ADI DUCTULATOR. Based on research conducted by Texas Tech University as well as Tennessee Tech University, to study the efect of compression in flexible duct on air flow efficiency, ADI created the Ductulator. This Duct Size Calculator's data is based on flexible duct laying in a straight line on a level surface,and nearly fully stretched (4% ...Air duct pressure loss. Friction loss calculation is made in rectangular or round ventilation ducts. Fill in the form below. Unit system. : Duct type. : Duct position.The Duct Sizing Calculator is a hand held sliding calculator used for sizing supply and return duct systems using the equal friction, or velocity reduction design method. Front of calculator includes scales for friction, velocity, round duct size, weight per linear foot of round duct, surface area in square feet per lineal foot of round duct ...By multiplying air velocity by the cross section area of a duct, you can determine the air volume flowing past a point in the duct per unit of time. Volume flow is usually measured …Aug 21, 2023 · Cleaning helps not only remove them, but may also remove blockages that can help make your system run more efficiently. Keep reading to learn more about the cost of duct cleaning services. 2024 Duct Cleaning Costs. Calculate local project costs by entering your zip code. Typical Price Range. $ 450 - $ 1,000. Formula. The formula for air duct sizing involves the calculation of air velocity (V) and duct cross-sectional area (A) to determine the air volume flow rate (Q), expressed in cubic feet per minute (CFM). Q = A × V. This equation comes from the principle of continuity in fluid mechanics which states that for incompressible flow, the product of ... The velocity of an air duct with area 16 sq.ft and air flow of 10 CFM would be : V = 10 / 16 = 0.625 FPM. When converted to FPS, it is 0.0104 FPS. Air duct also termed as ductulator is a passage that is used to provide fresh air into rooms, buildings etc., Air ducts may be in circular, square and in rectangular shapes. Enter the square footage and height of your kitchen. Select the type of heating equipment. Specify the number of hood duct turns or ignore it. Click the " Calculate " button. Kitchen Range Hood calculator will help you estimate the exhaust ventilation capacity by kitchen size to remove heat, odors, moisture, and smoke.Duct and vent cleaning costs $25 to $45 per vent or $0.15 to $0.25 per square foot. Air duct sanitizing costs $70 to $150 more to prevent mold growth. An air duct inspection costs $80 to $180. Cleaning the HVAC system costs $60 to $370 more for a furnace or AC unit. Air duct cleaning cost - chart.This calculator allows for calculating the mixed air temperature of a third air source. An example of a third air stream is a Bypass air duct that goes from the supply air plenum back to the return air plenum. Trane has an excellent Engineers Newsletter describing Dehumidify with Constant-Volume Systems.Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator. Ducts or Pipes through Steel Joists - Maximum Sizes. Maximum sizes of …Duct Calculator Elite TM is an industry leading tool designed to simplify the job of duct sizing for HVAC professionals. This app allows users to calculate duct size, velocity, pressure drop, and flow rate for ductwork . Duct Calculator Elite TM features a highly intuitive interface which allows users to easily enter values with precision (without the …mdot = Q / (cp x Δt) Calculate air mass flow rate from cooling load.AllDuctCalc™ - HVAC Air Duct Calculator v2 Updated 10/26/15: Provide inputs in the blue boxes, other inputs optional.The Duct Pressure Loss Calculator is an essential tool used to estimate the pressure drop or loss that occurs within a duct system due to various factors such as friction, length, diameter, velocity of airflow, and gravity. Its primary function is to calculate the pressure loss (ΔP) occurring in the duct, offering insights into the system’s efficiency.The Duct Size Calculator is a quick reference tool for approximating duct size and equivalent sizes of sheet-metal duct and flexible duct. A new duct-sizing calculator from ASHRAE and the Air Distribution Institute (ADI) allows HVAC air-distribution-system