Title: Determination of Boiling Range or Temperature and Distillation Range
- Objective: This test method provides a method of measurement of Boiling Range or Temperature and Distillation range of liquids.
- Principle: The Boiling Range or Temperature and Distillation range is the temperature interval, corrected for a pressure of 101.3 kPa, within which a liquid, or a specified fraction of a liquid, distils under the conditions specified in the test. This test method covers the determination of Boiling or Distillation range of liquids boiling between 30°C and 350°C, that are chemically stable during the distillation process, by manual or automatic distillation procedures. This test method is applicable to organic liquids such as hydrocarbons, oxygenated compounds, chemical intermediates, and blends thereof.
3. Procedure:
- Apparatus:
The apparatus ( Figure -1) consists of a round bottom distillation flask (A), a straight tube condenser (B) which fits on to the side arm of the flask and a plain-bend adaptor (C) attached to the end of the condenser. The lower end of the condenser may be bent to provide a delivery tube, or it may be connected to a bent adopter that serves as a delivery tube. A calibrated thermometer is inserted in the neck of the flask so that the upper end of the mercury reservoir is 5 mm lower than the junction of the lower wall of the lateral tube. The thermometer is graduated at 0.2 ° intervals and the scale covers a range of about 50°. During the determination, the flask, including its neck, is protected from draughts by a suitable screen.
- Method:
If the liquid under examination distills below 80°C, cool it to between 10°C and 15°C before measuring the sample for distillation. Assemble the apparatus and place in the flask 100 ml of the liquid being examined, taking care not to allow any any liquid to enter the side-arm. Insert the thermometer and shield the entire heating and flask assembly from external air currents. Add few pieces of porous material and heat rapidly to boiling using Bunsen burner (or electric heater or heating mantle) and an asbestos plate pierced by a hole 33 mm in diameter. Record the temperature at which the first drop of distillate falls into the receiver and adjust the rate of heating
to obtain a regular distillation rate of 4-5 ml per minute. Record the temperature when the last drop of liquid evaporates from the lowest point in the distillation flask or when specified percentage has distilled over. Correct the observed temperature reading for any variation in barometric pressure from the normal (101.3kPa) using the following expression
t1 = t2+K (a-b)
where t1 = the corrected temperature
t2 = the observed temperature
a = 101.3 when the barometric pressure is measured in kilopascals (kPa) or 760 when measured in torr.
b = barometric pressure at the time of determination (refer below table)
K = correction factor indicated in table
Variation of correction factor with temperature.
| Boiling Range | KPa | Ktorr |
| Less than 100 | 0.30 | 0.040 |
| 100-140 | 0.34 | 0.045 |
| 141-190 | 0.38 | 0.050 |
| 191-240 | 0.41 | 0.055 |
| More than 240 | 0.45 | 0.060 |