local exhaust ventilation 7

1-When selecting a fan for ventilation system, why should you know about AMCA?

2-What are the functions of fan?

3-Use your own words to briefly describe the advantages and disadvantages of radial, forward- and backward-inclined fans, if you want to use them in LEV system.

4-Please indicate the positive (+) or negative (-) pressure: Static pressure at the upstream of fan is _____, and at downstream of fan is _____. Pressure on the back side of blade is ____, and on the forward side of blade is _____. Static pressure on the inlet of fan (LEV) is ____, and on the inlet of fan (LEV) is _____.

5-Why can FSP represent the system losses (p 8-4)?

6-The inlet of fan has SP of -5 “w.g. and VP of 2 “w.g., while the outlet of fan has SP of +1 “w.g. and VP of 2 “w.g. Show your calculation for FTP and FSP.

7-Why shouldn’t you have the fan running on the “backside” of fan curve (that is, not run on the left of the peak SP, but on the steep part of the curve)?

8-1) Why should you avoid running the fan at a speed above 10% of rated rpm (that is at 110% rated rpm)? 2) Please calculate the % of changes in power (assume fan wheel diameter remains the same) if RPM increases 10%.

9-According to the six in and three out rule, what are the lengths of straight duct that should be provided into and out of a fan which will be connected to 10″ round ductwork? You need to specify which duct into or out of the fan for full credit.

10-You are designing a ventilation system with the following parameters. What is the required shaft horsepower (sph) for the ventilation system, and what rated power motor (rhp) would you like to choose? FTP = 15.0 inch w.g.; Q = 1,300 scfm; ME = fan efficiency = 0.65; Kdl = 1.05; STP (d = 1); c = 6356.