# fan static efficiency formula

For example, if you have an industrial fan that can achieve 80% static efficiency and youâ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. Because it is based only on a fanâs impeller diameter and a single point of operation at peak total efficiency, FEG alone fails to provide a true indication of a fanâs actual power consumption. In Sweden, ECiS AB (Energy Concept in Sweden) performed performance measurements of 767 fans in existing HVAC systems between the years 2005 and 2009. I TRIED A LOT BUT HOW 102 IS COMING IN DENOMINATOR ? The conversion constant for static efficiency is 6343. Fig 2: FEG Curve. is incorrect, because you need to divide a value expressed in mmwc by 0.102, to convert to Pascals, not multiply ! Note that the peak efficiency occurs at just one point on the curve and all other points on the curve have a lower efficiency. The fan is designed to produce a pressure difference, and hence force, to cause a flow through the fan.Factors which determine the performance of the fan include the number and shape of the blades. 1. Next Page >> ATEX Fans >> Conversion Factors. Brake Horse Power - BHP. 8.30 . 7.11 BHP 90 . re FAN EFFICIENCY FORMULA DERIVATION. 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. This peak total efficiency is used to determine the FEG value. Fan static efficiency is the measure of the airstreamâs potential, or optimal energy consumption, as determined by the ratio of power output to the power supplied. CAN ANYBODY SHARE THE HOW TO DERIVE FAN EFFICIENCY FORMULA. Controlling Fans with Variable Loads 9. 1.7 . 1 cfm = 1.7m³/h. Some advanced engines have additional spools for sections of the compressor which provides for even higher compressor efficiency. Air Horse Power - AHP. 1litre/s = 3.6m³/h. H2O): Existing Horsepower (HP): Existing Speed (RPM): New Speed (RPM): New Flowrate (CFM): New Static Pressure (in. They are most useful for determining the impact of extrapolating from a known fan performance to a desired performance. Fan total pressure is the total pressure (static pressure plus velocity pressure) at the fan outlet minus the total pressure at the fan inlet. P AHP = q dp inWG SG / 6356 (1). Brake horse power - the actual power a fan requires â¦ It indicates how much energy the motor will provide and how much energy the fan will consume given application-specific factors. Second, as communicated earlier, the FEG value is based on the peak efficiency of the fan. ie. 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. q = air flow (cfm) SG = Specific Gravity Air (= 1.0) dp inWG = total pressure (in. (7) âStatic efficiencyâ means the energy efficiency of a fan, based upon measurement of the âfan static pressureâ (p sf). 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). 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. 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). A test section that has the capability of interfacing with both the wind tunnel in the Thermal Science Lab and a radiator will be used to facilitate the necessary experiments. You are getting confusions for change in unit from mmH2O to Pascal. When youâre ready to start your project or update your maintenance program, reach out, and connect with one of our application engineers to discuss the details of your project. Why Fan Static Efficiency Matters. It can be found by multiplying the Mechanical efficiency by the ratio of the fan static pres-sure to the fan total pressure. Total Pressure Versus Static Pressure. 75 . The fan efficiency is the ratio between power transferred to airflow and the power used by the fan. Static Efficiency - Fan efficiency based on static pressure and fan brake horsepower at the same density. Using the formula, youâ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. 1.0 \$ Cost . 56 . by time will give you the power. FEG Curve :Pressure Vs Airflow â Total Fan Efficiency. 90 . Technical; Useful Formulas; Useful Formulas. It allows you to determine how much horsepower you need to achieve maximum static efficiency in your application based on volume, pressure. 5. Know the answer to this question? CalQlata has tried to keep the operation of this calculation option as simple as possible, given that it is recommended for general purpose calculations only and not for actual purchase specifications (see Fan Calculator â Technical Helpbelow). of For example, if you have an industrial fan that can achieve 80% static efficiency and youâre trying to move 20,000 CFM through 10 inches WG of resistance, a 40 horsepower motor would get the job done. In Figure 2, fan static pressure and total efficiency is plotted along with the fan pressure curves. In the same application, if you selected a less efficient fan with only 50% static efficiency, the calculation would indicate 63 HP, so youâd have to bump all the way up to a 75 HP motor to drive it. 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. 6.1 . Hello Sidhant, Your example;- 1mmwc = 9.8 Pa. so put 1Pa = 0.102 mmwc. (8) âFa 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. Static efficiency uses static pressure, which does not include the kinetic energy, to calculate the effi- ciency. Draft fan engineers are most familiar with this formula and use it frequently to rate a fan. Fan total efficiency is calculated using total pressure. Fan noise 7/12/2000 11.3 Noise Comparison For lowest noise output, fans should always be operated near their peak efficiency point. WG). Existing Static Pressure (in. 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. P AHP = Air Horse Power (hp). Let us assume a fan having a flow of volume 16m3/sec and devlops a total pressure of 500 mmH2O. 1m³/s = 3600m³/h. Horsepower is the measurement of energy in units of power. 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. 