Key points
In a critical worldwide market that is central to the manufacture of many everyday products, AODD pumps offer efficiency, reliability and versatility that can result in optimised operations
As we approach the bicentennial of the ceramics industry – large-scale ceramics production originated in Europe around 1830 – its recent expansion has given it great importance for many countries. Over the past few decades, the production of tiles and sanitaryware has spread across the globe from its traditional base in European countries and the United States.
The emerging markets in the BRIC countries (Brazil, India and China) in many ways are now leading the way in the manufacture of tiles, while Mexico and Turkey are helping set the pace, along with China, in the production of sanitaryware.
The basic definition of ‘ceramics’ – “articles made from clay hardened by heat” – does not adequately express anymore how a slew of advances in ceramic-manufacturing technology has helped transform the industry. Giant silos and ovens, printers that can literally emboss any type of image on a tile, and robots for the automated enameling of sanitaryware are some of the examples of this great transformation.
All of which requires the need for huge ceramics plants of more than 100,000 m2, where 350 or more air-operated double-diaphragm (AODD) pumps are moving highly abrasive products such as barbotine and ceramic enamel every day around the clock.
Assessing The Operation
Though global ceramic plants can be located on any continent and the products they produce can number in the thousands, the ceramic-manufacturing process is essentially the same in any ceramic plant around the world. The transfer of very abrasive materials, solid-laden slurries and corrosives are part of the manufacturing process, from tiles to sanitaryware.
Finding a way to identify the best efficiencies for the process, i.e., the highest flow rate with volumetric consistency and with the lowest air consumption, with a greater mean time between failure (MTBF), is really the greatest challenge for ceramic-plant operators.
The preparation of the barbotine (the base material in tile and sanitaryware manufacturing) is key to the process. AODD pumps are often used to transfer the barbotine, from the atomisation process to the storage silos and then to the pressing room.
That can be easier said than done, however, as the transfer of barbotine requires high flow rates for a very abrasive liquid at a high temperature. In tile production, the Engobe and Glazer application process is key, where the pump’s ability to provide the greatest MTBF makes the difference.
In sanitaryware production, the moulds must be filled as quickly as possible, and as smoothly as possible, without the generation of air bubbles that can create craters in the pieces. In both cases, most of the pumps that are used have 2″ and 3″ (51 mm and 76 mm) inlets and outlets since they must deliver high flow rates with low air consumption. You also need a simple pump that is very reliable and very efficient.
Traditionally, two pump technologies have been used in ceramic production: the first is the progressive cavity pump, which has a number of operational shortcomings in these applications. These include an inability to consistently handle liquids with high levels of abrasives, which leads to increased maintenance cost; wear on expensive stators, rotors and mechanical seals that will eventually need to be replaced; and overall higher purchase, operating and repair/replacement costs.
The second common pumping technology used is the peristaltic (hose) pump, which can deliver liquids with a high amount of abrasive particles, but to do that, it may be necessary to oversize the pump since it needs to be run at low speed. There is also the fact that the hoses will wear out rather quickly and need to be replaced, meaning higher costs for maintenance and repair/replacement.
There is also the ever-present chance that a hose will burst during a production run. This will require it to be outfitted with an alarm in case leakage occurs since the pump will need to be shut down immediately or a catastrophic failure may result.
AODD Pumps To The Rescue
In general, it is the design and method of operation of AODD pumps that enable them to reliably outperform their progressive cavity and/or a peristaltic (hose) pump cousins in ceramics production. The simple design of AODD pumps features few moving parts, which simplifies maintenance, while the seal-less construction results in fewer leaks, a critical consideration when handling very abrasive and solid-laden liquids that are prevalent in the manufacture of ceramics.
AODD pumps are available in a choice of metal and plastic housing constructions, while a wide array of elastomers can be used in the diaphragms, some of which eliminate abrasion concerns. AODD pumps also possess the capability to move liquids with low air pressure. This is a powerful combination that fits the needs of ceramics manufacture.
