DATREND Systems venTest, Руководство по эксплуатации

Страница: 96 / 117

venTest OPERATORS MANUAL
• Another important factor is the temperature of the respective gas. If a gas contained in a
closed container is heated, pressure will increase. On cooling down pressure will
decrease.
With a flexible container being able to expand, i.e. where pressure inside can adapt itself to
ambient pressure, the container will expand (volume will increase) with temperature rising. On
cooling down the container will contract (volume will decrease).
The ratio between pressure (P), volume (V) and temperature (T) are shown in the gas law:
P1 x V1 P2 x V2
T1 T2
The gas law therefore says that the ratio between pressure, volume and temperature has to be
the same, both before and after modification of ambient conditions.
Example: At a temperature of 20°C and a pressure of 1 bar a gas
takes up a volume of 1 l. The gas is now heated up from T1 = 20°C
(293.2K) to T2=30°C (303.2 K)
a) The container's walls are flexible (as stated in the example above):
Volume can expand (V1 to V2), pressure remains the same (P1=P2=P). The gas law can
now be adapted as follows:
P1 x V1 P2 x V2
T1 T2
leads to
º
V1 V2
T1 T2
Result: V2 =
V1 x T2
T1
In our example: V2 = 1 litre * 303.2/293.2 = 1.034 litre
Appendix A
#
Page 82