Understanding Rotary Valve Design – Features & Accessories

Understanding Rotary Valve Design – Features & Accessories

Along with applying the right type of valve for the intended use, comes some choices in accessories features that enhance a rotary valves functionality.  Here we give a review of the various options available for Magnum Systems rotary valves and their benefits.

The following accessories are installed on the rotary valve housing itself; these are standard design features that can be supplied on our rotary valves, just talk with your CSP and they will help guide you to the right solution for your application.

Shaft Air Purge (SAP)

The most common feature across our entire line of rotary valves is the Shaft Air Purge or (SAP). The SAP introduces a small amount of compressed air into the end-plate to the seals to prevent product from coming in contact with the shaft seals. Obvious benefit here is prolonged seal life. Even if our rotary valves are supplied without this feature when purchased it can always be added on in the field after the fact. Every end-plate already has the proper inlet designed and drilled into it as a standard feature.

Cavity Air Purge (CAP)

In addition to shaft air purge, Magnum Systems offers Cavity Air Purge (CAP) on our Closed End Rotor Models (Type 2, Type 6 and Type 8) when installed in a pressure pneumatic conveying system. CAP reduces abrasion on the rotor shroud and end-plates of the rotary valve.

This patented design uses low-pressure air from the convey blower and purges the material from the cavity between the rotor shroud and the housing end plates. This air serves two purposes: to prevent the product dust from reaching the shaft packing, and, more important to the life of the overall rotary airlock, it blows off material that would attempt to settle on the top flat surface of the closed end rotor.

Bearing Cooling Kit

No surprises here, the name speaks for itself. The bearing cooling kit is an option for high temperature applications greater than 400° F to extend the life of the bearings and prevents binding.

Zero-Speed Switch

The zero-speed switch is a safety feature that can be supplied with any model of rotary valve we offer. It is installed into the shaft guard on the non-drive end of the rotary valve and is wired into the control system. When airlock rotation stops (say the valve locks up, for instance) an electric signal and alarm sounds and can also signal to automatically shut off equipment.

Additional accessories are offered to be installed above or below the valve depending on the function and application type.

Inlet Hopper

An inlet hopper or isolation hopper is used to “isolate” displaced air or “blow-by-air” in a pressure pneumatic conveying system. Sometimes seen on a bulk bag unloading application when used in a pressure system, installing a dual rotary valve set up where a rotary valve on the top of the inlet hopper allows product to flow into the hopper and the airlock on the discharge of the hopper allows the product to be metered into the convey line but displace the pressure differential from the convey line. Also used on dust collection system, with sock type filters or stand-alone pulse jet systems. Additional options like level indicators, inspection windows and access openings may be added for monitoring and inspection of material.

Vented Inlet Adapter

The vented inlet adapter is a more economical version of the larger isolation hopper, still venting “blow-by-air” and empty rotor pocket air on dilute phase pneumatic conveying systems. These improve rotary airlock filling efficiency reducing RPM’s and energy cost.

Pellet Valve

A pellet valve is installed on the inlet side of a rotary valve and reduces shearing of pellets or granular products by wiping the product from the tip of the rotor surface before entering the airlock housing. We provide this valve in a lot of plastic pellet handling applications. Essentially the pellet valve reduces the pocket fill of the rotor and in turn reduces product degradation. Also increases the rotary valve’s life of operation due to reduced wear on the rotor and airlock housing.

Finger Guard

The finger guard prevents operators from injury so they are not able to accidentally get a finger into the housing where it could be sheared off by the rotor. The guard is flange mounted and can be installed on the inlet or discharge side. Typically, they are used in two applications; First in open discharge applications like under a dust collector, secondly it is installed on the inlet side if you have an airlock under a manual bag dump station going into a pneumatic convey line.

Maintenance Gate

Maintenance gates are a low-profile gravity flow material shut off gate. Prevents the material from falling out when it is necessary to remove equipment beneath the bin for service. Maintenance Gates are intended for use only where very infrequent closing of the gate is required.

Straight Through Discharge Adapter

Finally, the straight through discharge adapter is utilized in pneumatic conveying applications and effectively introduces material into the convey stream in a low turbulence manner. Adapts Rotary airlocks to several different size pneumatic convey lines. Carbon steel, aluminum, or stainless-steel pipe or tube available.

We hope you have better understanding of the accessories available for Magnum Systems’ rotary valves. If you want to discuss these options for your specific application, please contact the CSP for your area.

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