Fan Selection Guide
Nearly 30 Years of Experience
In the realm of dust collection, a crucial decision lies in the selection of the appropriate fan. With myriad options and methodologies, we've distilled nearly three decades of expertise and countless successful installations into this guide. Our aim is to help you navigate the process and make the best choice for your next fan.
At Ecogate, we advocate for the use of a highly efficient, direct-drive fan installed on the clean side without system errors. This fan should feature a premium efficiency inverter duty motor, ideally without an inlet box, and a piezometer ring for precise air volume measurement.
Calculating Total Air Volume
As a starting point, determine the Total Air Volume for all workstations linked to the system. Use 4,500 FPM air velocity drop for general dust for smaller machines, and 6,000 FPM for all CNC machines and any machines that produce a high volume of sawdust. For other materials, refer to the recommended air velocity drops per the most recent version of "Industrial Ventilation - A Manual of Recommended Practice" by ACGIH.
Factoring in Future Changes
Ask if the customer plans to add, remove, replace, or relocate workstations within the upcoming 12 months. These potential changes should be incorporated into the air volume calculations.
Pressure Loss Calculations
Next, calculate the total pressure losses at Peak Air Volume (typically 100% of the Design Air volume as determined in the previous step) to the furthest workstation in the duct system, which usually incurs the highest pressure losses. Include hood losses based on manufacturer information or measured values from the same or similar workstation, duct system losses calculated at peak air volume, abort gate losses, dirty filter losses, duct and elbows between filter and fan inlet, fan silencer losses (if applicable), and return air losses (if applicable).
Ensure all pressure losses are accounted for in your calculations. If the fan is to be installed without an inlet box, maintain a minimum of three to five duct diameters between the elbow and fan inlet, and the same at the fan outlet to eliminate “system error”. Utilize an evasé (stack) at the fan outlet for optimal fan efficiency.
Engaging Fan Suppliers
Request fan suppliers to propose a direct-drive fan for an air volume not less than 85% of the total design air volume. This fan should be suitable for the calculated total pressure losses at the elevation Above Sea Level (ASL) where the fan will be installed, and at the highest temperature the fan will operate. If the customer or installer prefers a fan with an inlet box, the supplier must provide fan curves with the inlet box. We favour a fan where the pressure on the left side of the fan curve from the standard operating point is higher than at the operating point.
If a supplier cannot provide the fan curve with the inlet box, Ecogate will not utilize this fan. If a customer requests a fan for an air volume lower than 85% of the total design air volume, we will need written confirmation of such a request to proceed.
Author: Ales Litomisky