Article #18: Pump Reliability – What Does this Term Mean to You?
This proposed
discussion is for the ultimate purpose of making the appropriate decisions in
developing, installing and operating a pumping system.
I personally narrow the responsibility for 'reliability' with the following
statement: "Fundamental
reliability is an engineering responsibility, not a maintenance function.
Maintenance cannot be expected to correct problems that require major changes
in system design requiring capital investment".
Management should not
hold the maintenance department responsible for equipment failures over which
they (maintenance) have no control. Example: mechanical seal failures
frequently can be traced to improper operating conditions, piping
configurations and/or inadequate NPSH margin. None of these are typically in
the control of the maintenance department. Maintenance personnel need to
understand the issues in these areas that are creating an impossible task for them
to correct and take the issue to management to provide the necessary corrective
action and funding.
Per Webster's Seventh New Collegiate Dictionary - "Reliability: the quality
or state of being reliable. Reliable: suitable or fit to be
relied on". If
Webster's cannot offer a more precise definition, we have a challenging task
ahead of us.
Developing a reliable pumping system requires the interaction of
individuals with the expertise in at least the following areas:
Process Engineering
Civil (concrete, space layout)
Piping
Design
Procurement
Power
(electric motors)
Instrumentation
(controls and instruments)
Pump
Applications
Maintenance
Operations
One of the more difficult challenges in a task involving a
number of individuals that must contribute to an interacting functional system
(such as a pumping system) is to understand the definitions used by various
groups for the common terms that are used in communication. There have been
major errors that have cost significant money, time and even injury because of
this issue.
It is nearly impossible to achieve agreement to use a common definition of even
the most moderately complex terms between the various technical and trade
groups without a major reeducation effort. This is frequently complicated by the
fact these groups frequently communicate only by information contained in data
sheets. The expedient task is to identify the various definitions being used
for a given term and attempt to design the system to compensate for these
variations. This requires that the one selecting and specifying the
requirements of the supporting functions (the pump Application Engineer) that
make up the pumping system be knowledgeable in the definitions and practices
that tend to be used by these various groups and then - attempt to compensate
for the inadequacy of the definitions being used.
In some cases it may be necessary to request a specific group to alter their
design approach to provide for the 'tolerances' their specific definition has
and the negative effect it can have on the final product (the pumping system).
My definition of Reliability is:
A system that will function for a specified period of
time, that is of reasonable length and compatible with the process
requirements, without unpredictable shutdown or failure.
Robert J. Hart
Robert J. Hart Enterprises, LLC
Note: Bob Hart has spent 27 years as a Principal Consultant in the
Rotating Machinery Group with the Engineering Department of the DuPont Company, Wilmington, DE
What is YOUR definition of Pump Reliability?
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