Page 1
This grease duct is ETL listed to standard UL
-
1978 and does not have to be
welded in the field.
Non
-
Welded Grease Duct Systems
Installation, Operation, and Maintenance Manual
FOR YOUR SAFETY
TWO MAJOR CAUSES OF GREASE DUCT RELATED FIRES: (1) FAILURE TO MAINTAIN
REQUIRED CLEARANCE (AIR SPACE) TO COMBUSTIBLE MATERIALS AND (2) FAILURE TO
CLEAN GREASE LADEN DUCTS. IT IS OF UTMOST IMPORTANCE THAT THIS GREASE DUCT
BE INSTALLED ONLY IN ACCORDANCE WITH THESE INSTRUCTIONS. DO NOT INSTALL
GREASE DUCT WITHOUT FIRST READING THESE INSTRUCTIONS VERY CAREFULLY.
Grease duct installed in accordance with these installation instructions will comply with
national safety standards and building codes.
This booklet contains complete information on details concerning dimensions, installation and
clearances to combustibles. For any additional construction information, refer to Duct Work
Catalog.
February 2014 Rev. 20
A0011047
Page 2
TABLE OF CONTENTS
WARRANTY ............................................................................................................................................ 3
LISTINGS ................................................................................................................................................ 4
APPLICATION ......................................................................................................................................... 4
MECHANICAL ......................................................................................................................................... 5
Joint Sealant ....................................................................................................................................... 5
Sealant Features ............................................................................................................................. 5
Table 1 – Sealant Usage Chart ....................................................................................................... 5
Grease Duct Standard Connection ...................................................................................................... 6
Fig.1 – Joint Assembly .................................................................................................................... 6
Collar & Adjustable Duct Connections ................................................................................................. 7
Fig. 2 – Adjustable Duct Overlap ..................................................................................................... 7
Collar & Adjustable Duct Vertical Installation ........................................................................................ 7
Table 2 – Minimum Overlap ............................................................................................................. 7
Fig. 2a – Adjustable Duct Overlap ................................................................................................... 7
Fig. 2b – Collar & Adjustable Duct Installation.................................................................................. 8
Risers – Factory & Field (Bolted & Welded) Risers .............................................................................. 8
Fig. 3 – Field Installed Riser - Bolted ............................................................................................... 9
Fig. 4 – Duct Drain .......................................................................................................................... 9
Duct Drains ......................................................................................................................................... 9
Grease Manifold Tee ........................................................................................................................... 9
Fig. 5 - Grease Manifold Tee Position .............................................................................................. 9
Access Door (Tee Cap) Assembly ..................................................................................................... 10
Fig. 6 – Access Door Assembly ..................................................................................................... 10
Fan Adapter Plate ............................................................................................................................. 11
Fig. 7 – Fan Adapter Plate ............................................................................................................. 11
Prevention of Grease Accumulation in Horizontal Grease Duct .......................................................... 11
Alignment & Bracing of Grease Duct .................................................................................................. 11
Table 3 – Horizontal Support Spacing ........................................................................................... 11
Horizontal Support & Support Spacing .......................................................................................... 11
Fig. 8 – Horizontal Support Details ................................................................................................ 12
Wall Guide Support & Support Vertical Spacing ............................................................................. 12
Table 4 – Vertical Support Spacing................................................................................................ 12
Fig. 9 – Vertical Support Details .................................................................................................... 13
Grease Duct Assembly Examples ...................................................................................................... 14
Fig. 10 - Grease Duct Installation Guide ........................................................................................ 14
Fig. 11 - Grease Duct Installation Guide ........................................................................................ 15
Fig. 12 - Grease Duct Installation Guide ........................................................................................ 16
CLEARANCES ...................................................................................................................................... 17
Table 5 – Clearance – Grease Duct ................................................................................................... 17
Zero Clearances to Combustibles ...................................................................................................... 18
METHODS USED TO TEST DUCT AFTER ASSEMBLY ....................................................................... 18
Method 1 – Light Test per IMC 506.3.3.1 ........................................................................................... 18
Method 2 – Smoke Test .................................................................................................................... 18
GENERAL DUCT WEIGHT ................................................................................................................... 18
Formula 1 – 20 Gauge Duct............................................................................................................... 18
Formula 2 – 18 Gauge Duct............................................................................................................... 18
NOTES .................................................................................................................................................. 19
CLEANING & MAINTENANCE RECORD .............................................................................................. 20
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Page 3
WARRANTY
This duct work system is warranted to be free from defects in material and workmanship, under normal
use and service, for a period of 12 months from the date of shipment. This warranty shall not apply if:
1. The equipment is not installed by a qualified installer per this installation guide, this guide should
be kept with the equipment once installation is complete.
