Duct Pressure Loss Chart Pdf


Most of the instruments can measure DP, temp,air flow and velocity. The low-velocity systems HVAC Ducting Principles and Fundamentals Duct System Design Basics. Duct-sizing charts are based on this law. Vanstone or other proprietary connections are available. A one-way duct system can be where the equipment is placed at one end of the structure, or when the ducting feeds one-way out from a mechanical room to a tee which feeds two ways. Minimum bend radius to center line is one diamater. U of I bulletin. feet (each elbow = 5 feet). INSTALL MALE FITTINGS IN CORRECT DIRECTION. The pressure loss in piping increases depending on connected pipe length and operation capacity of the compressor. Residential Heat Loss & Heat Gain. However, great care must be taken when installing a flexible duct system. The terms pipe, duct,and conduit are usually used interchangeably for. Therefore the pressure loss is 0. The major loss, or friction loss, in a circular duct in galvanized steel with turbulent flow can for imperial units be expressed. Hood static pressure •O m for:rhest – The losses are characteristic of the hood shape and are defined as the hood entry loss He (e=entry) –He is caused by dynamic losses and turbulence in the inlet. A liver parasite. CFA: Conditioned floor area. smacna-duct-construction-standards-2005-pdf 2/12 Downloaded from www. planer, bandsaw, table saw), 2 inches is a good general number to plan your duct design by. w4 = P (_zJQ3/2W +3H) 2 (5) 103Sd - 4Jfl Unlike Equation 4 for the rou11d duct, it is difficult to i11cor-Pressure Loss Pressure Path Sections Differential ' (Pa) (Pa) 1 5. d e = equivalent duct diameter (inches). For pressure design of this heavy wall pipe consult the standard. Smacna Duct Design Fitting Loss Coefficients PDF N REPS. com 290 Corporate Drive s PO Box 7408 s Lumberton, NC 28358 TITAN FLOW CONTROL, INC. Most of the instruments can measure DP, temp,air flow and velocity. (Final Report on ASHRAE Research Project No. There can be large savings for both these components if the particular design is at the limit of a pipe/duct size, and right-sizing of the HVAC system resulted in a step down in size for the main branches. For most pipe runs there will be multiple minor loss elements connected by sections of straight pipe. For conventional applications including low frequency. To determine the pres-sure drop for a given GPM the following formula may be used. (500 Pa) limits of the fibrous glass duct system; the fibrous glass duct system may be used on the low pressure side; and insulated flexible ducts may be used as run-outs from trunk ducts to diffusers. 27 inches, resulting in a static pressure downstream from the filter of 0. , square versus 45° entry taps, conical versus straight taps, etc. Temperature: Barometric Pressure °C: mb : Air Density = kg/m 3. 1 Zoning 22. 4) AHU and Duct Selection. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features Press Copyright Contact us Creators. With over 80 years’ experience, Iplex has an excellent understanding of the challenges the water industry faces. Seals Multiple Conduits Can seal conduits of all sizes and is reenterable. of water (50 ft of EL) – Mentions Entrance Fitting • ACCA Manual D, Residential Duct Systems (2009) – Residential Industry Standard for Sizing Ducts (if done at all) – Group 11, Flex-duct Junction Boxes and Radius Bends • Gilman reference – 1951 etc. Through the years. 022” of an inch. File Type PDF Ashrae Duct Fitting Calculator Excel Sheet Duct, Fittings Pressure Loss Calculation Autodesk Revit Architecture 2013 - Ashrae Duct Fitting Tables - U. This calculation Excel program makes it possible to carry out the calculation of the pressure losses on the duct works and air distribution systems. Duct Size Friction Loss Rate. Air friction loss in 90° bends is the net difference between the total pressure loss of a duct installed in a 90° bend and the straight run losses upstream and downstream of the bend. U of I bulletin. 42 inches in the return, so 0. 56 Air at 80 OF and standard atmospheric pressure flows through a furnace filter with an average velocity of 2. Since pressure and temperature are directly related, when the pressure is increased, the temperature is also increased. Therefore the pressure loss is 0. Leakage test pressure should not exceed duct pressure class level. Do not use harsh detergents, solvents or splashing water etc. Example 27. It holds 24″X24″ filters with a depth of up to 20″. 52 is the total static pressure measured in the ducts about 6 inches from the unit flanges. The Sure Flow Check valve is designed so that it is centralized between the flanges when the stud bolts are in position. As a result, all pressure pipe products undergo a variety of testing and quality procedures. This work was supported in part by Universiti Malaysia Pahang. 8980 to End) Revised as of July 1, 2007 Protection of Environment Containing a codification of documents of general applicability and future effect As of July 1, 2007 With Ancillaries. 2 Duct Hanger Spacing 21 10. Assumptions A velocity in the main duct (0-1) of 8 m/s. 15 inches of water. Duct tee pressure loss The next fitting we'll look at is the tee which connects the main duct to the branches, we'll use the example of the tee with the ID letter H between G and J in the system. Pressure Classes ½, 1, 2 Pressure Class 3 Pressure Classes 4, 6, 10 Transfer Air Ducts Outdoor Air Ducts Return Air Ducts 0. For that the required air duct diameters and pressure loss shall be determined under condition of permissible air sped in the duct. 0739 in mercury; 1 ft 3 /min (cfm) = 1. At equilibrium conditions, the heat loss or gain from the attic or basement, as indicated in Figure 2, is equal to the heat loss or gain to the building through the ceiling or floor. dP is labelled as a _pressure_ drop instead of a head loss. • Where possible use a single exhaust duct per dryer Sub Title • Dryers are to run with a positive outlet pressure. section with the higher pressure loss/gain to determine pressure losses/gains through a system. Pull the insulation over the duct and pull the vapor barrier over the sleeve. pressure tends to build up toward the end of the duct, resulting in too much airflow in branches near the ends. Last take-off run to be located 12" - 18" from end. The exhaust fan is sized to handle 100% of the return air pressure drop, which consists of the return duct, exhaust duct and relief damper when the unit is in full economizer mode. 6 40 0 20 Material 0 A. 14 ρ Density PD Sheave Pitch Diameter d Diameter P℄ Pressure at Pump Centerline. STAINLESS STEEL PIPE CHART Visit us at http:/www. The Mach number and speed of the flow also decrease across a shock wave. Once the TEL and ASP are calculated you simply use the chart to intersect the two to calculate the design friction rate for the duct design. Flexible Air Duct 2/16. For example if we calculated a 300′ equivalent