• Can create vibration in stall. The intersection of the system curve and the static pressure curve defines the operating point. Fan curves are simply graphs showing fan performance, normally with air volume on the horizontal “x” axis, and pressure on the vertical “y” axis. This post will address both these mistakes and suggest how to avoid them. View Fan Curves.pdf from ENGINEERIN 427 at King Fahad University of Petroleum and Minerals. Page 6 of 35 The Basics of Axial Flow Fans Typical Air-Cooled Heat Exchanger Fan Fig. Unfortunately, this model does not permit the direct calculation of fan efficiency from airflow and pressure; rather, it correlates efficiency to the dimensionless flow term ( φ), which requires both airflow and fan speed as inputs. 5. fan airflow-pressure curve. motor is actually mounted in your system can be obtained using the air fl ow-static pressure characteristics curve and system impedance. System Effects Most of the time fans are tested with open inlets, and designs that do not have an integral inlet bell will be tested with one to simulate inlet ductwork. Following the fitting, the equation P(X) is expressed via Chebyshev polynomial. Consequently, oversized fans not only cost more to purchase and to operate, they create avoidable system performance problems. The fan curve in our example provides some fan noise level information in dBA on the CFM vs SP Curve. Shape of the Curve The shape of the stage curve has an influence on the predictabil ity of off design performance by the fan laws. BDB Twin Fan BDB series are also available in twin fan version, with two double inlet fans mounted on the same shaft. 1 2.0 Fan Engineering Nomenclature ACFM - Actual cubic feet per minute of air moved by the fan. Pressure drop due to heating coils are treated as … To obtain a fan curve the fan is placed in a test rig in which air pressure and volume can be measured and the pressure can be varied by adjusting a damper or venturi of known characteristics. 3 0 . Sound levels, efficiency, and other parameters may also be displayed. c = fan curve condition at standard density 1 = inlet, condition 1 2 = outlet, condition 2 in = inlet out = outlet SL = sea level des = design eff = effective. • Fan curves are typically given in terms of total pressure vs. volumetric flow rate • A typical fan running at a fixed speed can provide a greater volumetric flow rate for systems with smaller total pressure drops (if we’re to the right of the peak in the fan curve). Default setting Fan Curve The graphic presentation of a fan’s performance charac-teristics, showing airflow, static pressure and brake horse - power. Oversized fans generate excess flow energy, resulting in high airflow noise and increased stress on the fan and the system. Fan Curve - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. 3. Tjernlund Products, Inc. • 1601 Ninth Street • White Bear Lake, MN 55110 • (651) 426-2993 • (800) 255-4208 • FAX (651) 426-9547 • www.tjernlund.com 1.25 0 0 500 1000 1500 2000 2500 CFM (STD. Static efficiency vs Air Flow rate. Fan performance is often represented in the form of fan curves. fan curve the operating point lies depends entirely on the ductwork. FAN PERFORMANCE CURVES MQL02 (Fan 09-04 Class I) MQL03 (Fan 09-06 Class I) 16 ENVIRO-TEC MQL Modular Air-Handling Units OR ET9-E 45 MQL06 (Fan 12-09 Class I) MQL04 (Fan 10-07 Class I) ENVIRO-TEC 17 MQL - Units FORM ETEG MQL08 (Fan 12-12 Class I) MQL10 (Fan 15-11 Class I) 18 ENVIRO-TEC MQL Modular Air-Handling Units OR ET9-E 45 MQL12 (Fan 18-13 Class II) MQL12 (Fan 18 … SP vs Air Flow rate. fan curves with data from a single model. FAN CURVES CFM vs EXTERNAL STATIC PRESSURE FAN SIZE C - AS L3, L4 1/6 H.P. • Fan curves shown are applicable to 120/208/240 and 277 volt, single phase ECM motors. Figure 1 provides a typical illustration of fan curves. Fan specification is usually not a precise science and can be done confidently when the fan application is understood. Knowing how to read and work with a fan curve can keep you out of trouble when selecting a fan for a specific operating condition. 4 0 . reconcile this field data with the fan curve provided by the manufacturer. In the many curves shown in the Figure, the curve static pressure (SP) vs. flow is especially important. It simplifies the performance curve of the fan to match the impedance curve of the system. The curves are based on a specific set of conditions which typically include speed, volume, efficiency, static pressure and power required to drive the fan at the given set of conditions. In order to obtain in-situ fan performance curves for variable air volume (VAV) air handling units (AHUs) with predicted uncertainties, airflow measurements for an extended time and a tailored calibration procedure were proposed and validated in this SELECTION TIPS • When fan stalls, it can’t produce as much lift. Based on the application, four parameters need to be determined. The first thing to note about the fan curve graph is that it has 3 axes: Horizontal Bottom Axis = Air Volume Flow Rate (SCFM or m3/sec.) A review of the curve of the fan. ANSYS It consist of three curves, 1. The fan will operate at the place where the system line intersects the fan curve. 3 0 . 