2. The equipment is not installed in accordance with federal, state and local codes and regulations.
3. The equipment is misused or neglected.
4. The equipment is not operated within its published capacity.
5. The invoice is not paid within the terms of the sales agreement.
The MANUFACTURER shall not be liable for incidental and consequential losses and damages
potentially attributable to malfunctioning equipment. Should any part of the equipment prove to be
defective in material or workmanship within the 12-month warranty period, upon examination by the
MANUFACTURER, such parts will be repaired or replaced by the MANUFACTURER at no charge. The
BUYER shall pay all labor costs incurred in connection with such repair or replacement. Equipment shall
not be returned without MANUFACTURER’S prior authorization and all returned equipment shall be
shipped by the BUYER, freight prepaid to a destination determined by the MANUFACTURER.
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Page 4
LISTINGS
This grease duct is ETL listed to standard UL-1978 when installed in accordance with these installation
instructions and National Fire Protection Association Standard “NFPA 96, Standard for Ventilation Control
and Fire Protection of Commercial Cooking Operations”.
APPLICATION
The listed grease duct is suitable for use in commercial cooking installations for the removal of smoke
and grease laden vapors. The grease duct system includes all components for a complete exhaust
system from the hood to the exhaust fan inlet.
Grease duct installations require provisions for cleaning the interior of the duct. NFPA 96 cleanout
requirements are as follows:
1. A cleanout must be provided at each change of direction except where the entire length of duct
can be inspected and cleaned from either the hood or the discharge end.
2. On horizontal duct runs, at least one (1) 20” diameter opening must be provided. Where the
opening is smaller than 20” diameter, openings large enough to permit cleaning must be provided
at intervals of no more than 12’.
3. Openings must be at the side or the top, whichever is more accessible. When the opening is on
the side of the duct, the lower edge of the opening must be at least 1 ½” above the bottom of the
duct. For the listed grease duct, this is accomplished by the use of the grease manifold tee and
cleanout cap.
4. On vertical duct runs where personnel entry is possible, access must be from the top of the riser.
Where entry is not possible, access must be provided at each floor.
NOTE: ACCESS REQUIREMENTS ARE SUBJECT TO CHANGE IN ACCORDANCE WITH LOCAL
CODE. LOCAL AUTHORITIES SHOULD BE CONSULTED FOR EXACT REQUIRMENTS. GREASE
DUCT MAY BE CONNECTED ONLY TO HOODS IN A SINGLE FIRE ZONE ON ONE FLOOR. DO
NOT CONNECT GREASE DUCTS TO ANY OTHER PART OF THE BUILDING VENTILATION OR
EXHAUST SYSTEM.
When grease duct is installed in accordance with these installation instructions and the joints are sealed
properly with the recommended sealant, the system will contain a grease fire within the duct. A grease
fire can burn at extremely high temperatures. This system should be dismantled and inspected after any
exposure to a grease fire. Any section that is distorted or discolored should be replaced. All joints in the
system should be examined. Because the sealant expands to assure a positive seal in the case of a fire,
any sealant that has been exposed to high temperature must be replaced. This will ensure that the
system maintains its integrity against fire conditions in the future. The manufacturer of this grease duct
can not be responsible for grease duct systems that are not properly maintained or have been subjected
to one or more grease fires.