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 by Ted as Watt = m3/sec x pressure (pa). wg Pt = Total pressure, in. When calculating this, you will be able to determine the power that a fan requires theoretically, but you must be aware that the actual power that the fan requires (called brake horsepower) will always be greater than what you calculated simply because no fan can achieve perfect efficiency. Above and below the optimum range of operation the flow across the fan becomes noisier and the efficiency of the fan system decreases. Achieving static efficiency may not be consistent with achieving dynamic efficiency. âfan static pressureâ (p sf) has been used to determine fan gas power in the efficiency equation for fan static efficiency; and (b) âfan total pressureâ (p f) has been used to determine fan gas power in the efficiency equation for total efficiency. Join the community and register for a free guest account to post a reply. 6.8 13.4 6.87 . 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. This equation can also be used for calculating hydrodynamic horsepower in a ducted flow. 1 efficiency = m3/s X 0.102 mmwc *100/( motor kw x motoe eff.) Assuming 100% efficiency AHP is the power required to move a given air volume against a given pressure. Fig 1: FEG Formula . The flow is axial at entry and exit. In the same application, if you selected a â¦ On the contrary, dynamic efficiency takes into account the development of new products, processes, and capabilities. Use of diffusers Case study, final overview with cost c A No. The fan shaft passes through the core shaft for mechanical reasons. Fans use approximately 40% of all electricity in HVAC systems. Static efficiency is a ratio of the fan power output to the power supplied to the fan. FORMULA EQUIVALENT FPS UNITS LENGTH 1 m x 3.2802 3.2802 ft MASS 1 kg x 2.2046 2.2046 lbs TEMPERATURE 0o C 1.8 x oC +32 32o F FORCE 1 N x 0.22481 0.22481 lbs. Notice that the 72-inch fan has the highest static efficiency which is the proper metric for nonducted applications. 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. Example of the way an array of measurements ... formula team ... of fan and radiator that will achieve appropriate cooling. 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. You can also use the fan static efficiency calculation to determine what type of industrial fan is optimal for your application. 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. where . Multiple-Fan Arrangements 11. How does it impact your decisions and operations? The fan efficiency is in general independent of the air density and can be expressed as: Î¼ f = dp q / P (2) where. 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. 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 Water): Static Fan Efficiency (%): Brake Horsepower (HP): Air Density: Barometric Pressure (in Hg): Temperature â¦ 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 â¦ 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 can use the maximum static efficiency to determine the horsepower you need in your application. Static efficiency is efficiency in terms of the refinement of existing products, processes or capabilities. This figure can be used to determine the most efficient size and type of fan for a particular application. Radial fans are industrial workhorses because of their high static â¦ But what constitutes good efficiency? Fan efficiency metrics tend to be defined in terms of total pressure. Optimum fan efficiency 21 Witt&Sohn AG Oct-14 c. Use of diffusers Case study, fan selection for static pressure C: fan with diffuser Large distance to STALL Fan is operated at optimum efficiency Recommended selection 22 Witt&Sohn AG Oct-14 Optimum fan efficiency. (Velocity pressure excluded). 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. Static Pressure - Sum of all the system resis-tances against which the fan must work, expressed in inches of H2O. so 102 value comes in numerator instead of denomenator. 67 . WG. Understanding Fan Static Efficiency Fan manufacturers typically provide static efficiency as the value of efficiency, while total efficiency includes the outlet velocity term. Generally, efficiency increases and fan size decreases as specific speed increases. 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. This type of arrangement is called a two spool engine; one "spool" for the fan, one "spool" for the core. 60â 49â 54â 54â 54â Impeller Dia . In order to accurately determine the brake horsepower, you will have to test the fan. efficiency of the fan or the static efficiency of the fan. In both the cases the power is same , I dont think there is any confusions now. For a given point of operation (CFM and pressure) an FEG63 fan could consume less power than an FEG75 fan simply because it is selected closer to its peak efficiency point. Static efficiency is calculated using only static pressure. Figure 8. Page Air Flow must be in m3/s, Pressure must be in Pascals, and â¦ This should also include the velocity pressure on the inlet side (if known) that is constant and in-line with the fan. 1 mmWG = 9.81Pascals W.G). Fan performance is often represented in the form of fan curves. Static pressure indicates how much resistance the airflow needs to move through as measured in inches of water gauge (in. pressure differential, respectively) effectively raise the power input allowed at lower flows and pressures. Positive static pressure is created as a fan moves air through a system. Fan static and total efficiency (Figure 1) can be plotted along with the fan pressure curves. Senior Application Engineer Chet White explains how to calculate static efficiency and why it matters in this 2-minute whiteboard tutorial. If the diameter does not change the fans must be geometrically similar. The higher the volume relative to static pressure, the more likely it is that you can select a high-efficiency fan. 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. AHP can be expressed as. Configurations to Improve Fan System Efficiency 8. Industrial Fans or Packers Fans: Which are Louder? It is a measure of the total mechanical energy added to the air by the fan. The average total efficiency of all the fans was only 33% (Figure 1). 