Honeywell RABO G100, Инструкция по эксплуатации, Страница: 14 / 176

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2. Structure and function
Operating principle
Rotary gas meters are volume-measuring devices for gaseous media which
operate according to the positive displacement principle. Due to their
volumetric measuring principle, their functioning is not influenced by the
installation and they are therefore ideal for compact measuring systems
without an inlet section. They record the gas volume at operating conditions
and are approved for custody transfer applications. Electronic volume
conversion devices can be used in order to convert the volume.
Measurement procedure
Two rotating impellers which look like a figure of eight when viewed in cross-
section are mounted in a single housing with one inlet and one outlet (see
Fig. 1). The two impellers are coupled together using synchronizing gears.
When gas flows, the impellers rotate without touching one another and
propel a gas volume to the outlet which is defined by the cyclic volume. One
rotation of the system thus corresponds to a defined gas volume. The
revolutions of the impellers are transferred to the mechanical index via a
reducing gear and a magnetic coupler. The rotary gas meter is adjusted
using a pair of gears in the index.
Fig. 1b | Working principle of rotary gas meters
Fig. 1a | Working principle of rotary gas meters
Housing
Inlet Outlet
¼ cyclic volume
Impeller
Synchronizing gears