Grease duct systems size and capacity information may be obtained from the “ASHRAE Handbook –
Fundamentals” or from the “Air Pollution Engineering Manual” of the “US Environmental Protection
Agency”. Refer to the grease duct systems catalog for descriptions and dimensional data of parts.
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Page 5
MECHANICAL
Joint Sealant
The joint sealant used to seal all joint assemblies is a 3M product. 3M Fire Barrier 2000 + Silicone
Sealant is a ready-to-use, gun-grade, one-component silicone elastomer that cures upon exposure to
atmospheric humidity to form a flexible seal. 3M Fire Barrier 2000 + Silicone Sealant, when installed
properly, will control the spread of fire before, during and after exposure to open flames. It will stop the
spread of noxious gas, smoke and water and maintain the integrity of fire rated assemblies and
construction. NO SEALANT SUBSTITUTES MAY BE USED.
Sealant Features
1. Superior adhesion.
2. Capable of withstanding 2000 °F + temperatures.
3. Class 25 sealant, per ASTM 920.
4. Re-enterable/repairable.
5. Provides up to 4-hours fire-rating.
6. Cures upon exposure to atmospheric humidity.
7. Working time 30 minutes.
8. Cure time 14 to 21 days.
9. Applied with a standard caulk gun.
Table 1 – Sealant Usage Chart
DIAMETER DUCT PERIMETER FT
8" 2.16 30 7
10" 2.68 30 6
12" 3.21 30 5
14" 3.73 30 4
16" 4.25 30 3.5
18" 4.78 30 3
20" 5.30 30 3
24" 6.35 30 2.5
3M FIRE BARRIER 2000 PLUS USAGE
AVERAGE FEET
PER TUBE
NUMBER OF
JOINTS PER TUBE
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Grease Duct Standard Connection
1. Apply a continuous bead of proper sealant around the flange to be joined. The bead should be
¼” thick and continuous.
2. Join the two flanged ends of the duct section together.
3. Fill the “V” clamp with the proper sealant. The bead should be inside the “V”.
4. Install the “V” clamp around the duct sections. Both duct flanges should be inside the “V”.
5. For horizontal duct runs, the “V” clamp hardware should be located on the top side of the duct
and be orientated between the 3 and 9 o’clock position on the duct.
6. NEVER install the “V” clamp with the hardware orientated on the bottom side of the duct on
horizontal runs.
7. Secure the “V” clamp around the duct by tightening the ¼-20 hardware to 85 in-lbs.
8. See Fig. 1 below for details.
9. Remove any excess sealant from the inside of the duct surface.
IMPORTANT: THE HARDWARE USED TO ASSEMBLE THIS DUCTWORK IS SPECIFICALLY
DESIGNED FOR THIS APPLICATION. NO SUBSTITUTE HARDWARE IS ALLOWED. ALL
REPLACEMENT HARDWARE MUST BE PURCHASED FROM THE DUCTWORK FACTORY.
Fig.1 – Joint Assembly
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Collar & Adjustable Duct Connections
The collar and the adjustable length duct have two major
functions: (1) Make up odd lengths of duct as needed in short
runs as in termination of the duct at the exhaust fan. (2) Serve as
an expansion joint for thermal expansion in larger runs of duct.
When used in systems of any orientation, it can perform both
functions simultaneously. The adjustable duct section is overlapped
to allow grease to drain back to the hood in both vertical and
horizontal installations See Fig.10. The adjustable duct is flanged
at one end only. The collar is constructed of the same material as
the duct, and is also designed with a ½” flange that is connected to
the standard duct section using the joint assembly method listed
above See Fig.1. Collars are also sealed using high temperature
silicone that compresses around the adjustable duct when the collar
hardware is tightened. The collar is designed to securely hold the
adjustable duct, while allowing for thermal expansion.
