Considering the aging of changeover valves, leakage is a common issue that all changeover valve designs must confront, especially slider-type changeover valves. These valves rely on manual adjustment or pressure-activated seals and are susceptible to factors such as wear from slider movement, dissolution of the seal pressure ring, and damage to the filter element removal. The maintenance of these mechanical seals can range from weekly to once a year. Maintenance requires disassembly and reassembly, which is a time-consuming and costly process. It is crucial to keep the slider clean before maintenance to prevent polymer leakage into the circuit and other equipment.

A method to significantly reduce such system leaks is to increase the head pressure. Your intuition might suggest that reducing pressure is preferable, as it applies less stress to the system. However, considering that seals are designed to respond to pressure during extrusion, they only act on the peaks when the pressure is high. At lower pressures, the seals become slightly loose. When the extruder is idle or operating at a drip feed rate with minimal pressure on the seals, low-viscosity materials are particularly prone to leaks. An upgraded slider seal featuring a full-steel segmented ring design can address this issue, offering a lifetime leak-free guarantee, regardless of temperature and low viscosity. This allows the seal to operate leak-free in high-temperature coating applications.

Material leakage may occur over time in bolted mesh changers that do not operate with mechanical seals. The leakage of these processed mesh changers is essentially always caused by mechanical damage, thus they are designed for a rather narrow material viscosity range. Therefore, you should not apply a mesh changer designed for high pressure and high viscosity with gaps to low viscosity melt filtration without the manufacturer's approval or modification.