Purchasing vortex flowmeter

Dear All,
For buying vortex flowmeter to measure a fluid such as ethylene, do companies that sell this kind of flowmeter like Endress Huaser have special facility to calibrate this flowmeter based on data we have sent to them? if they does not have a fluid such as this one what they do? Do they send it to another company to calibrate or is it possible to calibrate it with more accessible fluid such as water and with calculating some factors they just change those parameter to read flow's quantity of ethylene? full information in this regard will be appreciated.
I once heard a rumor that a very high end flow calibration lab actually calibrated a gas meter on a gas blend (not air, but a blended gas) for what amounted to a small fotune. It seems that the standard flow calibration flow stands use water. Those technologies that need it, provide a K factor for the meter to compensate for fluid properties.

Vortex counts the vortices. It's the vortice formation frequency that matters. The shedding frequency is independent of fluid properties such as density, viscosity, conductivity, etc., as long the flow is turbulent enough for vortex shedding to occur.

I think a wet water calibration suffices.