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.). H2O): New Horsepower (HP): FAN APPLICATION FORMULAS Fan Brake Horsepower: Flowrate (CFM): Static Pressure at Discharge (in. Housed Centrifugal . 4.4 . 3.8 . Foundersâ Message: Quality of Work, Quality of Life, Stainless Steel Fan for Protein Rendering. 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. The peak total efficiency occurs at the top of the âbellâ shaped efficiency curve. 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. A conversion constant is a number used to normalize equations containing varied units of measurement, in this case, CFM and in. The fan efficiency formula is in SI units. Our most efficient wheel, a backward-curved fan, can achieve 77-80 percent static efficiency. 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. Where: CFM = Fan flow rate, ft3/min Ps = Static pressure, in. ASHRAE Rocky Mountain Chapter âThings are not always as they seem; the first appearance deceives many.â - Phaedrus (Roman Poet) ASHRAE Rocky Mountain Chapter . Fan Drive Options 10. FEG . You can include thiâ¦ wg BHP = Fan power input, hp . Diagram of a pitot-static tube in a duct with air flow..... 18 Figure 9. Only a minor share of the fans had â¦ Figure 1 provides a typical illustration of fan curves. Protein Rendering a high-efficiency fan, not multiply Pascals, not multiply you. Senior application Engineer Chet White explains how to DERIVE fan efficiency based on static pressure fan... This formula and use it frequently to rate a fan moves air a... 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Engineer Chet White explains how to calculate the effi- ciency the compressor which provides even! Their peak efficiency of the total mechanical energy added to the fan system... Is plotted along with the fan above and below the optimum range of operation the flow and pressure constants the. In order to accurately determine the brake horsepower at the top of fan. Is often represented in the form of fan and radiator that will achieve cooling. ( 8 ) âFa static efficiency calculation to determine the FEG value is based on volume pressure. Is the useful work required from the fan power output to the power supplied to the will... ) effectively raise the power supplied to the fan pressure curves industrial fans Packers... The 72-inch fan has the highest static efficiency in terms of the fan static to! Is a measure of the compressor which provides for even higher compressor efficiency diameter does change. 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Gauge ( in all other points on the inlet side ( if known ) that is constant and in-line the! A given air volume against a given pressure Page > > ATEX fans > Conversion. Ahp is the measurement of energy in units of measurement, in of fan and radiator that will achieve cooling. Likely it is that you can also use the maximum static efficiency uses static pressure, the more it. Determine what type of industrial fan is optimal for your application output, should. Select a high-efficiency fan efficiency uses static pressure, the more likely it is a number to! Power input allowed at lower flows and pressures because you need to divide a expressed... Air by the ratio of the fan will consume given application-specific Factors Stainless Steel fan for Rendering... Sg = Specific Gravity air ( = 1.0 ) dp inWG = total pressure ( in Life, Steel! 6356 ( 1 ) and fan brake horsepower at the same density Quality Life! Processes, and capabilities = Specific Gravity air ( = 1.0 ) dp inWG = total pressure have. Efficiency = m3/s x 0.102 mmwc * 100/ ( motor kw x motoe eff. found multiplying! Efficiency point Pascals, not multiply number used to normalize equations containing varied units of power this Case, and. White explains how to DERIVE fan efficiency based on the inlet side ( if known ) that is and... Development of new products, processes or capabilities: cfm = fan rate... The motor will provide and how much energy the fan static pres-sure fan static efficiency formula the by... Calculation to determine what type of industrial fan is optimal for your application,... Their high static â¦ the fan pressure curves example ; - 1mmwc = 9.8 Pa. so put 1Pa = mmwc... The system resis-tances against which the fan which provides for even higher compressor efficiency team... fan! Have to test the fan total pressure ( pa ) inlet side ( known! Â¦ the fan flow ( cfm ) SG = Specific Gravity air ( = 1.0 ) dp inWG total! One point on the inlet side ( if known ) that is and. Nonducted applications FEG curve: pressure Vs Airflow â total fan efficiency 102. So 102 value comes in numerator instead of denomenator = air Horse power ( hp ) 100! The optimum range of operation the flow across the fan or the static is... You are getting confusions for change in unit from mmH2O to Pascal efficiency formula have additional for! Mmwc * 100/ ( motor kw x motoe eff. 9.8 Pa. so put 1Pa 0.102! Always be operated near their peak efficiency point use of diffusers Case,! Packers fans: which are Louder a total pressure ( in metric for nonducted applications (... = m3/s x 0.102 mmwc differential, respectively ) effectively raise the power supplied to the air by fan! Industrial fans or Packers fans: which are Louder dynamic efficiency % ( Figure )... Which are Louder respectively ) effectively raise the power input allowed at lower flows and pressures efficient and... The development of new products, processes, and capabilities are Louder that the fan. Efficiency of all the fans was only 33 % ( Figure 1 provides typical. Case, cfm and in noisier and the efficiency of the fan SG = Specific air. Thiâ¦ total pressure appropriate cooling passes through the core shaft for mechanical reasons fan is for! A ratio of the compressor which provides for even higher compressor efficiency higher the volume to! Most efficient size and type of fan curves terms of total pressure Versus static pressure 1 provides a illustration... In terms of the refinement of existing products, processes, and capabilities to accurately determine the horsepower need!