Figure 1: Two non-metallic pumps assure
dependable delivery of neutralizing
chemicals in the Gaylord scrubber
design. Controlled feeding of 50%
sodium hydroxide is provided by a Vanton
Flex-i-liner® rotary pump which supplies
it on demand from the pH probe in the
fiberglass sump. Continuous
recirculation of the neutralizing fluid
is accomplished with a Vanton
polypropylene cantilevered shaft, sump
Pump Upgrading Improves
Scrubber Performance and
Reduces Down Time
Gaylord Foundry Equipment, Inc.
Caustic soda, Sodium hydroxide, Sulfuric acid
FLEX-I-LINER Sealless Self-Priming Peristaltic Pumps,
SUMP-GARD Thermoplastic Vertical Pump
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Reprinted from Pollution Equipment News
The management philosophy behind the quality reputation of packed
tower recirculatory scrubbers manufactured by Gaylord Foundry
Equipment, Inc. of Independence, Missouri combines the Truman "the
buck stops here" doctrine with the Gaylord belief that "building it better
isn't an option, it's the way we do it."
This explains why, despite the broad acceptance of their equipment, the
engineering department recommended a major design change which
involved upgrading the two pumps which are critical to continuous,
safe, environmentally satisfactory and economical performance of their
An analysis of reported field problems indicated that the prime cause of
downtime and maintenance could be traced to pump failures under the
severe operating conditions they had to face. Depending on the
specific service, the pumps had to be able to handle dilute, as well as
concentrated sulfuric acid or sodium hydroxide. The use of these
scrubbers in conjunction with resin bonded core/mold operations in the
foundry, involves additional problems of abrasion from sand particles.
Not only must all wetted parts of the pumps be inert to the corrosive
chemicals, but they must be highly impact- and wear-resistant as well.
To better understand the scrubbing systems, let's examine a typical 13' 10" tall 4000 cfm SO• packed tower scrubber as shown in the accompanying sketch.
The SO• gas coming from the core machines enters through the air intake
and flows upward through a deep bed of packing media consisting of
polypropylene slotted ballast rings. Prior to the start of this upward flow of
SO• gas, the packing rings have been, and continue to be, thoroughly wetted
by a 5% by weight caustic solution supplied from the 190 gallon fiberglass
In the original design, Gaylord used an externally mounted centrifugal
plastic pump for the continuous circulation required. Due to repeated
failure of the carbon seals, and the messy cleanup required, the design
engineers replaced this pump with a Vanton polypropylene SGH vertical
sump pump. This resulted in the elimination of the seal and cleanup
problems. The SGH pump utilizes an integral pump/motor cantilever
shaft and requires no seals or sleeve bearings in contact with the
pumped fluid. The hollow shaft motor is protected from corrosive
fumes by means of a special vapor seal. No metal contacts the fluid.
Even the stainless steel shaft is sleeved in thermoplastic. Flow is
maintained at 155 gpm against a 65' tdh.
The caustic solution is pumped through the spray nozzle in the shower
head, which thoroughly saturates the packed media. The neutralized
scrubbed air passes from the packed media through a 6" thick high
efficiency polypropylene mist eliminator pad. The fine knitted wire
mesh takes out the suspended droplets of caustic solution, allowing
only clean, dry air to return to the atmosphere through the exhaust
blower. The entrained fluid drains back into the sump.
The use of a pH probe constantly monitors the recirculation solution,
which must be kept highly alkaline to assure neutralization of the sulfur
dioxide gas. When the ph drops below 8.5 the scrubber automatically
regenerates itself. This is accomplished by discharging a portion of the
spent solution, energizing the caustic transfer pump to meter a
controlled quantity of chemical and then adding make up water until the
sump is at its preset level.
In the original design, Gaylord employed a bellows pump. Experience
showed excessive maintenance and long lead time to secure
replacement parts. The new designs incorporate a Vanton ¼ HP
Flexi-i-liner® rotary diaphragm pump which has demonstrated greater
reliability and more accurate metering of the concentrated sodium
hydroxide on demand.
The Vanton design incorporates a Hypalon flexible liner in a Teflon body
block. The pump is self-priming, completely sealless, and inert to the
caustic. There are no stuffing boxes, check valves, gaskets or other
potentials for leakage.
Gaylord also manufactures a similar scrubber for the foundry industry
that uses a sulfuric acid based scrubbing solution. Since the Vanton
pump designs limit fluid to nonmetallic materials that are compatible
with sulfuric acid and caustic soda, purchasing and inventory
requirements are simplified, and pump maintenance is cut to a
According to Gaylord's vice president, Kevin Crawford, there has not be
a single reported pump failure since the pump upgrades went into
effect more than a year ago.
In the 1950, Vanton developed a revolutionary all-plastic pump for use in conjunction with the first heart-lung device. The design limited fluid contact to only two non-metallic parts: a plastic body block and a flexible liner. This was the birth of our Flex-I-Liner rotary pump. Its self-priming sealless design made it an industry standard for the handling of corrosive, abrasive and viscous fluids as well as those that must be transferred without contaminating the product. Vanton now offers the most comprehensive line of thermoplastic pumps in the industry.
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(+44) 01260 277040
Vanton Pumps (Europe) Ltd.
Unit 4, Royle Park
Congleton CW12 1JJ