Scope and field of application
This International Standard specifies a method of liquid
flow-rate measurement in closed conduits by measuring the mass of
liquid delivered into a weighing tank in a known time interval. It
deals in particular with the measuring apparatus, the procedure,
the method for calculating the flow-rate and the uncertainties
associated with the measurement.
The method described may be applied to any liquid provided that
its vapour pressure is such that any escape of liquid from the
weighing tank by vaporization is not sufficient to affect the
required measurement accuracy. Closed weighing tanks and their
application to the flow measurement of liquids of high vapour
pressure are not considered in this International Standard.
This International Standard does not cover the cases of
corrosive or toxic liquids.
Theoretically, there is no limit to the application of this
method which is used generally in fixed laboratory installations
only. However, for economic reasons, usual hydraulic laboratories
using this method can produce flow-rates of 1.5 m3/s or
Owing to its high potential accuracy, this method is often used
as a primary method for calibration of other methods or devices for
mass flow-rate measurement or volume flow-rate measurement provided
that the density of the liquid is known accurately. It must be
ensured that the pipeline is running full with no air or vapour
pockets present in the measuring section.