length with an available static pressure of 0. Ashrae Duct Fitting Database Pdf. It is recognized that the use of manual duct calculators is normal, and that computer-aided duct design is becoming more popular; however, it is important to learn the manual friction chart method of duct sizing that is the foundation of these other methods. Quiet-Duct. Sizes shown are nominal. Test up to 1210 cfm at 4 in. 003 litres per second per square metre of duct surface area. Through the years. equivalent length at a velocity of 925 feet per minute. SAC Code 995413 -. The exhaust fan can be either a propeller fan or a centrifugal fan. In addition to spiral round and flat oval duct and fittings, SPOT produces rectangular duct and fittings, industrial duct, acoustical and thermal panels, sound attenuators and custom sheet metal work. Additional friction pressure losses occur due to fittings. Pipe Friction Loss Calculations Flow of fluid through a pipe is resisted by viscous shear stresses within the fluid and the turbulence that occurs along the internal pipe wall, which is dependent on the roughness of the pipe material. Air Flow and Duct Size Chart. The static pressure loss in a system caused by friction between moving air and the duct wall, expressed as in w. 8000 cfm fan ½” wg. Installed compression ratios in new residential construction have been visually observed by the author to vary from 10% compression to over 50% compression. Pressure Classes ½, 1, 2 Pressure Class 3 Pressure Classes 4, 6, 10 Transfer Air Ducts Outdoor Air Ducts Return Air Ducts 0. For example, if the relative humidity is 40% and the temperature is 30 deg C, then the saturation vapor pressure is 42. You don't need a current copy, a 40 year old copy is just as good for duct loss. A liver parasite. The types of fittings to be used based on the designer's calculations of fitting losses (i. This design methodology sizes the supply duct system for a constant pressure loss per unit length. 8980 to End) Revised as of July 1, 2007 Protection of Environment Containing a codification of documents of general applicability and future effect As of July 1, 2007 With Ancillaries. Hood static pressure •O m for:rhest – The losses are characteristic of the hood shape and are defined as the hood entry loss He (e=entry) –He is caused by dynamic losses and turbulence in the inlet. The main disadvantage of this method is that there is no equalization of pressure drops in duct branches unless the system has a symmetrical layout. Construction services of other residential buildings such as old age homes, homeless shelters, hostels etc. 0-in) diameter circular duct. Size the return grille and duct to remove 340 CFM from the pressure zone according to your favorite duct sizing method. static pressure curves are shown for 60 Hz and 50 Hz (broken line) inputs. A four-inch HEPA filter, which increases active media surface by 50 percent over a two-inch filter, lowers the pressure drop to between 0. You can have hot wire and Pitot tube style sensors depending on what you are needing to check. The Pressure Relief Valve should not be discharged prior to installation or when pressure testing the system. Minor Losses VII. The duct friction pressure drop is assumed to be 0. What parameter replaces the diameter for non-circular duct calculations?. The hydrostatic test pressure is usually between 1. Sizes shown are nominal. The system back pressure MUSTNOTbe higher than 0. 1-800-459-4822 800-459-3828. 90 degree turns in forced air ducting are to be avoided whenever possible. Duct Size Calculator Cfm We try to simulate the real world scenario as much as possible, but It is not always. Static Pressure •Static pressure is the resistance to airflow from objects in the air stream •Filters, coils, heat exchangers, registers, grills, balancing dampers and, of course, the duct itself, are just a few •After the resistance of these objects is subtracted, the balance is what is available for the duct system. ) medium/high pressure (from 3” w. Some sizes of round duct and fittings under negative pressure require reinforcing as shown on the gauge tables (see page 2-2). adequate size. 1 Zoning 22. Suppose that the air duct diameter is 200 mm and air speed is 1. 22) where the apparent friction factor fapp combines the effects of the wall shear stress and increase in pressure drop due to the accelerating core in the entrance region. Some contractors, in an honest effort to reduce static pressure, install turning vanes or scoops at the entrance to a duct branch, as shown in Figure 2. Design CFM 4" CFM 6" CFM 8" CFM 10" CFM 12" 60 6x4 60 4x6 90 4x8 120 4x10 150 4x12 90 8x4 110 6x6 160 6x8 215 6x10 270 6x12 120 10x4 160 8x6 230 8x8 310 8x10 400 8x12 150 12x4 215 10x6 310 10x8 430 10x10 550 10x12 180 14x4 270 12x6 400 12x8 550 12x10 680 12x12 210 16x4 320 14x6 490 14x8 670 14x10 800 14x12 240 18x4 375 16x6 580 16x8 800 16x10 950 16x12 270 20x4 430 18x6 670 18x8 930 18x10 1100. equivalent length at a velocity of 925 feet per minute. 16 Up to 11” 40’ EL 12” to 15” 55’ EL 16” to 21” 75’ EL 22” to 27” 100’ EL 28” to 33” 125’ EL RETURN AIR SYSTEM No. resistance required in a flexible air duct. DUCT ELBOWS, SQUARE THROAT No. Determine the static pressure drop in main duct - SP from chart is 0. Available as Microsoft Excel spreadsheet download. Title: Duct System Sizes and Airflow Quick Chart Created Date: 8/21/2006 11:56:03 AM. (and therefore enough pressure drop) to allow stable control. pressure loss. DUCT SIZING 13 8. Call us at +1 (773) 869-1774 or email [email protected]. Last take-off run to be located 12" - 18" from end. This chart is to be used in place of the standard friction chart published in the ASHRAE Handbook of Fundamentals. BACK TO BASICS: DUCT DESIGN - AIRAH. Minor Loss - Head or Pressure Loss in Air Duct Components - can be expressed as. loss of useful energy. 5 in pipe diameter has a velocity of 8 ft/s and produces a friction loss of 77 feet per 100 feet of pipe. All IPEX pressure pipes and fittings are manufactured to standards from various recognized organizations such as the AWWA, CSA, ASTM and others. Friction Loss in Fittings Valves As an aid, liquid sizing constants (Cv values) are shown for valves. Duct-sizing charts are based on this law. Heat loss through the duct walls is an expected and inevitable drain on the system. section with the higher pressure loss/gain to determine pressure losses/gains through a system. The maximum hydrostatic test pressure must be recorded at the lowest point along the pipeline, and must be compensated for temperatures other than 73ºF. At the intersection point, draw a line straight down to the free area velocity line. Industrial Duct Silencers. For 230 VAC operation, add a 2 after the K. Use a soft cloth to clean. @ 50Pa pressure loss (m/s) R3T30. Duct and Pipe fittings loss HVAC R engineering Eng Tips. and POW series attenuators, the static pressure loss is charted for each model at different airflows. 