Measuring
16
9.4 Viscosity determination of gases
The viscosity determination of gases has to be done with ball
G which is made out of glass.
1
The measuring tube must be closed with rubber stop-
pers fitted with glass stopcocks.
Measuring tube, glass ball and gas must be clean and
dry.
2
The tube is flushed several times with the gas to be
tested to push out any remains of air. Then the tube fil-
led with the gas sample is closed with the stopcocks
and raised to the test temperature.
The calculation of the gas viscosity is based on the compari-
son with the viscosity of air at 20
C (
= 1815
10
--5
mPa
s):
gas
= F
G
F
A
1815
10
--5
(mPa
s)
where:
gas
: viscosity of the gas at the temperature T
F
G
: falling time of the ball in the gas at the temperature T
F
A
: falling time of the ball in air at a temperature of +20
C
Viscosity of the air at a temperature of +20
C:
1815
10
--5
(mPa
s)
