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ROTO-DISC® CASE HISTORY
MID-WEST FLAVOR COMPANY
A high percentage of foods, pharmaceuticals and pigments
are produced as dry powders and granules. The production
process to make these powders requires mixing, blending
sifting and grinding, all of which require valves. Since
many of the powdered products are soluble, they become sticky
and can gum-up the seats and mechanisms of slide valves
such as knife gates and orifices valves when mixed with
liquids. The seal cavities of these valves harbor contamination
and spoiled product. Also, these materials can have poor
flow characteristics that bridge over the center vane of
a “butterfly” valve.
A few years ago, Erik Ludwigson, a consulting engineer,
selected Roto- Disc® valves to avoid these problems
for the discharge of mixers at a flavor company in the mid-west.
The spherical shaped, quarter-turn Roto Disc® has no
sliding seal to leak and no cavity to collect contamination.
The stainless steel dome wipes against a glass-filled Teflon®
seat, cleaning itself as it closes. Unlike a butterfly valve,
the Roto-Disc® has unobstructed flow geometry.
In this case the whole interior of the valve was polished
to a 220 grit finish. Thus, the shaft bushings are flush
with the inside of the valve. The valve is easily cleaned
with interior CIP nozzles.
ROTO-DISC® AIRLOCK
(DOUBLE-DUMP) CASE HISTORY
PHARMACEUTICAL RESEARCH PROJECT
A US research team, sponsored
by a multi-national pharmaceutical
company was searching for a
way to accurately regulate
the addition of powdered reactants
to solvents in reactors while
maintaining an inert atmosphere.
They also wanted to be able
to contain a potential 100
PSI explosion. The team contacted
Roto-Disc® Company, for
assistance in developing solutions.
Roto-Disc® Company proposed
a turn-key airlock “double-dump”
assembly to feed the chemicals
from a screw feeder into the
reaction vessel. Equipment by
Roto-Disc® Company included
two (2) Roto-Disc® valves,
an inlet piece, a flanged intermediate
accumulator chamber with a reducer
to a view window that was installed
between the valves and an electronic
cycle-timer control (see figure
1 below). To satisfy the requirement
for corrosion resistance to a
wide range of chemicals, all
wetted parts were made of Hastelloy®-C
or Teflon®. The accumulator
chamber was designed by Roto-Disc® to
accommodate the volume of material
specified for each cycle. It
also included various ports
needed for sensors and minor
material additions. The microprocessor-based
cycle timer control had a custom
program that worked in conjunction
with the position switches on
the valves. Interior surfaces
of all Hastelloy® surfaces
were polished and the entire
assembly was designed for ledge-free
flow of product.
Since maintaining maximum pressure of 100psi during an
explosion and frequent cycling with low maintenance were
core requirements, the heavy-duty construction and tight
sealing of the Roto-Disc® valves was ideal for the customer’s
application. The research team is very happy with the finished
assembly and the pharmaceutical company that sponsored the
project is evaluating the design for inclusion into future
projects.
ROTO-CLEAN™ CASE HISTORY
CONTINENTAL MILLS/KRUSTEAZE DIVISION
Continental Mills, Krusteaze
Div. produces various types and
flavors of cake mix at their
Hopkinsville, Kentucky Plant.
Three large mixers are one of
the last processing steps before
packaging. These 10’ X 4’ ribbon
mixers have two (2) 10”outlets,
one for acceptable product and
one for rejects of off-spec mixes.
Every batch goes through thorough
quality control testing.
The mixers were originally equipped with lip-seal type
swing gates. The swing gates were powered by an air cylinder
and were contoured to the curvature of the mixer shell.
There were many problems with these expensive valves. Principally,
material adhering to the lip of the plug would prevent complete
closure of the valve. This allowed sifting out of a steady
stream of ingredients during mixing due to the force of
the rotating ribbon. The loss of minor ingredients could
thus affect quality and thus result in a reject of entire
batches. In addition, power or air failure could allow the
valves to fail open, thus dumping good product on the plant
floor.
According to Scott Seebold, plant engineer, both sanitation
and cross contamination prevention between batches were
issues. Any valve installed at the bottom of the mixers
had to be cleaned frequently. Mr. Seebold selected the Roto-Clean™
because they can be disconnected and disassembled in minutes
without any tools. The patented Roto-Clean™ valve is
disassembled in 3 easy steps resulting in not a single part
left together. Each part can then be cleaned or sanitized.
Mounting of the valves was by
welding a ferrule (extended
as part of the valve) to the
outlet of the mixer. This allowed
the valves to be mounted very
close to the rotating mixer
blade, with clearance as close
as _”. The valve bodies
were fabricated of Aluminum
for reduced weight and for ease
of handling during assembly
and disassembly. The original
valves had a sheet metal cowling
to prevent dust from getting
to the atmosphere when the valves
were open. This was unnecessary
for the Roto-Clean valves. The
discharge was simply quick coupled
to a chute (also fabricated by
Roto-Disc® Company).
Dimensions and curvature of the
chutes were as required for
the each mixer. Since these valves
are actuated by 80psi compressed
air, the existing solenoid air
control valves were able to
be reused. Thus the customer’s
rewiring was minimized.
Continental Mills had previous good experience with Roto-Disc®
valves at their plant in Washington
State. Mr. Seebolt and Krusteaze
in Kentucky are very pleased
with the performance and ease
of cleaning of the valves which
have now been in service for
many years. The savings in
maintenance and spare parts
have more than paid for the
valves many times over.
