An interview with a dryer specialist from Air Products PRISM Membranes.
Q: What is the current level of involvement that Air Products has in train brake related applications?
A: We supply our product line of PE air dryer membranes to several builders of air compressor systems that go on various types of trains. These customers are located in both Europe and North America, and all of our membrane products are manufactured in St. Louis, Missouri USA.
Q: Why must compressed air (on trains) be dried?
A: Trains often use compressed air to power various components such as brake systems, pneumatic door systems, and even pantographs. Any humidity in the compressed air can cause deterioration and corrosion. Drying the compressed air with membrane dryers eliminates the risk of malfunctioning. Air dehydration is especially important when trains travel to areas with outdoor temperatures below freezing. In this case, the membrane dryer prevents moist compressed air from freezing and clogging the lines.
Q: What type of trains require these air dehydration systems?
A: The majority of the trains that utilize our air dryer membranes are passenger trains. Some are high speed trains and even local street cars.
Q: Where are the membrane systems located in the train?
A: That depends on the type of train. In some installations, the system is inside a sheltered area of a train car, while other installations have the membrane system located externally on the roof! This means that our membrane dryers may be exposed to very hot or very cold temperatures and even harsh weather.
Q: What about other drying technologies?
A: Other compressed air drying technologies are common as well, but membrane dryers are often selected for their convenient smaller size, lighter weight, and mobility. Recently, a large, well-known compressor company had a prototype design that included a desiccant dryer. Maintenance technicians would have been required to use lift assist equipment to perform service on the dryer. Ultimately, the customer committed to membrane dryers in place of the desiccant due to the ease of accessibility and nearly 400 pound difference in weight.