Fans in Pneumatic System Design

Air Systems Design, Inc. offers a full line of fans for handling all pneumatic conveying system needs.

Paper Handling Fan and WheelA choice of four (4) wheels are offered, each of which are tailored to handle specific materials under specific conditions. Generally when sizing a fan there are two (2) to three (3) fan sizes that will yield the required cubic feet of air per minute (CFM) and total static pressure.

It is recommended that the largest fan be used so that it runs at the lowest tip speed, reducing fan noise while extending the life of the fan. This, however, does not necessarily mean that the noise level will be acceptable to OSHA, but acceptable levels can be achieved through the use of optional enclosures and silencers.

Heavy-Duty Paper Handling Wheel

This particular wheel is used for chopping thru magazines, signatures, slab waste, box board, newspaper, corrugated waste and chip board. Any product that can be torn or ripped can be chopped by this wheel. It has a back plate and six (6) blades that are gusseted to both the blade and hub while being secured to the back plate as well. The blades range in size from 3/8" thick to 1" thick. Based on wheel weight and speed they can develop up to 18' of total static pressure.

High Speed Paper Handling Wheel

This wheel can handle the same grades as the Heavy Duty Wheel mention above. It however, has blade thicknesses of 3/16" to 1/4", which greatly reduces wheel weight. Based on weight and speed, this wheel can develop up to 30" of total static pressure. It is important when selecting a fan utilizing this type of wheel that the largest allowable fan size be used to keep down the wheel RPM. Due to the blade thickness being reduced with this wheel, the life span may be reduced because of wear and tear on the wheel itself. It therefore may be necessary to use a harder metal (abrasion resistance steel) to increase wheel life depending on the material and volume being conveyed.

LS Wheel

This wheel is generally used after rotary knives, shredders or on small stringy material. Due to its design which consists of six (6) blades gusseted to a hub with no back plate, it does not cut thru material. It however, can easily convey dust or small stringy material at reduced horsepower. This wheel comes in both the Heavy Duty Design for developing up to 18" of total static pressure and the High Speed Design for developing up to 30" of total static pressure.

Chopper Wheel

This wheel is a true chopper wheel and is generally used on high speed applications such as winders up to 8,000 FPM with either extra wide or heavy trim. It also has the capability of handling twelve (12) ribbons from a sheeter while cutting thru any roping that might occur. The wheel itself consists of six (6) 1/4" blades that are attached to the hub and a back plate. The blades are gusseted as in both the paper handling and high speed wheels, however in a different arrangement. Each blade has a 1î square block welded to it that has been machined and level to the bore. A harden and sharpened steel blade (1/4" high x 1-1/8" long) which is replaceable is bolted to the square block for true cutting capability. The inlet tube to the fan which is 1/4" thick is made to be adjustable so that the clearance between itself and the cutting blade can be set depending on the application. This wheel and housing can develop up to 12,000 CFM at 40" total static pressure.

All of the above wheels are incorporated into fan packages which are shipped in complete units. They are constructed using top grade materials and components to ensure reliability while operating as efficiently as possible. The fan housings are continuously welded to ensure that they are built sturdy and have the ability to absorb the loading seen by a material handling fan. The shafts are machined from the best grade of ground, polished and straightened shafting available. The bearings are the highest quality self aligning roller bearings available for speed and loading conditions. Inlet and Discharge collars are designed to be flanged or use vibration isolation sleeves. Typically the discharges are flanged but depending on rotation vibration isolators can be used to prevent transmission of vibration to the ductwork. The fan packages are offered in a variety of arrangements, with an Arrangement 1 being the most popular because of the fan and motor being mounted to a platform. The motor being mounted independently to a slide base according to a proper center distance allows for all fan speed changes to be possible. All fan packages include shaft guards, external grease fittings, heavy-duty bolted cleanouts, lifting eyes and shaft seal.

If noise reduction must be considered, we offer both sound enclosures and silencers. The sound enclosure itself attaches to the fan platform which will include steel decking. The enclosure is made from heavy gauge steel with 2" thick insulation and has an interior clearance of 6'-2" to allow sufficient room for maintenance. Entry is gain by way of a by-parting door with removable center support allowing for major changes. A low volume (500 CFM) roof exhauster is also provided to circulate air thru sound proof vents ensuring that the motor and drive are kept cool. Noise levels generally drop between 10-15 dba with the use of an enclosure depending on the product. For reducing noise levels at the entry points or hoods of the system, inline silencers are used. These are generally always used on the suction side of the fan system keeping the noise level at the production machine to a minimum. Discharge silencers can also be provided but are generally not used because most systems discharge into a separator and or filter.

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