3 Material Group No. Total pressure - static pressure + velocity pressure If a water manometer has one end that is just connected into a duct and the other end outside the duct, what will it measure? it will measure only static pressure. h f = Head Loss K = K L = Minor Loss Coefficient. The first form calculates the pressure or friction loss along a given length of pipeline with a specified inside diameter. Software interfaces for calculating major and minor head loss. The collar is available in three configurations, round, square/rectangular or oval. g and larger, shall be designed for a maximum duct velocity of 2500 fpm for duct mains and a maximum static pressure of 0. This feature operates by setting a base line static pressure based on the highest airflow the system. increases the pressure of the refrigerant. Evaluation of frictional pressure drop in ducts. Today we use all that to find out how big the ducts need to be. The length of the duct forming the bend was determined, and the friction loss of an. 1 Operation: Type I hood systems shall be designed and installed to automatically activate the exhaust fan whenever cooking operations occur. Duct Size Calculator Cfm We try to simulate the real world scenario as much as possible, but It is not always. Effective thermal insulation of the ductwork reduces this heat loss and helps to minimize energy usage. 10 inches of water (25 Pa) and the duct pressure drop is 0. Maicke† University of Tennessee Space Institute, Tullahoma, TN 37388 The isentropic flow equations relating the thermodynamic pressures, temperatures, and densities to their stagnation properties are solved in terms of the area ratio and Mach number. A 18 0 21 Drawn tube, glass, plastic 0 A. 3 m]) Note 2: The maximum recommended lined duct attenuation in any octave band is 40 dB. This is particularly important where the duct is exposed to high humidity conditions in attics, vented crawl spaces, unconditioned basements and utility rooms. Let us use the duct fitting for the diverging and converging flow used by ASHRAE Standard 120, as shown in Figure 1, as an example. • For mesh lined screens, multiply the pressure drop (Δ P) obtained from the charts by the corresponding correction factor shown in the Cv correction table. The system back pressure MUSTNOTbe higher than 0. File Size: 552 Kb In fluid flow, friction loss (or skin friction) is the loss of pressure or “head” that occurs in pipe or duct f Steel Beam Excel Calculations (Download For Free) File Size: 663 Kb This spreadsheet performs an analysis and design of simply supported and cantilever, steel beams bending abou. Pressure Loss Coefficient. As the fan total pressure, FTP, reflects the full increase in mechanical energy imparted by the fan, the difference between the two, i. Knowing the shear stress, the Poiseuille friction factor is easily determined:. The STINGER is revolutionizing the way we clean duct work today. Leakage to Exterior: Aggregation of all duct system leaks to the exterior of the CFA in a duct test. 0 gives administrative instructions relevant to the pressure cell. The total static pressure is several factors added together. Industrial Duct Silencers. RECOMMENDED PRACTICES FOR DUCTING LAYOUT 21 10. A four-inch HEPA filter, which increases active media surface by 50 percent over a two-inch filter, lowers the pressure drop to between 0. LENNOX EL296UHE INSTALLATION INSTRUCTIONS MANUAL Pdf Download. Marley NZ | Plumbing - Rainwater Products - Spouting and. 3 Material Group No. Through the years. air duct design chart 7 – frection loss for round duct equivalent area and duct class† o ' 'carrier duct design manual pdf download vetle kroken com april 10th, 2018 - carrier duct design manual carrier system design manuals carrier university the carrier system design manual is the first practical guide for. Most charts allow two 90 ° bends in the vent as they are written. 5 m], take ½ duct insertion loss before calculating breakout transmission loss (max. Inlet bells render such loss negligible and are available at nominal cost. The accurate prediction of pressure losses across in-duct fittings is of significance in relation to the accurate sizing and good energy efficiency of air-delivery systems. 1 Operation: Type I hood systems shall be designed and installed to automatically activate the exhaust fan whenever cooking operations occur. Apply the procedure for determining pressure losses in air distribution duct work ⭐⭐⭐⭐⭐Some 5 stars reviews from the students:. The pressure loss in pipes and tubes depends on the flow velocity, pipe or duct length, pipe or duct diameter, and a friction factor based on the roughness of the pipe or duct, and whether the flow us turbulent or laminar - the Reynolds Number of the flow. pdf Download Kirloskar screw chiller maintenance manual. Sometimes static pressure is given as Pascals (Pa). 47383 Medicaid Focus Chart Ablation, 1 or more liver tumor(s), percutaneous, cryoablation 52010 Medicaid Focus Chart Cystourethroscopy, with ejaculatory duct catheterization, with or without irrigation, instillation, or duct radiography, exclusive of radiologic service 58672 Medicaid Focus Chart Laparoscopy, surgical; with fimbrioplasty. – Most duct sizing tables use the roughness factor for smooth, galvanized sheet metal as the reference value. per 100 feet of duct. TD4 THERMOPLASTIC RUBBER FDA DUCT HOSE TD4 is a white thermoplastic rubber hose that is food and pharmaceutical compatible with FDA acceptable. Oval duct still offers favorable pressure loss coefficients compared to rectangular duct. The static pressure is 0. This Excel template can be used to calculate velocity and friction loss in air ducts. The hydrostatic test pressure is usually between 1. 2/28/2017RAC/ALA/6D312 Dynamic losses in duct 1 ) Pressure losses due to Enlargement 2 )Pressure loss due to contraction 3 ) Pressure loss at inlet and outlet of a duct 13. However, when they do occur, the most common symptoms are biliary colic and cholecystitis. planer, bandsaw, table saw), 2 inches is a good general number to plan your duct design by. Duct type: Metal Ductboard Flex Size by: Friction rate Velocity Friction Rate: per 100 ft. Define the components of pressure loss in an air distribution system. There are more complicated ways to figure the entry loss of your system, but we find it usually equals a loss of 1″ water gauge. This chart is to be used in place of the standard friction chart published in the ASHRAE Handbook of Fundamentals. The duct system is designed to provide progressively lower duct velocities as the air proceeds from the main duct to the branches. around the silencer or along the duct walls. cfm x static pressure (in. pf Pressure loss due to friction in pipes/ducts (Pa) p Pressure loss due to fittings, bends etc (Pa) Pressure loss factor Density (kg/m 3) Psf Specific fan power (Ws/litre) t Temperature (°C) tad Temperature of air/fluid in duct/pipe (°C) tas