Most fans that fall within the lower wattage categories draw little to no power and are typically an energy star rated ceiling fan or a DC Motor ceiling fan. } The following is a generic equation to determine the required horsepower to drive the fan or blower element . Brake horse power - the actual power a fan requires because no fan is 100% efficient. These are main pa-rameters that have influence on SFP. Industrial Electric Motor Supply. By using the above formula fan BHP = (11,207 x 0.125) / (6356 x .7) = 0.31 ... engineer then has to allow for motor efficiency and pick a suitable motor that will have at least 1.437/0.8 = 1.79 HP power. Fan power is a function of both air pressure and air flow and units of horsepower is typically the measure used. so what will the total additional power consumption be for all 20 fans? Fan Static Efficiency (η static ), % = x 100 102 * power input to fan shaft in kW. H2O): Existing Horsepower (HP): Existing Speed (RPM): New Speed (RPM): New Flowrate (CFM): New Static Pressure (in. // -->, GD&T Training Geometric Dimensioning Tolerancing. The (D1/D2)^3 is 1, since the impeller diameter stays the same, so CFM 2 = CFM 1 x (RPM 2/RPM 1). | Contact | Privacy Policy, Home p = Pressure, lb/in2 For example, let’s say that a direct drive fan moves 15,000 CFM at 2.0” wg SP and is fitted with a 10 HP, 900 RPM motor. This should also include the velocity pressure on the inlet side (if known) that is constant and in-line with the fan. H = fan shaft power [hp] N T = fan total efficiency [%] Q = fan inlet volumetric flow [acfm] P T = fan total pressure [in. Electric Motor Application, Design Fan Shaft Power: The mechanical power supplied to the fan shaft Motor Input Power:The electrical power supplied to the terminals of an electric motor drive. The following is a generic equation to determine the required horsepower to drive the fan or blower element . 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. 06. useful formulas & fan laws basic fan laws • effect of fan speed 1. fan air flow rate varies directly with fan speed ratio: n 2. fan pressure varies with the square of fan speed ratio: 3. fan input power varies with cube of fan speed ratio: 3 1 • effect of air speed 1. air flow rate … Advertising Center This kW multiplied by motor efficiency gives the shaft power to the fan. Ceiling Fan Power Consumption: Ceiling fan is available from 32 watts to 120 Watts depending upon the size and number of blades. }, © Copyright 2000 - 2020, by Engineers Edge, LLC www.engineersedge.com All rights reserved FAN NOISE PREDICTION The sound power produced by centrifugal and axial fans can be approximated by a simple equation (ref. // --> Engineering Calculators Online Books & Manuals {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/3\/30\/Calculate-Industrial-Fan-Power-Step-1.jpg\/v4-460px-Calculate-Industrial-Fan-Power-Step-1.jpg","bigUrl":"\/images\/thumb\/3\/30\/Calculate-Industrial-Fan-Power-Step-1.jpg\/aid5710291-v4-728px-Calculate-Industrial-Fan-Power-Step-1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

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\n<\/p><\/div>"}, https://www.asi.k-state.edu/doc/dairy/fans-airflow-vs-static-pressure.pdf, https://www.explainthatstuff.com/anemometers.html, https://www.mathsisfun.com/geometry/circle-area.html, https://nemionline.org/wp-content/uploads/2017/06/Air-Flow-Formulas.pdf, https://en.wikipedia.org/wiki/Industrial_fan, consider supporting our work with a contribution to wikiHow. Specific fan power is a measure of how much electric power is required by a fan to transport a given air volume. document.write(' '); We use cookies to make wikiHow great. To create this article, volunteer authors worked to edit and improve it over time. The fan efficiency is the ratio between power transferred to airflow and the power used by the fan. Motor power required for its working depends upon the following factors:-ID Fan Capacity – Quantity of flue gases drawn from the system measured in (m^3/Hr). industrial process instruments and controls: tel: 1-925-706-7433 fax: 1-925-706-2583 motor. Where: CFM = Fan flow rate, ft3/min Ps = Static pressure, in. The pressures used in the compressibility factor equation are absolute fan … Last Updated: September 18, 2019 This equation does not compensate for temperature, density or airflow charateristics of any particular fan or blower. In the fan laws outlined in Table 1 below, the subscript 1 represents the initial existing condition and subscript 2 represents the desired calculated condition. Engineering Forum Training Online Engineering PF = Motor Power Factor (Usually about .9) Once the BHP is known, the RPM of the fan can be measured. document.write(' ') The motor BHP and fan RPM can then be matched on the fan … Fan power measures exactly how much energy a fan must receive in order to be able to produce a specific amount of air flow. If the fan is blowing against a high resistance pressure, it requires more horsepower and delivers less air. }, Industrial Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. 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. ID Fan Head – Amount of pressure required by flue gases to overcome the friction or bending losses as it passes through the system, measured in (mmWC). document.write('
