Brake Horse Power - BHP. The conversion constant for static efficiency is 6343. As explained by Ted ,I am only showing you an example for calculation in both the units and I hope you doubt will be clear. The peak total efficiency occurs at the top of the “bell” shaped efficiency curve. Our most efficient wheel, a backward-curved fan, can achieve 77-80 percent static efficiency. This figure can be used to determine the most efficient size and type of fan for a particular application. 1.7 . Note that the flow and pressure constants in the FEP formula (250 cfm and 0.4-in. This is the useful work required from the fan. pressure differential, respectively) effectively raise the power input allowed at lower flows and pressures. 1 cfm = 1.7m³/h. In Sweden, ECiS AB (Energy Concept in Sweden) performed performance measurements of 767 fans in existing HVAC systems between the years 2005 and 2009. so 102 value comes in numerator instead of denomenator. FEG Curve :Pressure Vs Airflow – Total Fan Efficiency. Hello Sidhant, Your example;- 1mmwc = 9.8 Pa. so put 1Pa = 0.102 mmwc. Let us assume a fan having a flow of volume 16m3/sec and devlops a total pressure of 500 mmH2O. (8) ‘Fa Despite all the textbooks and handbooks, which describe the proper procedure for selection of fans, practice shows that fans in existing HVAC systems have very low total efficiency. Founders’ Message: Quality of Work, Quality of Life, Stainless Steel Fan for Protein Rendering. 67 . FLOW RATE 1 m3/s 1 m3/hr x 2118.9 x 0.58858 2118.9 CFM 0.5884 CFM VELOCITY 1 m/s x 32.8083 x 196.85 32.8083 ft / s 196.85 FPM PRESSURE 1 N/m2 x 0.00402264 x 0.00029530 … Static efficiency is a ratio of the fan power output to the power supplied to the fan. Air Horse Power - AHP. Fan total pressure is the total pressure (static pressure plus velocity pressure) at the fan outlet minus the total pressure at the fan inlet. (7) ‘Static efficiency’ means the energy efficiency of a fan, based upon measurement of the ‘fan static pressure’ (p sf). Notice that the 72-inch fan has the highest static efficiency which is the proper metric for nonducted applications. Static Pressure - Sum of all the system resis-tances against which the fan must work, expressed in inches of H2O. Why Fan Static Efficiency Matters. Fan performance is often represented in the form of fan curves. Using the formula, you’ll find that this fan will require about 19.7 horsepower, indicating a 20 horsepower motor, to reach the full performance potential of the volume to static pressure ratio. Senior Application Engineer Chet White explains how to calculate static efficiency and why it matters in this 2-minute whiteboard tutorial. Use of diffusers Case study, final overview with cost c A No. But what constitutes good efficiency? Volume is the quantity or velocity of air, gas, and/or other materials moving through the fan as measured in cubic feet per minute (CFM). At this point the ratio of the output power of the fan (Volume flow (m 3 /s) x Static Pressure development (Pa) and the electrical power input (W) is at its greatest and the sound pressure being produced by the fan will be at its quietest. Horsepower is the measurement of energy in units of power. Both the formulas are used in SI units and in general the work done theory the amount of air handle by a fan against a pressure is called work done and dividing workdone The fan efficiency formula is in SI units. Controlling Fans with Variable Loads 9. 12 issues of the leading cement industry magazine, your choice of complimentary handbook, plus unlimited access to CemNet.com News, Articles and HD Videos. Using the formula given in books using mmH2O as pressure, Kw = (m3/sec x Pressure mmH2O)  /102  = 16 x 500 /102 = 78.4 Kw, 2. 3, Cement Plant Operations Handbook 7th Edition, Global Cement Trade & Distribution Handbook 2nd Edition, Cement Plant Environmental Handbook 2nd Edition, 8-11 February 2021, Cemtech Middle East & Africa Virtual Event, Selecting and using raw materials for cement manufacture, Alternative fuels for firing cement kilns, Global Cement Report 13, December 2019 Database. 