Fig. 2 – Adjustable Duct Overlap
Adapter plate
Adjustable
duct
Collar
"V" clamp
Main duct
Vented curb
per NFPA96
See Table 2
min overlap
Collar & Adjustable Duct Vertical Installation
When the adjustable length duct and collar are installed in the vertical position between two fixed points,
such as the beginning support and the ending support, it should be installed just below the higher support. To
ensure proper axial alignment, wall guide support assemblies must be installed below the duct joint
immediately below the adjustable duct. This combination of parts will force the sliding inner and outer parts
of the adjustable duct to overcome collar friction allowing movement along the axis of the duct and thus
relieving expansion stresses which would otherwise develop between the fixed points of the heated vertical
duct.
1. Slide the adjustable collar over the adjustable duct. Flanges
should be opposite.
2. Slide the adjustable duct into the standard duct to the point
that the collar flange and the standard duct flange meet.
3. The adjustable collar and standard duct are joined and
sealed using the method listed above in Fig.1.
4. Slide the adjustable duct into the standard duct to the
desired length. The minimum overlap dimension depends
on the duct diameter. See Table 2. for proper overlap
dimensions.
5. The collar is sealed to duct using high temperature silicone.
6. Once the desired overlap has been met, tighten the ¼-20
hardware on the “V” clamp and the outside of the adjustable
collar to 85 in-lbs.
7. Inspect the connection for gaps in silicone.
Table 2 – Minimum Overlap
DIAMETER
8" 4”
10" 5”
12" 6”
14" 6”
16" 6”
18" 6”
20" 6”
24" 6”
MIN OVERLAP FOR
ADJUSTABLE DUCT
Fig. 2a – Adjustable Duct Overlap
See table 2
Adjustable duct
Adjustable collar
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Page 8
Fig. 2b – Collar & Adjustable Duct Installation
Risers – Factory & Field (Bolted & Welded) Risers
There are two options for the riser (connection to hood plenum); Factory welded and field welded or bolted.
Dimensional data identifying the size and location of the riser must be provided for factory installation. The
riser is fully welded to the hood plenum.
When field installed, the riser is shipped loose allowing the installer at the jobsite to decide on the final
location of the riser. Field installed risers help when the final location is not known or adjustments may have
to be made due to duct misalignments. Field installed risers may be welded or bolted in place.
1. Bolted risers come with two rings that are used for the connection to the hood plenum, one is
connected to the riser and one will be loose.
2. Locate the desired position of the riser on the top of the hood. Use the riser as a guide when
marking the top of the hood. Make sure that the hole location is inside the plenum area before
cutting.
3. Since the riser is going to be bolted on, a bolt hole circle is required. Use the loose ring as a guide.
4. Use the high temperature silicone provided to seal above and below the cut hole, there should be no
gaps in the silicone either around the cut hole or the bolt hole circle.
5. Center the riser over the cut hole and push down into the silicone. The silicone should be visibly
coming through the bolt hole circle on the riser ring.
6. Align the loose riser ring over the hole on the inside of the plenum and push into the silicone. Align
with the riser ring above the hood and bolt the two rings together using ¼-20 hardware.
7. Excess silicone should be removed, and the connection should be inspected for gaps and loose
hardware.
8. When joining standard duct to the riser use the method shown in Fig. 1 – JOINT ASSEMBLY.
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"V " clam p
Fig. 3 – Field Installed Riser - Bolted
Standard du ct
Riser w ith
reta ining ring
R e taining
rin g
To p o f ho o d
1/4-20 H ard w a re
Duct Drains
Drains are used to provide a point at which low points in the duct system can be
drained. Condensation and low lying water left over from duct cleaning can be
drained easily with the installation of the ball valve drain. Drains are designed to
aid in duct cleaning and can be used to drain grease into an approved grease
collection reservoir. Drains can be hard piped to an approved grease collection
reservoir, remove the cap and connect to the 1-1/2” NPT threads. See Fig. 4. for
details.
