Handbook of Solvents - George Wypych - ChemTech - Ventech!

1068 George Wypych
Table 15.1.1. Typical chemical and physical properties of solvents included in their
specifications
Acid acceptance Distillation range
Acidity Doctor test
Acid wash color Dry point
Alkalinity Flash point
Aluminum scratch Free halogens
Aniline point Initial boiling point
Appearance Iron concentration
Bromine index Kauri-butanol value
Color Non-volatile matter
Concentration of admixtures Permanganate time
Concentration of isomers Residual odor
Concentration of main component (or purity) Specific gravity
Concentration of sulfur Water concentration
Copper corrosion Water miscibility
15.1.33 VAPOR PRESSURE
The vapor pressure is the pressure of the vapor of a substance in equilibrium with the pure
liquid at a given temperature. Two procedures are used: an isoteniscope procedure
(standard) for measuring vapor pressures from 1x10 -1 to 100 kPa and a gas-saturation
pressure for measuring vapor pressures from 1x10 -11 to 1 kPa. 154-155 In the isoteniscope
method, a sample is deaerated by heating under reduced pressure. The vapor pressure is then
determined by balancing the pressure of the vapor against a known pressure of an inert gas.
The vapor pressure is determined at minimum three different temperatures.
In the gas-saturation method, an inert gas is passed through a sufficient amount of
compound to maintain saturation. The vapor is then removed from the gas by a sorbent or a
cold trap and quantitatively determined by gas chromatography or other suitable technique.
15.1.34 VISCOSITY
The viscosity of solvents can be determined by one of three methods: glass viscometer, 156
Saybolt viscometer, 157 and bubble time method. 158 Glass viscometry is applicable to
Newtonian, transparent liquids which because of volatility cannot be measured in
conventional capillary viscometers. The viscometer uses a purge gas which helps to transfer
the measuring liquid from a lower reservoir to the sample bulb. The time of flow is
measured for a fixed volume of liquid at a temperature controlled with a precision of 0.01 o C.
A set of liquids is available as viscosity standards in order to select the standard having
closest viscosity to the measured sample.
The Saybolt viscometer was developed for petroleum products. A sample of 60 ml
flows through a calibrated orifice and the time of flow is measured at a controlled tempera-