Temperature of air surrounding duct (°C) tad1 Temperature of air/fluid in the upstream end of the. FWA Type Problem The following figure shows a typical duct layout a) Size the duct system using the equal friction method. Convert between many different pressure equivalents. Consider a sudden expansion placed in a duct (Fig. This is connected to the low side of the differential pressure gauge to form the DP pressure measurement. Pressure Drop Calculator Excel. If you are using Flexible PVC pipe, look for the blue box inset in the yellow box for pressure ratings. h f = Head Loss K = K L = Minor Loss Coefficient. h minor_loss = ξ v 2 / 2 g (1) where. Enter a different temperature or pressure value in the appropriate box. 1-800-459-4822 800-459-3828. Tel: 910-735-0000 s Fax: 910-738-3848 s [email protected] For over 50 years, GF Harvel is acknowledged as the industry's leading manufacturer of PVC, CPVC, PP and PVDF piping systems, PVC and CPVC duct systems, and PVC and CPVC Rod, Bar & Machining Stock along with custom pipe solutions to meet any needs. Static pressure is in inches of water. flexible duct diameter (mm) 44 l/s Ø 150 92 l/s Ø 200 170 l/s Ø 250 275 l/s Ø 300 385 l/s Ø 350 503 l/s Ø 400 636 l/s Ø 450 785 l/s Ø 500 950 l/s Ø 550 revision 14/04/03 b-ds 1 flex sizing flexible ductwork flexible duct sizing guide. 00002) = 194 dB RE 20µ Pa Note: 20µ Pa is another way to write 0. Pressure Loss Coefficient. 1 Constant friction loss method 14 8. The second form calculates the minimum pipe size to limit pressure loss to a specified value. Say Reynolds number as 4500. 4 kg/m 2 = 0. 60 efficiency For Water: 1 lb/h = 500 gpm 1 ton = (gpm) ∆t/24 gpm x ft head 3960 x Efficiency Small pumps 0. The temperature reading is taken several pipe. 2 Velocity Reduction Method 17 8. It can withstand the maximum pressure load without loss of deformation, the material thickness can be reduced by 15% and reducing costs. The Pressure Drop Chart for Basket strainers indicates a drop of 0. Several sources recommend using 0. Tel: 910-735-0000 s Fax: 910-738-3848 s [email protected] SP (Static Pressure) is defi ned as the pressure in the duct that tends to burst or collapse the duct and is expressed in inches of water gage (˝wg). Free spreadsheet program for air duct friction loss calculation. , square versus 45° entry taps, conical versus straight taps, etc. In this duct-sizing method, the duct design is based primarily on a consistent pressure loss for each foot of duct. 17 Flow Rate: SCFM 192. DUCT ELBOWS, SQUARE THROAT No. Includes rigid duct loss, fitting loss, flex duct loss (@15% compression), and max static pressure for diffusers) Even at a leakage class of 48 (unsealed duct) at the maximum expected operating pressure (. 760 mm Hg = 1 atmosphere). Pressure Loss in 90° Angle Boot-Extended Baseboard Outlet Combinations (5-in. For a straight rectangular duct section with no fittings and the height (ff) presumed fixed by the ceiling clearance, tbe op­ timal width is given by. Short-cycle pressure changes in duct systems can cause temporary noise. Ductulator calculats duct dimensions using equal friction method or velocity method. Assuming a 2. Vanstone or other proprietary connections are available. Marley NZ | Plumbing - Rainwater Products - Spouting and. Metal bellows duct expansion joints are used in low pressure, higher temperature gas systems to compensate for thermal growth and vibration. Tests at 10 in. Pressure Loss Coefficient. Duct sizes shown on drawings shall represent the inside air stream clear area. For bare inlets, that loss is equal to the fan velocity pressure. charts and forms in some of the most critical areas of operations in the HVAC industry, testing, balancing, energy auditing, indoor air quality, load calculations, and cost estimating. YOUR ANSWER: Head loss 27. Openings into or out of noisy environments are primary systems for the application of industrial duct silencers. pressure to velocity is needed, a convergent duct is used. Select the appropriate K value for such and select D and f for Schedule 40 pipe from the table below where K is the pipe diameter in feet. SF Pressure Drop calculates pressure drops of flowing liquids and gases in pipes (laminar and turbulent flow). For example, a flow of 5 gpm for an 0. – Flat Pressure Loss = 0. PE Continuing Education. The 3" STINGER Duct Cleaner with Variable Speed Control comes pre-assembled with a 2-wire 20' hose & inline quick coupler. q = air volume flow - (cfm - cubic feet per minute). See Section 1. 7 (A) on Raceway Seals, and 501. pressure differences, history of carotid stenosis, history of TIAs, aortic arch eval, vertebral stroke, subclavian steal, abnormal ultrasound MRI neck with AND without contrast MRI SPINE Cervical spine: neck pain, radiculopathy, myelopathy, previous surgery within last 5 years MRI C-spine without contrast. When in the same cross-sectional area, the circumference of the rectangular duct with an aspect ratio of 1:3 is 40% longer than the circumference of the spiral duct, so a lot of the materials will be saved if. Sheet Metal Duct Friction Loss Calculator 1. The remaining branches, K, G, E, L, M, N, and B, are now sized to balance each branch with the same total pressure loss. 15 "of water. Extended Baseboard Outlets 29 29. edu Leakage Evaluation for Supply Duct in Figure 8-1, page 8-4 of the SMACNA HVAC Duct Design Manual. Air friction loss in 90° bends is the net difference between the total pressure loss of a duct installed in a 90° bend and the straight run losses upstream and downstream of the bend. The application allows performing various calculations for HVAC systems engineering. The Pressure Drop Chart for Basket strainers indicates a drop of 0. You can measure this by using a Magnahelic gauge or manometer and inserting the tube in the duct in two places - after the fan discharge and at the return before it enters the air handler. charts and forms in some of the most critical areas of operations in the HVAC industry, testing, balancing, energy auditing, indoor air quality, load calculations, and cost estimating. To calculate the pressure loss in the sections 1-6, use the pressure loss diagram for round air ducts. With over 80 years’ experience, Iplex has an excellent understanding of the challenges the water industry faces. 