Fluid Engineering is pleased to offer Donaldson® Torit® dust collector fan control panels featuring variable frequency drive (VFD) and airflow controller technologies.
The traditional industry standard for controlling the output of fan exhausting a dust collector is to mount a damper on the outlet of the fan to throttle the output of the fan. During system startup, the damper operating point is "dialed-in" and set. However, as the dust cake forms on the filters and they age, the pressure drop through the collector increases. System operators then have to adjust the fan damper setting in response to this change in pressure drop.
Donaldson® Torit®, the worldwide leader in industrial air 
filtration technologies, has developed a dust collection system controller panel that integrates the operation of the pulse cleaning of the dust collector filters with a VFD and airflow controller for the fan motor.
What is the AirFlow Controller?
The "heart" of this control panel is an Airflow Controller with Variable Frequency Drive (VFD). Once the airflow controller is set-up during the initial system "start-up", it never has to be manually adjusted again, which is not the situation with a manual fan damper. Dampers require manual adjustment of the airflow as the filter pressure drop changes.
How does it work?
The airflow controller is designed to insure that the velocity of the dust laden air remains at the prescribed rate based on your type of dust. The airflow controller communicates to the VFD to have the fan motor spin only as fast as necessary to maintain the prescribed pre-set airflow. By having the motor spin at a slower RPM you are able to "harness" the energy savings from reduced energy consumption from the fan motor.
What are the benefits?
Energy savings, extended filter life, less maintenance of motor and reduced noise.
By doing so, your filters are insured to achieve the longest filter life possible, avoiding the risk of an improper damper setting and prematurely terminating the life of your filters by having particulate impinge into the media and not be able to pulse clean out.
The VFD also accelerates the fan motor slowly, eliminating the "power spike" at start-up which is typically used as a billing "penalty peak" by utility companies. Slow acceleration of the motor also eliminates the stress on the motor from "across the line starting".
By insuring the longest filter life possible you are also reducing the operating cost of the system over its life by reducing the frequency of ordering and shipping new filters to your facility and disposing of the "exhausted" filters.
Additional benefits are reduced noise radiating from the fan housing when the fan is trying to push as much air as possible against the manual damper.
What is the payback?
Based on cost per kwh and the average number of hours per week that you operate the system, I may be able to calculate the anticipated annual energy savings from using the VFD and airflow controller. 
You will need to keep in mind that the calculated savings will not take into account the reduced operating cost from extending the life of the filters and the reduced maintenance required to adjust the airflow damper, the reduced shipping cost from having to order replacement filters less frequently, or the rebate that you may secure from using the VFD and premium efficiency 30 hp motor.
What is needed?
We will need your existing fan motor information to confirm if it will operate with a VFD and airflow controller however; a premium efficiency motor is designed to operate with a VFD. Additionally, the premium efficiency motor consumes less energy under normal circumstances when compared with an E-Pac efficient motor.
The concern with a TEFC (totally enclosed fan cooled) motor is cooled by a fan that is connected the rear end of the motor shaft. Since the airflow controller and VFD will have the motor spin only as fast as necessary to deliver the prescribed airflow, it will be spinning less than full speed. That means that the cooling fan will be spinning slower, which will result in the motor being warmer.