designers to size ducts more accurately, especially flex ducts under …Enter the square footage and height of your kitchen. Select the type of heating equipment. Specify the number of hood duct turns or ignore it. Click the " Calculate " button. Kitchen Range Hood calculator will help you estimate the exhaust ventilation capacity by kitchen size to remove heat, odors, moisture, and smoke. Adjustable Absolute Duct Roughness. If selected, Flexible roughness is 0.003 ft when. straight and fully stretched tight at 0% compression. (adjusted at other compressions), otherwise the. original method of constant 0.01 ft roughness is used. Use ASH RAE 2013 Flex Compression. QUICK-GUIDE. Select the duct material from the drop-down list (most duct sizing tools are typically based on galvanised steel ducting by default) Enter the air flowrate in cubic feet per minute (CFM) Enter an internal duct size in inches (this must be limited to a maximum aspect ratio of 5:1 for the results to be valid) The resulting velocity ... Highlights. Your air ducts deliver cool and hot air throughout your home. There are sheet metal, fiberglass-lined, fiberboard, and flexible ducts. Some signs you need a cleaning include dirty vents and a pest infestation. Air duct cleaning costs $380 on average and ranges between $270 to $490. A rectangular 6×6-inch duct has an airflow of 110 CFM. Bigger 6×12-inch ducts can handle 270 CFM airflow. The bigger the crosssection of ducts, the bigger CFM; that’s pretty obvious. The smallest 6×4 ducts can handle 60 CFM airflow. The biggest 42×12 ducts with 504 sq inch crosssection can handle 3000+ CFM airflow. A good HVAC duct sizing rule of thumb is to measure rooms in your home, the necessary airflow rates, and friction loss rate. Using these numbers you can calculate the appropriate HVAC duct size. For example, a one-to AC system typically uses 10-inch ducts, while a 4-ton AC system requires 18-inch ducts. There are several variables to …Air flow rates: information is provided on recommended air flow rates for each duct size. These flow rates are related to the volume of air needed for the HVAC system to maintain thermal comfort and air quality. Air speed: the graph illustrates the air speeds that can be obtained for the different dimensions of the ducts and air flow rates.Duct Calculator Elite TM is an industry leading tool designed to simplify the job of duct sizing for HVAC professionals. This app allows users to calculate duct size, velocity, pressure drop, and flow rate for ductwork . Duct Calculator Elite TM features a highly intuitive interface which allows users to easily enter values with precision (without the …Example of big metal round and rectangular ducts (3,000+ CFM airflow). To figure out exactly how big ducts you need for central air conditioning systems, we have prepared complete CFM duct charts for all different kinds of ducts:. Duct sizing chart for flex ducts (round ducts with 5-20 inch diameter).; Duct sizing chart for metal ducts (round ducts …2. Calculator of different ventilation parameters, with which will be able to obtain the diameter, the air speed, the airflow and the dynamic pressure of your installation. 3. Pressure drop calculation tool for installations with …Duct Calculator - CDI Curbs. Air Duct Calculator. Flexible Duct Friction Loss Calculator. 1. Enter Friction Loss Per 100' of duct (inches of water), Duct Airflow (CFM), Duct Length …50°F (27.8°C) 2″ (50mm) Recommended Duct Insulation Thickness for Concealed Ducts. So, if my dew point is 77°F (25°C) and the supply air temperature is 59°F (15°C), the temperature difference is 18°F (10°C) which is below 30°F (16.7°C). Therefore, my duct insulation should be 1″ (25mm) thick.Duct Sizing Calculator. The duct sizing calculation involves determining the proper ductwork size needed for an HVAC system. The formula used in this calculation is Q=VA, where Q is the airflow rate, V is the air velocity, and A is the area of the duct. Formula. The formula for air duct sizing involves the calculation of air velocity (V) and duct cross-sectional area (A) to determine the air volume flow rate (Q), expressed in cubic feet per minute (CFM). Q = A × V. This equation comes from the principle of continuity