Memorial Hermann Best Practices

July, 2013

SECTION 23 31 14 SHEETMETAL - SPECIAL DUCTWORK

PART 1 - GENERAL

1.01 WORK INCLUDED

A. Fabricate and install special duct work for:

1. Kitchen range exhaust duct

2. Dishwasher exhaust duct

3. Lab hood exhaust duct.

4. Isolation room discharge air exhaust ductwork.

5. Air distributing apparatus casing

1.02 RELATED WORK

A. Section 23 05 00: Common Work Results for HVAC

B. Section 23 31 13: Sheetmetal Ductwork

C. Section 23 33 00: Air Duct Accessories

D. Section 23 38 13: Commercial Kitchen Hoods

1.03 SUBMITTALS

A. Submit manufacturer's product data for review.

PART 2 - PRODUCTS

2.01 MATERIAL AND FABRICATION

A. Kitchen Range Exhaust Duct:

1. Fabricate, install and support ductwork as required by NFPA 96 and local codes.

2. Ductwork and support material: Carbon steel not less than 0.054" (No. 16 MSG) or stainless steel not less than 0.043" (No. 18 MSG) in thickness.

3. All seams, joints, and penetrations shall have a liquid tight continuous external weld, except where the duct stub collar of the hood or a listed ventilator is connected to the exhaust duct. Refer to NFPA 96 for details of this connection when used.

4. Install cleanout doors in the sides of the duct located at each change of direction and in straight sections not more the 20 feet apart. Openings shall be at the sides of duct and in horizontal sections shall be not less than 1-1/2" from the bottom of the duct. In interior duct installations, provide convenient one-hour rated ceiling access panels to provide access to cleanout doors.

5. See mechanical drawings for additional details for materials and installation and refer to NFPA for additional details relative to internal and external installation.

6. Paint exterior ductwork with paint and primer, suitable for application, to protect ductwork in accordance with NFPA 96, 4-6.2. Remove all rust and other debris from duct before painting.

B. Dishwasher exhaust ductwork: Welded aluminum above the ceiling and stainless steel from ceiling to dishwasher connection.

C. Lab Hood Exhaust Ductwork and Outside Exposed Exhaust Ductwork:

1. Exhaust air ductwork from all lab fume hoods exhaust systems and all associated fittings and dampers shall be welded construction of Type 316 stainless steel equal to United McGill.

2. Ductwork located outside, or exposed to elements, from building penetration to fan and also on fan discharge, along with all associated fittings and dampers, shall be welded construction of Type 316 stainless steel equal to United McGill. 2. Construction shall be a minimum of 20-gauge.

3. Exhaust fan discharge ductwork from fans to stack base and including stack as shown, shall be 316 stainless steel, all welded construction designed for a +3" static pressure class. Use flanged end connections internally welded together.

a. Stacks shall be provided with fully bolted and gasketed access manways which can be proven airtight up to +6" w.c.

b. Stacks shall be guy wired for support against a wind moment developed by 110 MPH, in a manner approved by structural engineer hired by mechanical contractor. Provide submittal with detail sketches of installation sealed by Texas licensed structural engineer.

c. Stack height for lab, isolation room and other hazardous exhausts shall have a stack discharge height a minimum of 10’-0” above finished roof level.

d. Conform to SMACNA guidelines for welding sheetmetal.

4. Intake ductwork at fan shall match construction class of exhaust system, minimum 2”.

5. Rain cap, flashing collar, and roof thimble.

D. Air distributing apparatus casing:

1. Construction: 18 gauge (16 gauge if over 10 feet high) galvanized sheetmetal formed in 1-1/2 inch high standing seam panels.

2. Form casing in a rectangular shape, with slope of air stream between system components limited to a maximum of 45 degrees.

3. Provide supplemental interior angle iron reinforcing before fan inlet, and exterior reinforcing after fan discharge, to avoid buckling and collapse during fan start-up and under extreme filter loading conditions.

4. Reinforce casing spans and walls in medium or high pressure casing, as outlined in SMACNA "Duct Manual".

5. Provide access doors as specified in Section 23 33 00.

6. Install access door in a 16 gauge (minimum) channel or zee-section frame provided in the casing.

7. Extend side members of access door frame from floor to roof line.

8. Provide internal duct sound liner in apparatus casings. Liner shall be CertainTeed "Ultralite", or approved equal.

9. Liner shall be 1" thick, UL listed, neoprene coated, mat faced, flexible fiberglass, and density of one pound per cubic foot. Provide liner that complies with UL 181 Erosion Test and has a flame spread rating of 24 or less and a smoke developed rating of 50 or less.

PART 3 - EXECUTION

3.01 INSTALLATION, APPLICATION, ERECTION

A. Apparatus casing:

1. Rivet or bolt casing panels at floor line to a continuous 2"x2"x1/4" galvanized angle attached on 18 inch centers by expansion shields and bolts to a concrete curb or floor as detailed on drawings.

2. Join walls and roof similarly or by flanging casing and attaching to masonry by bolts and expansion shields on 24 inch centers.

3. Seal standing seam joints and attachment joints with either liquid high velocity duct sealant, mastic, or caulking compound applied so that pressure differential drives sealant into joint.

4. Seal piping and conduit penetrations air and moisture tight with sealant plates and gaskets.

5. Sound liner:

a. Adhere liner to the duct with a continuous coating of approved adhesive and with adhesive clips or welded studs, on 16" centers.

b. Provide coating of Foster CP-30 on air entering side and seal other joints with metal or fiberglass cloth so that liner will be smooth to air flow.

B. Boiler Stack:

1. Install and support as shown on drawings.

2. Paint inside and outside with two coats of high temperature silicone vehicle paint.

C. Dishwasher Exhaust Duct:

1. Install as shown on drawings.

2. Support ductwork as specified under this Division.

3. Slope ductwork toward dirty side of dishwasher as shown on mechanical drawings.

3.02 CLEANING AND TESTING

A. Clean and test work as specified in Section 23 05 00.

END OF SECTION

SHEETMETAL – SPECIAL DUCTWORK

23 31 14 - Page 3