1) HVAC LOAD CALCULATION (IRC M1401. Friction Loss in Fittings Valves As an aid, liquid sizing constants (Cv values) are shown for valves. When this length is exceeded. They can answer a lot of questions for you. Minor Losses VII. Minor losses must be included in the head loss term in the energy equation. CLOSE CELL NEOPRENE GASKET Neoprene 1/4” x 1/2” (50’ rolls - 1500’ per box) E-Z Flange Jr. Weight loss is also recommended for BP reduction in overweight individuals. If a gas is static and not flowing, the measured pressure is the same in. 75 inches of water column. A four-inch HEPA filter, which increases active media surface by 50 percent over a two-inch filter, lowers the pressure drop to between 0. if you enter an inside dimension for one input, enter an inside dimension for your other inputs. It is difficult to calculate the device’s pressure loss, so an estimation for the maximum air flow of 1. NOTE: Although it is not an engineering acceptable practice, for most typical duct systems, a default friction rate of. STAINLESS STEEL PIPE CHART Visit us at http:/www. Pull the insulation over the duct and pull the vapor barrier over the sleeve. CFM25: Cubic feet per minute of air leakage at 25 pascals of pressure Total Leakage: Aggregation of the entire systems duct leakage in a duct test. Steps to figuring what size piping your compressed air system needs: 1. Disclaimer [PDF] Conflict of Interest [PDF] View Abstract Dr John DeWitt discusses his article, "EUS pancreatic function testing and dynamic pancreatic duct evaluation for the diagnosis of exocrine pancreatic insufficiency and chronic pancreatitis" from the February issue. In this duct-sizing method, the duct design is based primarily on a consistent pressure loss for each foot of duct. The total static pressure is several factors added together. Using the ABMA standard radiation loss chart, this would yield a savings of 0. 40 inches w. If the pressure drop across the filter is 0. This is particularly important where the duct is exposed to high humidity conditions in attics, vented crawl spaces, unconditioned basements and utility rooms. Tapered reducers, like the one below, change duct diameters with minimal static-pressure loss. This is used for the density calculation and the high side input to the differential pressure measurement. Thus the static pressure before each terminal or branch is maintained constant. Minimum bend radius to center line is one diamater. YELLOW JACKET® manufactures HVAC supply products, our products include gauges, hoses, adapters, recovery equipment, gauges & more. get10things. As the fan total pressure, FTP, reflects the full increase in mechanical energy imparted by the fan, the difference between the two, i. INTRODUCTION. Schedule 40 head loss per 100' values are usually used for other wall thicknesses and standard iron pipe size O. 1 Duct Sheet Metal Thickness 20 9. 10 Classes 150 300 400 150 300 400 150 300 400 Temp. The recommendations can change from model to model even on the same brand's products so consult the owner's manual or installation instructions for your specific model. Upload your work as a single PDF file on the BBL. While this value certainly varies for any given type of tool (e. get10things. BACK TO BASICS: DUCT DESIGN - AIRAH. Some contractors, in an honest effort to reduce static pressure, install turning vanes or scoops at the entrance to a duct branch, as shown in Figure 2. DUCT ELBOWS, SQUARE THROAT No. All IPEX pressure pipes and fittings are manufactured to standards from various recognized organizations such as the AWWA, CSA, ASTM and others. Plastics Technical Manual. This application will help you calculate the individual equivalent length of valves and fittings commonly used in industrial piping routes. For correct and safe heater operation an automatic control and protection system is recommended, including the following functions: regulation of the heating capacity and temperature of the air heated up; filter clogging control by a differential air pressure sensor;. If the manometer reading is higher than 0. This restriction (friction loss) adds to the TEL (total equivalent duct length) of the system. A four-inch HEPA filter, which increases active media surface by 50 percent over a two-inch filter, lowers the pressure drop to between 0. Check Angie's List for FREE to access top-rated Pros, exclusive online deals and more than 12 million verified reviews from real people. The remaining branches, K, G, E, L, M, N, and B, are now sized to balance each branch with the same total pressure loss. a = length of one side of rectangular duct (inch) b = length of adjacent side of rectangular duct (inch) De= circular equivalent of rectangular duct for equal friction and capacity (inch) Source: 2001 ASHRAE Fundamentals, p. 200 100 80 60 40 20 10 8 6 5 4 3 2 1. The static pressure loss in a system caused by friction between moving air and the duct wall, expressed as in w. 1116-TRP) February 2005 Minneapolis, Minnesota. A straight pipe causes a greater head loss than a bent pipe. Therefore the. assembly with Flat Oval Duct. The recommendations can change from model to model even on the same brand's products so consult the owner's manual or installation instructions for your specific model. DUCT PRESSURE CLASS Duct pressure classes are to be identified on the contract drawings. For interior lined ductwork, upsize duct to maintain clear area inside lining. Bile duct problems present at birth. The last step is to size the return grille and duct to match the total of the supply registers. These pressures normally refer to values in (perhaps notional) plenums at the entrance and exit of a duct or a system fitting such as a valve. L = n x hv x 100 hf Where : L = additional equivalent length, ft hv = velocity pressure at V2, in. 6 Pressure washing and finishing brush In general, sewer ducts must. The Screen openings chart indicates the % open area of 100 mesh is 30%. planer, bandsaw, table saw), 2 inches is a good general number to plan your duct design by. The head loss represent pressure losses, (or load losses) in the conduct of air systems, Hydraulic or other fluids. 320 cfm in 8" duct yields. The pressure loss in piping increases depending on connected pipe length and operation capacity of the compressor. Duct Fitting Database ashrae org. Let us use the duct fitting for the diverging and converging flow used by ASHRAE Standard 120, as shown in Figure 1, as an example. And insufficient airflow. 5CLR) Elbows @ 4000 ft/min with. dP is labelled as a _pressure_ drop instead of a head loss. There are more complicated ways to figure the entry loss of your system, but we find it usually equals a loss of 1″ water gauge. (Final Report on ASHRAE Research Project No. 1HVAC - HVAC Product Supplier. sheet metal ducts with fibrous glass duct liner may be used on the high pressure side if design static pressure exceeds the 2 in. v = flow velocity (m/s, ft/s) g = acceleration of gravity (m/s 2, ft/s 2) But how this formula can be used for the compressible fluid - air - not taking into. Duct Design Fundamentals Pressure Losses -Friction Comparison of Different Velocities and Roughness Observations: • Factor of ~15 increasing pressure loss from 1000 -4000 fpm • 0. , & Cimbala, 365). Flexible Duct Coupling 90º Elbow Ductwork Most common type of installation Quieter than built-in blower Can be sized for length of duct run Duct under negative pressure, safest operation 10’ Stack height, per NFPA 45 Horizontal runs taper back to hood 3-5 duct diameters between elbow and blower. Read Round Duct Diameter (inches) and Friction Loss (inches of water). The Pressure Relief Valve should not be discharged prior to installation or when pressure testing the system. To maintain reasonably uniform air Pressures in the air-distribution system, the length of a single-size trunk duct should be limited to about 24 feet. Do not touch the metal parts of the. This is the most widely used method of sizing lower pressure, lower velocity duct systems. Duct Leakage Test Form Customer Information: Name: Address: City: State/Zip: Phone: Email: Building Address: (if different from above) Street: City/State: Test Conditions: Date: Time: Indoor Temperature (F): Outdoor Temperature (F): Floor Area (ft2): System Airflow (cfm): Cooling Size (tons): Heating Size (btu): Primary Location of Supply. Air Ducts - Friction Loss Diagram. Now for this we need to consider that the air is moving in two directions, straight through and also turning off into the branch so we need to. One duct diameter is added for each additional 1,000 fpm (Stevens, 2008). 