Hvac duct construction wasilewski

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Hvac duct construction wasilewski

  1. 1. HVAC Duct Construction Bob Wasilewski Project Manager, Technical Resources SMACNA
  2. 2. HVAC Duct Construction Standards WHAT? WHY? HOW?
  3. 3. Todays Program1st – 2nd Edition HVAC-DCSReview Joints and LimitationsTransverse Joints & ReinforcementsUse of the Pressure Class TablesTie Rod Addendum
  4. 4. Documents Preceding 2nd Edition HVAC-DCSLow Velocity Systems Duct Manual– First Edition 1959– Second Edition 1963– Third Edition 1967Low Velocity Duct Construction Standard– 1969
  5. 5. Documents Preceding 2nd Edition HVAC-DCSLow Pressure Duct Construction Standard– Fifth Edition 1976High Velocity Duct Systems Manual– First Edition 1965High Velocity Duct Construction Standards– Second Edition 1969
  6. 6. Documents Preceding 2nd Edition HVAC-DCSHigh Pressure Duct Construction Standards– Third Edition 1975Duct Liner Application Standard– First Edition 1971– Second Edition 1975
  7. 7. Documents Preceding 2nd Edition HVAC-DCS Flexible Duct Installation Standards – First Edition 1979 – Second Edition 1980 HVAC Duct Construction Standards -- Metal and Flexible – First Edition 1985
  8. 8. Major Changes from First EditionGENERAL Text edited to be more reader-friendly Reading aids added Static pressure only as the basis for duct construction classification -- velocity levels deleted (Table 1-1)
  9. 9. Major Changes from First EditionChapter 7 revised to facilitate use forequivalent and comparable tests and ratingsModel project specification addedReminders to designers to show all requiredfire, smoke, radiation and volume controldampers on contract drawings are accented
  10. 10. Major Changes from First Edition Boiler breeching omitted Volume damper construction is more specific Lead radiation shielding added Metrics are included Air terminal runouts and supports are revised
  11. 11. Major Changes from First EditionRECTANGULAR DUCT REVISIONS Negative pressure construction given for 4", 6", and 10" w.g. Six feet reinforcement schedules added Reinforcement schedules extended to 120" width
  12. 12. Major Changes from First Edition Tie rod alternatives expanded for both positive and negative pressures TDC and TDF joint systems included and rated as T-25a and T-25b joints T-24a joint added as a modification of T-24
  13. 13. Major Changes from First Edition Use of 26 gage added for 4", 6" and 10" pressures Trapeze hanger tables expanded to cover the 120" width range Duct liner pin schedule adjusted Infrequently used joints (T-4, 8, 17, 18, 19, 20 and 23) omitted
  14. 14. Major Changes from First EditionRound, Flexible and Oval Duct Revisions Duct pressure classes revised to be positive and negative at 2", 4" and 10" w.g. Crimped joint connection length changed from 1" to 2" Rectangular branch taps into round added for straight or 45 degree lead-in-entry
  15. 15. Major Changes from First Edition Type 1 reinforcement of oval duct now has an internal tie rod (based on ASHRAE test program) Maximum support spacing for round flexible duct and connector changed from 10 feet to 5 feet Additional riser support details are provided
