To Convert To... | Multiply... | By... | ||
Atmospheres | (atm) | Bar | -- | 0.9869 |
Bar | Atmospheres | (atm) | 1.0133 | |
British Thermal Units | (Btu) | Joules | (J) | 0.000948 |
Calories | (cal) | Joules | (J) | 0.2388 |
Centimeters | (cm) | Feet | (ft) | 30.48 |
Cubic feet | (ft3) | Cubic meters | (m3) | 35.32 |
Cubic inches | (in3) | Cubic centimeters | (cm3 or cc) | 0.061 |
Cubic meters | (m3) | Liters | (l) | 0.001 |
Feet | (ft) | Centimeters | (cm) | 0.03281 |
To Convert To... | Multiply... | By... | ||
Gallons, Imperial | -- | Gallons, U.S. | (gal) | 0.8327 |
Grams | (g) | Ounces | (oz) | 28.35 |
Inches | (in) | Centimeters | (cm) | 0.3937 |
Joules | (J) | British Thermal Units | (Btu) | 1055 |
Kilocalories/hour | (kcal/h) | Btu/hour | (Btu/h) | 0.252 |
Kilograms | (kg) | Pounds | (lb) | 0.4536 |
Kilojoules | (kJ) | Watt-hours | (Wh) | 3.6 |
Kilometers/hour | (km/h) | Miles/hour | (mph) | 1.609 |
Kilopascals | (kPa) | Pounds/square inch | (psi) | 6.895 |
Kilowatts | (KW) | British Thermal Units/hour | (Btu/h) | 0.0002931 |
Liters | (l) | Cubic Feet | (ft3) | 28.32 |
To Convert To... | Multiply... | By... | ||
Meters | (m) | Feet | (ft) | 0.3048 |
Miles/hour | (mph) | Kilometers/hour | (km/h) | 0.6215 |
Millimeters | (mm) | Inches | (in) | 25.4 |
Newtons/square meter | (N/m2) | Pounds/square inch | (psi) | 6,895 |
Ounces | (oz) | Grams | (g) | 0.035274 |
Pounds | (lb) | Grams | (g) | 0.002205 |
Pounds/cubic foot | (lb/ft3) | Grams/cubic centimeter Kilograms/cubic meter | (g/cm3) | 62.43 |
Pounds/cubic inch | (lb/in3) | Grams/cubic centimeter | (g/cm3) | 0.03613 |
Pounds/square inch | (psi) | Bar | -- | 14.504 |
Square centimeters | (cm2) | Square feet | (ft2) | 929 |
Square feet | (ft2) | Square centimeters | (cm2) | 0.001076 |
Square inches | (in2) | Square centimeters | (cm2) | 0.155 |
Square meters | (m2) | Square feet | (ft2) | 0.0929 |
Torr | Inches Mercury | (in. Hg) | 0.03937 | |
Watts | (W) | British_Thermal_Units/hour | (Btu/h) | 0.2931 |
Thermocouple | Useful/General | Notes |
1370-1700°C | Easily contaminated, require protection. | |
C* | 1650-2315°C | No oxidation resistance. Vacuum, hydrogen or inert atmospheres. |
95-900°C | Highest output of base metal thermocouples. Not subject to corrosion at cryogenic temperatures. | |
95-760°C | Reducing atmosphere recommended. Iron leg subject to oxidation at elevated temperatures--use larger gauge to compensate. | |
K** | 95-1260°C | Well suited for oxidizing atmospheres. |
650-1260°C | For general use, better resistance to oxidation and sulfur than Type K. | |
870-1450°C | Oxidizing atmosphere recommended. Easily contaminated, require protection. | |
980-1450°C | Laboratory standard, highly reproducible. Easily contaminated, require protection. | |
T** | -200-350°C | Most stable at cryogenic temperatures ranges. Excellent in oxidizing and reducing atmospheres within temperature range. |
Calibration Type | Temperature Range | Tolerances | ||
°C | °F | Standard | Special | |
Thermocouple Wire Type | ||||
B | 870 to 1700 | 1598 to 3092 | ±0.5% |
|
Extension Wire Type | ||||
EX | 0 to 200 | 32 to 392 | ±1.7ºC | ±1.0ºC |
Compensating Extension Wire Type | ||||
BX | 0 to 200 | 32 to 392 5 | ±3.7ºC |  |
Cryogenic Range Wire Type | ||||
E | -200 to 0 | -328 to 32 | ±1.7ºC or ±1% | 7 |
1. Where tolerances are given in percent, the percentage applies to the temperature being measured in degrees Celsius. For example, the standard tolerance of Type J over the temperature range 277 to 750ºC is ± 0.75 percent. If the temperature being measured is 538ºC, the tolerance is ± 0.75 percent of 538ºC, or ± 4.0ºC. To determine the tolerance in degrees Fahrenheit, multiply the tolerance in degrees Celsius times 1.8.