0-in) diameter circular duct. To help in the selection process, the following information will be required: Physical size of particulate. Do not use harsh detergents, solvents or splashing water etc. Positive Pressure Bursting Pressure various gauges of spiral tubing These tables are given only as a courtesy. planer, bandsaw, table saw), 2 inches is a good general number to plan your duct design by. 2 Pull the insulated flexible duct through the opening until it is well extended and straight. Our experienced team actively work and collaborate with customers and the industry to provide safe, secure and innovative water solutions today and into the future. 10 Classes 150 300 400 150 300 400 150 300 400 Temp. Our experienced team actively work and collaborate with customers and the industry to provide safe, secure and innovative water solutions today and into the future. Total Duct Loss ("wg) 450 3 Gore 10. Hart & Cooley lists a Pressure Loss through the diffuser at. Vanstone or other proprietary connections are available. creases pressure loss and reduces air flow. Download duct static pressure calculator excel sheet XLS. Class 1 air duct requirements, the system must withstand UL 181/ULC S110 tests such as erosion, pressure loss, impact, collapse, puncture, static load and fire retardancy (30 minute flame penetration test). Charlotte Pipe ® has been relentless in our commitment to quality and service for more than a century. 3 Permanent Pressure Loss The amount of unrecovered loss due to a flow element is known as permanent pressure loss. The system will need to achieve a leakage rate of less than 4 CFM (cubic feet per minute) per 100 square feet of the home. Title • Maximum exhaust duct length: • Type 1 dryers = 35 equiv. 08 may be used in lieu of performing the above calculation. BACK TO BASICS: DUCT DESIGN - AIRAH. Therefore the. These pressures normally refer to values in (perhaps notional) plenums at the entrance and exit of a duct or a system fitting such as a valve. The pressed form of the ventilation piece helps to reduce. 7 m) of water head pressure and up to 90-foot (27 m) surges. At equilibrium conditions, the heat loss or gain from the attic or basement, as indicated in Figure 2, is equal to the heat loss or gain to the building through the ceiling or floor. By connecting a pressure gauge to the taps of the damper, the pressure drop across the damper blades can be measured. 98 inches of water column - and surprised when their trainer asserted the airflow through the unit was probably OK. In areas of Southeast Asia, cholangiocarcinoma is associated with liver fluke infection, which can occur from eating raw or undercooked fish. Figure 5 shows this corresponds to the radius being half of the width of the duct. 40 80 10S 40S 80S. Improper installation that allows sagging, sharp bends, kinks, and crimping of flexible duct will increase the friction loss of the system and increase the total amount of static pressure that the indoor blower. Caution! Do not. wg (A) and reading across to damper position 4 and then down, the airflow ‘Q’ can be determined to be approximately 340 cfm. 70 IWC CFM= 1200 CFM Step 2) Device Pressure Losses (DPL). Smacna Duct Design Fitting Loss Coefficients PDF N REPS. Duct friction, which as the name implies, is the frictional drag of the fluid moving along a rough surface, the duct wall. For example, when a fan is moving air through a duct system, two types of pressure are encountered: velocity pressure and static pressure. The recommendations can change from model to model even on the same brand's products so consult the owner's manual or installation instructions for your specific model. Use insulated duct or duct board in unheated spaces. Industrial Duct Silencers. static_pressure_calculator_r3. 5 duct diameters when the duct velocity is 2,500 fpm or less. 3 m]) Note 2: The maximum recommended lined duct attenuation in any octave band is 40 dB. Girth rings and other duct reinforcing are available. pressure tends to build up toward the end of the duct, resulting in too much airflow in branches near the ends. The pressure losses are due to changes in direction or velocity of the air and occur at transitions, elbows, and duct obstructions, such as dampers, etc. Welcome to Endot Endot Industries, LLC is a producer of: Endot Industries, Inc. Problem: If the velocity in the duct is 4000 fpm and the area of the duct is 1. The STINGER is revolutionizing the way we clean duct work today. Nailor Industries, Inc. 30’ of duct and the one elbow will have a loss equivalent to the following: Duct Loss = x 3. •If loss cannot be avoided, estimate loss and select fan for higher pressure Two Components of System Design of Duct R R Length of Duct Length. For that the required air duct diameters and pressure loss shall be determined under condition of permissible air sped in the duct. 7 m) of water head pressure and up to 90-foot (27 m) surges. ) or 175 psig (2 in. or greater pressure, at a capacity about twice that of the Cobra. ) For WEIGHT PER FOOT please see PVC & CPVC PIPE SPECS Weight Per foot and dimensions. Air Flow and Duct Size Chart. The clean or replace filter message will pop up when the filter is full. How To Perform A Heat Loss Calculation — Part 2. Before further discussion, an explanation of convergent ducts, divergent ducts, and the behavior of air within these ducts should be made. The head loss represent pressure losses, (or load losses) in the conduct of air systems, Hydraulic or other fluids. com on January 13, 2021 by guest course of day-to-day operations of pharmaceutical/biotech research and manufacturing. Calculations are for Grade B seamless pipe to specifications ASTM A53M, ASTM A106M or API 5L. 018 † Inlet pressure (psig) 0 † Temp (F) 70° † Galvanized metal roughness (ft). 