Question on velocity obtained from Duct-sizing wheels
Question on velocity obtained from Duct-sizing wheels
(OP)
Does anyone know why the velocity calculated from a "ductolator" is different than what is calculated mathematically?
For a given duct size and cfm, the air velocity indicated on my ductolator is much different than what the velocity would be if it were calculated out using the formula: velocity = CFM/Face Area. When I contacted my local Loren Cook rep and ask the question, he indicated that ductolators add a safety factor to the velocity calculation. When I asked him what that safety factor is and what is it supposed to represent, he could not find an answer for me.
Any thoughts on this?
For a given duct size and cfm, the air velocity indicated on my ductolator is much different than what the velocity would be if it were calculated out using the formula: velocity = CFM/Face Area. When I contacted my local Loren Cook rep and ask the question, he indicated that ductolators add a safety factor to the velocity calculation. When I asked him what that safety factor is and what is it supposed to represent, he could not find an answer for me.
Any thoughts on this?





RE: Question on velocity obtained from Duct-sizing wheels
RE: Question on velocity obtained from Duct-sizing wheels
You are then calculating the velocity through the rectangular area?
RE: Question on velocity obtained from Duct-sizing wheels
RE: Question on velocity obtained from Duct-sizing wheels
RE: Question on velocity obtained from Duct-sizing wheels
An equivalent 'square duct' will result in having very close to the same area as a round duct. Something rectangular will end up with a larger area yet be deemed equivalent for pressure loss. Bigger perimeter, more area for friction I would suppose.
20 inch round similar to 18x18, 35x10 or 50x8