2. Copper versus copper compensating extension wire, usable to 100ºC (212ºF) with maximum deviations as indicated, but with no significant deviation over 32 to 0 to 50ºC (122ºF) range. Matched proprietary alloy compensating wire is available for use over the range 0 to 200ºC (32 to 392ºF) with tolerances of ±0.033 mV (±3.7ºC5).
3. Not an ANSI symbol.
4. Copper (+) versus copper nickel alloy (-).
5. Due to the non-linearity of the Types B, C R and S temperature-EMF curves, the error introduced into a thermocouple system by the compensating wire will be variable when expressed in degrees. The degree C tolerances given are based on the following measuring junction temperatures:
6. Thermocouples and thermocouple material are normally supplied to meet the tolerances specified in the table for the normal specified range. The same materials, however, may not fall within the cryogenic tolerances in the second section of the table. If materials are required to meet the cryogenic tolerances, the purchase order must so state. Selection of materials usually will be required. Tolerances indicated in this table are not necessarily an indication of the accuracy of temperature measurements in use after initial heating of the materials.
7. Little information is available to justify establishing special tolerances for cryogenic temperatures. Limited experience suggests the following tolerances for Types E and T thermocouples:
For Both Wye and Delta (Balanced Loads) | Wye and Delta Equivalent |
VP = Phase Voltage | WDELTA = 3 WWYE |
3-Phase Wye (Balanced Load) | 3-Phase Open Wye (No Neutral) |
IP = I L | IPO = I LO |
3-Phase Delta (Balanced Load) | 3-Phase Open Delta |
IP = I L/1.73 | VP = VL |
A. Heat required for start-up
B. Heat required to maintain the desired temperature
The power required (kW) will be the heat energy value (kWh) divided by the required start-up or working cycle time. The kW rating of the heater will be the greater of these values plus a safety factor.
The calculation of start-up and operating requirements consist of several distinct parts that are best handled separately. However, a short method can also be used for a quick estimate of heat energy required.
You should always include a safety factor of varying size to allow for unknown or unexpected conditions. The size of the safety factor is dependent on the accuracy of the wattage calculation. Heaters should always be sized for a higher value than the calculated figure. A factor of 10% is adequate for small systems that are closely calculated; 20% additional wattage is more common. Safety factors of 20% and 35% are not uncommon, and should be considered for large systems, such as those containing doorsthat open or are large radiant heat applications. You'll also want to predict how long your system will operate without failure, so examine the amount of heater life you'll be needing. And because electricity costs money, take efficiency factors into account so your system will cost as little as possible to operate.
With these considerations in mind, carefully review them all to be sure you do, in fact, have definitive information to decide on a particular solution to your heating problem. Some of this supporting information may not be readily available or apparent to you. You may find it necessary to consult the reference tables and charts in this reference data section, or reference a book that deals with the particular parameter you need to define. At the minimum, the thermal properties of both the material(s) being processed/heated and their containing vessel(s) will be required.
Figuring a safety factor requires some intuition on your part. The list of possible influences can be great. From changing ambient operating temperatures, caused by seasonal changes, to a change in material or material temperature being processed, you must carefully examine all the influences.
Generally speaking, the smaller the system with fewer variables and outside influences---the smaller the safety factor. Conversely, the larger the system and the greater the variables and outside influences — the greater the safety factor.
Watts | Volts Single Phase | Volts 3 Phase | |||
120 | 240 | 480 | 240 | 480 | |
100 | 0.83 | 0.42 | 0.21 | 0.24 | 0.13 |
350 | 2.92 | 1.46 | 0.73 | 0.85 | 0.43 |
700 | 5.83 | 2.92 | 1.46 | 1.70 | 0.85 |
1100 | 9.17 | 4.58 | 2.30 | 2.65 | 1.33 |
1500 | 12.5 | 6.25 | 3.12 | 3.62 | 1.82 |
1900 | 15.8 | 7.92 | 3.96 | 4.58 | 2.29 |
3000 | 25.0 | 12.5 | 6.25 | 7.23 | 3.62 |
6000 | 50.0 | 25.0 | 12.50 | 14.50 | 7.25 |
1. Based upon combined natural convection and radiation losses into 70ºF environment.
2. Insulation characteristics
k = 0.67 @ 200ºF
k = 0.83 @ 1000ºF.