22) where the apparent friction factor fapp combines the effects of the wall shear stress and increase in pressure drop due to the accelerating core in the entrance region. is a producer of: Water Pipe and tubing, 1/2" through 8" made with PE 4710 resin for a 25% higher pressure rating. Includes rigid duct loss, fitting loss, flex duct loss (@15% compression), and max static pressure for diffusers) Even at a leakage class of 48 (unsealed duct) at the maximum expected operating pressure (. the static pressure loss by as much as a factor of 10. Right D ACCA Manual D Duct Calculation Amp Sizing. Enter a different temperature or pressure value in the appropriate box. edu Leakage Evaluation for Supply Duct in Figure 8-1, page 8-4 of the SMACNA HVAC Duct Design Manual. 4 Air Velocity: Grease duct systems serving a Type I hood shall be designed to provide an air velocity within the duct system of not less than 500 feet per minute (2. When no inlet duct is used, entrance loss must be added to the static pressure calculated for the system. About Damper Sizes The building’s mechanical plans provide a summary of required dampers. 3 inwg /100ft 5. 5 times the Design Pressure Rating of this component. Dielectric power loss factors tan for typical cable insulations are: XLPE (1,5 to 3,5) 10–4 EPR (10 to 30) 10–4 Oil cable (18 to 30) 10–4 II) Current-dependent losses The current-dependent losses consist of the following components: - Ohmic conductor losses - Losses through skin effect - Losses through proximity effect. The position of the duct relative to the ventilated or air-conditioned space and the geometry of the fittings etc. around the silencer or along the duct walls. To calculate the pressure loss in the sections 1-6, use the pressure loss diagram for round air ducts. 5” diameter pipe and the friction loss as marks along the curve. This is connected to the low side of the differential pressure gauge to form the DP pressure measurement. One way to use the charts is to enter base scale at value corresponding to the width of duct, say 14 inches (follow broken lines in either chart). DROP CALCULATIONS DUCT PIPE PRESSURE LOSS CALCULATIONS''HVAC Duct Construction Standards Public 10 / 33. Local pressure losses are caused by the fluid flow through the duct fittings: which change the direction of the flow (elbows, bands, etc. Duct sizing is covered very well in ACCA Manual D and is fairly straightforward. The recommendations can change from model to model even on the same brand's products so consult the owner's manual or installation instructions for your specific model. Title • Maximum exhaust duct length: • Type 1 dryers = 35 equiv. For example, when a fan is moving air through a duct system, two types of pressure are encountered: velocity pressure and static pressure. The system back pressure MUSTNOTbe higher than 0. 8 N/m 2 (Pa)= 0. All products are made in the USA. If no data is available, use the generic flexible duct friction loss chart in ACCA Manual D. It varies with velocity, duct size and length, and wall roughness [10]. Most cyclones have intake ports of 6" to 8", and some two-bag collectors have 5"- or 6"-diameter intakes, so consider at least a 5" main duct. 2 we can specify a 0. Obviously, the pressure drop through a round duct can be significantly less than the rectangular one. g and larger, shall be designed for a maximum duct velocity of 2500 fpm for duct mains and a maximum static pressure of 0. Call us at +1 (773) 869-1774 or email [email protected]. Oval Duct is an economical option when space constrains prevent the use of round duct. Wall Thickness - t - (inches) Inside Diameter - d - (inches) 1/80. Note 1: For lined duct lengths up to 15 ft [4. 3 kPa) Lp = 20Log(101,300/0. When we last visited with lead installer John and his helper Charlie, they had learned how to measure external static pressure on a new system. Pressure drop calculation tool for installations with straight sections and duct system elements. OUR MISSION. For example, a flow of 5 gpm for an 0. For example, if we select an attenuator model C2P-071 with an air flow of 4m3/s, the pressure loss is 50Pa. Biliary colic pain comes on suddenly, is constant, severe, and located in the middle or right of the upper abdomen. com Round duct and rectangular duct comparison. of water (50 ft of EL) – Mentions Entrance Fitting • ACCA Manual D, Residential Duct Systems (2009) – Residential Industry Standard for Sizing Ducts (if done at all) – Group 11, Flex-duct Junction Boxes and Radius Bends • Gilman reference – 1951 etc. Supporting Outside Metal Helix, Retains Flexibility. A comprehensive duct layout indicating sizes, design airflows, pressure class, and routing of the duct system. Dryer Venting Comparison Chart. This hvac duct sizing calculator is very simple and it calculates the duct friction loss value and air velocity inside the duct. Therefore the pressure loss is 0. However, estimating changes in the size of main pipe and duct runs provided important insights. 2 2009 ASHRAE Handbook—Fundamentals (SI) p s,2 = static pressure, gage at elevation z 2, Pa V 1 = average velocity at section 1, m/s V 2 = average velocity at section 2, m/s ρ a = density of ambient air, kg/m3 ρ= density of air or gas in duct, kg/m3 Δp se = thermal gravity effect, Pa Δp t = total pressure change between sections 1 and 2, Pa Δp t,1-2 = total pressure loss caused by. pf Pressure loss due to friction in pipes/ducts (Pa) p Pressure loss due to fittings, bends etc (Pa) Pressure loss factor Density (kg/m 3) Psf Specific fan power (Ws/litre) t Temperature (°C) tad Temperature of air/fluid in duct/pipe (°C) tas Temperature of air surrounding duct (°C) tad1 Temperature of air/fluid in the upstream end of the. It will release easily due to the pressure sensitive backing. The pressure drop across the dust collector, like coils or filters, must be obtained from the manufacturer of the device. • Available Static Pressure (ASP): – Blower ESP minus component pressure losses – Component pressure losses e. 4 kg/m 2 = 0. See full list on theengineeringmindset. DUCT SIZING 13 8. 2 0 40 200 400 600 800 AIRFLOW C. 2" to 14" diameters. BACK TO BASICS: DUCT DESIGN - AIRAH. – Darrell DUCT SIZING CHARTS Residential Main Trunk Runs for Approximately 450-CFM Per Ton - USE Manual D!. Provide flexible duct connection on all rotating equipment. 70 IWC CFM= 1200 CFM Step 2) Device Pressure Losses (DPL). Note: Charts reflect values for standard air density at sea level; approx 14° C When the exhaust system is designed to operate above 610m altitude, below 0° C or above 49° C The duct pressure loss obtained must be corrected for air density. By calculation the pressure drop of the bend only was then determined. ) or 175 psig (2 in. Our experienced team actively work and collaborate with customers and the industry to provide safe, secure and innovative water solutions today and into the future. At 1:00 pm each day the system will take a reading and record the change in static pressure. About Damper Sizes The building’s mechanical plans provide a summary of required dampers. 