AODD Pumps Solid-Body Plastic AODD Pumps Deliver the Operational Ability for Abrasive Media

Author / Editor: Sergio Avila / Dominik Stephan

Sometimes, beautiful products need dirty processes. Elaborate jewelry for example, might be treated with aggressive tarnision fluids. The consumer does not know — but the manufacturer should. Learn what to expect when pumping abrasive fluids and why solid body plastic AODD pumps might do the trick.

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Rugged solid body plastic AODD pumps are well suited for the transfering of abrasive media even under harshest conditions.
Rugged solid body plastic AODD pumps are well suited for the transfering of abrasive media even under harshest conditions.
(Picture: Almatec)

Though the actual originator of the epigram, “Laws are like sausages, it’s better not to see them being made,” is unknown — it is generally attributed to the 19th century German statesman Otto von Bismarck — the sentiment that it portrays is easy to grasp: While we may like and respect the outcome, sometimes it’s best not to know how it was arrived at.

The same saying can also apply to the manufacturing industry. You may be dazzled by the shine on the chrome of a new automobile or marvel at your mirror-like reflection on the surface of a highly glazed piece of pottery, but you really have no idea just how harsh the manufacturing conditions needed to be in order to produce the desired end result. Innumerable objects that we see and use in our daily lives only achieved their final form after a production process that may have included the use of any number of abrasive media in order to create the finished product.

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Tackling Aggressive Fluids

This article will examine several manufacturing applications or components where abrasive chemicals are used and the best type of pump technology to incorporate in those processes. Choosing the right pump will not only ensure that the desired final product is produced, but that the entire manufacturing process will be completed efficiently and effectively at a cost-conscious rate, and with a minimum of potentially costly pump maintenance and downtime.

More about dealing with abrasive fluids? Read also PROCESS Pump Meeting Gives Practical Guidelines!

Know Your Process –It’s Your Job ...

While consumers may be blissfully unaware of the trying conditions that were required to produce their favourite piece of jewelry or the ink that is used to print the words on their daily newspaper, the manufacturers of those, and thousands of other products, are not....

The conditions in which their products are created must be a front-of-mind concern for manufacturers, as are the specific pieces of equipment that are used to complete the manufacturing process. Examples of the types of manufacturing processes or components that can require abrasive chemical compounds would include:

Pickling Baths — Per Aspera ad Astra

When metal is “pickled,” in a process that is also known as tarnision, a surface treatment is used to remove any impurities, such as inorganic contaminants, stains, rust or scale that can discolor the steel. The pickling bath, or tarnision liquor, that is used to facilitate this treatment primarily consists of hydrochloric acid, though steels with an alloy content greater than six percent must be pickled in two stages — the initial hydrochloric acid stage, followed by submersion in another strong acid, such as nitric, phosphoric or hydrofluoric.

In jewelry–making pickling is used to remove the oxidation layer from copper, which occurs after heating. The waste product from steel pickling, known as pickling sludge, includes acidic rinse waters, metallic salts and waste acid, all of which make it a hazardous waste that needs to be neutralized with lime before it can be disposed of in a landfill.

Silicon Carbide Slurries — Versatile Cutting Liquids

Slurry is a generic term for any type of thick suspension of solids in a liquid. Silicon carbide slurry is used in a variety of applications in the construction, ceramics, paper and explosives industries, among many others. It is made from a mixture of powdered silicon carbide, also known as carborundum, that is suspended in polyethylene, diethylene glycol or an oil-based fluid. Silicon carbide is an extremely hard, durable, heat-resistant compound. Grains of silicon carbide can be sintered together to help form very hard ceramics that can be used in the manufacture of such diverse products as solar cells, car brakes, clutches and bulletproof vests.

Because of its degree of hardness, silicon carbide is often used as a cutting liquid, or slurry, in, for example, the manufacture of solar cells and wafers. Most silicon carbide slurries are mixed by the manufacturer, who purchase the silicon carbide powder by the size of the “grit” needed, then mix it with their preferred liquid. Once the slurry is created, it is pumped to storage tanks.

Electroplating — Coating the Electrochemical Way

Electrodeposition is the name of the process used in electroplating. Basically, in the electrodeposition process metal ions in a solution are transferred via an electric field to coat an electrode. It is primarily used to deposit a layer of a material, such as a metal, on an object in an attempt to give it a preferred property, like wear-resistance, lubricity or corrosion protection. The electrodeposition process occurs when the components are introduced to an electrolyte solution that contains one or more dissolved metal salts and other ions that enable the flow of electricity. Depending on the object that is to be plated, the electrolyte solution can be very abrasive.

Printing Inks — Quite An Abrasive Mixture

Printing inks are actually divided into two categories: writing inks and printing inks, with printing inks consisting of two distinct subcategories, ink for conventional printing (where an image is transferred to the paper or object to be printed on via mechanical plate) and ink for digital non-impact printing (such as electrophotographic and ink-jet technologies).

