Dear Mr Clun,
As per the techical dictionary definition
1.An instrument for measuring the flow of viscous liquids, such as blood (In medical field,an instrument for measuring the velocity of the blood current in the arteries).
2. An instrument for measuring currents, especially the force or intensity of electrical currents; also called as galvanometer.
if you search using any search engine you will get thousands of hits.
A rheometer measures flow properties of a fluid. Fluid may be a liquid or a gas or a solid powder because fine powders behave very much like liquids. In case of liquids and gases you measure mainly viscosity. In case of powders you measure cohesivness, flow function and some other properties relevant to free flow of a powder from a silo and similar.The equipment is not universal for all purposes.
m777182
Sorry but I've never heard of a rheometer which you could use to measure air properties, the viscosity is several orders of magnitude lower than liquids so your hypothetical instrument would have to be devoted to purely gas measurements.
What is it you actually need to do? You could use capillary tubes along with the Hagen-Poiseuille equation to infer gas viscosity from flow measurements.
Regards, HM.
No more things should be presumed to exist than are absolutely necessary - William of Occam