90 . Figure 8. is incorrect, because you need to divide a value expressed in mmwc by 0.102, to convert to Pascals, not multiply ! Static efficiency is calculated using only static pressure. Above and below the optimum range of operation the flow across the fan becomes noisier and the efficiency of the fan system decreases. Fig 2shows the pressures through a fan, each of which is described below: Inlet Pressure; is the static pressure on the inlet side of the fan. Fan BHP = (cfm x static press "w.c.) / (6356 x fan efficiency) Fam Motor HP = fan bhp / motor efficiency Following are values from a propeller fan manufacturer's catalog for a particular fan: Static press. You are getting confusions for change in unit from mmH2O to Pascal. Fans and Blowers Bureau of Energy Efficiency Figure 5.1 Centrifugal Fan Figure 5.2 Axial Fan Centrifugal Fan: Types The major types of centrifugal fan are: radial, forward curved and backward curved (see Figure 5.3). Example of the way an array of measurements ... formula team ... of fan and radiator that will achieve appropriate cooling. Draft fan engineers are most familiar with this formula and use it frequently to rate a fan. You can also use the fan static efficiency calculation to determine what type of industrial fan is optimal for your application. Fan static and total efficiency (Figure 1) can be plotted along with the fan pressure curves. 1 Static Efficiency - Fan efficiency based on static pressure and fan brake horsepower at the same density. Fig 2: FEG Curve. 6.8 13.4 6.87 . Second, as communicated earlier, the FEG value is based on the peak efficiency of the fan. Static efficiency uses static pressure, which does not include the kinetic energy, to calculate the effi- ciency. Fan noise 7/12/2000 11.3 Noise Comparison For lowest noise output, fans should always be operated near their peak efficiency point. WG. An axial fan is a type of fan that causes gas to flow through it in an axial direction, parallel to the shaft about which the blades rotate. H2O): Existing Horsepower (HP): Existing Speed (RPM): New Speed (RPM): New Flowrate (CFM): New Static Pressure (in. Next Page >> ATEX Fans >> Conversion Factors. Fig 1: FEG Formula . The factor of 102 is used to convert mmWC into pascals because the formula for the static fan efficiency in SI units is;-, Static Fan Efficiency =  Volume (m3/s) * Pressure gain (Pa) /  Power input (W) * 100, But, if the pressure is measured in mmWC instead of Pascals and Power is expressed in kW, the formula can be derived as follows;-, Therefore 1Pa = 1/9.81 = 0.102 mmWC  (or, divide mmWC by 0.102 to get Pa), So, Static Fan Efficiency =  [Volume (m3/s) * Pressure gain (mmWC) / 0.102] /  [Power input (kW) * 1000] * 100, or  Static Fan Efficiency = [Volume (m3/s) * Pressure gain (mmWC)]  /  [Power input (kW) * 1000 * 0.102] *100, or  Static Fan Efficiency = [Volume (m3/s) * Pressure gain (mmWC)] *100 /  [Power input (kW) * 102], efficiency = m3/s X 0.102 mmwc *100/( motor kw x motoe eff.). Radial fans are industrial workhorses because of their high static … 60” 49” 54” 54” 54” Impeller Dia . Diagram of a pitot-static tube in a duct with air flow..... 18 Figure 9. The fan efficiency is the ratio between power transferred to airflow and the power used by the fan. In the same application, if you selected a less efficient fan with only 50% static efficiency, the calculation would indicate 63 HP, so you’d have to bump all the way up to a 75 HP motor to drive it. Fan total efficiency is calculated using total pressure. of Brake horse power - the actual power a fan requires … wg BHP = Fan power input, hp . Fan static efficiency is the measure of the airstream’s potential, or optimal energy consumption, as determined by the ratio of power output to the power supplied. Join the community and register for a free guest account to post a reply. Assuming 100% efficiency AHP is the power required to move a given air volume against a given pressure. Generally, efficiency increases and fan size decreases as specific speed increases. by time will give you the power. Air Flow must be in m3/s, Pressure must be in Pascals, and … On the contrary, dynamic efficiency takes into account the development of new products, processes, and capabilities. The fan efficiency is in general independent of the air density and can be expressed as: μ f = dp q / P (2) where. It allows you to determine how much