At HOSS we frequently discuss what it takes to ensure a successful and reliable pump
installation. Horizontal pumps are complex, engineered rotating equipment. They operate
with large motors, at high speeds, pumping harsh fluids in challenging ambient conditions.
There’s a big difference between the installation requirements of a small single stage
centrifugal pump and high pressure horizontal pumps. Reliable operation requires a system
design approach, application expertise, and adherence to best practices.

A horizontal pump “system” is more than the flange-to-flange skidded pump package. All
upstream and downstream factors must be considered, including piping size, layout, valves,
instrumentation, and control logic. Foundation design and piping support are also part of the
pump system. With all these variables, it quickly becomes clear that pump system reliability
is a much larger challenge than providing a reliable pump package. A good place to start
before designing a new pump system is API Recommended Practice 686. While generic, this
260 page document provides a roadmap of applicable standards that inform the design of the
pump system.

Thankfully, designing a pump system can be simplified by following best practices that have
been proven to work. It’s also helpful to over-design elements of the system that are
inexpensive in relation to the total project cost. For example, we are frequently asked by
customers familiar with API 610 pumps to provide foundation loading diagrams. A proper
foundation for a HOSS unit consists of thick concrete and rebar, it’s not complex and not a
major cost in the total system design, but does ensure pump longevity. The job of the
foundation is to structurally support the weight of the pump system and dissipate vibration
from the pump unit. Instead of spending valuable time calculating exactly the right
foundation thickness and rebar spacing, it’s a lot simpler to make a quick estimate and then
oversize by a large margin. For example, if a quick estimate indicates an 8 inch foundation
with 12 inch rebar spacing, specify the foundation to be 12 inches thick with 6 inch spacing.
It may cost a little more, but if you experience any vibration problems after installation, you
can immediately rule out the foundation as the culprit. Boost pump output and quantity of
piping supports are other examples where having more than the minimum is a good thing.
You don’t want to be doing NPSH and nozzle loading calculations in the field if you can avoid
it.

Careful selection of each pump system component goes a long way towards ensuring
successful operation and equipment reliability. HOSS has simplified this selection process by
offering standard control valves, filter pots, and VFDs on each project proposal that are
matched with the quoted pump unit. These components are stocked at our Tulsa and Midland
facilities for quick delivery in a variety of sizes to handle various flow rate and horsepower
requirements.

In our experience, piping is the most frequent root cause of problems in a pump system.
Piping seems simple, which is one reason why it can be overlooked in the design process.
However, every detail can have a significant impact on pump operation. Size of the pipe
dictates frictional head loss as the fluid travels to and from the pump. Poor layout of the
piping also has an impact, with frequent bends and diameter changes resulting in friction loss.
Careful layout is an important factor in the proper operation of instrumentation and valves.
Most need a minimum of 5-10 pipe diameters of straight piping before and after the
component to dissipate turbulent flow energy for proper operation and low vibration. Flow
meters and pressure transducers are especially susceptible to turbulent flow effects. It’s
difficult to diagnose or control a pump system if the output of the instrumentation has large
fluctuations due to turbulent flow.

Control logic can be the most difficult system design challenge. Selecting the method of
pump control and setting the various control parameters presents hundreds of choices, each
with varying risk and effect on pump operation. HOSS firmly believes that these choices
should be made as a team, with the end user and our pump application expert discussing the
pros and cons of each decision before implementation. It’s important to revisit the control
parameters during the commissioning process. Top performing pump systems are “tuned” on
site to account for variables that cannot be exactly predicted during the design process. This
includes details such as alarm thresholds and PID loop settings.

A best practice is to maintain a strict hierarchy between the site control logic (usually
through a PLC) and each pump’s control logic. A site PLC is well equipped to provide start
and stop permissives based on the overall control needs of the entire site, but most are
poorly suited to customizing control for individual pumps. Centrifugal pumps are ideal for
variable speed operation, however the vast majority of PLCs do not have prebuilt logic to
consider centrifugal pump performance behavior across a speed range (as shown in “tornado”
curves). A graphical user interface (GUI) designed for quick setpoint navigation and
adjustment significantly reduces commissioning time and leads to easier maintenance in the
future.

HOSS will soon be releasing a revolutionary touchscreen controller integrated into our next
generation KODIAK VFD to dramatically reduce setup time and easily implement complex,
precise variable speed pump control. To receive more information when this product is
launched next month, enter your contact information here: https://www.hosspumps.com/kodiak/.

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