Operation principle of flow measurement, Dynamic viscosity, Density – Fluke Biomedical VT305 User Manual
Page 65
Gas Flow Analyzer
Operation Principle of Flow Measurement
51
Operation Principle of Flow Measurement
A differential pressure measurement is used to find the flow in the flow channel. To make the pressure difference, a linear flow element is used as a flow
resistance. See Figure 44.
Pressure Difference ∆p
Linear flow element
Gas Flow Q
gyo046.eps
Figure 44. Linear Flow Element
η
: dynamic viscosity of the gas (Pa s)
p: Gas density (kg/m
3
)
c1, c2: device-specific constants (channel geometry)
Dynamic viscosity
•
The viscosity of a medium, is its resistance to flow and tear off of the flow.
•
The viscosity is strongly contingent on the temperature.
•
The viscosity of the medium is slightly dependent on pressure and humidity of the medium.
Density
•
Density is the unit of mass per unit volume of the medium.
•
Density is strongly contingent on the pressure and temperature.
The influence of environmental conditions is the reason why the flow is occasionally transformed to standard conditions.