A: Michael Kline, Vortex Global, says:
Whether it’s a gravity-flow, dense-phase, or dilute-phase pneumatic conveying application, the physics of dry bulk material movement will have a dramatic impact on wear within any system. For this reason, assessing what system areas are more susceptible to material impact and carefully designing a system to protect these areas from rapid wear is necessary.
Generally, a manufacturing process will likely realize its highest degree of wear in areas where the material flow pattern or air pressure are subjected to dramatic change or disruption. This includes elbows in system ductwork, directional changes from diverting or converging, a sudden halt in material flow, aspiration of displaced air, and many other variables in system design.
Diverter valve construction options
For abrasive powders, pellets, and granules — such as sugar, salt, chemicals, and others — Type 304 and Type 316L stainless steel options are available to provide a valve with the appropriate abrasion resistance.
In heavily abrasive applications — such as industrial sand, cement, limestone, glass, fly ash, and others — a valve’s body and material contact areas are often constructed from carbon steels and other abrasion-resistant steels. Several gauges of steel exist, so when selecting valve construction materials, assessing your material’s characteristics and determining which Brinell hardness number (BHN) of steel is most appropriate for withstanding abrasion is important.
Added valve features
In flap- and bucket-style diverters, the valve’s inlet and outlet legs can be fitted with replaceable abrasion-resistant liners, which are often made from abrasion-resistant steels, chromium carbide, or ultrahigh-molecular-weight polyethylene (UHMW-PE) or polyurethane. While the diverter body may be capable of handling abrasion, abrasion-resistant liners allow materials to abrade on replaceable parts rather than on the body itself, which significantly extends the diverter’s useful life. For return on investment (ROI) purposes, abrasion-resistant liners are of great value because they make the difference between maintaining replaceable parts or replacing a whole diverter.
Some diverter valves can also be equipped with rock box liners, also known as honeycomb liners, along their bucket blades and outlet chutes. The rock box design allows dry, abrasive materials to accumulate in gridded areas so that, as materials flow through the diverter, particles abrade on themselves rather than on the diverter’s material contact areas.
Another modification that can be made to some diverter valves is the addition of a dead pocket inlet. As materials pass through the diverter’s inlet, trace amounts accumulate in the dead pocket. Then, as materials continue to flow through the diverter, the dead pocket ensures that particles abrade upon themselves rather than on the inlet.
Finding the right valve solution
Selecting proper equipment is critical to the success of any manufacturing process. Misapplied components and deficient designs can cause unexpected maintenance costs and process inefficiencies that negatively impact a company’s overall profitability and performance. From fine powders to abrasive rock and everything in between, dry bulk material characteristics are endless. There’s no all-encompassing solution for every application, so it’s best to work closely with your material handling components supplier to determine what will best satisfy your needs.
Vortex Global, is the parent company of Vortex, Salina, KS, which supplies slide gates, diverter valves, iris diaphragms, and loadout equipment for the dry bulk solids handling industries.