Efficient Plant October 2017 - 44
taken into consideration, and that's why we ask so
Operator error (follow procedures):
McCormick said 75% to 80% of his troubleshooting work involves centrifugal pumps.
The rest of the time he spends working on
rotary-lobe, positive-displacement, and gear
pumps, with the occasional seal-less pump.
An example of operator error with these
pumps is letting a non-self-priming pump run dry.
Seals will fail quickly without proper lubrication.
"It's the product that lubricates the seal-whether it's beer or water or milk-the liquid is what
is going to lubricate the seal base, which is the
stationary and the rotary element. If the operator
doesn't realize this, he may not ﬂood the suction
head of that pump which could cause it to burn up
Temperature is one of many factors that determines proper pump speciﬁcation. In this application, a pump
transfers wort, at a temperature of 212 F, from a brew kettle to the fermenter in a beer-brewing operation.
Eventually, it's going to cavitate and make so
much noise they are going to want to leave the
room. I've had people call me and say the cavita-
"In the case of ceramic, it inherently does not
tion sound has scared them so much they didn't
expand. It wants to, but it can't. What I mean by 'it
McCormick said. "It can also affect the material.
want to go near it. This only happens occasionally.
wants to, it tries to, and it can't' is that it develops
Some of that can be removed during the ﬁltration
Most operators are pretty savvy. But it's important
microscopic hairline cracks and eventually those
process. A lot of breweries have some type of
to be aware."
turn into larger cracks, and the seal will begin to
ﬁltration at the end of the system before it goes to
packaging or bottling.
Misapplied seals (specify correctly): You
cannot only misapply an entire pump, but you
"Beyond that, there have even been some
"It's not just messy when a seal leaks,"
"Some plants don't do it like that. Some
can also misapply an entire seal, McCormick
instances where a ceramic seal totally disinte-
think that cloudy beer is the death of beer. I saw
grated or blew apart-not into a million pieces,
a bumper sticker once that read, 'If God wanted
"I do a lot of work in breweries, and the
but the cracks can become so many and so big
our beer to be ﬁltered, he wouldn't have given us
people who brew beer want it as hot as they can
that everything just falls apart. So, for high-tem-
get it," he said. "They want to brew at 210 to 212
perature applications, I get people to shy away
degrees-sometimes hotter than that. The prob-
from ceramic and instead use silicon carbide or
cially when processing sanitary products. "We
lem with temperatures like that is they generally
tungsten carbide because they are much more
have all heard about product recalls where there
use a ceramic seal, but ceramic does not handle
resilient to thermal shock." (See Sidebar, p. 42-
may be metal shavings in a product that may turn
thermal shock very well. Thermal shock is like
Mechanical Seal Faces)
out to be parts of a seal," McCormick said. "This
the screen door at your house. When it is hot it
Contamination (don't lose the batch):
This contamination can be a concern, espe-
doesn't happen often because usually when the
expands and it sticks sometimes. When it's colder,
With rubber seals and parts, contamination
seal starts leaking they shut the system down.
it opens and closes freely."
can be a problem. Unwanted elements can get
But that doesn't mean that something can't get in
into the product being processed if the seal is
there, and that is when your quality-control people
get involved with the product.
Almost every material known to mankind
expands when exposed to heat, McCormick said.
RELIABLE PUMPING SUPPLEMENT