SPECIAL FEATURE
SELECTING 2-WAY DIVERTER VALVES FOR YOUR PNEUMATIC CONVEYING SYSTEM
1. Rotary Plug Diverters
S
electing a diverter valve for your pneumatic conveying application can be a difficult task, especially when you consider the different designs and manufacturers.
Proper selection and application of diverter valves can offer improved plant efficiency, adding to a company’s overall profits while reducing downtime and maintenance costs.
Factors to Consider Cost Issues: The purchase price of
a diverter valve is only one of many cost factors to consider. Other cost factors are freight, installation, maintenance costs, and production down time. Material cross-contamination due to internal valve leakage is another cost issue that should be considered.
System Design: System design will influence the selection of your diverter.
Consideration should be given to issues such as product size or “footprint”. Air and/or material leakage past the diverter will affect system capacity and blower/line size calculations.
Dilute or Dense Phase: Consider
whether the system is designed for dilute phase pneumatic conveying (vacuum or pressure) or dense phase pneumatic conveying. Dilute phase is defined as conveying line pressures to 15 psig/1 bar, while dense phase is pressure to 90 psig or 6 bars. Each manufacturer will pressure rate their particular diverter design. Accordingly, valve size can also determine system pressure capabilities.
Material Handled: The characteristics
of the material being handled should be considered as well as the materials particle size, weight, hardness, abrasiveness and flowability.
Actuators: Depending on system
requirements and power availability, diverters may be selected with choice of actuators; manual, air actuated, electric motor actuators with choice of electrical enclosures and hydraulic actuators.
Safety: No matter which valve type
is chosen for an application, make sure individual safety features are in place for each valve used. Ensure that all moving parts are shielded from pinch points.
This article analyses four diverters
commonly used in dilute phase, vacuum, and dense phase pneumatic conveying.
1. Rotary Plug Diverters A rotary plug diverter has an internal
plug that rotates to align the inlet and outlet. To divert material to the opposite port, the plug is rotated approximately 150° causing what was the outlet port of the plug to align with the inlet of the housing and the plug inlet port to align with the outlet port of the housing.
BENEFITS:
• Material is not cross contaminated when conveyed through the same line.
2. Flapper Style Diverters
• Seals are outside of the material flow stream and protected from blast abrasion.
• Line pressure drop is minimal. 44 Bulk Solids Today
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