constant, P is the pressure, M the molar mass, and T the absolute temperature.
This means that a gas at 300 K and 1 bar will have its density doubled by increasing the pressure to 2 bar or by reducing the temperature to 150 K.
Osmium is the densest known substance at standard conditions for temperature and pressure.
[edit] Density of water
See also: Water density
Temp (°C) Density (kg/m3)
100 958.4
80 971.8
60 983.2
40 992.2
30 995.6502
25 997.0479
22 997.7735
20 998.2071
15 999.1026
10 999.7026
4 999.9720
0 999.8395
−10 998.117
−20 993.547
−30 983.854
A pound of water, is a pound of water.
While at 32°F it takes up less space(has high density) then at 140°F(takes up more space). Its still 1 pound.
A cu ft of water at 32°F, will weigh more then a cu ft at 140°F. Density of that cu ft has changed, and no longer weighs the same.
Take a kettle(6 quart size) and fill it to within 1/8" of the top with cold water from the faucet. Check its temp. Weigh it. Then heat it on the stove to 160°F. Then weigh it again. It will weigh less. Because as the water expands, it will overflow the kettle. Let it cool back down. Weigh it again. It will still weigh as much as it did when it was at 160°F. But, the water level will be lower then the 1/8" below top you first started with.
Its the density per cubic foot(inch, yard, centimeter, etc) that changes.
But a pound is a pound.
While at 32°F it takes up less space(has high density) then at 140°F(takes up more space). Its still 1 pound.
A cu ft of water at 32°F, will weigh more then a cu ft at 140°F. Density of that cu ft has changed, and no longer weighs the same.
Take a kettle(6 quart size) and fill it to within 1/8" of the top with cold water from the faucet. Check its temp. Weigh it. Then heat it on the stove to 160°F. Then weigh it again. It will weigh less. Because as the water expands, it will overflow the kettle. Let it cool back down. Weigh it again. It will still weigh as much as it did when it was at 160°F. But, the water level will be lower then the 1/8" below top you first started with.
Its the density per cubic foot(inch, yard, centimeter, etc) that changes.
But a pound is a pound.
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