must depend on the development of
engineering education and effective
professional training. We have to focus on
the fact that knowledge is the key for any
progress. One may revise my article titled
“Knowledge Recommended” which was
published in Control Design magazine in
October 2008.
the needs and situation of end-user
requirements.
H ow should an end - user
approach the process
instrumentation design process ?
W hat are the high - level
W hen selecting P rocess
instrumentation technology , what
are some key considerations an
end - user should make to ensure
success ?
Selecting process instrumentation
technology is a compromise between
many parameters so it is considered a
MCDM (Multi-Criteria
Decision
Making) problem. It is preferable to apply
one of the decision making systematic
methodologies such as AHP (Analytic
Hierarchy Process). Selection criteria
should be set according to the needs of
end-user and has to include at least the
following parameters:
1. Performance characteristics: That is
including all the specifications regarding
the required performance of certain
instrumentation in a certain process
such as accuracy, resolution, rangeability,
sensitivity, repeatability, dynamic
performance, etc.
2. Environmental conditions: This is
essential to specify the necessary
protection degree to make sure that any
instrumentation is working properly with
regard to both safety requirements and
operational conditions.
3. Influences to processes: The extent to
which the processes will be disturbed
during the measuring process. For
example, significant pressure loss can be
caused to processes in some techniques of
flow measurement.
4. Durability: According to application
requirement, durability and ruggedness
of process instrumentation should be
considered.
5. Maintainability and Operability:
Maintenance requirements and ease of
use and operating are presenting the
running cost of certain instrumentation.
6. Purchase Cost: Initial cost should be
put with its right weight according to
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PECM Issue 31
best practices you typically
recommend ?
The end-user should be involved
in the design process of process
instrumentation. I mean that a mutually
beneficial relationship between
manufacturers and end-user should be
found. Manufacturers are always doing
their best to have this relationship as
they see it’s a matter of business to be
able to sell their products. The missing
effort is that of the end-user side
especially who has low experienced
engineers unqualified technicians.
It is very important for end-user
personnel to keep updated with all
the news of the latest developments
regarding process instrumentation by
following the appropriate technical
journals regularly. Contributing in
surveys that conducted by technical
entities from time to time. Trying to be
a member of some technical nonprofit
organizations which work in subjects
related to process instrumentation.
Effective contributions of end-users
in seminars and technical conference
are also recommended and supply
the manufacturers with their feedback
about any new developments and
about the application needs are usually
considered as a useful input for the design
process of process instrumentation.
W hat are some common pitfalls
you see end - users encounter
in the specification , design
and / or application of process
instrumentation ? H ow can end -
users best avoid such pitfalls ?
Selecting process instrumentation
through bids and choosing the least
price, lack of experience of the engineers
who write down the specifications, and
following vendor’s sales representatives’
recommendations without being enough
qualified to review the details are
common pitfalls encountered by end-
users.
To avoid such pitfalls, an end-user should
put certain criteria with specific weight
for price according to the application
requirements so that the reputable
vendors, usually having the highest
price products, could not be excluded.
Appropriate recruitment process for
instrumentation engineers should
be accomplished. Continual training
programs with the highest standard
norms should be submitted in order
to keep the instrumentation engineers
familiar with the state-of-the-art
technologies in process instrumentation.
Another important issue that should be
considered is asking for help from other
departments within the facility when
needed. For example, when specifying