All types of inks are made with a wide variety of components, many of which can be abrasive....

Color inks, for example, are made with a solvent that is generally produced from petroleum distillates, linseed oil or soybean oil, while the pigments are made up of various dyes. Titanium dioxide can be used to adjust the color characteristics of inks. All types of inks may also contain additives such as lubricants, waxes, surfactants and drying agents.

Lime Slurry — the Constant Risk of Plating Out

By definition, lime slurry is an alkali formed of a suspension of calcium hydroxide in water. It has a variety of uses in industrial, municipal and environmental applications, such as metals precipitation, odor control, sludge stabilization, lime softening and pH adjustment but also as a fertiliser. While it is easy to pump by itself, when lime slurry reacts with water a condition known as “plating out” may occur during which the lime precipitates from the water.

Consequently, all surfaces that come in contact with the lime slurry are in danger of being coated and caked with lime, including the pumps that are used to transfer it. This behaviour can cause certain types of pumps to malfunction or even damage process components. Lime slurries can also contain additional abrasive solids, such as grit and pebbles, that can wear down a pump’s internal components and lessen its efficiency and reliability.

Ceramic Mass/Glaze — Finishingfor the Masses

Mass finishing is a common method of metals finishing that cleans, deburrs and polishes the treated surface, for witch an abrasive ceramic media is used during the finishing process. Glaze is defined as “a layer or coating of a vitreous substance that has been fused to a ceramic object through firing” ad is a common surface treatment for ceramics.

Before application, glazes can be abrasive, as they consist of miniscule shards of glass-forming silica in combination with a metal-oxide mixture consisting of sodium, potassium and calcium, which allow the glaze to melt; aluminium, which stiffens the glaze and prevents it from running; colorants such as iron oxide, copper carbonate or cobalt carbonate; and opacifiers like zirconium oxide and tin oxide. The handling of large quantities of finishing or glaze liquids is among the most demanding processes for a pump....

A Variety of Options — But In the End, There Can Be Only One

While many types of pumping technologies have been tried and found wanting in these (and other) harsh manufacturing applications, one has proven to be a reliable performer where a wide range of abrasive components need to be handled safely, efficiently and reliably: Solid Body Plastic Air-Operated Double-Diaphragm (AODD) Pumps.

Solid Plastic AODD Pumps Set the Standard

Solid body plastic AODD pumps have many features that set them apart from the competition when the subject is abrasive-handling. For starters, they do not require electricity, they are self-priming and they can pump a wide range of abrasive media, from slurries to liquids with suspended solids. Basically, plastic AODD pumps are positive-displacement pumps that have a diaphragm in each of their two pumping chambers. These diaphragms are connected by a shaft so that when the compression stroke takes place in one chamber during the pumping process, the suction stroke takes place simultaneously in the other chamber.

Learn about Versatile AODD Pumps for Plating and Metal–Finishing

This results in efficient, reliable, cost-effective, repeatable operation when handling any abrasive liquids or compounds. Almatec has been a pioneer in the design and production of plastic AODD pump technology since its founding in 1984. Today Almatec, headquartered in Kamp-Lintfort, Germany, markets its proven E-Series family of pumps that are specifically designed for use in abrasive-handling applications.

Available in a Variety of Polymer Materials...

All E-Series pumps offer the user a solid design and most are constructed of polyethylene (PE), which offers excellent abrasion-resistance when used with slurries and other abrasive media. The E-Series pumps, thanks to their PE construction, have been shown to last seven times longer than pumps that are made with polypropylene — while having similar chemical-resistance characteristics — and be 1.6 times more durable than stainless-steel pumps. Solid PE also delivers better sealing, higher static weight, smoother operation and better torque retention than other popular materials of construction.

For specific applications, E-Series pumps can also be constructed of PE conductive, PTFE and PTFE conductive. All of the pump’s cylinder valves are constructed with PTFE with the diaphragms (EPDM, PTFE/EPDM and NBR) and ball valves (EPDM, PTFE, NBR and stainless steel) available in a range of materials.

...Providing Features That Stand Out From the Rest

All of the housing parts on an E-Series pump are tightened to each other via special housing bolts. However, instead of single bolts that press punctually against the housing, all of the bolts are tightened against a diaphragm-sized ring on each side of the pump. This results in a more even spreading of the bolt force and an increase of the permissible torque, which enhances safety and reliability. An optimized flow pattern reduces the pump’s flow resistance for more efficiency and lower air consumption.

Three Decades Experience inTackling Abrasive Products

It’s a fact of manufacturing: abrasive liquids and compounds need to play a role in the creation of some of the world’s most recognizable products. These products only get made, however, if the equipment used to produce them can meet the challenges of handling and transferring a wide range of harsh and abrasive chemicals. For three decades, Almatec has identified the challenges inherent in abrasive-handling applications and has developed and provided the solid body plastic AODD pumping technology that is best suited for use in these demanding manufacturing atmospheres.

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* The Author is Product Specialist of Pump Solutions Group (PSG).

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