This is also commonly called rotary feeder, rotary vane feeder or an airlock feeder. The rotary valve is used to dose or feed dry powder or granular products from a storage hopper or chute into a process below. The rotary feeder is precision machined to allow minimal air leakage losses through the rotor. The two general types are a drop through and a blow through feeder.
In a drop through rotary feeder product that is stored above fills into the pockets of the rotor. When the rotor tuns and a full pocket reaches the open flanged discharge of the feeder, the material drops out under gravity and falls into the process below. A drop through type can also be used for pneumatic conveying, however, it will require a feeding tee which allows the product to fall into the air stream of the conveying system.
The other type of rotary valve, the blow through is almost only used for adding product to a pneumatic conveying system. With this feeder the pressurised air supply (from a blower or fan) is connected onto the one end of the rotary valve and the conveying line onto the other. As the rotor turns, the contents under gravity are exposed to the air stream and become suspended in the air stream.
For both cases, when used in a pneumatic conveying system the air on the underside of the rotary vane feeder has a higher pressure than that above. This pressure differential results in air leakage between the rotor and the housing.
In a quality product such as feeders from DMN Westinghouse, the tolerances are custom machined to the product’s temperature. Another source of leakage air is from the empty pockets that are filled with air at a higher pressure which escapes into the product above when it rotates up. This air can be vented out of the pockets before being released into the material inlet. The DMN rotary valves are supplied with vent holes for this purpose.
DMN Westinghouse has developed rotary valves for all types of applications and industries. For any application where internal cleaning and hygiene is required, they have quick cleaning options which allows the end plate to be removed and the rotor slides out with guides. This is particularly useful in the food and certain chemical industries where no contamination is permissible.
The range of DMN Westinghouse diverter valves are designed for splitting or even converging the material stream in a pneumatic conveying line. The diverter valves are designed for specific applications, products and industries in pneumatic conveying lines.
Plug Diverter: Two channel design with minimal maintenance requirements. The standard valves are suitable for pressures up to 3 bar using static seals, while for pressures up to 6 bar they are supplied with inflatable seals. For abrasive products the plug diverter can be supplied with wear resistant pipes.
Ball Diverter: These robust diverters are suitable for use with abrasive products as well as high pressure and temperatures. They have replaceable wear bushings on the outlet and the advanced design allows the seals to be replaced with the valve remaining in place. Versions are available that conform to ATEX 2014/34/EU.
Tube Diverter: Two types of tube diverters are available, the first with 2 or 3 ports and the second is a multi -ort with up to 14 ports. Both type of tube diverters have inflatable seals, are suitable for line pressures from -0.8 to 3 bar and temperatures from -20˚C to 100˚C. The design ensures smooth product contact surfaces with minimal product degradation. The tube diverters are suitable to diverge or converge the material stream. ATEX 2014/34/EU models available.
Pinch valves can be used in countless applications but are predominantly installed in lines where powders are pneumatically conveyed, in slurry lines, for food grade applications where no material traps are permissible, for a corrosive medium, for a fibrous product, for liquids containing solids or even as a shut-off valve on a bulk road tanker.
A pinch valve is closed in two ways, by using a pressurised gas or liquid that has a higher pressure than that within the pipeline, thereby squashing the sleeve together which forms a tight seal. Alternatively, the sleeve is pressed together mechanically using a handwheel, an actuator or even a stepper motor.
Air Operated Pinch Valves: these pinch valves are closed using either compressed air or a pressurised liquid. The gas or fluid commonly has to have a pressure of about 2 bar above the line pressure to ensure a tight seal. When the pressure in the housing increases above the line pressure, the sleeve begins to compress until it forms a tight seal. These pinch valves are suitable for maximum line pressures of 6 bar, with the larger bore valves dropping to 3 bar.
AKO has the following pneumatic type pinch valves:
- Type VF: Flanged type of valves with an aluminium housing and aluminium, steel or stainless steel bushing. Standard nominal sizes are available from 40 NB to 300 NB with DIN PN10 or ANSI drilled flanges.
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- Type VMC: this is a flexible, modular range of valves with replaceable end connections. These valves are compact, lightweight, have no dead spots, free passage and are available in 7 different end connections. Sizes range from 10 NB to 150 NB, but not for all connections. The housing and end connections are available in aluminium, stainless steel or POM – with exceptions for some sizes and end types.
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- Type VMP: this range is similar to the one above, but more compact and only available with an internal thread from 10 to 50 NB in size. They are only available with a POM body and socket ends.
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- Type VM: small bore pinch valve from 10 to 50 NB with the body and sockets made from PVC and a maximum line pressure of 6 bar.