horsepower you need to achieve maximum static efficiency in your application based on volume, pressure. Static pressure indicates how much resistance the airflow needs to move through as measured in inches of water gauge (in. 8.30 . H2O): New Horsepower (HP): FAN APPLICATION FORMULAS Fan Brake Horsepower: Flowrate (CFM): Static Pressure at Discharge (in. Existing Static Pressure (in. ie. The best forecast is that the target static efficiency for non-ducted fans will be 62% at the fan shaft, and the target total efficiency for ducted fans will be 68% at the fan shaft. where . Using the formula given by Ted as Watt = m3/sec x pressure (pa). Note that the peak efficiency occurs at just one point on the curve and all other points on the curve have a lower efficiency. efficiency = m3/s X 0.102 mmwc *100/( motor kw x motoe eff.) Static efficiency is efficiency in terms of the refinement of existing products, processes or capabilities. Positive static pressure is created as a fan moves air through a system. Understanding Fan Static Efficiency Fan manufacturers typically provide static efficiency as the value of efficiency, while total efficiency includes the outlet velocity term. P AHP = Air Horse Power (hp). They are most useful for determining the impact of extrapolating from a known fan performance to a desired performance. The Fan Laws are a group of useful equations for determining the effects of a change in the speed, the diameter of the fan and the density of air in the system. q = air flow (cfm) SG = Specific Gravity Air (= 1.0) dp inWG = total pressure (in. You can include thi… ASHRAE Rocky Mountain Chapter “Things are not always as they seem; the first appearance deceives many.” - Phaedrus (Roman Poet) ASHRAE Rocky Mountain Chapter . Some advanced engines have additional spools for sections of the compressor which provides for even higher compressor efficiency. But, if the pressure is measured in mmWC instead of Pascals and Power is expressed in kW, the formula can be derived as follows;- 1 mmWC = 9.81Pa. 1.0 $ Cost . 3.8 . If the diameter does not change the fans must be geometrically similar. FANS AND BLOWERS Bureau of Energy Efficiency 87 6.1 Introduction This section describes the method of testing a fan installed on site in order to determine the performance of the fan in conjunction with the system to which it is connected. ANSI/ASHRAE/IES 90.1-2013 requires fans have a fan-efficiency grade (FEG), as defined in AMCA 205, Energy Efficiency Classification for Fans, of 67 or higher. ‘fan static pressure’ (p sf) has been used to determine fan gas power in the efficiency equation for fan static efficiency; and (b) ‘fan total pressure’ (p f) has been used to determine fan gas power in the efficiency equation for total efficiency. It is a measure of the total mechanical energy added to the air by the fan. For example, if you have an industrial fan that can achieve 80% static efficiency and you’re trying to move 20,000 CFM through 10 inches WG of resistance, a 40 horsepower motor would get the job done. psF = fan static pressure, Pa pdF = fan dynamic/velocity pressure, Pa pd = system dynamic/velocity pressure, Pa V = velocity of air, m/sec PWL = sound power level Formulae 1 to 4 can be applied to any fan provided the diameter does not change. This equation can also be used for calculating hydrodynamic horsepower in a ducted flow. 1 mmWG = 9.81Pascals use the fan static efficiency calculation to determine what type of industrial fan is optimal for your application, connect with one of our application engineers, Industrial Fan Types and the Fan Static Efficiency Calculation, Choosing the Right Motor Speed for Your Industrial Fan. re FAN EFFICIENCY FORMULA DERIVATION. For more information on fan static efficiency, check out these additional articles: We welcome comments and questions via our LinkedIn Page, and you can always Contact Us or Request a Quote for more details. 75 . Static efficiency is the product of the volume and pressure you need in your application divided by the product of the conversion constant and horsepower, as follows: You can use the maximum static efficiency to determine the horsepower you need in your application. 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