in fluid mechanics which states that for incompressible flow, the product of ... The pressure drop across a valve can be calculated using the valve’s Cv (flow coefficient) value and the flow rate. The equation is: Pressure Drop (psi) = (Cv × Q^2) / (SG × ΔP) where Q is the flow rate (in gallons per minute), SG is the specific gravity of the fluid, and ΔP is the pressure drop across the valve.Duct-U-Lator. This app works as a Ductulator and Pressure Loss (friction) calculator which has the following functions. Converts Duct Shape or Size to Another. Determines Sizes for a Given Friction Rate. Determines Sizes for a Given Velocity. Determines Sizes for a Given Velocity and a Friction Loss Rate (simultaneous output)Lindab Vent Tools app streamlines ventilation system calculations with practical tools for HVAC professionals. This handy app offers a collection of practical calculation tools for the HVAC industry, including duct dimensioning, pressure drop, airflow, and offset calculation for Lindab's products. The app also includes a k-factor calculator for versatile use …This article provides information on how to use the Ductwork Calculator for air flow CFM, friction loss and velocity. It explains the process of duct sizing diameter with accurate results when the right information is plugged into it. The article also gives a detailed explanation of each step in the process and what data … See moreDuct Sizer ( Ductulator) for HVAC air ducts. It is designed for calculating and sizing duct dimensions according to air volume CFM, roughness, velocity, etc. It is available in SI and British IP units. Duct sizing needs a ductulator or software but this excel calculator performs the same calculations.2. Calculator of different ventilation parameters, with which will be able to obtain the diameter, the air speed, the airflow and the dynamic pressure of your installation. 3. Pressure drop calculation tool for installations with …September 17, 2023 by GEGCalculators. Converting round to rectangular duct sizes depends on specific design factors. As a rough approximation, a round duct with a diameter of 6 inches might correspond to a rectangular duct of 8×4 inches, but these conversions vary based on project requirements. Precise calculations should be made using HVAC ...To adequately calculate the speed of air in ducts, we have to primarily calculate the cross-section of the duct. Shape-wise, ducts can be: Round. The area of round flex ducts is calculated as π*R 2 where R is the radius of the duct. Example: 10-inch round duct has a radius of 5 inches.The equivalent diameter of a rectangular tube or duct can be calculated as (Huebscher) de = 1.30 (a b)0.625/ (a + b)0.25(1) where. de = equivalent diameter (mm, inches) a= length of major or minor side (mm, inches) b= length of minor or major side (mm, inches) Hydraulic diameter - the "characteristic length" used to calculate the dimensionless ...Undersized return air ducts result in the ducts and grills being more noisy than usual and the air conditioner components becoming stressed, thus reducing the lifetime of the unit. Use our handy return air duct size calculator or charts below to help you determine the correct return air vent size for your home.An HVAC duct calculator or ductulator is a tool that can be used to calculate the ideal size of your HVAC ducts. It factors in the area size and temperature, air flow velocity, friction loss, and static pressure of the HVAC system.Quickly find the duct diameter best suited to your needs, based on the desired air flow rate and the air velocity in the network. The tool will give you the diameter best suited to your …Ducting Calculators and Air Volume Converter. Nordfab can offer technical assistance with determining whether our ducting is best for your application and with designing duct installations. Please contact us with your requirements. Input CFM Input Velocity (FPM) Ideal Round Duct Diameter Duct Friction in Straight Duct. Calculate. For 1000 CFM, we need 1650.12 FPM to 11,459.16 FPM, if we use 4-10 inch round ducts. This is quite an enormous air velocity (11,459.16 FPM is equal to 130 miles per hour (mph)). Now, let’s have a look at the 2nd part for rectangular air ducts, starting