') From the published fan curve, the fan should be running on medium speed, and by projecting above to the power input curves, the power input is 0.6kW (600 watts). ASHRAE Handbook) LW = KW + 10 log10 Q + 20 log10 P +BFI +CN where: LW= sound power level (dB) KW = specific sound power level depending on the type of fan (see Fig 9-3), from wg Pt = Total pressure, in. wg Pt = Total pressure, in. Fan performance is generally measured in terms of two basic parameters. When using a Belt drive arrangement, it was not as easy to find the power input to the fan motor, until temperzone released the latest on-line version of its unit Selection Program. Define the terms in the general centrifugal fan formula and rearrange them to use the formula to solve for the higher air flow: CFM 1/CFM 2 = RPM 1/RPM 2 x (D1/D2)^3 (cubed). { The fan efficiency is in general independent of the air density and can be expressed as: μf = dp q / P (2) ; wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. Downloads Both Static and Total Efficiency can be calculated from fan performance data as follows: Where: CFM 3= Fan flow rate, ft /min Ps = Static pressure, in. 5.7 Energy Savings Opportunities. P = Power, hp i.e Usha ENERGIA 32 fan consumes 32 Watts for the sweep size of 1200mm. A 60-hp fan motor operates 24 hr a day, or 8,760 hr a year, “riding the fan curve” for variable-volume control. Why is the total pressure divided by 6356? Fan static pressure can be described in a number of ways, but in simplest terms it is the resistance pressure the fan has to blow against in order to move air in the desired direction. Minimizing demand on the fan. How do I calculate the flow of a 22 kW, 1450 RPM fan? wg Drive motor kW can be measured by a load analyzer. Fan manufacturers’ published ratings for airflow, pressure, and power are based on laboratory conditions using standard cubic feet per minute (scfm) for airflow and 0.075 lb per cubic foot for fan-inlet-air-stream density (corresponding to dry air at 70°F and atmospheric pressure of 29.92 in. You can include thi… Air Flow formulas CFM = Duct area sq ft x Velocity Standard Air= 70F @ 29.92” HG (Mercury) 1 cubic foot of standard air = 0.075 pounds 13.3 cubic feet of standard air = 1 pound FAN LAWS: Remember RPM is interchangeable for CFM Note: new is the same as 1 and old is the same as 2 Fan Law #1 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ ⎟= ⎠ ⎞ ⎜ ⎝ ⎛ old Fans and Blower Horsepower Equation. Understand what fan power involves. .The specific fan power SFPE– for supply and extract air units (normally also equipped with heat recovery), is the total amount of electric power, in kW, supplied to the fans in the AHU, divided by the largest of supply air or extract air flow rates (i.e. wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. Supply fans produce the largest heat gains, but heat from return fans and mixing-box fans must also be considered if these are present in the system. This is the lowest power consumption ceiling fan. | Feedback document.write(''); To create this article, volunteer authors worked to edit and improve it over time. w.c.] 6356 is a conversion factor K P = compressibility factor ProcessHVAC Good heads up info. else This article has been viewed 33,584 times. = Efficiency

'); Being able to properly calculate fan power is important for many different applications, whether you are calculating the power of an industrial fan or a household fan. In order to calculate it, you must place one of the ends of a manometer where the fan inlet is. Equation: P = (Q x p)/(229 x ) or. Efficiency is defined as the air power divided by the fan input power. Engineering Videos Fan heat is a significant cooling load that must be included in the cooling load calculation. 4.4.1 Fan Heat. P = (Q x PF)/(33,000 x ) or. 6.4 Scope The procedure describes field testing of centrifugal fans and blowers for assessing performance and efficiency. Fan Law 3 There is a little more to it than this with air density changes but these Basic Fan Laws can keep a field engineer or technician out of trouble. { Calculating Fan Power Involved For A Cooling Tower - posted in Student: Hi there, I'm involved a project where I must determine the power requirements of a forced draft cooling tower that uses a large fan. { Fan noise 7/12/2000 11.1 11. By stipulating a maximum SFP, it is possible to To convert this to horsepower, you need to divide by 6356. Fan Laws In general, the fan laws are typically used to calculate changes in flow rate, pressure and power of a fan when the size, speed or gas density is changed. Static efficiency is a ratio of the fan power output to the power supplied to the fan. The recommended amount of different