Vaneaxial Fans Axiad II Adjustable Pitch Airfoil (Model ... - Aerovent

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Guide to AXIAD II Performance ChartsThis bulletin presents AXIAD II axial fan performance charts, which show in graphical form volume (CFM), pressure (in. w.g.),efficiency, blade position, and fan brake horsepower (BHP) relationships encountered in the most common AXIAD II fan, rotorand blade combinations operating at motor speeds associated with 60 Hertz operation (900, 1200, 1800, and 3600 RPM). Data onother sizes of fans and fans operating at different speeds is available from the factory.A typical AXIAD II performance chart is represented above. You will notice that the charts are presented on the basis of totalpressure. The pressure shown as total pressure is the sum of static pressure, velocity pressure, and impact pressure loss. Staticpressure is generally given, while velocity pressure and impact pressure loss are calculable by methods explained elsewhere in thisbrochure, and at greater length in other Aerovent publications.The operating point of a fan can be determined by knowing any two of the six parameters plotted in the fan charts. Generally,selections are made by establishing total pressure and reading across the total pressure line (in. w.g.) to the intersection with thevolume (CFM) line; and noting the blade position and efficiency. BHP is established by reading down the volume line to the previouslyestablished blade position, locating the brake horsepower by reading horizontally across the chart. In selecting an AXIAD IIfan it is best to choose a size that will operate at a point that is in the vicinity of the maximum efficiency oval.An important consideration in fan selection is the relation of the selection point to the stall line. The stall area is located at theupper end of the blade angle lines and must be avoided. Fan operation in this area is unstable, producing vibration, hunting andsurging. To ensure avoiding the area, fan selections should use only 90% of the available pressure at the specified flow. Calculationof a system parabola will show that only by allowing this safety margin can an error involving underestimation of static pressurebe corrected by the relatively simple method of increasing blade angle.AXIAD II NomenclatureFTFA - 140 - 5 - 2 (+) 885 - MOTOR SPEEDFan SizeWith Vane Section, ( ) = Less VanesFull Bladed, if 1 = Half BladedHub Size will be 3 with 6 or 3 Blades4 with 8 or 4 Blades5 with 10 or 5 Blades4 Aerovent Bulletin FA-300
Fan SelectionStraight-Through Airflow in Any DirectionThe data presented in this manual allows the reader to arrive at a fan selection, starting with airflow, pressure, and downstream ductvelocity of the system. Generally, for any given set of the above conditions, there are a number of fans that are possible selections.The parameters for separating these selections are generally (1) brake horsepower, (2) acoustics, and (3) first cost.The table below shows nine possible selections to meet the conditions: 40,000 CFM, 2.5 inches static pressure, discharging intoa plenum at 500 feet per minute. It may be of value to the reader to use the selection pressure calculations, efficiency calculations,and brake horsepower calculations. The sound data shown here is presented on the fan curve, and this is correctable to octave bandreadings as shown on pages 42 through 44.The weight that the designer gives to each of the factors involved in selection is something that varies with each individualcase. One would note from perusing the data that fans number 1 and 2 are the most compact, fans number 3 and 4 are the leastexpensive, fans number 5 and 9 are the quietest, and fans number 8 and 9 take up the greatest amount of space and tend to be veryexpensive. Under normal circumstances we suggest that the designer, after thoroughly investigating the nine possibilities, wouldtend to narrow them down to fan number 3 versus fan number 5. In this case, the designer must balance a 10% HP savings and 6dB lower noise output of the FTFA-112-5-2 + with diffuser against a cost differential approximately 40% which favors the FTFA-112-4-1. The final selection should be the result of a thorough systematic cost analysis that your Aerovent representative will behappy to assist you with.ExampleGiven:Flow = 40,000 CFM Static Pressure = 2.5" w.g. Discharge Condition: into Plenum, V4 = 500 FPMFAN FAN VANETOTAL EFFICIENCYOVERALL RELATIVEOUTLET RPMBHPNO. FTFA SECTION PRESSURE PERCENT PWL COST1 100-3-2 NO CONE 1800 3.08 74 26.2 106 522 100-4-1 NO CONE 1800 3.20 71 28.4 109 533 112-4-1 NO CONE 1800 2.88 75.5 24.0 109 514 112-4-2 NO — 1800 3.50 77 28.8 109 505 112-5-2 YES DIFF 1200 2.98 85.5 21.9 103 816 125-4-2 YES DIFF 1200 2.72 78 22.0 106 767 125-5-2 YES — 1200 3.15 85 23.3 107 808 125-5-2 YES DIFF 1200 2.76 85.5 20.3 105 89®5 Aerovent Bulletin FA-300
Page 1: ®The Industrial Choice.AXAID II ®
Page 6 and 7: Performance Data - FTFA 056-3-2+Per
Page 8 and 9: Performance Data - FTFA 071-3-2Perf
Page 44 and 45: Sound Power Correction FactorsFANRP
Page 46 and 47: AIRFLOW (CFM)CHART 3ANNULAR VELOCIT
Page 48 and 49: pv + pi (inches W.G.)FPMDuct Veloci
Page 50 and 51: Dimensional DataC-D Diffuser and Co
Page 52: PROPELLER FANS | TUBEAXIAL & VANEAX

Vaneaxial Fans Axiad II Adjustable Pitch Airfoil (Model ... - Aerovent

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