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Hello, RCIA Family! Over the 30 years of experience with these Air Operated Dual Diaphragm Pumps, we, at Pressure Washer Products noticed that some pumps seem to have recurring issues. These symptoms present as frozen mufflers (with ice), air motors that seem to fail too frequently, foamy output and a few others. These symptoms don't hit just one AODD Pump manufacturer. It seems to occur across the brands. It always seems to occur in the most humid of climates, to a select few users and often in the bigger pumps . We pride ourselves on carrying the best products available for the best prices as well as providing free technical support to you. These symptoms were baffling until we discovered a blog entry by All-Flo. Contrary to a lot of information out there, the air from the compressor should not be cooled. This means that you shouldn't submerge the air hose supplying the AODD pump in water. I apologize in advance. We do not wish to create anything other than adding to the vast resource we have all created here on RCIA. I copied and pasted the whole entry below. How All-Flo Is Breaking the Ice in the Air Operated Diaphragm Pump IndustryBy Robert Allen posted 7 Nov, 2011 Air operated diaphragm pumps have earned a reputation in the industry as the low maintenance, easy-to-operate pump option–and rightfully so. However, seasoned diaphragm pump operators know the importance of getting clean, dry air to their pumps in order to avoid a common challenge: freezing. Built-up ice can block your pump’s exhaust system, resulting in slowing or stopping of production. This post will briefly explain how freezing happens as well as several steps All-Flo has taken prevent freezing in our air operated diaphragm pumps. How Freezing Occurs Compressed air expands as it runs through the air operated diaphragm pump and becomes very cold very quickly, sometimes dropping down to -10°F. These low temperatures typically are a result of using the pump at high-discharge pressures. Cold air can’t hold as much water vapor as warm air, so this creates a condition known as “super-saturated air,” when the air contains more moisture than it can hold in a stable condition. Ice forms when that super-saturated air impacts a cold surface, such as a bend in an exhaust pipe or some place that acts as a seed surface for vapor to condense on. Points of impact build up ice for two reasons: They provide a place for tiny ice particles in the air to stick. Any points of impact—anything that sticks out into the air flow—becomes a place where ice build-up can occur.The surfaces are colder, so they accumulate ice through deposition faster. Deposition is where vapor in the air turns directly into solid ice on a surface. Ice buildup is highly dependent on the surface temperature. In the same way that wind-chill is the worst when you are facing directly into the wind, surfaces that are impacted by cold air will be colder.One step you can take to reduce the freezing problem is to install a dryer on your compressor and only run clean, dry air through your pumps. Removing the muffler—including the muffler plate and rubber seal—is one solution that usually eliminates icing completely, as ice typically only forms on those components. However, the increased exhaust noise usually makes this option impractical for most users. Adding a dryer should be the first step to minimizing the freezing issue. Fluids Being Pumped Can Contribute to Freezing Fluids with a higher viscosity will cause the pump to work harder and could contribute to more ice build-up. For example, consider a 2” All-Flo pump running at 60 psi inlet air pressure. If this pump is running at 10 psi discharge pressure, the temperature at the exhaust will be around 42°F. However, if this same pump is running at 55 psi discharge pressure (closer to its maximum capacity) the temperature at the exhaust will be about 2°F. As the pump approaches its maximum capacity, the temperature at the exhaust significantly decreases, which can result in freezing. Normal Single Muffler Preventing the Problem Through Research We are constantly examining and testing our pump designs to minimize the risk of freezing. So, even if you don’t have a dryer installed on your air compressor, All-Flo pumps have built-in mechanisms to keep the risk of ice build-up at bay. Some of these design features include: Muffler Plate with Heat Sink. All-Flo research showed that ice buildup could be dramatically reduced by adding a large heat sink to the muffler plate Straight exhaust path. The fewer turns the air has to take, the fewer opportunities there are for ice to form and accumulate. But when surfaces obstruct or redirect air flow, ice can form (see Figure 1).Single exhaust. At All-Flo, we have engineered all our pumps to have a common, single exit port for the main exhaust, allowing cold air to exit directly into the muffler with minimal contact with impinging surfaces.Thermally engineered muffler plateIn an effort to continue offering the finest engineered diaphragm pumps available, we are continually researching and testing new pump designs and configurations using real-world tests along with the latest mechanical and thermal Finite Element Analysis software. One of the newest pump designs All-Flo will soon release features an exhaust system designed to function as a heat-sink, drawing heat to the inside surfaces from the surrounding environment and the rest of the pump, effectively preventing those surfaces from becoming cold enough for excessive ice buildup. http://all-flo.com/blog/how-all-flo-is-breaking-the-ice-in-the-aod-pump-industry/