in a similar location that indicated contact between the two parts. The rubbing
contact inside the pump bowl is shown in Figure 2.
While the impeller was being handled after cleaning, it still gave off an
odor of the residual chemical from the process. This was unusual since there
should have not been any pockets in the impeller where the fluid could get
trapped. By accident, when the impeller was tipped on its side, some residual
fluid drained from one of the balance holes drilled through the back side of
NEED A PRESSURE TRANSDUCER?
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Utility, reliability, and value are what make
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pressures, even in the most demanding
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and shock. When local indication is
required (in addition to remote
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Type X1005 Xmitr™
Learn more about the unique
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G2 transducers by visiting
www.ashcroft.com or
contacting the factory at
800-328-8258.
G2 Transducer
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Ashcroft Inc.
250 East Main Street
Stratford, CT 06614, USA
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the impeller. Upon closer inspection, a
small recess in the PFA liner inside the
balance hole was found. Figure 3 shows
a close up picture of the typical damage
seen in the balance holes.
A new impeller was placed inside
the pump and the damaged impeller
was kept for further analysis. The impeller was thoroughly flushed to remove all
residual process fluid. The cleaned part
was cut into sections to reveal the source
of the defects. The cross-sectional cut
showing the balance hole, PFA liner,
and stainless steel core is seen in Figures
4 and 5.
Lastly, small blisters were noted on
the rear pump cover where the mechanical seal gland is attached and seals
against the pump casing. The operating conditions were well known for this
service, and since this was a new pump
installation there were no maintenance
issues to investigate other than ensuring the pump was properly installed
initially.
Working with the OEM
Now that all the failure modes were
identified, a meeting with the local
OEM supplier was held at the plant
to review the findings. The OEM lead
engineer was then contacted and the
information was sent for review. The
Albemarle purchasing agents were
involved at this point due to the nature
of the failure and the warranty claim on
the parts for OEM defects.