2-ply, air-tight inner core. For any given fitting, users enter the flow rate and fitting information and obtain loss coefficient data and associated pressure loss. Air Flow and Duct Size Chart. ety of duct materials can be used with attic installations. pf Pressure loss due to friction in pipes/ducts (Pa) p Pressure loss due to fittings, bends etc (Pa) Pressure loss factor Density (kg/m 3) Psf Specific fan power (Ws/litre) t Temperature (°C) tad Temperature of air/fluid in duct/pipe (°C) tas Temperature of air surrounding duct (°C) tad1 Temperature of air/fluid in the upstream end of the. 6 Pressure washing and finishing brush In general, sewer ducts must. DUCT LEAKAGE CLASS *Consult the HVAC−Air Duct. Spiral Pipe of Texas’ products are manufactured in accordance with the latest SMACNA, ASHRAE and SPIDA standards. 8000 cfm fan ½” wg. 4D charts as a material property library to be used by the script. The main disadvantage of this method is that there is no equalization of pressure drops in duct branches unless the system has a symmetrical layout. Duct Pressure Class Static Pressure Limit Maximum Air Velocity m/s Air leakage limts l/s/m2 Positive Pa Negative Pa Low pressure – Class A 500 500 10 0. PRODUCT DATA & SUBMITTAL. Nailor Industries, Inc. 4 Using a caulking gun, seal around both hoods to. By using this method of calculating duct pressure loss, the equivalent length of each fitting is added to the total duct length to establish the pressure loss through the duct system. Ductulator calculats duct dimensions using equal friction method or velocity method. The difference between the total pressure reading and the static pressure reading is the Velocity Pressure. The 2" static pressure loss for "entry loss" is a general number for any type of tools. 2 CFM allowed by spec. Box 927 (381 Carwellyn Road) Abbeville, SC 29620. From this point of intersection, follow the vertical line down to the bot-tom of the chart to determine the approximate pressure drop. heating and plumbing obstructions), direction of joists (for running pipe), electrical service, locations of doors and windows. 0" loss for this example, the resistance at the fan outlet is: SP outlet = 1. If the system back pressure is less than 0. 25 divided by 27. Pressure class, as defined by SMACNA, shall be clearly indicated on drawings with appropriate symbols. If there is any doubt that a pipe size may create a pressure drop, use the next largest size. 5 sqm, what is the flow rate in the duct. 75 inches of water column. An excessive number of bends in a vent can overcome the drafting action completely. Last take-off run to be located 12" - 18" from end. 4 Using a caulking gun, seal around both hoods to. To calculate the pressure loss in the sections 1-6, use the pressure loss diagram for round air ducts. 26” WC is lost across the A/C coil (when wet), 0. 5 m, v=5m/s, _=0. Velocities in each successive runs are reduced such that the gain in static pressure due to reduction in velocity pressure equals the frictional pressure drop in the next duct section. c) Balance the system and Select and size the dampers. Maicke† University of Tennessee Space Institute, Tullahoma, TN 37388 The isentropic flow equations relating the thermodynamic pressures, temperatures, and densities to their stagnation properties are solved in terms of the area ratio and Mach number. One duct diameter is added for each additional 1,000 fpm (Stevens, 2008). Any flow will find the sudden area increase difficult to negotiate. Duct,Elbow,transitio,drop pressure in every piece. Explain the use of the equal friction method on the sizing of air distribution duct work. This feature operates by setting a base line static pressure based on the highest airflow the system. 15”/100 ft) * (9’) = -0. 1 inch water = 248. 2-ply, air-tight inner core. pdf Download Powerboss generator manual. Duct tee pressure loss The next fitting we'll look at is the tee which connects the main duct to the branches, we'll use the example of the tee with the ID letter H between G and J in the system. Duct borne noise tests (sound levels in inlet and outlet duct)-measurement in accordance with one of the EN ISO standards - reverberation room (3741), free field (3744), in-duct (25136) - measurements at specified duty point - results shall not be affected by noise generation in throttling device (artificial external pressure). Since the low pressure valves have an undercut disc, they have less of an interference fit between the disc and the seat. If the pressure drop in the shortest duct run (say A-B) is 10 Pa, then the damper in this run has to be closed to provide an additional pressure drop of 90 Pa, so that the required airflow rate to the conditioned zone 1 can be maintained. Therefore, their bubble-tight. A four-inch HEPA filter, which increases active media surface by 50 percent over a two-inch filter, lowers the pressure drop to between 0. For interior lined ductwork, upsize duct to maintain clear area inside lining. A liver parasite. I expect you will find that your ductwork is restricting the flow. feet (each elbow = 5 feet). Most charts allow two 90 ° bends in the vent as they are written. Flexible Air Duct 2/16. Explain the use of the equal friction method on the sizing of air distribution duct work. C Friction Loss Coefficient (For Duct Fittings) P Pressure CCF 100 Cubic Foot Pa Atmospheric Pressure CFM Volumetric Flow: Cubic Feet Per Minute Pab Absolute Pressure Cp Specific Heat Pa Pascals Cv Flow Constant (IP) π Pi = 3. pressure tends to build up toward the end of the duct, resulting in too much airflow in branches near the ends. (500 Pa) limits of the fibrous glass duct system; the fibrous glass duct system may be used on the low pressure side; and insulated flexible ducts may be used as run-outs from trunk ducts to diffusers. BACK TO BASICS: DUCT DESIGN - AIRAH. There are more complicated ways to figure the entry loss of your system, but we find it usually equals a loss of 1" water gauge. All products are made in the USA. You don't need a current copy, a 40 year old copy is just as good for duct loss. 3 What is the resistance pressure drop in a duct measuring 700 × 400 mm, if the air flow through it. DUCT PRESSURE CLASS Duct pressure classes are to be identified on the contract drawings. If it is not practical to install a straight section of duct at the fan outlet, the fan speed may be increased to overcome this pressure loss. The Manuals are committed to making the best current medical information accessible to health care. Air Flow and Duct Size Chart. , square versus 45° entry taps, conical versus straight taps, etc. Using Microsoft Excel's trendline function, the slope of each data set was determined and taken to be K L /2g in the following equation: Figure 5: Head Loss in Fittings (Cengel, Y. For conventional applications including low frequency. * include fittings in the Duct TEL. we calculated the pressure loss for this sub-duct.