1 0 . FAN STALL. compressor curve at one speed and deriving a comparable point at a different speed, for similar conditions, of pressure, temperature, molecular weight and compression exponent. A receiver operating characteristic curve, or ROC curve, is a graphical plot that illustrates the diagnostic ability of a binary classifier system as its discrimination threshold is varied. Motor MAX MIN 1 ROW 2 ROW NOTES: 1. 5 0 . Fans coupled in series . However, the system impedance cannot be measured without a measuring equipment, so fan with 1.5 to 2 times higher air fl ow than the actual Max air fl ow should be selected (operating air fl ow is one-third to two-thirds of maximum air fl ow). • Fan sounds “rough”, may pulse. Forward Curve- Sometimes referred to as a “squirrel cage” fan, forward curve fans are used in most residential and light commercial HVAC equipment. 2. Motor CFM EXTERNAL STATIC PRESSURE 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 100 300 500 700 900 1100 FAN SIZE D - AS L4 1/4 H.P. 5 0 . To select for twin fans, use the curves of single fan with the following factors :- Volume x 2 Absorbed Power x 2.15 Speed x 1.05 Noise + 3 dB This series is available in type S2, C2 or T2 TECHNICAL SPECIFICATION KQFS PSC FAN CURVE, UNIT SIZE 4 KQFS PSC FAN CURVE, UNIT SIZE 5 0 . • Fan curves are use to define the operating point. 6 Max Min 1 Row HW 2 Row HW Fan Capacity (CFM) External Static Pressure (”WG) 2200 1800 1400 1000 1000 600 200 0 . • Try to select in the centre of a fan curve when looking at AP fans. • The fan curve is a graphical representation of a number of inter- related parameters. The fan speed will change along with the Smart Speed curve. After the motion airflow has been calculated, select an appropriate fan motor based on the value.The motion airflow when the fan motor is actually mounted in your system can be obtained using the airflow-static pressure characteristics curve and system impedance.However, Example （3） × ×≒0.5（） ××≒（） （）×（）≒（） （ 2 0 . A hypothetical system curve is shown at right, along with the same example fan curve as used above and curves for two of the same fan in series, two in parallel, and the same single fan operated at 80% speed, with operating points for each scenario circled. Tonal sounds can increase. Fans should be selected to operate at the stable region. The method was originally developed for operators of military radar receivers, which is why it is so named. fan curve and is where the fan is selected to operate. • Understanding this relationship is essential to designing, operating a fan system and it is the key for optimum selection of fan. BHP vs Air Flow rate. Offer NOV.6,2014-R2-order Page 4/9 AHU-01 CAL070 From date 06-Nov-14 Position ClimCalc Vers. 380 T: 0844 856 0590 Sentinel Totus2 D-ERV - Mini Model 0 0.05 0.10 0.15 0.20 0.25 0 100 200 300 400 500 600 0.60 0.50 0.40 0.30 0.20 0.10 0.00 Air Volume m3/s Pressure Pa Absorbed Power kW Eldridge works with this type of data every day. Some fan curves will also include an efficiency curve so that a system designer will know where on that curve the fan will be operating under the chosen conditions (see Figure 5.6). Fan curves graphically depict fan performance data of CFM, RPM, SP, and BHP. The fan curve is graph depicting the various points that the fan can operate. Utilizing the function curve and data provided in the reference material, this paper identifies interactions among major parameters affecting the static pressure and flow of the fan. These fans are for low to medium static applications. In fact, someone once said that we at Eldridge “study air for a living”. • Therefore the airflow drops dramatically. Click on the Fan > CPU/ PUMP/ SYS fan setting . External Static Pressure (ESP) consists of down stream ductwork, coils, flex, duct, etc. 5.2. Calculation of the curve for coupled fans. Hudson Products Corp. 2. Fans and Blowers Bureau of Energy Efficiency 97 Figure 5.5 System Characteristics . 1 0 . It indicates the amount of CFM the fan will provide at a given total static pressure, which is dependent on the connected ducted system. This operating point is at air flow Q 1 delivered against pressure P 1. Current fan speed How to use the Smart Fan control panel The Smart Fan control panel contains 4 dots which allow you to drag and adjust the Smart Speed slopes. (Actually the second mistake is dealt here in Part-1 and the first in Part-2). THE FAN LAWS. They are the most budget friendly and the least efficient blade design. WE HAVE THE TECH-NOLOGY. When the curve of the system does not cut the curve of the combination, or cut the prolongation of this curve before fan B, fan B will give a higher airflow than the coupling of A and B in parallel. The white dot will create strip chart in real time. Fan Curves. This system curve can then be plotted on the fan curve to show the fan's actual operating point at "A" where the two curves (N 1 and SC 1) intersect. 4 0 . IN-LINE FAN CURVE. 2 0 . It then follows that curve segment AC is the left side of the fan curve and is considered to be the unstable portion of the curve. Notes: 1. Unstable operating regions (stall, or left of peak) are typically not shown. Unit Size Coil Airflow CFM (Dry Flo w) Cooling Capacity Water Power Input @ FLA (Watts) Rw FP I C QT (BTUH ) S FlowRate GPM WPD ft-wg 6 3 14 2 600 16000 12000 3.6 7.4 280 4 21000 14000 4.5 15.1 280 10 3 14 2 1000 29000 21000 6.7 37.5 510 4 4 33000 22000 7.3 11.1 510 15 3 14 6 1500 38000 29000 8.5 7.4 … The best way to introduce the concept of FSP is to first point out what it is not.
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