- Type VT: specifically designed to be fitted onto bulk road tankers, this is a lightweight and compact valve only available with an aluminium housing and bushing and in two sizes: 80 NB and 100 NB both flanged to DIM 28459.
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Mass Flow Measurement
DenseFlow: For unlimited volumetric throughput measurement in dense phase pneumatic conveying lines. There is no flow restriction in the conveying line and the measurements are independent of the velocity of the material. The DenseFlow is available from 10 NB to 125 NB. It is a maintenance free unit and the high pressure unit can be installed with line pressures of 25 bar… VIEW IMAGE
MaxxFlow: Designed to measure the mass flowrate for high capacities. It has a completely open cross section and low installation height of 300mm, therefore can easily be installed in the process. It can be placed in a vertical or inclined pipe, but always after mechanical equipment such as a feeder or conveyor.
Some of the benefits of the MaxxFlow are: no upper limit on throughput volume, max pressure of 10 bar and 120˚C, totally dust-tight, product not in contact with measuring process, wear resistant since it is internally lined with a ceramic tube.
The MaxxFlow is ideal for filling of tankers and trucks that are not standing on a weighbridge. This allows an accurate mass to be discharged. The MaxxFlow can also be installed in pneumatic conveying lines to measure the product flow… VIEW IMAGE
PicoFlow: This unit was designed for low conveying capacity, it essentially operates above a dust measuring device, typically from 100 g/h to 100 kg/h with a minimum flow velocity of 2 m/s. This unit is inserted into the air stream and can be used in both metallic and non-metallic pipes (the latter requires a metallic shield around the outside of the pipe… VIEW IMAGE
SolidFlow: Used for continuous mass flow measurement of dry powders or granular products from a few kg/h up to a maximum of 20 t/h. The sensor does not obstruct the flow of material and is installed flush with the ID of the pipe or duct. Very fine powders from 1 x 10-6 mm to 10 mm can be measured… VIEW IMAGE
M-Sens: Used to measure the moisture content of product in hoppers or equipment (screw conveyor or belt conveyor). This can be done continuously or periodic. The unit is robust, has a protective ceramic disc to protect wear of the sensor. It is suitable for dust, powder, granules and other types of bulk product…. VIEW IMAGE
Dusty: Used to detect dust particles suspended in a gas stream, such as on the clean air side of a dust filter. The Dusty continuously measures any dust particles. When a pre-set level is exceeded, an alarm output is triggered. The unit can also be easily upgraded providing a 4-20 mA output thus allowing trends to be measured… VIEW IMAGE
AirSafe: Installed in work places to measure the dust concentration present in the surroundings. Typically this would be installed for early detection of dust that could be hazardous to humans or reach a concentration where it could become combustible and cause an explosion. The AirSafe could be installed to prevent dust explosions such as in a grain mill…. VIEW IMAGE
ProSens: Enables dust to be measured in large ducts and even at high temperatures up to 700˚C, making it the ideal solution for exhaust ducts of large bag houses or furnaces. The ProSens can provide an absolute value or be used to record trends… VIEW IMAGE
SpeedFlow: Used to continuously measure the speed of dust, powders or particles in metal ducts or pipes in free fall or pneumatic conveying applications. The minimum velocity that can be measured is 0.75 m/s up toamaximumof35 m/s. The system provides a 4-20 mA output signal… VIEW IMAGE
FlowJam: The sensor is used to detect flow in a duct, chute or even a cyclone. The unit is insensitive to material deposits, it can be used for almost any pipe diameter, with a ceramic adaptor t is possible to install it for process temperatures up to 1000 ˚C. The FlowJam can detect flow through non-conductive walls. The FlowJam Plus is able to distinguish whether a no flow detection is due to no material present or a material blockage… VIEW IMAGE
SlideControl: Used to measure and detect flow in an air slide without making contact with the material. The SlideControl uses microwave technology to measure the distance between the sensor and the flowing material. With this information it can calculate the mass flow rate by assuming a constant velocity. The sensor will also detect if the material stops moving or there is no material present… VIEW IMAGE
Paddy: Used to measure particle sizes downstream of a screen in a free fall pipe arrangement. Essentially it consists of two sensors, the first being a reference sensor and the second the measuring sensor. If a screen beak occurs, the Paddy will immediately detect this. The standard unit can detect particles up to 10 mm in size (larger ones on request). The special measuring tube is available from 100 mm to 200 mm ID and requires a 450 mm installation height… VIEW IMAGE
ProGap: Microwave technology enables contactless level detection of dry products in pipes, tanks and containers. Detection is possible through non-conductive materials and with a ceramic adaptor can withstand temperatures up to 1000 ˚C. The ProGap is insensitive to material build-up and can be used over a distance of 25 m… VIEW IMAGE
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