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Baycrest Centre for Geriatric Care
Apotex Building 5th Floor
HHA #2151048-01
Section 23 31 13
Ductwork
Page 5 of 18
Table 2: Duct System Pressure and Seal Class
No.
7
Ductwork System
Supply air ductwork from discharge side of fan to
inlet of terminal box or reheat coil;
Static pressure
construction class
Pa (in.wg.)
Seal
class
Sealing requirements
(1)(2)(3)(4)
+750 (3)
Return air ductwork on discharge side of fan.
8
Return/Exhaust risers in mechanical rooms and
vertical service spaces (duct shafts).
-750 (3)
9
Supply air ductwork upstream of HEPA filters,
including diffusers with integral HEPA filters.(5)
+750 (3)
10
Return and/or exhaust air ductwork on suction
side of fans other than in mechanical rooms and
vertical service spaces.
-500 (2)
C
Transverse joints and
other connections
11
Supply air ductwork on downstream side of
terminal units or reheat coil;
250 (1)
C
Transverse joints only
125 (½)
D
No sealing
Exhaust air ductwork on discharge side of fan;
Fan coil units, suction and discharge.
12
Supply air and return air ductwork from roof top
air conditioning units, 5 tons or less
Notes for table 2:
(1) Transverse joints are connections of two duct or fitting elements oriented perpendicular to flow,
(2) Longitudinal seams are joints oriented in direction of flow,
(3) Duct wall penetrations are openings made by screws, non-self-sealing fasteners, pipe, tubing, rod
and wire,
(4) Other connections such as spin-ins taps and other branch fittings inserted into cut openings in duct,
access door frames, insertion type control elements and duct joints at equipment are to be treated as
transverse joints.
(5) This pressure class also applies to supply ductwork downstream of a terminal box or reheat coil
which serve diffusers with integral HEPA filters.
3.3
Fittings - Rectangular Ductwork
.1 Refer to Annex A at the end of this Section for illustrations of referenced fitting types.
.2 Elbows:
.1 Elbows are to be installed as shown, or if not shown, in descending order as listed in table 3.
(a) for clarity, elbows types are to be selected based on the highest order number (where 1 is the
highest) which will fit the available space.
Table 3: Rectangular Duct, Elbows
Issued For Tender