Grease Manifold Tee
The grease manifold tee is used to provide access for cleanout to comply with
NFPA 96 requirements. It is equipped with an internal blank that acts as a grease
dam and gasket. The access port is then closed with a cleanout cap or tee cap.
The location of the access port in the tee is dependent on the orientation of the tee
in the final installation. Access port location is coded as Position 1, 2, 3, 4 see
Fig. 5. Access ports are never located where grease can build up and fall out
once the cleanout cap is removed.
Fig. 4 – Duct Drain
Tee
Adapter
Drain
Fig. 5 - Grease Manifold Tee Position
Position #1 Position #2
Grease Dam
Position #3 Position #4
9
Incorrect
Installation
Access Door
Removed for Clarity
Page 10
Access Door (Tee Cap) Assembly
Access doors (tee caps) are available 8” to 24”. They work in conjunction with the manifold tee as previously
shown in Fig. 5. The tee joint connection is shown in Fig. 1 – JOINT ASSEMBLY; however, the installation
of the access door is slightly different so read the following instructions very carefully. Consult NFPA 96,
Chapter 7, Section 7.3.1 “Openings shall be provided at the sides or at the top of the duct, whichever is more
accessible, and at change of directions”.
1. Select the location and the position of the access door.
2. All tee joints will be connected as shown in Fig. 1 – JOINT ASSEMBLY except for the access door.
3. Apply the proper sealant to the flange of the tee that will be used for access to the duct system.
4. Apply a ¼” continuous bead around the flange.
5. Center the inside blank (grease dam) over the opening of the tee and apply pressure. Pushing the
inside blank down onto the tee flange sealant, securing the inside blank to the tee flange.
6. Apply enough pressure to create a positive bond between the tee flange and the inside blank.
Remove excess sealant after making parts concentric (centered).
7. Apply a ¼” continuous bead around the inside blank 1” from the outside edge.
8. Center the listed gasket over the inside blank and push the gasket down into the sealant securing the
gasket to the inside blank.
9. Sealant will begin to cure upon exposure to atmospheric humidity. It will form a flexible seal.
10. Once the sealant is dry attach the access door using a “V” clamp. Ensure flanges are in the “V”
before tightening ¼-20 hardware to 80 in-lbs.
Fig. 6 – Access Door Assembly
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Fan Adapter Plate
The fan adapter plate (Transition Plate) is designed to
connect to a roof curb. The duct section is welded to
the underside of the adapter plate. The adapter plate
is formed to provide a slope to allow grease deposits
to flow back towards the duct. When connected, see
Fig. 7, the plate mounts on top of the fan curb, which
supports the fan housing. The plate may be
positioned off center within the curb provided that the
minimum distance to combustibles is maintained. In
the event that the plate is positioned off center, trim
off excess plate material to allow for fan placement.
Secure the plate to the curb using a minimum of three
fasteners per side. A suitably sized fastener provided
by others is used. The fan adapter plate can be used
to maintain distance to combustibles and also for
vertical support.
Adapter plate
(Optional)
Adjustable duct
Fig. 7 – Fan Adapter Plate
Exhaust fan
Secured to
curb by others
Ceramic
gasket
Vented curb
Prevention of Grease Accumulation in Horizontal Grease Duct
Duct systems serving Type 1 hoods shall be constructed and installed so that grease cannot collect in any
portion of the duct system. The duct system shall slope not less than ¼” per linear foot towards the hood or
toward an approved grease collection reservoir. Where horizontal ducts exceed 75 feet in length, the slope
shall not be less than 1” per linear foot. Offset collars have been designed to meet the above specification.
