Buct Size Colculation Mcquay Free Software
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I am using Design Tools duct calculator from the McQuay web site. I have a customer that wants me to force 3000cfm of air through a 10x8 sheet metal duct.
(Yes, that's 3000cfm) To find a fan big enough to do this and to determine if the duct can even withstand the pressure I need to know what my Static Pressure is going to be. Using the calculator I am coming up with a velocity pressure of 2.0234 in.WC and a head loss of 5.019 in.WC/100 ft. Is my static pressure 2' or 5'?
Or am I doing this wrong. If I look at the Trane ductulator a 10X8 duct at 3000cfm is 4.5 Friction loss Per 100 ft. Is my static pressure 4.5'? Set me straight guys. Have you tried to get some fan data from the manufacturer of the fan. Most have charts that will tell you what the CFMs will be at a certain static pressure.
I would think that you could use the chart in reverse. You have calculated the velocity pressure correctly, but that is not what you need.
Duct Size Calculation Mcquay Free Software 2017
According to Manual Q, Chapter 2, metal rectangular duct can handle up to 10'wc (that is high in my opinion). This duct is going to have a velocity of 5800fpm. Bram stoker dracula german download. How long is the run before it branches out to individual duct runs?? The exhaust is actually for a series of electrical rooms. It is a straight duct from the first floor to the roof. Three floors, about 45' vertical.
He wants to add a run to a Cafe' close by to exhaust food odors that other tenants are complaining about. There has been no engineering and I believe once he sees the budget cost he will change his mind. This scenario has brought some questions to mind as to how I would determine the static pressure. So the measurements are: 3000cfm through 45’ of 10x8 uninsulated sheetmetal duct. What is the static pressure?
Duct Size Calculation Mcquay Free Software Download
Beenthere, how did you determine 8”? Don't have any of the good software at home, but, if you add you friction rate, and velocity pressure, you'll be close to the static pressure, so I rouonded up to 8'. And you won't get away with light guage duct. As some one else posted, you'll be aroung 18 guage. I think you'll find that code will require fire dampers.
Also where is the 3000cfm of mua coming from, and has he considered how much additional load it will put on the resturant a/c system, if all 3000 are from the resturant. 3000cfm of make up air, could be 15 tons of additional a/c load, depending where you are located. You may want to check his exhaust system for his grille, it may be the cause of the trouble. Hello all Like everyone else there is not enough information for me to figure this one out.
But lets Assume: What we know: 3000 CFM 10 x 8 Duct 45' of duct Lets say we had a fan of Unknown type in a room connected to a piece of 10 x 8 duct 45' long. No gooseneck, fire dampers, or diffuser.
Our total pressure (Pt) using 4.5' w.c. Friction Pt = (F/100 x Measured Length) / 100 Pt = (4.5 x 45) / 100 Pt = 2.025 (this would be our Straight run pressure drop) Lets find our Velocity pressure: Pv = V / 4005 squared Pv = 5600 / 4005 squared Pv = 1.9 'w.c. Lets find our ASSUMED static: Ps = Pt - Pv Ps = 2.025 - 1.9 Ps =.125 'w.c. Assumed static would be.125' w.c. Does it make sense??? We do have a higher Velocity pressure and no end cap on the system just a straight run of duct. Also this is ASSUMED because we are not taking into consideration Fan inlet and outlet pressure loss, fitting loss.
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