Q4) When selecting flow meter, what
are some key considerations an end-user
should make to ensure success?
A: End-users need to know:
If it’s safety then either a SIL rated
device or proven-in-use criteria will
come into play.
•
Finally, what are the lifecycle
considerations? What reliability
is required? I would think that
reliability would always be required
????) What is the cost of installation,
commissioning, testing and
maintenance of each option, and
how do these factors offset different
instrument costs?
• The reason for installing the
measurement in question. Is it
control, custody transfer, batching, or
indication? These reasons determine
the value of the measurement which,
in turn, influences the budget for the
measurement point. • The properties (viscosity, pressure,
temperature, conductivity) of the
fluid to be measured. Also the
required turn-down ratio and what is
required in terms of accuracy. What
repeatability and response time are
needed? These factors will rule some
technologies in, and some out. As this high-level list of requirements
suggests, selecting flow measurement
technologies is not simple, so we
recommend that you speak to an expert if
you are not sure.
What the requirement of the physical
installation are (e.g how much space
/ straight runs are available) and
what is the maximum allowable
pressure drop? A: The meter should be installed in such
a way that it is always full of product. For
liquid application wherever possible the
meter the meter should be installed in a
vertical line with the flow in an upward
direction.
•
•
Are there environmental and
personnel safety considerations that
would make a design with fewer leak
points preferable? Is this a process
control or process safety application?
Q5) What is the best location of a flow
meter in a piping system?
Pumps , pipe bends, reductions etc can
cause disturbances in the flow profile
, and the designer should be careful to
take these into account so as to minimise
these effects.
Q6) What are some pitfalls you see
end-users commonly encounter in flow
meter applications? How can end-users
best avoid and/or respond to such appli-
cation pitfalls?
A: The pitfalls we see the most often
are a lack of process detail, or incorrect
assumptions about the application. This
leads to poor specification, which in turn
leads to meters of the wrong size being
installed.
The most common consequences are
high pressure drops across the meter
and lower accuracy than the end user
expected. It is also critical that the person
specifying the meter understands the
reason for the measurement point. Batch
control has different requirements from
utility flow monitoring, which is different
again from Custody Transfer or simple
indication.
Ensure you have accurate process
information and a clear functional
specification to avoid these pitfalls. If in
doubt, talk to a flow measurement expert.
Q7) How does the industry intend to
expose the applications that did not meet
expectations? And what is the procedure
for achieving that?
Issue 30 PECM
91