Selecting a valve for tough bulk solids
A bulk solids valve must be able to handle dry and slurried materials without jamming, leaking, or breaking or causing material degradation, crosscontamination,
or other problems. Demanding solids applications with difficult materials, temperature extremes, and high operating frequencies pose even tougher valve requirements. The trouble is, many valves used for solids were originally designed
to handle liquids and gases, and some solids valves operate in ways that shorten their service life and lead to other problems. This article focuses on one
bulk solids valve — the dome valve — that overcomes many of these problems and is ideally suited to demanding applications.
Typical bulk solids applications for valves include
feeding and discharging a mixer or other process
vessel, feeding from a nonpressurized hopper into a
pressure or vacuum conveying line, feeding from a hopper to a loss-in-weight feeder, and discharging a weigh hopper. Surprisingly, many plants use valves that were originally designed for liquids and gases for these bulk solids applications, or they use poorly designed solids valves that leak, jam, or fail, causing material degradation, cross-contamination, and other problems. Abrasive solids can rapidly wear the valve’s contact parts, seals, and seat, leading to leaks and other problems. Large particles can jam the valve’s closure device or break other internal components. Rather than deflecting particles, the closure device can cut or break large particles, producing unwanted fines. Hidden pockets inside the valve can fill with material, causing cross-contamination or slowing valve operation.
Before we discuss how to choose a dome valve that can
eliminate these problems, let’s take a closer look at the
problems other valves have.