The collar is used in conjunction with other accessories such as tee’s and elbows to maintain the above
listed slope in horizontal duct runs. The “V” clamp hardware should be located on the top side of the duct and
be orientated between the 3 and 9 o’clock position on the duct. Never install the “V” clamp with the hardware
orientated on the bottom side of the duct on horizontal runs.
Alignment & Bracing of Grease Duct
Grease duct has the characteristics of a continuous stainless steel pipe and it will expand and contract along
its entire length with changes in its temperature. For this reason, conventional methods of attaching guides
and braces to the outer wall of the grease duct cannot be used. Correctly installed support rings, saddles
and wall guide assemblies will serve to keep the duct aligned, provide for adequate resistance to lateral
loads and allow the free axial expansion and contraction movement. A simplified rule for duct expansion is
that the axial growth will be approximately 1 inch per 100 feet of pipe length for each 100 degrees Fahrenheit
the exhaust vapor temperature is above the surrounding air temperature.
Horizontal Support & Support Spacing
Horizontal duct runs are supported using either 2 X 2 X 1/8” angle
or Unistrut, horizontal support spacing is shown in Table 3. When
cutting the angle or Unistrut to length there must be a minimum of 2”
on either side of the duct or duct wrap. It’s important that the 3/8”
threaded rod suspending the angle or Unistrut does not rub against
the duct or duct wrap. Once the angle has been cut to length it is
suspended using 3/8” threaded rod (minimum). Appropriate sized
holes are drilled/punched in either end of the angle. The 3/8”
threaded rod is secured to the angle or Unistrut using appropriate
sized hardware, washers are used on the top and bottom before
installing nuts, double nuts are used to make sure bottom nuts do not
come loose, see Fig. 8.
Table 3 – Horizontal Support Spacing
HORIZONTAL
DIAMETER
8" 10'
10" 10'
12" 10'
14" 10'
16" 10'
18" 10'
20" 10'
24" 10'
SUPPORT SPACING
(FEET)
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Fig. 8 – Horizontal Support Details
IMPORTANT: VERTICAL & HORIZONTAL SUPPORTS SHOWN IN THIS MANUAL ARE
RECOMMENDED. SUPPORTS BY OTHERS MUST BE APPROVED BY THE MANUFACTURER AND
AHJ. SUPPORT SPACING MUST BE AS STATED IN THIS MANUAL.
Wall Guide Support & Support Vertical Spacing
Angle / Unistrut
The wall guide is to be attached to Non-Combustible and Combustible surfaces. The wall guide is
constructed of 12 gauge steel and is comprised of a full ring, brackets, angle struts, wall support plates and
hardware for assembly (Includes mounting hardware to secure supports to gypsum walls constructed using
25 gauge steel studs), see Fig. 9. The ring, which is split in two halves for ease of assembly, is constructed
of 12 gauge steel. With the addition of a spacer between the two halves, the diameter is 1/8” larger than the
outside diameter of the duct. This is to allow for thermal expansion.
The wall support should be installed at the joint of the duct and below the “V” clamp so the “V” clamp moves
away from the support ring. The wall guide assembly is designed for 2 to 18 inches clearance from duct to
non-combustible / combustible walls. The side struts may be placed either up or down as is convenient. This
assembly is intended to resist lateral or side loads only and is not for carrying the weight of the vertical
grease duct. The horizontal struts allow for attachment to the wall after the grease duct has been positioned.
The angle of attachment may vary as needed for the duct to wall clearance. Wall supports shall be used at
the proper spacing shown in Table 4 for vertical duct support, with appropriate expansion joints to allow for
thermal expansion and wall guides for lateral stability.
