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Description / Abstract:
SCOPE AND FIELD OF APPLICATION
This Standard specifies the geometry and method of use (installation
and flowing conditions) for
orifice meters of 6 mm to 40 mm (¼ in. to 1½ in.) line
size when they are inserted in
a conduit running full. It also gives necessary information for
calculating flow rate and its
associated uncertainty.
It applies only to differential pressure devices in which the flow
remains subsonic throughout the
measuring section, flow is steady or varies only slowly with time, and
the fluid is considered
single-phase. In addition, the uncertainties are given in the
appropriate sections of this Standard
for each of these devices within the pipe size and Reynolds number
limits, which are specified.
This Standard covers devices for which sufficient calibrations have
been made to enable the
specification of coherent systems of application and to enable
calculations to be made with certain
predictable limits of uncertainty.
The devices introduced into the pipe are called primary devices. The
term primary device also
includes the pressure taps and the associated upstream and downstream
piping. All other instruments
or devices required for the measurement or transmission of the
differential pressures are known as
secondary elements, and in combination are referred to as the
secondary devices. This Standard
covers the primary devices; the secondary devices will be mentioned
only occasionally, as and when
necessary for the proper operation of the primary device.
The different primary devices covered in this Standard are
(a) orifice plates used with corner pressure taps;
(b) orifice plates used with flange pressure taps;
(c) specially designed orifice meters with integral fittings.