Bronkhorst Mini CORI-FLOW - Manual (Page 13)

BRONKHORST CORI-TECH B.V.
What changes are allowed ?
How many changes in quantity for certain process conditions are allowed without the need of a new zero
procedure for the (mini) Cori-Flow depends on the influence this will have on the mass in the tubes.
As soon as a fluid will be measured at its critical point, a small change in process conditions like temperature
or pressure can already result in a rapid increase or decrease of density and/or dynamic viscosity. This will also
influence the mass (flow) in the sensor tubes and therefore the zero stability. So please try to avoid phase
changes or almost phase changes.
E.g. CO2 and Ethylene have a large transition area (“no meat, no fish”). Experiences in practice turned out that
measuring (and even controlling) in such an area can be highly accurate.
So measuring in critical, or even supercritical area’s, is good possible with (mini) Cori-Flow. Inaccuracies are to
be expected when a phase change takes place. See also gas or liquid.
Temperature changes of several °C or pressure changes of several bar for e.g. Air when measuring at 20°C
and 5 bara will not be a problem. This will not affect density or dynamic viscosity that much.
However when measuring e.g. Ethylene at 10°C and 52 bara, a small increase of temperature or decrease of
pressure will already result in large changes of density and even phase change. This last example might need
a new zero procedure to get rid of offset errors due to zero stability.
Error visualization
-> time
Temperature considerations
Effects on accuracy:
(Mini) Cori-Flow sensors do have an internal temperature measurement device for measuring fluid temperature
and compensation on mechanical changes of the sensor due to temperature changes.
0 %
+ x % error (zero stability)
- x % error (zero stability)
+/- 0.05% repeatability
9.17.050 page 13