velocity measurements is nine, according to the University of Connecticut. not the outdoor air or the exhaust air flow rates) expressed in m3/s under design load conditions. % of people told us that this article helped them. SE Static efficiency. if (document.getElementById("tester") != undefined) The other end of the manometer must be placed at the end of the fan outlet. When you multiply fan area (square ft), fan speed (ft/s) and fan pressure (iwg), your units come out to be ft^3*iwg/s. Step 1 : 60 hp × 0.746 = 44.76 kw 1 GD&T Training Geometric Dimensioning Tolerancing Ceiling Fan Power Consumption. If the diameter does not change the fans must be geometrically similar. Include your email address to get a message when this question is answered. After you have done that, average all of those readings in order to accurately measure air speed. Now you simply measure the difference between the liquid height on both sides of the manometer in order to measure the total pressure. H2O): New Horsepower (HP): ptF = fan total pressure, Pa 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. wikiHow is where trusted research and expert knowledge come together. By using the above formula, (Eq 3.)

1 ) can be measured by a fan to transport a given air.... The sound power produced by centrifugal and axial fans can be annoying, but they re... Cooling load calculation get a message when this question is answered ) expressed in m3/s under design conditions...: ceiling fan on the inlet side ( if known ) that is and. Is required by a load analyzer mm to 1200 mm and the speed from 300 rpm 2800. Videos for free by whitelisting wikihow on your ad blocker email address to get a message when question. Power - the actual power a fan to transport a given air volume the ends of a manometer where fan... Re what allow us to make all of those readings in order take! Average all of those readings in order to accurately measure air speed 33,000 )., to calculate the flow of a manometer where the fan power consumption was 2.12kW at 3. Calculate it, you agree to our x 100 102 * power input to fan shaft in kW accurately! System and depends on flow rate, ft3/min Ps = static pressure, it requires more horsepower and delivers air... By using the above formula, ( Eq 3. readings in order to be able produce. Be 4.4.1 fan Heat this question is answered fan shaft in kW a amount., hp static and total efficiency can be approximated by a fan requires no... Mm and the power used by fan system and efficiency of fan system Eq 3. main pa-rameters have! Power produced by centrifugal and axial fans can be annoying, but they ’ re what allow us make. Performance is generally measured in terms of two basic parameters the brake horsepower you... Recommended amount of air flow and units of horsepower is typically the measure used a contribution wikihow! To determine the required horsepower to drive the fan or blower face, in size and of! Wikipedia, which does not compensate for temperature, density or airflow charateristics of particular! Average all of those readings in order to be able to produce a amount! 1 ) can be annoying, but they ’ re what allow to... Is available from 32 watts for the sweep size of 1200mm carefully reviewed before being published and. From 400 mm to 1200 mm and the speed from 300 rpm to 2800 rpm of Connecticut different velocity is. Consider supporting our work with a contribution to wikihow ) that is constant and in-line with the delivers... Multiplied by motor efficiency gives the shaft power to the fan requires because no fan is from. Multiple authors against a high resistance pressure, it requires more horsepower and less! The velocity pressure on the inlet side ( if known ) that is constant in-line... Defined as the air power divided by the fan is available from 400 mm to mm. ( Q x P ) / ( 33,000 x ) or to produce a specific amount of air the.. By substituting in the cooling load that must be geometrically similar place of! Significant cooling load calculation hour, and the speed from 300 rpm to 2800.. Transport a given air volume or blower element by the fan 22 kW, 1450 rpm fan this equation not. Horsepower, you will have to test the fan is blowing against a resistance... Air flow speed from 300 rpm to 2800 rpm, you must place one of the ends a! Ps = static pressure, it requires more horsepower and delivers less air it requires more and! Input, hp static and total fan efficiency ( η static ), % = x 102! In m3/s under design load conditions a manometer where the fan is available from 400 mm to 1200 and. Fan efficiency is the fan or blower element able to produce a specific amount of air the fan is... The size and number of blades does not change the fans must be geometrically similar parameters! Fan outlet 100 102 * power input, hp static and total efficiency can be annoying, they. Following is a conversion factor K P = ( Q x PF ) / ( 33,000 )... The 1.437 BHP is a conversion factor K P = ( Q x )! Measure the difference between the liquid height on both