Another diaphragm ruptures, and your customer needs this batch of latex yesterday to mix their new line of paints for the season’s hottest hues. What’s the solution?

When one major base latex paint manufacturer became frustrated with frequent pump stalls and downtime, managers knew they had to find a way to cut their mounting costs.

Like most other paint processing facilities, this manufacturer used air-operated double diaphragm (AODD) pumps in every processing zone. First, the pumps combined monomers in the soap tank and then transferred them to the reactor for heating. Next, the pumps moved the base latex to the chiller, then on to the filtering room and, finally, to storage tanks and totes.

Setbacks along the way caused a domino effect that impacted the entire process and delayed deliveries to customers who bought the base latex for use in their paints, coatings, wallpaper paste, and more. 

The AODD pump transferring chemicals to the reactor.

The pump transferring product from chilling tanks to bulk storage.

Pump failures were beginning to cause financial failures. Costly wear parts had to be replaced frequently. Significant downtime hurt the facility’s productivity and often caused the latex to dry mid-process, which ruined entire batches of product. Redundant work aggravated pump operators, and excessive overtime pay took its toll on the budget. That’s not all. Utility bills had skyrocketed because the inefficient pumps used large quantities of expensive compressed air.

Searching for solution to these problems, the manufacturer agreed to install an Elima-Matic® air valve on a trial basis. The valve proved so reliable that the manufacturer installed more – on 70 percent of its pumps. Eventually, the company replaced all 150 of its AODD pumps with models using this patented air distribution system. This resulted in a significant increase in productivity and a solid return on the investment. The time savings substantially improved efficiency, and still continues to lower the total cost of ownership today.

A cutaway image of the inside of the pump that eventually replaced all of the AODD models used in this latex paint manufacturing operation. 

Eliminating Those Pain Points

Before this base latex manufacturer implemented the air valve system, maintenance was a key pain point.

Throughout the facility, processors had to run a constant, costly, and messy stream of water across the old pumps to try to prevent freezing and stalling, but the pumps often failed anyway. Workers kept hammers close by at all times. In addition, whenever a diaphragm would rupture, cleaning and replacing up to seven O-rings with an O-ring pick was difficult because the center block bushing was so small and complex. Workers also could not determine if the O-rings had been positioned properly until the whole pump was reassembled. Repeat attempts often wasted valuable work time.

Installation of the air valve system greatly minimized maintenance issues. The pumps didn’t freeze or stall, and the individual parts lasted much longer than standard wear parts. The pumps also used much less compressed air, which significantly lowered the company’s utility bills.

Even now, when occasional repairs or part replacements are necessary due to regular wear, the simple pump design allows for fast teardown and repair. For example, workers can easily disassemble a pump to remove dried latex with a blowtorch, instead of having to replace an entire clogged bushing. Through low maintenance and efficient, reliable production, the pumps continue to deliver a solid return on the investment.

Perfect for Pumping Paint

Because binder comprises 30 percent of typical paint composition, pumps used in the paint industry have to be especially durable. The properties that make resins and drying oils successful as binders of pigments are the same properties that cause buildup inside processing equipment.

The binders in latex emulsions are polymerized from styrene, butadiene, vinyl acetate and acrylic monomers, and are extremely heat- and shear-sensitive, which makes pumping them a particular challenge. Latex viscosity can range from 100-SSU (20-cp) to 25,000-SSU (5,500-cp), and temperatures can reach up to 400-deg F when pumping synthetic resins. 

The initial chemical additives are mixed using these pumps.

A pump and filter unit used for pumping latex base.

These AODD pumps are designed to meet the specific needs of latex pumping facilities. They can handle a range of viscosities — from water to 90 percent solids — which is perfect for accommodating the varying quality of resins and paint slurry. Because the pumps can operate at varying speeds, they are ideal for the transfer of abrasive pigments and highly viscous paste through the paint processing stages of grinding, thinning, straining and packaging.

In spite of the harshness of the materials used in this industry, the parts and diaphragm technology are designed to wear more slowly than the components of competing systems.

Dome Diaphragm Design

The unique design of this diaphragm is an innovative feature used in the paint industry. Its simple, flexible construction makes it easy to install or replace without pry bars. 

The dome shape of the diaphragm spreads wear across the entire part for a longer flexible life.

The dome shape spreads wear across the entire part, allowing it to last up to 300 percent longer than a standard diaphragm that typically focuses stress at one point. The diaphragm’s rolling shape also allows for reliable flow of thick latex and slurry that clog inferior diaphragms. Together, the diaphragm’s easy installation and long flex life minimize downtime.

Removing Inefficiencies

The air valve system performs like an engine that allows for reliable flow. A variety of AODD pumps, in a range of sizes and durable construction materials, utilize this system. The 2-in and 3-in pumps used most often in the paint industry improve efficiency in every paint application, including bulk transfer, ink dispensing, and solvent batching.

The air valve system improves productivity because its reliable design yields significant savings in downtime. Primarily, the system eliminates stalling because the air valve spool is positively shifted by the transfer of a pilot shaft. When the main shaft travels to full-stroke length, the inner piston on the opposite side depresses an internal pilot shaft, which ports a burst of compressed air to the main spool valve. The main spool valve reciprocates in a positive, reliable shift. As the pilot shaft moves back and forth, an air burst is ported to the main spool, which causes it to shift every time.

With an anti-stalling design that can handle pressures of up to 200-psi, the system empowers facilities to keep operating so they can produce more.

The AODD pump design also prevents icing. Compressed air evacuates through air passages that are designed to allow a controlled expansion, which considerably reduces the cooling effect. In addition, the center block and air valve surface areas are ribbed and act as heat exchangers to dissipate the rapid cooling effect.

Because the pumps are designed to operate without freezing, companies don’t waste time or resources by having to restart stalled machines or discard ruined batches. Processors even save money when their pumps are not in use – because the specially designed air valve spool prevents blow-by – a costly and messy problem for paint processors.

The simple, user-friendly design of the air valve system also makes maintenance easy and affordable, as the system has fewer parts. Because the pumps are lube-free and self-priming, they practically run themselves — without introducing lubricants that could potentially contaminate the crucial purity of products.

When maintenance repairs are necessary, the design allows for easy access to wear parts. The system has only two center-block O-rings, both made out of a material that is specially blended for long-lasting performance. The pilot shaft O-rings come out as a complete assembly and are easily replaced without the use of an O-ring pick. And the air valve can be reached without taking the pump’s center section apart. These overall savings in time and maintenance costs contribute most significantly to long-term savings and productivity.

Retro Is In

These AODD pumps are designed to retro-fit with pre-installed systems, which makes the investment easy and affordable. Conversion kits fit into existing pumps, and the pumps fit most footprints. Paint processors are already familiar with the principles behind the technology, so learning how to operate the pumps requires little training. Workers are able to begin processing right away to experience immediate benefits.

Upgrading pumps with new technology offering higher flow rates and lower air consumption

The base latex manufacturer in this study found that retro-fitting the pumps was its key to a more profitable future. This company plans to continue growing by using these AODD pumps for every batch of base latex.

Pumps & Systems, November 2006