3. For molded ceramic fiber products and packed or tightly packed insulation, losses will be lower than values shown.
For 2 or 3 inches Insulation: multiply by 0.84 For 4 or 5 inches Insulation:multiply by 0.81
For 6 inches Insulation:multiply by 0.79
Material | Specific Heat Btu/lb.-°F | Emissivity | ||
Polished Surface | Medium Oxide | Heavy Oxide | ||
Blackbody |
|
| 0.75 | 1.00 |
Inconel® 600 | 0.11 | 0.20 | 0.60 | 0.92 |
Nichrome,-80-20 | 0.11 | - | - | - |
Tin | 0.056 | - | - | - |
Material | Specific Heat | Emissivity |
Asbestos | 0.25 | Most Non-Metals: 90 |
Paper | 0.45 |
Temperature °C | Resistance Value Ω | Tolerance DIN-IEC-751 | |
Class A | Class B | ||
-200 | 18.52 | ±0.55-(±0.24) | ±1.3-(±0.56) |
300 | 212.05 | ±0.75-(±0.27) | ±1.8-(±0.64) |
Element Metal | Temperature Range | Benefits | Base Resistance | TCR (Ω/Ω/°C) |
Platinum | -260 to 850°C | Best stability, good linearity | 100 Ω at 0°C | 0.00385 (DIN-IEC-761), 0.003916 (JIS 1604-1981) |
Copper | -100 to 260°C | Best linearity | 10 Ω at 25°C | 0.00427 |
Nickel | -100 to 260°C | Low cost, High Sensitivity |  |  |
SOLUTION | TYPE OF HEATER | Â | SOLUTION | TYPE OF HEATER | Â | SOLUTION | TYPE OF HEATER |
 |  |  |  |  | |||
Acetic .................................. PTFE* or Quartz | Â | Copper Cyanide ................. 304 Stainless Steel | Â | Nitric Hydrochloric Acids... PTFE* or Quartz | |||
Acetane 70, 80 .................................... PTFE* | Â | Copper Fluoborate ............................... PTFE* | Â | Nitric Phosphoric ....................... Quartz | |||
Actane Salt .......................................... PTFE* | Â | Copper Pyrophosphate ..... 304 Stainless Steel | Â | Oil ................................................ Steel | |||
Acid Sulfate .......................... PTFE* or Quartz | Â | Copper Strike .................... 304 Stainless Steel | Â | Oleic Acid ..................... PTFE* or Quartz | |||
Alcorite ................................ PTFE* or Quartz | Â | Copper Sulfate ..................... PTFE* or Quartz | Â | Oxalic Acid.....................PTFE* or Quartz | |||
Alkaline Cleaners (Electrified)....... 304 Stainless Steel | Â | Cyanide ............................ 304 Stainless Steel | Â | Paint Stripper (Alkaline) ........ 304 Stainless Steel | |||
Alkaline Soaking Cleaners .... 304 Stainless Steel | Â | Deionized Water .......... 316 Stainless Steel or Titanium | Â | Perchlorethylene .......... 316 Stainless Steel | |||
Alodine (most formulas) ....... 316 Stainless Steel | Â | Deoxidizer (Etching) ...............PTFE* or Quartz | Â | Phosphoric Acid (No Fluoride) ....... PTFE* or Quartz | |||
Alstan ............................... 304 Stainless Steel | Â | Deoxidizer Non-Chromated ....... 316 Stainless Steel | Â | Phosphate Cleaner ..... 304 Stainless Steel | |||
Aluminum Bright Dip ............ PTFE* or Quartz | Â | Dichromic Seal ..................................... Steel | Â | Phosphate .................. 316 Stainless Steel | |||
Aluminum Cleaners .............. 304 Stainless Steel | Â | Diethylene Glycol ................ 304 Stainless Steel | Â | Potassium Acid Sulfate ..... PTFE* or Quartz | |||
Aluminum Chloride .............. PTFE* or Quartz | Â | Diversey, 511, 514 ................................ PTFE* | Â | Potassium Cyanide ........ 304 Stainless Steel | |||
Aluminum Sulfate ................ 304 Stainless Steel | Â | Dow Therm ...................... 316 Stainless Steel | Â | Potassium Hydroxide .... 304 Stainless Steel | |||
Ammonia ............................ 304 Stainless Steel | Â | Dye Solutions .................... 304 Stainless Steel | Â | Potassium Hydrochloric ..... PTFE* or Quartz | |||
Ammonia Persulfate ............. PTFE* or Quartz | Â | Ebonal C ........................................... Titanium | Â | Potassium Permanganate........... PTFE* or Titanium | |||