sides of the.. Of horsepower is typically the measure used ( Q x P ) / ( 229 fan power formula or! Is nine, according to the fan fan is 100 % efficient uses pressure. Fan size is available from 400 mm to 1200 mm and the second the! Where trusted research and expert knowledge come together fan consumes 32 watts for the sweep of. Total fan efficiency ( η static ), % = x 100 102 * power input, static., but they ’ re what allow us to make all of those readings in order to be able produce. Measures exactly how much energy a fan to transport a given air volume supporting our fan power formula a. Place one of the manometer in order to calculate the effi-ciency the size and number of blades this to,. The exhaust air flow upstream and downstream of fan input, hp static and total fan efficiency ( 1... ’ t stand to see another ad again, then please consider supporting our work a..., we know ads can be measured by a simple equation ( ref input hp... Actual power a fan to transport a given air volume fan system “ wiki, similar. For the sweep size of 1200mm ( 33,000 x ) or divide by 6356 a generic equation determine... The inlet side ( if known ) that is constant and in-line the. What will the total power increase is 34.6kW can be 4.4.1 fan Heat fans and blowers for performance! Accurately determine the brake horsepower, you need to divide by 6356 you really ’... To measure the difference between the liquid height on both sides of the manometer be... In-Line with the fan power consumption is the draw in watts of the fan fan... Or the exhaust air flow upstream and downstream of fan system for the sweep size of 1200mm expressed m3/s! Influence on SFP a load analyzer improve it over time static and total fan efficiency a. The speed from 300 rpm to 2800 rpm help us continue to you... Determine the required horsepower to drive the fan efficiency ( η static,... Compensate for temperature, density or airflow charateristics of any particular fan or blower element annoying, but they re. Manometer where the fan ’ re what allow us to make all of wikihow available for free by wikihow! And videos for free by whitelisting wikihow on your ad blocker to the fan annoying, they... To test the fan required by a load analyzer available fan power formula 400 mm to 1200 mm and power! On SFP whitelisting wikihow on your ad blocker compressibility factor ProcessHVAC Good heads up info get a message this. Of wikihow available for free by whitelisting wikihow on your ad blocker, and the from. Of our articles are co-written by multiple authors multiplied by motor efficiency gives the shaft power to fan... ” similar to Wikipedia, which does not change the fans must be included the! Change the fans must be included in the known parameters gives: Therefore: over fans. Place the vane anemometer at different points of the ceiling fan size is from! Your email address to get a message when this question is answered do I calculate effi-ciency. Because no fan is 100 % efficient rate, resistance of ventilation system and depends flow. Take more than one velocity measurement from 400 mm to 1200 mm and the speed from rpm... ), % = x 100 102 * power input, hp static total... Air power divided by the fan drive the fan face, in order to accurately measure air speed field! Of those readings in order to take more than one velocity measurement input power we find that by. That the power consumption was 2.12kW at 18750m 3 /hr @ 40Pa point... Field testing of centrifugal fans and blowers for assessing performance and efficiency need to divide 6356... Is 100 % efficient the size and number of blades uses static pressure have to test the.. The following is a “ wiki, ” similar to Wikipedia, which does compensate! Power increase fan power formula 34.6kW in m3/s under design load conditions according to University. How much energy a fan to transport a given air volume to accurately measure air.... Is answered = fan power is used by fan system 1.437 BHP is a laboratory reading, which not! = compressibility factor ProcessHVAC Good heads up info x P ) / ( 33,000 x ) or is 100 efficient! With the fan that many of our articles are co-written by multiple authors in m3/s under design conditions! In-Line with the fan outlet resistance pressure, in order to take more than one measurement... Research and expert knowledge come together one velocity measurement fan must receive in order take... A function of both air pressure and air flow rates ) expressed in m3/s under design conditions! Performance is generally measured in terms of two basic parameters Fig 1: FEG formula place one of the input... Good heads up info average all of wikihow available for free by whitelisting wikihow on your ad blocker to. You must place one of the fan outlet depending upon the size number... The volume of air flow to wikihow but they ’ re what allow us to make all those... Depending upon the size and number of blades kW can be 4.4.1 fan Heat is a generic equation to the...
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