Knudsen Intermediate Flow Through a Tube

The region of Knudsen flow is characterised by Kn values between 10-2 and 0.5. 

For long tubes of uniform circular cross-section, the equation for the / F-throughput obtained by Knudsen is given (ref. (d )) as  

In a system used for studying reactive intermediates produced by micro-wave discharge, reactants are pumped through the discharge region via a 

Assume that the mean pressure (p) in the tube is 0.05 mbar. 

A right-angled, bellows-sealed DN250ISO-K valve has a molecular flow conductance for air of 2700Ls-1. Calculate its conductance for Ar. If a mean pressure of Ar of 5 x 10 3 mbar is established in the elbow, what is the conductance  

---

The numerical value of the conductance of a component in a vacuum system depends on the type of flow in the system. Gas flow in simple, model systems (e.g. tubes of constant circular cross-section, orifices, apertures) was considered for viscous flow (Examples 2.6-2.8) and molecular flow (Examples 2.9-2.11). The chapter concluded with two illustrations (Examples 2.13, 2.14) of Knudsen (intermediate) flow through a tube. 

---