Ammonium Bi Fluoride......................... PTFE* | Â | Electroless Copper .............................. PTFE* | Â | Rhodium ........................ PTFE* or Quartz | |||
Ammonium Chloride ........................ Titanium | Â | Electroless Nickel ............... PTFE* or Titanium | Â | Rochelle Salt Cyanide .........304 Stainless Steel | |||
Ammonium Nitrate ............. 316 Stainless Steel | Â | Electroless Tin (Acid) ........... PTFE* or Quartz | Â | Ruthenium Plating..............PTFE* or Quartz | |||
Anodizing (Aluminum).............. PTFE* or Quartz | Â | Electroless Tin (Alkaline) .... 316 Stainless Steel | Â | Salt (Actine) .................................. PTFE* | |||
ARP 28, 80 Blackening Salts... PTFE* or Quartz | Â | Electro Cleaner .................. 304 Stainless Steel | Â | Sea Water .................................. Titanium | |||
Arsenic ............................. 304 Stainless Steel | Â | Electro Polishing ................... PTFE* or Quartz | Â | Silver Bromide ........... 316 Stainless Steel | |||
Barium Chloride .............. Quartz or Titanium | Â | Enthone 80 Acid ................................. PTFE* | Â | Silver Cyanide ........... 304 Stainless Steel | |||
Benzoic Acid ................................... Titanium | Â | Ethylene Glycol .................................... Steel | Â | Silver Lume ............... 304 Stainless Steel | |||
Black Nickel ......................... PTFE* or Quartz | Â | Ferric Ammonium Oxide ..... 316 Stainless Steel | Â | Silver Nitrate ............. 316 Stainless Steel | |||
Black Oxide (Hi-Temp) ....... 304 Stainless Steel | Â | Ferric Chloride ....... PTFE*, Quartz, or Titanium | Â | Sodium Bisulfate .......... PTFE* or Quartz | |||
Black Oxide (Low-Temp) .................. Titanium | Â | Ferric Nitrate ..................... 304 Stainless Steel | Â | Sodium Carbonate .................... Titanium | |||
Bonderizing ....................... 316 Stainless Steel | Â | Ferric Sulfate .................... 304 Stainless Steel | Â | Sodium Chlorate ........................ Titanium | |||
Boric Acid ........................................ Titanium | Â | Fluoborate ............................................ PTFE* | Â | Sodium Chloride .......................... Titanium | |||
Brass Cyanide .................. 304 Stainless Steel | Â | Formic Acid ..................... 316 Stainless Steel | Â | Sodium Cyanide ......... 304 Stainless Steel | |||
Bright Nickel ........... PTFE*, Quartz, or Titanium | Â | Glycerol ........................... 304 Stainless Steel | Â | Sodium Dichromate (Hot Seal) ... 316 Stainless Steel | |||
Bright Copper Cyanide ....... 304 Stainless Steel | Â | Immersion Gold ................ 304 Stainless Steel | Â | Sodium Hydroxide ......................... Steel | |||
Bronze (Alkaline)................. 304 Stainless Steel | Â | Gold-Acid .............. PTFE*, Quartz, or Titanium | Â | Sodium Hypochlorite .................... PTFE* | |||
Brown Oxide ................................... Titanium | Â | Gold Cyanide .................... 304 Stainless Steel | Â | Sodium Persulfate ......... PTFE* or Quartz | |||
Burnite ................................. PTFE* or Quartz | Â | Grey Nickel ............ PTFE*, Quartz, or Titanium | Â | Stannate ....................................... Steel | |||
Butyric Acid .................................... Titanium | Â | Hot Seal Dichromate ......... 316 Stainless Steel | Â | Stanostar .................... PTFE* or Quartz | |||
Cadmium Black ................... PTFE* or Quartz | Â | Hydrochloric Acid ................. PTFE* or Quartz | Â | Stearic Acid .............................. Quartz | |||
Cadmium (Alkaline) ............ 304 Stainless Steel | Â | Hydrofluoric Acid ................................. PTFE* | Â | Sulfamate Nickel ........ PTFE*, Quartz, or Titanium | |||
