Article #18: Pump Reliability – What Does this Term Mean to You?
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:
Civil (concrete, space layout)
Power (electric motors)
Instrumentation (controls and instruments)
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
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?