Calculating Friction Loss in Ducting for Dust Collection System | 40 HP Motor

[simranjohal]

Hi, I just started my first job and I have to complete one unfinished project. This is a dust collector system and i have the ducting blue print but I am not sure how to calculate the friction losses in the ducting. I have the dust collector in place plus the ducting diagram, need some help with calculations. Dust collector has 40 HP motor and attached ducting

 

[SteamKing]

The first thing you'll need to find out is something about the construction of the ducting itself: what kind of material is used, what sort of surface roughness you'll find inside.

It's not clear from your diagram where the supply of air is and where it exits, but that can be corrected by showing a few arrows in the proper locations.

What you have is a duct system with multiple branches. It's similar to say, a municipal water system, where one reservoir feeds multiple users thru a water main and branch system. You can calculate the flows in the branches of the system by iteration or by use of software to do the tedious calculations. But, in the main, you should pick up a textbook on Fluid Mechanics or Hydraulics (Streeter or White are two good references).

https://www.amazon.com/s/ref=dp_byl...M.+White&sort=relevancerank&tag=pfamazon01-20

https://www.amazon.com/gp/search/re...&Adv-Srch-Books-Submit.y=14&tag=pfamazon01-20

 

[russ_watters]

In practice, all you need here is a spreadsheet and a ductulator (or other duct friction calculator). List the airflow and dimensions of every leg of the duct, read the friction loss off the ductulator, multiply by length, and add them all together.

...is there not someone at the company mentoring you?

 

[Dutchwayne]

As a new hire and in a first time job, go ask questions. Think them through, but no one will expect a new hire to know what they are doing for all of it. They will want you to ask when you get stuck. After 30 years, I still go and ask questions. In truth, if you know all the answers, you are ready for more challenges.

I have trained probably over 100 young engineers fresh out of school. The single most important thing for rookies to realize is they do not have all the answers and you must ask questions. No rookie has been fired for asking intelligent questions. Take a few minutes and talk to your mentor or supervisor. And take notes so you don't repeat.

 

[alphy]

Hello, congratulations on your new job! I can help you with calculating the friction losses in your dust collection system. Friction loss in ducting is caused by the resistance of air flowing through the ducts. It is important to accurately calculate this in order to ensure proper air flow and efficiency of your system.

To calculate the friction loss, you will need to know the air flow rate, duct diameter, duct length, and the type of duct material being used. You can use a friction loss calculator or an equation such as the Darcy-Weisbach equation to determine the friction loss.

First, determine the air flow rate in cubic feet per minute (CFM) using the 40 HP motor. This can be found in the motor's specifications or by using a CFM calculator. Next, determine the duct diameter and length based on your blueprints. Then, identify the type of duct material being used and its corresponding friction factor.

Plug these values into the Darcy-Weisbach equation: friction loss = (f x L x V^2)/(d x 2g), where f is the friction factor, L is the duct length, V is the air velocity, d is the duct diameter, and g is the acceleration due to gravity (32.2 ft/s^2). This will give you the friction loss in feet of water per 100 feet of duct.

Alternatively, you can use a friction loss calculator, which will require you to input the same values and will give you the friction loss directly.

It is important to note that friction loss is dependent on air velocity, so make sure to consider this when designing your system. Higher air velocities will result in higher friction losses.

I hope this helps you in completing your project. If you have any further questions, please don't hesitate to ask. Best of luck!