ROTO-CLEAN™ CASE HISTORY
EURAND AMERICA
Eurand America, a Dayton, Ohio based company, produces micro-encapsulated
time release pharmaceuticals. The production of these pharmaceuticals
involves charging dry solids into reactors full of various
solvents. The charging port is then closed for the reaction
to take place. The dry solids are conveyed to receivers
above the reactor by vacuum. Pressure differential across
the valve can be from 30 PSI to full vacuum. It is important
that the valves seal securely and that they are easy to
disassemble and clean between batches of different pharmaceuticals.
Ralph Lindon, of Eurand chose Roto-Clean™ valves to
replace ball valves because the Roto Clean™ valve can
quickly and easily be disconnected and disassembled without
tool in just a few minutes. By custom fabrication of the
inlet and discharge, the Roto-Clean™ valves fit the
exact dimension of the previous ball valves, so installation
was accomplished without any piping modifications. In addition,
the solenoids, air actuators and proof switches for the
Roto-Clean™ were custom positioned to avoid the need
for control tubing or piping this explosion proof installation.
Eurand can now clean the valve
in 3 to 4 minutes. They can
be completely disassembled and
all the individual pieces, including
the shaft “O” rings,
can be separated and washed
individually. Reassembly is accomplished
in a few minutes without tools-
With sanitary gloves on if necessary.
Roto-Clean™ valves are available in sizes 3, 4, 6,
8, 10, and 12” through port diameter. Inlets and outlets
can be customized to suit the application. The inlets for
example, could be connected to a mixer above by weld neck
directly onto the mixer body or by quick release Tri Clover
flange or of course by a regular bolting flange.
Likewise, the discharge can have these same flange choices
to provide complete no tool removal from service. In some
cases the outlet has a simple socking neck.
ROTO-FLATE™ CASE HISTORY
HIGH TEMPERATURE HAZARDOUS MATERIAL RECOVERY
Hazardous substances are in many present day disposable
products. EPA restrictions can require the removal of the
hazard before land filling or incineration. One processor
of small volume, highly contaminated waste uses a continuously
fed calciner at high vacuum (1 to 2mm Hg) and at temperatures
of 750°F to drive off small quantities of the hazardous
material to a recovery system. Cold product is air-locked
into the processor on a cycle frequency of about 20 minutes.
Likewise hot decontaminated waste is air-locked out at a
temperature of up to 750°F. The hot, spent residue is both
angular and abrasive causing harsh wear on the feeding equipment
and take away valves. The valves need to be extremely tight
to prevent leakage of air into the process. Excess nitrogen
and oxygen would overload the recovery system, causing hazardous
material to be released into the atmosphere.
When the system was first installed it was fed and discharged
by two (2) pairs of inflatable seal butterfly valves acting
as airlocks. Unfortunately, these butterfly valves failed
on startup because they required special retaining flanges
which were not provided. After correcting for this the seals
failed again after a short time as a result of wear. With
the butterfly valves, the seal is exposed directly to the
hot product both above and below the vane. The sharpness
of the product along with the action of the butterfly vane
against the hot inflatable seal simply cut the elastomeric
seal of the valve.
The customer considered many types of valves for replacements.
Rotary vane feeders were disqualified because these type
of valves typically have a clearance of .003” to .006”.
Under high vacuum, this allows considerable leakage even
when the valves are in new condition. Considering the wear
such vane-type rotary feeders experience from abrasion and
rubbing, the leakage through this clearance would quickly
become massive. Other types of valves such as metal-seated
butterfly valves, ball valves, slide gates and knife gates
were also considered and rejected for the same concern.
It was finally determined that only class 6, bubble-tight
valves would be acceptable for this application.
Four (4) Roto-Flate™ valves in two (2) double-dump
arrangements were eventually installed as the replacement.
The Roto-Flate™ provides bubble-tight sealing by using
compressed air or gas to inflate an elastomeric seal against
the dome. In this application, the upper valve on the inlet
to the calciner is opened while the lower valve remains
closed to allow material to fill the intermediate chamber.
The top valve is then closed and the lower valve is opened
to charge the contaminated product into the processor. Cycle
frequency is about once every 20 minutes. The processor
feed is at ambient conditions and since the lower inlet
valve is separated from the processor by a 3’ long
screw feeder, there is not much radiant or conductive heat
applied to the inlet valves.
At the discharge end however, the temperature of the product
is as high as 750° F and flows over the back of the opened
valve dome for as much as 20 minutes at a time. Since the
temperature of the dome would approach the product temperature,
contact between the dome and the silicone inflatable seal
when the valve was closed might fry the seal against the
hot dome. Likewise on the lower valve of the discharge air-lock
assembly, the 750° F product could lay on the dome for 20
minutes at a time and thus similarly destroy the elastomeric
inflatable seal.
Two steps were taken to handle this issue. First, the seals
for the two discharge valves were made of silicon rubber
which has a temperature limit of about 400°F. Second, the
backs of the dome (which is normally concave) on these two
“hot” valves, was enclosed with a welded plate,
creating a small cavity. The shafts were also axially drilled.
This allows 50° F chilled water to be channeled through
one shaft, through the cavity in the dome and out thru the
other shaft. The chilled water is also circulated thru coils
around the body that are imbedded in heat transfer cement
and thru hollows on the mating flanges on the processor.
For abrasive dry materials, only an inflatable seal valve
can maintain itself thru many cycles in a bubble tight condition.
Thus the only significant ingress of air into a vacuum process
is from the intermediate chamber at each cycling. Since
the cycling is infrequent this leakage is very small.
The valves have been in continuous
operation for several years
and no replacement parts have
been provided to the customer
by Roto-Disc® Company. The
customer is pleased with the
service of the valves so far
and expects to purchase additional
valves for a future system.
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