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2.1.2
Piping Construction
It is preferred to install the flowmeter upstream of a flow control or shut-off valve, as the
back pressure provided by the valve will be beneficial to system accuracy; do not operate a
flowmeter directly discharging to atmosphere. Piping should be designed so that the
flowmeter is full of liquid at all times; this is achieved by designing the inlet and outlet
piping for the flowmeter to be lower than all surrounding piping
.
For vertical installations the liquid should travel from bottom to top, i.e. it should rise
vertically through the flowmeter. This will ensure that the flowmeter remains full of liquid
and will stop air entrapment in the meter.
All piping surrounding your flowmeter should be well supported on secure footings,
preferably at the point where the piping joins to the flowmeter; unsupported piping will
cause severe pipe stress on the flowmeter.
The best piping designs provide a bypass line, as shown in the following diagram, which
allows isolation of the flowmeter and strainer from the main process line. The benefits of
installing a bypass line are that your system can be purged before start-up, and any
maintenance on the flowmeter or strainer can be carried out quickly and economically
without interrupting critical processes.
2.1.3
Mechanical Support
All flowmeters of nominal size 3” and 4” must have adequate mechanical support. Failure to
adequately support the flowmeter and the connected piping may result in structural damage
to the flowmeter housing. It is recommended that a solid structural support be provided at the
first flange connection, on both sides of the flowmeter. If possible, the housing of the
flowmeter can be directly supported, however piping should still be supported as close as
possible to the flowmeter. It is never acceptable to support the flowmeter and use the housing
of the flowmeter to support the weight of your piping.
Strainer
Flowmeter
Isolation valve
Isolation valve
By-pass valve
