# Understanding conductance, Ce in compressed air flow

#### TENichols94

I'm looking at classifying air flow characteristic of pneumatic components and I've decided to follow an ISO standard (ISO:6358). It states that the flow rate is a related to the inlet and outlet pressure $$\displaystyle \frac{p_{2}}{p_{1}}$$, which would make since for compressible flow. For a component the conductance $$\displaystyle Ce=\frac{q_{v}}{p_{1}} \sqrt{\frac{T_{1}}{T_{0}}} =\frac{q_{m}}{\rho_{0} p_{1}} \sqrt{\frac{T_{1}}{T_{0}}}$$ where $$\displaystyle q_{v}$$ is volume flow rate at standard conditions, $$\displaystyle q_{m}$$ is mass flow rate at actual conditions, and the subscripts denote $$\displaystyle 1$$ are inlet conditions, and $$\displaystyle 0$$ are standard conditions.
I was wondering if anyone knew where this relationship is derived?
The experimental setup is basically a pressure drop experimental system that has the capabilities to record standard condition flow rate, temperature and pressure at inlet and outlet locations of the component under test.

#### TENichols94

I'm looking at classifying air flow characteristic of pneumatic components and I've decided to follow an ISO standard (ISO:6358). It states that the flow rate is a related to the inlet and outlet pressure $$\displaystyle \frac{p_{2}}{p_{1}}$$, which would make since for compressible flow. For a component the conductance $$\displaystyle Ce=\frac{q_{v}}{p_{1}} \sqrt{\frac{T_{1}}{T_{0}}} =\frac{q_{m}}{\rho_{0} p_{1}} \sqrt{\frac{T_{1}}{T_{0}}}$$ where $$\displaystyle q_{v}$$ is volume flow rate at standard conditions, $$\displaystyle q_{m}$$ is mass flow rate at actual conditions, and the subscripts denote $$\displaystyle 1$$ are inlet conditions, and $$\displaystyle 0$$ are standard conditions.
I was wondering if anyone knew where this relationship is derived?
The experimental setup is basically a pressure drop experimental system that has the capabilities to record standard condition flow rate, temperature and pressure at inlet and outlet locations of the component under test.
Anyone?

#### Woody

I don't know for sure,
but I would suggest you look at conservation of energy and momentum.