Maintenance Technology May 2017 - 32

FLUID HANDLING

Slurry-Pump Tips:
Extend Mechanical
Seal Life

Selecting the right pump with the right type of mechanical seal is the first step toward slurrypumping success. (Photo copyright ITT Goulds Pumps)

ALTHOUGH YOU MAY CONSIDER mechanical seals to be relatively small
components in slurry-pumping systems, they can be the crucial bridge between
failure and success. An incorrect or poor seal selection can cause major damage to
the pumping system. The bottom line: If your operation wants to get the most from
its slurry pumps, the choice of mechanical seals is crucial. Fluid-handling experts
at Crane Engineering (Kimberly, WI, craneengineering.net) offer several tips for
extending the life of these components.
- Jane Alexander, Managing Editor

Lubricating Film Matters
According to Crane Engineering's fluid-handling experts, regardless of your
pumping application, a lubricating film at the sealing interface is always needed.
A film that is too thick will increase leakage and may allow particulate between
the mechanical seal faces, increasing wear from abrasion. Conversely, a film that
is too thin will generate heat and degrade materials. Keeping the sealing interface
cool and clean will promote longer seal life.

Crane Engineering is a distributor of industrial-grade pumps, valves, filters,
wastewater-treatment equipment, and other fluid-processing technology. Services
include repair, corrosion-resistant coatings, and skid-system design and fabrication. For more information and instructional videos, visit craneengineering.net.

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MAINTENANCE TECHNOLOGY

Seal Considerations
As discussed in a recent blog post
on craneengineering.net, increasing
slurry-pump reliability starts with
an understanding of the challenges
involved in moving highly abrasive
fluids such as manure, cement, and
starch. These pumps clearly have their
work cut out for them. Thus, when
selecting a mechanical seal for slurry
service, pay attention to these details:
■ Robust design characteristics.
Heavy slurry usually involves a high
solid content. A seal design that can
withstand erosive impacts while
protecting the seal faces is a must.
Specially designed seals for slurry
applications typically feature durable
construction materials, hardened
faces, and heavy-duty springs to
ensure the seal faces have the correct
pressure setting to seal the system.
■ Restriction bushings. When
pumping a slurry mixture, process
pressure will naturally drive the
particle-filled fluid into the sealing
interface, causing abrasion and
accelerated wear. A restriction
bushing isolates the mechanical seal
from the harsh process so that the
seal is mostly sealing the cleaner,
cooler flush fluid.
■ Proper flushing. A proper flushing
plan will keep abrasives away from
the seal faces. Seal flushing also
keeps things moving in the stuffing
box to prevent solids stagnation
and build-up. As with any pumping
application, you should always avoid
dry running conditions.

Additional Considerations
Choosing the proper seal for a slurry
pump is just part of the equation. It's
also imperative to select the right pump
for the job (blog.craneengineering.net/
how-to-select-the-best-slurry-pump)
and to maintain it properly.
As with other pumping systems,
poor equipment conditions caused
by bad bearings, cavitation, excessive
impeller loads, and misaligned shafts
can lead to excessive vibration and
shock to the mechanical seal. A slurry
pump running under these conditions
will generate more heat and more
opportunity for abrasives to enter the
sealing interface. MT
MAY 2017

http://www.craneengineering.net http://www.craneengineering.net http://blog.craneengineering.net/how-to-select-the-best-slurry-pump http://www.craneengineering.net

Table of Contents for the Digital Edition of Maintenance Technology May 2017