OD + 4"
3/8" Threaded Rod
Duct
Duct Wrap
Inner Layer
Duct Wrap
Outer Layer
See table 3
6" Collar
Table 4 – Vertical Support Spacing
DIAMETER VERTICAL SUPPORT SPACING (FEET)
8" 10'
10" 10'
12" 10'
14" 10'
16" 10'
18" 10'
20" 10'
24" 10'
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Page 13
Fig. 9 – Vertical Support Details
IMPORTANT: VERTICAL & HORIZONTAL SUPPORTS SHOWN IN THIS MANUAL ARE
RECOMMENDED. SUPPORTS BY OTHERS MUST BE APPROVED BY THE MANUFACTURER AND
AHJ. SUPPORT SPACING MUST BE AS STATED IN THIS MANUAL.
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Page 14
Grease Duct Installation:
Grease Duct Assembly Examples
Fig. 10 - Grease Duct Installation Guide
Adjustable ducts and standard
ducts can be used to terminate
at the transition plate. The duct
is fully welded to the transition
plate at the factory.
The illustration shown provides useful information
on the installation of grease duct systems. Each
installation is specific to the application and the job
site. When duct systems are installed outside,
welded seams must be painted with corrosion
resistant high temperature paint. If you encounter a
situation not covered by this illustration, refer to the
guide or consult the factory. Remember, if the
distance to a combustible surface is less than 18
INCHES you will need to wrap the duct in a listed
duct wrap to get “ZERO CLEARANCE TO
COMBUSTIBLES”.
Exhaust fan
Vented curb per NFPA-96
IMPORTANT INFORMATION
PLEASE READ BEFORE INSTALLING
This duct is designed to be installed
in application where the duct system
is a minimum of 18" to combustible
surfaces, duct installations that cannot
maintain 18" minimum clearance to a
combustible surface must be insulated
using a clearance reducing, listed grease duct
insulation, see details in this guide.
Offset collar
Tee assembly with access door
has been used due to offset in
the duct. Access doors are used
when there is a change in direction
or where areas of duct are not accessible.
Adjustable duct
Adustable
collar
The vertical support assembly is
designed for 2" to 18" clearance
from duct to non-combustable
surface.
Offset collar used to
pictch horizontal duct runs
See table 2
Riser
Fan adapter plate
with ceramic gasket
Tee - Access door
3/8" Threaded Rod
Minimum.
First vertical support
at joint #1 after change
in direction
45 degree elbow
Standard duct
Adapter
Y Tee
Adjustable duct
Adustable
collar
Standard duct
temperature above the surrounding air temperature.
Offset collar
Unistrut / Angle
Adjustable ducts are used
on runs over 100 ft to compensate
for thermal expansion. The duct will
grow approximately 1" per 100 ft of
duct length for each 100 °F exhaust vapor
See table 3
Standard duct
Adustable
collar
Adjustable duct
Standard duct
Offset collar
Tee - Access door
Riser
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Page 15
Grease Duct Installation:
Fig. 11 - Grease Duct Installation Guide
Adjustable ducts and standard
ducts can be used to terminate
at the transition plate. The duct
is fully welded to the transition
plate ate the factory.
Fan adapter plate
with ceramic gasket
Exhaust fan
Adjustable duct
Vented curb per NFPA-96
Adustable
collar
The illustration shown provides useful information
on the installation of grease duct systems. Each
installation is specific to the application and the
job site. When duct systems are installed outside,
welded seams must be painted with corrosion
resistant high temperature paint. If you encounter
a situation not covered by this illustration, refer to
the guide or consult the factory. Remember, if the
distance to a combustible surface is less than 18
INCHES you will need to wrap the duct in a listed
duct wrap to get “ZERO CLEARANCE TO
COMBUSTIBLES”.
The vertical support assembly is
designed for 2" to 18" clearance
from duct to non-combustable
walls.
Standard duct
Standard duct
"V" clamp
Tee assembly with access door
has been used due to offset in
the duct. Access doors are used
when there is a change in direction
or where areas of duct are not accessible.
See table 2
See table 4
The vertical support assembly
is used at the first connection
after the change of direction.
45 degree elbow
Tee - Access door
Standard duct
Adjustable ducts are used
on runs over 100 ft to compensate
for thermal expansion. The duct will
grow approximately 1" per 100 ft of
duct length for each 100 °F exhaust vapor
temperature above the surrounding air temperature.