with the 2nd calculator: Air Ducts - Cross Sectional Areas; Example - Generated Noise in Duct by Air Flow. The cross section area of a 200 mm duct can be calculated as. A = π ((0.2 m) / 2) 2) = 0.0314 m 2 The noise generated in the duct with an air flow velocity 10 m/s can be calculated as. L N = 10 + 50 log (10 m/s) + 10 log (0.0314 m 2) = 45 db The noise generated in the same … The Digitized Ductulator is a free online calculator for sizing HVAC ducts. Use it in one of two ways; either enter the duct size to find the equivalent CFM, or input the CFM to find the right size of rectangular, round or flex duct. Click here to use the Ductulator. Use the right size duct. Duct that's too big, or too small can cause problems ... A duct calculator is a tool used to determine the correct size of ducts in an HVAC system. How do I use a duct calculator? You’ll need to know the air volume flow rate, the velocity …Duct-U-Lator. This app works as a Ductulator and Pressure Loss (friction) calculator which has the following functions. Converts Duct Shape or Size to Another. Determines Sizes for a Given Friction Rate. Determines Sizes for a Given Velocity. Determines Sizes for a Given Velocity and a Friction Loss Rate (simultaneous output)Download HVAC Duct Quantities, Weight and Area Calculation Sheets. Air Duct quantity can be estimated in sq. meters or kilograms. These excel sheets will enable you to calculate or estimate the duct weight or the duct surface area.HVAC Ductwork Sizing Calculator. On this page: How to size your HVAC ductwork? Understanding measurement units for ducts. Using Modernize's HVAC and …Duct and vent cleaning costs $25 to $45 per vent or $0.15 to $0.25 per square foot. Air duct sanitizing costs $70 to $150 more to prevent mold growth. An air duct inspection costs $80 to $180. Cleaning the HVAC system costs $60 to $370 more for a furnace or AC unit. Air duct cleaning cost - chart.TO CALCULATE DUCT SIZE: Enter Air Quantity (Flow Rate) Enter either Friction Loss or Velocity. The software will automatically detect the calculation method; Click Calculate …The Duct Area Calculator is a powerful tool designed to help individuals and professionals in the HVAC industry determine the cross-sectional area of rectangular and circular ducts. This essential calculation aids in optimizing airflow, ensuring efficient ventilation systems, and maintaining optimal indoor air quality.Calculate the equivalent size of spiral ducting when you have only been given the rectangular duct dimension (it works the other way also) ... Mechanical Air Supplies Ltd is a company registered in England & Wales. Co. Number 2711708 | VAT No. : 608 9556 06. V = 0.408 Q/D 2. Components. = Air velocity inside the duct (feet/s) = Air flow rate inside the duct (GPM) = Air flow rate inside the duct (inches) Metric Equation. Determine the following formula, which can be used to calculate the air duct velocity: V = 1.274 Q/D 2. Components. Enter the air flowrate in litres/second (can change to cubic metres/second by use of drop-down to the right of the input) Enter an internal duct diameter (this can be any number, it doesn’t need to be standard duct size) To get an idea of the equivalent rectangular duct size, adjust the aspect ratio. Note that only aspect ratio up to 5:1 are ...Minor or Dynamic losses in duct systems are pressure losses caused by. Minor or dynamic pressure loss in air duct system components can be expressed as. Δpminor_loss = ξ ρ v2 / 2 (1) where. ξ = minor loss coefficient. Δpminor_loss = minor pressure loss (Pa (N/m2), psf (lb/ft2)) ρ = density of air (1.2 kg/m3, 2.336 10-3 slugs /ft3)AIR DUCT CALCULATOR : by Michael J. Rocchetti PE Mechanical Engineer . Metric Units. Flow rate M^3/S: Velocity M/S: Pressure Pascals: Temperature C: Length Meter: Duct Material: Uncoated Carbon Steel: PVC Plastic Pipe (smooth) Aluminum (smooth) galvanized steel (medium smooth) galvanized steel (average smooth) fiberglass duct …Kurb Air Duct Calculator. ductulator.app. Calculation Method. Static Pressure Loss [inW/100ft] Air Flow [CFM] 3000 FPM. Round Duct Air Velocity. Infinity FPM. …About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright ...The Ultimate HVAC Duct Calculator Guide: Increase Efficiency and Improve Airflow. HVAC duct calculators play an essential role in determining the proper size of ductwork for heating, ventilation, and air conditioning systems. Properly sized ducts are critical to maintaining optimum airflow, improving energy efficiency, and ensuring the …How Much Does an HVAC Replacement Cost in 2024? Average Cost Range: $6,465 - $11,877. Use the calculator below for a more accurate local estimate. Use Modernize's 2024 cost calculator to get accurate HVAC replacement cost. Get local price ranges by zipcode for cooling, heating or both!Duct Sizing Calculator. The duct sizing calculation involves determining the proper ductwork size needed for an HVAC system. The formula used in this calculation is Q=VA, where Q is the airflow rate, V is the air velocity, and A is the area of the duct. Sheet Metal Duct Friction Loss Calculator. 1. Enter Duct Airflow (CFM), Duct Velocity (FPM), Duct Length and the number of bends. 2. Read Round Duct Diameter (inches) and Friction Loss Per 100' of duct (inches of water). 1. Enter Friction Loss Per 100' of duct (inches of water), Duct Airflow (CFM), Duct Length and the number of bends. Duct CFM @ .08 supply .05 return. This calculator does not replace good ACCA manual D or SMACNA principles. It does however provide basic duct sizes and CFMs based on these principles. This calculator can be used to estimate CFM or duct size using round Metal or Flexible "properly installed" typical duct runs. For 1000 CFM, we need 1650.12 FPM to 11,459.16 FPM, if we use 4-10 inch round ducts. This is quite an enormous air velocity (11,459.16 FPM is equal to 130 miles per hour (mph)). Now, let’s have a look at the 2nd part for rectangular air ducts, starting with the 2nd calculator: Now, to properly calculate the return grille size, we have to make these two assumptions: Face velocity is 500 FPM (feet per minute). This is the speed at which the return grille sucks the air from your house into your ducts. Free grille area is 70%. As we know, the grille is always bigger than the duct through which the airflow flows.Air Duct Calculator -Slide Rule Style. This rectangular air duct calculator is the technicians favorite. Provides the following information with one setting:- Friction- Velocity- Round Duct Size- Surface Area...and more. Size: 4" x 8.5". ISBN No. 9781622709823Sturdy construction of heavyweight calculator board with 6 metal eyelets. Enter the air flowrate in litres/second (can change to cubic metres/second by use of drop-down to the right of the input) Enter an internal duct diameter (this can be any number, it doesn’t need to be standard duct size) To get an idea of the equivalent rectangular duct size, adjust the aspect ratio. Note that only aspect ratio up to 5:1 are ... Highlights. Your air ducts deliver cool and hot air throughout your home. There are sheet metal, fiberglass-lined, fiberboard, and flexible ducts. Some signs you need a cleaning include dirty vents and a pest infestation. Air duct cleaning costs $380 on average and ranges between $270 to $490.October 9, 2023 by GEGCalculators. The size of a return air duct should generally be based on the HVAC system’s capacity. A common rule of thumb is to aim for approximately 400-450 CFM (cubic feet per minute) of airflow per ton of HVAC capacity. For example, a 2-ton system might require a return duct with a size of around 16 inches in diameter.The velocity reduction method can be used when sizing air ducts. Equivalent Diameter - Rectangular vs. Circular HVAC Ducts Rectangular equivalent diameter for air flows between 100 - 50000 cfm. Fluid Flow - Equivalent Diameter Convert rectangular and oval duct geometry to a equivalent circular diameter - online calculator with imperial and SI ...Apr 6, 2024 · The Duct Size Calculator is a quick reference tool for approximating duct size and equivalent sizes of sheet-metal duct and flexible duct. A new duct-sizing calculator from ASHRAE and the Air Distribution Institute (ADI) allows HVAC air-distribution-system designers to size ducts more accurately, especially flex ducts under varying amounts of ... The Ductulator - Duct Sizing Calculator is a hand held rotating calculator used for sizing supply and return