Determination of boiling range

These explanations are available in these general analysis books; you can take a look

Determining the boiling range is troublesome; nowadays, many manufacturers no longer use this method for various products and instead opt for chromatography. Only those that cannot be replaced by instruments are used

Pay attention to temperature control; it must not get out of control or experience overheating； Pay attention to the control of cooling water to avoid water supply interruptions and insufficient cooling capacity. Now there are automatic distillation analyzers, which make it convenient to determine the distillation range of oils.

During heating, the temperature must be controlled stably. Prevent bumping. Prevent gas entrainment.

1. Pay attention to controlling the temperature of the cold bath; for gasoline, it should be between -5 and 0°C (a mixture of ice water), and some instruments have settings for this purpose. Diesel is generally 50°C. 2. When preparing parallel samples, make sure to stagger the heating times of the two furnaces by about 5 minutes; this prevents conflicts and chaos when reading the temperatures. 3. Ensure the initial and final distillation times. New users should pay attention when operating: when starting to heat a cold furnace, set the heating control to between 100-150 (for diesel) or 50-100 (for gasoline). Do not make any changes before the initial distillation begins; this usually ensures a proper timing for the initial distillation and makes it proceed more smoothly. Figure it out based on the characteristics of the instrument. For the final distillation time, when making the last adjustment to the heating temperature at the 90% point for gasoline, it is generally advisable to increase it by 2–3 units; for diesel, at the 95% point, the adjustment is usually made by increasing the temperature by 1–2 units. This usually meets the requirements, but it’s best to determine the appropriate value based on one’s own equipment. 4. Ensure the distillation speed. After the initial distillation, it is necessary to maintain a consistent distillation rate by adjusting the heating intensity so that the flow rate is 18–22 drops per 10 seconds, which will meet the requirement of 4–5 milliliters per minute. 5. The residue should be poured into a 10-milliliter measuring cylinder while it is in a flowing state, and the reading taken after cooling.