BS 4591:1990 download.Method for Determination of distillation characteristics of organic liquids (other than petroleum products).
1 Scope and field of application
BS 4591 specifies an apparatus and method for the determination of distillation characteristics of volatile organic liquids which (excluding petroleum products) having a boiling point in the range 30 to 300 °C approximately and are stable during distillation in atmospheric conditions.
2 References
Iso 3405, Pet roleum products — Determination of distillation characteristics.
Iso 4626, Volatile organic liquids — Deter,nination of boiling range of organic solvents used as raw materials.
3 Definitions (see iSO 3405 and ISO 4626)
3.1
initial boiling point
the temperature noted (corrected, if required) at the moment when the first drop of condensate falls from the tip of the condenser during a distillation carried out under standardized conditions
3.2
final boiling point
the maximum temperature noted (corrected, if
required) during the final phase of the distillation of
a sample carried out under standardized conditions
3.3
dry point
the temperature noted (and corrected, if required) at the moment of vaporization of the last drop of liquid at the bottom of a flask, during a distillation carried out under Standardized conditions
3.4
boiling range
the temperature interval between the initial boiling point and the dry point
4 Principle
Distillation of a test portion, under carefully defined conditions in order to determine either
4.1 the temperatures corresponding to the condensate volumes defined in the International Standard for the product under test: these temperatures shall be corrected as indicated in clause 9. unless the nature of the product provides only for a difference of temperature between two volumes of condensate, (plotting temperature as a function of volume); or
In each of the two narrower sides of the draught screen are two air-vent, holes 25 mm in diameter situated below the heat-resistant shelf, as shown in Figure 5.
In each of the four sides of the draught screen are three air-vent holes with their centre 25 mm above the base of the draught screen. These holes occupy the positions shown in Figure 5, the diameter of the holes situated centrally in the wider side being 25 mm, and the diameter of the remaining 10 holes 12,5 mm.
At the middle of each of the wider sides, a vertical slot for the side tube of the distillation flask, dimensioned as shown in Figure 5, is cut downwards from the top of the screen. A removable shutter, conforming to the dimensions in Figure 5, is provided for closing whichever vertical slot is not in use.
A shelf of hard heat-resistant board 6 mm in thickness and possessing a centrally cut circular hole 110 mm in diameter, is supported horizontally in the screen and fits closely to the sides of the screen, to ensure that hot gases from the source of heat do not come into contact with the sides or neck of the flask. The supports for shelf may consist of triangular pieces of metal sheet firmly fixed to the screen at its four corners.
In one of the narrower sides of the screen, a door is provided having the dimensions shown in Figure 5 and overlapping an opening in the screen by approximately 5 mm all round.
In each of the narrower sides of the screen, a mica window is placed centrally with the bottom of the window level with the top of the heat-resistant shelf. The dimensions and the positions of the windows are shown in Figure 5.
5.1.6 Heat-resistant board
In addition to the heat-resistant shelf referred to in 5.1.5, a heat-resistant board 150 mm square and 6 mm in thickness is required. It has a central hole of 50 mm diameter, unless otherwise stated in the specification for the material under test.
5.2 Assembly of the apparatus
Assemble the distillation apparatus as shown in Figure 1.
Record, as appropriate,
— temperature as a function of volume (4.1):
— volume as a function of temperature (4.2).
In addition, record the atmospheric pressure and the temperature of the barometer on taking the reading.
8 Corrections to barometer readings
Atmospheric pressure is generally measured by means of a mercury barometer (Fortin type), having a brass scale calibrated in millibars (mbar). A Standard atmosphere (atm) = 1 013,25 mbar = 101 325 Pa (see ISO 31.3).
NOTE If the barometer is calibrated in millimetres of mercury, multiply the observed value by 1,332 89 (rounded up to 1.333) in order to obtain the corresponding value in millibars.
If. however, the pressure reading is given in pascas (Pa). note the following equivalent values:
1 bar = 1 000 mbar = 105 Pa = 100 kPa = 0.1 MPa
(see Iso 31-3).
8.1 Index correction
Initially correct the observed barometer reading in accordance with the inspection certificate issued with the instrument. The reading thus corrected gives the atmospheric pressure as would be indicated by a correctly adjusted barometer at the temperature and at the latitude of the place of observation.
8.2 Temperature correction to 0 °C Correct the value obtained in 8.1 to 0 °C, taking into account the temperature at which the reading was taken and the type of barometer used.
If the mercury barometer is of the Fortin type, or of any other type in which the mercury is set to a fiducial level when the barometric reading is taken, apply the correction given in Table 2.
If the barometer used is of the Kew type, i.e. one in which the barometric reading is taken without adjusting the level of the mercury in the reservoir, the temperature correction will differ somewhat from that given in Table 2. The temperature coefficient of a Kew pattern barometer depends to a small extent on its dimensions, but sufficient accuracy will be obtained, in general, if the temperature correction to a reading of a Kew pattern barometer is taken to be 5 % in excess of that given in Table 2.
9.1.2 Correction for barometric pressure When the barometric pressure, corrected as in clause 8, deviates from 1 013,25 mbar, apply further corrections (see clause 10) to the observed distillation temperatures, as indicated in the specification for the product under test, or in the literature.
9.2 For volume readings as a function of temperature (see 4.2)
These corrections shall be applied before commencing distillation.
9.2.1 Correction for thermometer error
If the thermometer gives incorrect readings at the specified distillation temperatures, corrected in accordance with 9.2.2, correct the readings by adding the amount of error if the thermometer is reading high, or subtracting the amount of error if the thermometer is reading low.
Also make corrections for the emergent stem of the thermometer when using a thermometer calibrated for total immersion.
11 Test report
The test report shall include the following particulars:
a) an identification of the sample; b) the reference of the method used;
c) the results and the method of expression used;
d) any unusual features noted during the determination:
e) any operation not included in BS 4591 or in the International Standards to which reference is made, or regarded as optional.