duct systems using the equal friction design method. This accurate, easy-to-use duct size calculator includes scales for friction loss per unit length, air volume, air velocity, round duct diameter and rectangular duct diameters.The head loss calculator below is based on formula (1) : Air Volume Flow - q - (cfm) Equivalent duct diameter - d e - (inches) Duct Length - (feet) Equivalent Diameter - … Duct Calculator EliteTM is an industry leading tool designed to simplify the job of duct sizing for HVAC professionals. This app allows users to calculate duct size, velocity, pressure drop, and flow rate for ductwork . Duct Calculator EliteTM features a highly intuitive interface which allows users to easily enter values with precision ... The Digitized Ductulator is a free online calculator for sizing HVAC ducts. Use it in one of two ways; either enter the duct size to find the equivalent CFM, or input the CFM to find the right size of rectangular, round or flex duct. Click here to use the Ductulator. Use the right size duct. Duct that's too big, or too small can cause problems ...HVAC Ductwork Sizing Calculator. On this page: How to size your HVAC ductwork? Understanding measurement units for ducts. Using Modernize's HVAC and …Air Duct Elbow Loss. Calculation of pressure loss in elbows on ventilation ducts. Fill in the form below. Wid. (W)/Heig. (H) Calculation of local losses in elbows in ventilation ducts.Air Flow Conversion Calculator. CUI Devices' air flow conversion calculator can be used to convert between common units for volume air flow and air velocity flowing past a point in a specified area of duct. To use the calculator, enter your air velocity or volume air flow and duct area/type, select your units, click calculate air flow, and your ...The chart below can be used to estimate velocities in air ducts. The default values are for air flow 400 cfm (680 m3 /h) , duct size 8 in (200 mm) and velocity 1150 fpm (5.8 m/s) . Download and print Air Ducts - Velocity …The Digitized Ductulator is a free online calculator for sizing HVAC ducts. Use it in one of two ways; either enter the duct size to find the equivalent CFM, or input the CFM to find the right size of rectangular, round or flex duct. Click here to use the Ductulator. Use the right size duct. Duct that's too big, or too small can cause problems ... Formula. The formula for air duct sizing involves the calculation of air velocity (V) and duct cross-sectional area (A) to determine the air volume flow rate (Q), expressed in cubic feet per minute (CFM). Q = A × V. This equation comes from the principle of continuity in fluid mechanics which states that for incompressible flow, the product of ... Air Duct Calculator. Double-sided. Side 1 = standard ducloator with calculations for both round and rectangular duct. Side 2 = Continental vs competitive cross reference for some common GRDs and a Grille sizing chart. Qty 25/package. Calculation of pressure drops of flowing liquids and gases in pipes and pipe elements (laminar and turbulent flow). New version of Online Calculator is available: www.pressure-drop.online. Pressure Drop Software for Excel: Druckverlust Software …Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator. Ducts or Pipes through Steel Joists - Maximum Sizes. Maximum sizes of …Nov 11, 2023 · The Duct Area Calculator is a powerful tool designed to help individuals and professionals in the HVAC industry determine the cross-sectional area of rectangular and circular ducts. This essential calculation aids in optimizing airflow, ensuring efficient ventilation systems, and maintaining optimal indoor air quality. The pressure losses in ducts are caused by friction between the air and the duct surfaces, as well as by fittings and bends in the duct system. How do you calculate CFM from pressure drop? CFM (Cubic Feet per Minute) can be calculated from pressure drop using the fan laws, which relate CFM, pressure, and fan performance.HVAC Ductwork Sizing Calculator. On this page: How to size your HVAC ductwork? Understanding measurement units for ducts. Using Modernize's HVAC and …Mar 25, 2024 · The ductulator calculator is a specialized tool used in the HVAC industry to determine the most efficient duct sizes for air distribution within a space. It helps calculate the perfect balance between duct size, air velocity, and airflow, ensuring the HVAC system operates at peak efficiency. This balance is crucial for maintaining comfortable ... Enter the air volume in CFM [l/s]. Select an input criteria and enter its value. Optional: Enter a constraining rectangular duct dimension in inches [cm] Click the Calculate button. …