Cadmium Fluoborate ........................... PTFE* | Â | Hydrogen Peroxide ............. PTFE* or Quartz | Â | Sulfur .......................... PTFE* or Quartz | |||
Calcium Chloride ............................. Titanium | Â | Indium ................................ PTFE* or Quartz | Â | Sulfur Peroxide ........... PTFE* or Quartz | |||
Calcium Hypochlorite ....................... Titanium | Â | Iridite (4-75,4-73,14,14-2,14-9)...... 316 Stainless Steel | Â | Sulfuric Acid ............... PTFE* or Quartz | |||
Carbonic Acid .................................. Titanium | Â | Iridite (1,2,3,4-C,7,8,15) ....... PTFE* or Quartz | Â | Sulphamic Acid ............... PTFE* or Quartz | |||
Caustic Etch ........................................ Steel | Â | Iron Fluoborate .................................... PTFE* | Â | Tannic Acid ........................... Titanium | |||
Caustics .............................................. Steel | Â | Iron Phosphate ................... 316 Stainless Steel | Â | Tin Nickel ...................................... PTFE* | |||
Caustics (highly concentrated 20% and over)... Steel | Â | Isoprep (186,187,188) ....... 316 Stainless Steel | Â | Tin Plating (Acid) (Stanus/Sulphate)...PTFE* or Quartz | |||
Chlorine/Wet ....................... PTFE* or Quartz | Â | Isoprep Acid Salts ............................... PTFE* | Â | Tin Plating Acid (Fluoborate) ........... PTFE* | |||
Chloride ............... PTFE*, Quartz or Titanium | Â | Jetal .................................. 304 Stainless Steel | Â | Tin Plating (Alkaline) .... 304 Stainless Steel | |||
Chlorosulfuric Acid .......................... Titanium | Â | Lead Acetate .................... 304 Stainless Steel | Â | Trichlorethylene .......... 316 Stainless Steel | |||
Chromic Anodizing ............... PTFE* or Quartz | Â | Lime Saturated Water (Alkaline)......316 Stainless Steel | Â | Trioxide (Pickle) ............. PTFE* or Quartz | |||
Chromic Acetate .................. PTFE* or Quartz | Â | Linseed Oil ........................ 304 Stainless Steel | Â | Turco (4181, 4338) ..... 316 Stainless Steel | |||
Chromic Nickel .................... PTFE* or Quartz | Â | Magnesium Hydroxide........ 304 Stainless Steel | Â | Unichrome ...................... PTFE* or Quartz | |||
Chromium (No Fluorides)............PTFE*,Quartz, or Titanium | Â | Magnesium Nitrate ............... PTFE* or Quartz | Â | Water ......... 316 Stainless Steel or Quartz | |||
Chromium (Fluoride) ............................ PTFE* |  | Manganese Phosphate ..... 316 Stainless Steel |  | Wood’s Nickel Strike .... Titanium, PTFE*, or Quartz | |||
Citric Acid ........................................ Titanium | Â | McDermid 629 .................................... PTFE* | Â | Yellow Dichromate .......... PTFE* or Quartz | |||
Clear Chromate .................... PTFE* or Quartz | Â | Mercuric Chloride ............................ Titanium | Â | Zinc Acid ...................... PTFE* or Titanium | |||
Cobalt Nickel ........... PTFE*, Quartz, or Titanium | Â | Muriatic Acid ....................... PTFE* or Quartz | Â | Zinc Ammonium Chloride........ Quartz or Titanium | |||
Cobalt Plating .................. 304 Stainless Steel | Â | Nickel (Plating Solution) (Watts) ...PTFE*, Quartz, or Titanium | Â | Zinc Cyanide................ 304 Stainless Steel | |||
Cobra Etch .......................................... PTFE* | Â | Nickel Acetate Seal ......... 316 Stainless Steel | Â | Zinc Phosphate ........... 316 Stainless Steel | |||
Copper Acid ......................... PTFE* or Quartz | Â | Nickel Chloride .................................... Titanium | Â | Zincate .................... 304 Stainless Steel | |||
Copper Bright Acid .............. PTFE* or Quartz | Â | Nitric Acid ............................... PTFE* or Quartz | Â | Â | Â |