All of these features combine to offer many benefits for the user, including:
- Wetted components that are impervious to damage from abrasive, viscous and solid-laden liquids
- Seal-less design that virtually eliminates leaks
- An air motor that can operate in dry, humid or dirty atmospheric conditions
- Consistent startup pressures that will not damage the pump or piping
- Easy assembly and disassembly
- High energy efficiency
- Self-priming, dry-run and high suction-lift capabilities that rule out a slow start
- Simple maintenance with low associated costs for repair or parts inventory/replacement
- Easy automation that is achieved by simply closing the discharge valve
Here’s a closer look at operational capabilities of common sizes of AODD pumps and how they can be used in two key stages of the ceramic-production process, which can require pumping pressures of up to 125 psi (8.6 bar):
- Painting and enameling booth
- 1″ (26 mm): A bolted metal configuration allows this pump to achieve flow rates up to 56 gpm (212 L/min), depending on the diaphragm type, with the ability to handle solids as large as 1/4″ (6.4 mm)
- 1-1/2″ (38 mm): This larger bolted metal AODD pump can reach flow rates up to 135 gpm (510 L/min), again depending on the diaphragm type, with the ability to handle solids as large as 1/4″ (6.4 mm). An advanced liquid-chamber design allows the creation of these higher flow rates.
- Barbotine transference
- 2″ (51 mm): This bolted metal configuration enables the pump to achieve flow rates up to 181 gpm (685 L/min), depending on the diaphragm type, with the ability to handle solids as large as 1/4″ (6.4 mm)
- 3″ (76 mm): The larger inlet/outlet size of this bolted metal pump can achieve flow rates up to 271 gpm (1,026 L/min), depending on the diaphragm type, with the ability to handle solids as large as 1/2″ (12.7 mm)
The versatility of these AODD pumps also means they can be used in many other applications within a ceramic plant, such as to wash/clean sanitaryware moulds with corrosive chemicals, water treatment and filter press.
Advantages of AODD Pumps
A closer look at the built-in operational capabilities of AODD pumps indicates three main reasons why they have become a first-choice pump for use in ceramic applications:
- Optimised internal flow paths
- High-efficiency Air Distribution Systems (ADS)
- State-of-the-art diaphragm designs
An AODD pump with an optimised internal flow path will minimise the change of direction of the liquid that is being transferred, which reduces its velocity and the abrasive effect of any suspended solid. This also helps the flow stay laminar, which keeps solids in the current line, reducing the abrasive effect.
This new design allows the flow rate to be increased while still running the pump at lower strokes per minute (SPM), which allows a smooth, laminar flow that reduces the abrasive effect even more. The liquid path is also designed for longer diaphragm life, minimising the contact between the diaphragm and the liquid chamber.
These pumps are also easier to maintain through the elimination of unnecessary fasteners that can be hard to reach. The manifolds are also interchangeable, allowing modifications to be made quickly and easily.
Next-generation ADSs optimise air usage through a breakthrough design that reduces air consumption by as much as 60% through the elimination of the wasteful loss of air to the atmosphere at the end of each pump stroke. Many ceramic plants use a huge amount of 3” (76 mm) pumps that consume a large amount of air. Therefore, reducing air consumption by 60% is a tremendous benefit.
There have also been some significant advances in the materials used and designs of AODD pump diaphragms, all of which can improve performance and reliability in any severe liquid-handling application. Two of the most recent advancements in this area are:
- Integral Piston Diaphragms (IPD): These diaphragms have been designed to deliver an elevated level of performance, which makes them ideal for use in high-volume ceramics-manufacturing applications. Most significantly, the IPD design eliminates potential leak points at the outer piston, along with outer-piston abrasion that can compromise diaphragm life, especially when pumping abrasive fluids. IPDs are also easier to clean than traditional diaphragm models, which makes for faster changeovers within product runs.
- Quick-Install Diaphragms: These diaphragm models feature a unique convolute shape that requires no need to invert the diaphragm during installation, resulting in quick, easy installation with minimised risk of injury, making them a convenient like-for-like replacement for traditional diaphragms with corresponding reductions in pump downtime.
Conclusion
It’s obvious that ceramics are integral to ensuring the health, safety and happiness of their users around the world. That’s why their fast, reliable production is paramount in protecting the way of life that so many have come to expect. To meet the needs of this diverse, demanding and critical industry, a complete roster of AODD pump designs, many of which feature cutting-edge advanced technology, can provide improved efficiency, reliability and safety, all of which help maximise performance in the various unique, but critical, stages in the ceramics-manufacturing process.
