Specialty fans are categorized as those that are applied to a specific function. They oftentimes are standard centrifugal or axial designs that are modified to meet an application need. Alterations to the wheel, inlet, outlet, housing and supports are options without compromising performance needs.
Major groups would include:
FRP & PVC Fans – These are for corrosive environments that attack and degrade metal materials of construction. FRP and PVC are the most common plastic materials used to build these types of fans and blowers.
High Temperature Fans – Where temperatures in the airstream exceed 250 degrees F, fan designs need to change to accommodate the high operating temperatures without failure to bearings, metals, etc.
OEM Fans – Machine designs need an air mover that oftentimes needs to fit within tight space constraints.
Stainless Steel Fans – The need for corrosion resistance requires that we look beyond coated carbon steel and select the correct type of stainless, finish the surface treatment of the steel correctly and design for the gaseous constituents of the airstream or ambient environment.
IMPORTANT OPTIONAL FAN DESIGNS
There are also standard equipment designs that make a lot of sense for specific applications. These optional design features include:
When fan wheels or impellers have a build-up of particulate, grease or materials being conveyed, they need to be accessed for cleaning with minimal downtime. The build-up of materials on the fan wheel causes imbalance and vibration resulting in failure of bearings and shaft. This feature is available in both centrifugal and axial designs.
Paper Trim Fans
When conveying paper and cardboard products, reducing their size with a chopper wheel, allows the materials to be conveyed without pipeline clogging.
When the need for moving large sections of cardboard, long continuous strings of paper, or plastic matrix scraps from punching processes, trim fans can be used to “chop up” and convey cardboard, paper, plastic and other friable materials. These “chopper” fans reduce materials to a size that allows it to be pneumatically conveyed. The wheel construction is altered to a heavy duty design with up to 1/2” thick blades and sharpened blade tips are sometimes added to the wheel. The housing interior surfaces are assembled continuously and snag free with all interior nuts and bolts removed.
Dust Collector Fans
Mounting the fan on its inlet either in a vertical or horizontal plane, reduces the need for duct and reduces the fans footprint. These fans are referred to as horizontal mounted or flange mounted fans. This is a common design on dust collectors but can be applied to many more applications such as exhaust hoods, slant screens, wet wells, balers, product receivers, drop-out boxers and even paint booths.
An unhoused fan wheel uses the enclosure it exhausts from as the fan housing. This design is used in oven exhaust, furnace fans and custom air handlers.
Compressor Building Fans
SysTech designed LO-NOISE™ Modules, typically large diameter propeller fans, direct drive, used to ventilate heat or gasses and coupled with silencers to systematically address compressor station ventilation for natural gas transportation facilities. Integral 90° weather hoods, silencers, and AMCA rated non-sparking construction along with hazardous duty motors are standard. Optional items utilized include agricultural/insect screens or filtered intakes, along with backdraft dampers or diffusers for airflow control. Multiple fans operating in unison normally are controlled via MCC incorporating LEL detectors and variable frequency drives.