Jul 22, 2022 · Step 1: CFM – System Size & Blower Size. Sizing an HVAC System. Step 2: Maximum Friction Rate. Friction Rate and Ductwork Length. What is TEL? Step 3: Maximum Velocity. Summary of Ductwork Sizing Factors. Our Recommendation. The Pick HVAC Ductwork Calculator. . Best photo filter apps
JP Lamborn Co. ( JPL ) began producing flexible air ducts in 1961. Today the company operates four state-of-the-art manufacturing facilities and is the largest family-owned flexible air duct manufacturer in North America. JPL’s core values of manufacturing high-quality products, providing excellent service, innovation, and strong business ...V = 0.408 Q/D 2. Components. = Air velocity inside the duct (feet/s) = Air flow rate inside the duct (GPM) = Air flow rate inside the duct (inches) Metric Equation. Determine the following formula, which can be used to calculate the air duct velocity: V …The air duct calculator, or “ductulator,” is a commonly used tool for designing and installing duct systems. Unfortunately, many designers and technicians receive limited instructions on its correct use. This lack of instruction frequently results in duct systems that fail to perform as intended. It’s typical to find that delivered airflow into …Duct Calculator Elite https://apps.apple.com/us/app/duct-calculator-elite/id665701601The Ductulator - Duct Sizing Calculator is a hand held rotating calculator used for sizing supply and return duct systems using the equal friction design method. Includes scales for friction loss per unit length, air volume, air velocity, round duct diameter, and rectangular duct diameters. One side uses English units, the other side uses ...Ductulator - Duct Diameter Calculator. Enter the required volume & velocity to see the necessary duct diameter. Required Air Volume. m³/sec m³/hr. Required Air Velocity. m/sec. Duct Diameter. mm. Health and Safety Executive recommended minimum duct …CFM (10×12 Duct, 500 FPM) = 500 FPM × 10 Inches × 12 Inches / 144 = 416.67 CFM. We can see that the 10×12 duct generates 416.67 CFM of airflow at 500 FPM air speed. Now, we did a huge amount of calculations for these rectangular ducts at 1 FPM, 500 FPM, and 2000 FPM, and gathered all the results in this feet per minute to cubic feet per ...The equivalent diameter of a rectangular tube or duct can be calculated as (Huebscher) de = 1.30 (a b)0.625/ (a + b)0.25(1) where. de = equivalent diameter (mm, inches) a= length of major or minor side (mm, inches) b= length of minor or major side (mm, inches) Hydraulic diameter - the "characteristic length" used to calculate the dimensionless ...While air duct cleaning and repair lengthens its life span, ductwork typically needs major replacement every 15 years to work properly. The national average cost for full ductwork replacement is $1,450–$8,000; however, the cost can range anywhere from $250–$12,000 depending on home size, system accessibility, and materials used.Duct Calculator - CDI Curbs. Air Duct Calculator. Flexible Duct Friction Loss Calculator. 1. Enter Friction Loss Per 100' of duct (inches of water), Duct Airflow (CFM), Duct Length …Duct Size Chart. Do your own calculations and compare them to our chart – or use the chart for quick, accurate calculations for duct size based on CFM needed for a room. One size is given for round ducts, its diameter. You have two or three options for rectangular ducts that give you the same or nearly the same square footage per duct.The equal friction method for sizing air ducts is often preferred because it is quite easy to use. The method can be summarized to. Compute the necessary air volume flow (m 3 /s, cfm) in every room and branch of the system; Use 1) to compute the total air volume (m 3 /s, cfm) in the main system; Determine the maximum acceptable airflow velocity in the ….