ROTARY VALVES FEEDERS & AIRLOCKS

DIGIDALE precision-built Rotary Valves are ued throughout industry....Wherever precision volumetric feeding is required.  Many standard models, types and sizes are provided as per your specification & requirement.  Because of our years of experience in developing, testingand specifying rotary valves, we can help you choose the right valve for any application.

AIR LOCK FEEDERS

Rotary Air Locks and Feeders are usually used to accomplish 3 basic tasks.
a)    To feed material from bins or hoppers.
b)    To deliver fines from the collector while sealing against air loss.
c)    And to feed material to pneumatic conveying line against pressure.

DIGIDALE Rotary Air Locks are built to work under a variety of conditions.  Three basic designs cover the tasks described above.

DROP THRU TYPE

This is for gravity discharge of materials from storage hoppers and bins into receiving equipment or conveying lines.

SIDE ENTRY TYPE

This design, specially developed for plastic pellet handling and friable granular materials which tend to disintegrate while handling in conventional rotors, finds extensive application in the industry.  This design is accompanied with deflector plates and beveled rotor plates.

BELOW THRU TYPE

This design is always used with pneumatic conveying lines handling materials difficult to discharge from the rotary Air lock vanes.  This design occupies less height and is advantageous, where space is a constraint.

ROTOR TYPES

STANDARD ROTOR

This standard 8 or 6 vane rotor is the most commonly used for handling materials which do not stick to the rotor or have the tendency to disintegrate while handling.

BEVELLED ROTOR 

This is used along with the Side Entry-Air-Lock for materials that have a tendency to plastify and smear or pack  between the housing and rotor tips.  This trailing age of the rotor trips are machined  to a bevel, narrowing the land reducing frictional drag.

ROTOR WITH WEAR TIPS

This is a standard rotor with replaceable bars of steel, brass or Teflon or any other materials suiting the application.  This  is used where excessive wear of the rotor edge is anticipated.

This Valves are suitable for most dry dust such as Chemicals, Coffee, Detergents, Dry foods,Drugs, Flour, Grains, Plastic, Starch, Sugar etc.  Rotary Valves manufactured by Digidaleare used as metering devices feeders  and rotary air locks for dry free flowing materials of varying size shapes, used with blenders, mixers, tanks, silos, classifiers, dryers, collectors, hoppers, cyclones collectors, in virtually every industry.

SHALLOW POCKET ROTOR

These are reduced capacity rotors specially suited to handle sticky products which do not discharge easily from conventional rotor.  These  are normally accompanied  with an anti stick coating to promote discharge.

HOW TO SPECIFY ROTARY VALVES :-

Selecting the most appropriate Digidale Rotary valves for your application is extremely important.
The task may seem difficult because of the many types  and sizes of valves available....Drop-Thru, Side Entry, or Blo-Thru, choice of rotor designs; material of construction, optional features and special  design configurations.  Actually the selection is not difficult when the following steop-by-step procedure is used.

1.    Product Characteristics  :-  The product to be handled dictates the first decision to be made, whether the conventional Drop-Thru Valve will meet the requirement or if a Side Entry, or Bio-Thru Valve  should be used.

A.    Is it powder, granules, Chips or flakes, cubes or pellets ?  

Materials that are hard and of large grain ( such as plastic pellets ) may jam a conventional Drop-Thru Rotary Valve.

B.    Is it abrasive ?

Abrasive products may require valves of special construction, or special  plating at wear surfaces. Rotor vanes may require adjustable tips and housings equipped  with inspectionports.  Shrouded rotors and continuous purging  may be required.

c.     Does it pack or smear?  

Products that are heat sensitive may pack or smear and  require a valve with smooth interior surface, and sometimes, a coating with low friction coefficient (such as Teflon).  In some applications, the trailing edges of vane tips and sides are  bevelled to reduce friction.

2.   Application –– Is the rotary valve for metering or non-metering use?
Theapplication helps further define the model, size and rotor type.  Digidale Drop-Thru Valves are calculated at 100% pocket fill for metering applications.  Non-metering valves should be selected to have a minimum capacity of 1.5 times the volume required.  Side Entry Valves operate at a maximum of 40% pocket fill. 

3.   Volume & Weight –– How much and how fast? 

This establishes the size rotary valve required, for either metering or non-metering applications.  First determine: weight of product in kg per cubic mtr  and volume required in cubic mtr per hour.  Output capacity is computed based on the following. 

CAPACITY PER HR. (KGS.)        _{= M}³_/HR.
PRODUCT WEIGHT KG/ M³

 Valve capacity is a function of pocket fill and valve speed.  Valves for non-metering applications should be a minimum of 1.5 times required volume.

 To determine the Output Capacity Rating of a given valve use the following. 

VALVE CAPACITY (CU.MT./HR.) = ROTOR CAPACITY (CU.MT./REV.) x SPEED (RPM)  x 60 (REV./HR.)

4.Differential Pressure –– What will the differential pressure be across the rotor? 

Digidale’s Standard Rotary Valves are designed for negative or positive pressure. For requirements involving lower leakage, leakage, special rotors and seals, and tighter tolerances may be required.

5. Interface –– What are the flange size requirements? 

Often, the rotary valve is selected based on inlet and outlet sizes.  Digidale Rotors. Types B and C, are partially filled for applications requiring small throughput, but set size of inlet and outlet.  Where greater throughput is required without increasing the flange-to-flange dimension.  Style 2.  Double-Length Valves are often specified.

6. Operating Temperatures –– Will high operating temperatures be a factor?
Digidale standard Rotary Valves are designed for operation at suitable temperature. When higher temperature use is specified, special high-temperature bearings and packing are required, stress relief employed and tolerances reviewed.