  16. 16. DUCT SYSTEMS SIZINGS FIRE/SMOKE CODEFITTINGS, ETC. PROTECTION COMPLIANCE CODE DUCT COMPLIANCECONSTRUCTION SMACNA HVAC-DCS 2ND ED. 1995 INSPECTION CODE COMPLIANCE
  17. 17. DUCT SYSTEMS ENGINEER CONTRACTORDesign Considerations: Construction Considerations: CFM Panel Thickness (Gage) Static Pressure Pressure Class (as specified) Duct Size Panel Width/Height Fitting Type Joint Type/Spacing Construction Pressure Intermediate Reinforcement Class Type/Spacing
  18. 18. DEPENDENT VARIABLES
  19. 19. REGULAR DUCTSMaximum Deflection Maximum Test PressureJoint and Reinf. Sheet: Lab:1/4" on 48" w. 3/8" on 12" Dn. Class Rating + 50%W/200 on 1/2" on 13"-18"49"-120" 5/8"on 19"-24" Field: 3/4" on 25"-84" Class Rating + 25% 1" on 85"-120"Tolerance: Tolerance:+7.5% +10%
  20. 20. Duct SystemsUsed for the movement of air inHVAC/Exhaust systemsDucts are classified based on maximumoperating pressure– 0.5" w.g. positive or negative– 1.0" w.g. positive or negative– 2.0" w.g. positive or negative
  21. 21. Duct Systems (Continued)Ducts are classified based on maximumoperating pressure– 3.0" w.g. positive or negative– 4.0" w.g. positive or negative– 6.0" w.g. positive or negative– 10.0" w.g. positive or negative
  22. 22. TABLE 1-2STANDARD DUCT SEALING REQUIREMENTS
  23. 23. EXAMPLE 1Duct Size 24" x 24"Pressure Class 2" w.g.Sheet StockJoints/Reinforcements 8 ft / 4 ftStanding S
  24. 24. EXAMPLE 2Duct Size 42" x 24"Pressure Class 3" w.g.5 ft Coil LineJoints/Reinforcements 5 ft / 2 ½ ftTDC or TDF
  25. 25. MIDPANEL TIE ROD (MPT) ½" w.g. - 6" w.g. 37" - 96" Duct Dimension Rectangular Duct
  26. 26. Mid Panel Tie Rod AddendumJoints – AllTie Rods – Threaded Rod orTubing/Conduit with Threaded InsertAdditional Application Tables,Qualifications and Reader Aids Included
  27. 27. FIGURE 1-3 TIE ROD ATTACHMENTS
  28. 28. FIGURE 1-4 TRANSVERSE (GIRTH) JOINTS
  29. 29. FIGURE 1-4 TRANSVERSE (GIRTH) JOINTS
  30. 30. FIGURE 1-4A SPECIAL JOINT PROFILES
  31. 31. FIGURE 1-5 LONGITUDINAL SEAMS – RECTANGULAR DUCT
  32. 32. TABLE 1-24 UNREINFORCED DUCT (WALL THICKNESS)
  33. 33. TABLE 1-25T-1 FLAT DRIVE ACCEPTED AS REINFORCEMENT
  34. 34. FIGURE 1-7 UNREINFORCED DUCT
  35. 35. FIGURE 1-8 CROSSBROKEN DUCT & BEADED DUCT
  36. 36. FIGURE 1-9 DUCT REINFORCED ON TWO SIDES
  37. 37. FIGURE 1-10 DUCT REINFORCED ON ALL SIDES
  38. 38. FIGURE 1-12 DUCT OVER 120" (3048 MM) WIDE
  39. 39. FIGURE 1-15 CORNER CLOSURES - FLANGES
  40. 40. FIGURE 2-22 DUCT LINER INTERRUPTION
  41. 41. TABLE 3-2A ROUND DUCT GAGE UNREINFORCED POSITIVE PRESSURE
  42. 42. TABLE 3-2B ROUND DUCT GAGE NEGATIVE PRESSURE
  43. 43. FIGURE 3-1 SEAMS – ROUND DUCT AND FITTINGS
  44. 44. FIG. 3-2 TRANSVERSE JOINTS – ROUND DUCT
  45. 45. FIGURE 3-6 FLAT OVAL DUCTS
  46. 46. FIGURE 3-9 FLEXIBLE DUCT SUPPORTS
  47. 47. FIGURE 3-10 FLEXIBLE DUCT SUPPORTS
  48. 48. TABLE 4-1 RECTANGULAR DUCT HANGERS MIN. SIZE
  49. 49. TABLE 4-2 MINIMUM HANGER SIZES FOR ROUND DUCT
  50. 50. FIGURE 4-4 LOWER HANGER ATTACHMENTS
  51. 51. Questions &Answers

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