Exhaust
hood
Hood width
Riser
Height
33" min / 48" max
IMPOTANT INFORMATION
PLEASE READ BEFORE INSTALLING
Hood
height
Height
78"
This duct is designed to be installed
in application where the duct system
is a minimum of 18" to combustible
surfaces, duct installations that can not
maintain 18" minimum clearance to a
combustible surface must be insulated
using a clearance reducing, listed grease duct
insulation, see details in this guide.
Cooking
equipment
15
Page 16
Grease Duct Installation:
Fig. 12 - Grease Duct Installation Guide
Adjustable ducts and standard
ducts can be used to terminate
at the transition plate. The duct
is fully welded to the transition
plate at the factory.
The illustration shown provides useful information on the
installation of grease duct systems. Each installation is
specific to the application and the job site. When duct
systems are installed outside, welded seams must be
painted with corrosion resistant high temperature paint. If
you encounter a situation not covered by this illustration,
refer to the guide or consult the factory. Remember, if the
distance to a combustible surface is less than 18 INCHES
you will need to wrap the duct in a listed duct wrap to get
“ZERO CLEARANCE TO COMBUSTIBLES”.
Adjustable duct
Adustable
collar
The vertical support assembly is
designed for 2" to 18" clearance
from duct to non-combustable
walls.
The vertical support assembly is
mounted under the "V" clamp and
adjustable collar. This will allow
the vertical movement of the duct
system.
Adjustable ducts are used
on runs over 100 ft to compensate
for thermal expansion. The duct will
grow approximately 1" per 100 ft of
duct length for each 100 °F exhaust vapor
temperature above the surrounding air temperature.
Fan adapter plate
with ceramic gasket
Standard duct
"V" Clamp
Standard duct
Riser
Exhaust fan
Vented curb per NFPA-96
Adjustable duct
Adustable
collar
See table 2
Standard duct
"V" Clamp
PLEASE READ BEFORE INSTALLING
Standard duct
Riser
IMPOTANT INFORMATION
This duct is designed to be installed
in application where the duct system
is a minimum of 18" to combustible
surfaces, duct installations that can not
maintain 18" minimum clearance to a
combustible surface must be insulated
using a clearance reducing, listed grease duct
insulation, see details in this guide.
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CLEARANCES
This grease duct is primarily intended for use in non-combustible surroundings, when installed in a room
where enclosure is not required. Grease duct may be located at clearance to combustibles in accordance
with Table 5. Grease duct may be located in a corner formed by two combustible walls provided the
minimum clearance is maintained.
In all buildings more than one story in height and in buildings where the roof-ceiling assembly is required to
have a fire resistance rating, the duct must be enclosed in a continuous enclosure from the lowest fire-rated
ceiling or floor above the hood, through any concealed spaces, to or through the roof to maintain the integrity
of the fire separations required by the applicable building code provisions. If the building is less than 4
stories in height, the enclosure shall have a fire resistance rating of not less than 1 hour. If the building is 4
stories or more in height, the enclosure shall have a fire resistance rating of not less than 2 hours. The
clearance between the outside of the duct and the inside of the rated enclosure must be a minimum of 6
inches or required by code.
Combustible roofs or roof-ceiling assemblies may be penetrated using the vertical support assembly when
distance to combustible surfaces is maintained.
Table 5 – Clearance – Grease Duct
CLEARANCE TO
LIMITED
COMBUSTIBLES
DIAMETER
CLEARANCE TO
COMBUSTIBLES
8" 18" 3" 0"
10" 18" 3" 0"
12" 18" 3" 0"
14" 18" 3" 0"
16" 18" 3" 0"
18" 18" 3" 0"
20" 18" 3" 0"
24" 18" 3" 0"
The above figures represent air space, in inches, to surrounding
NOTE: See NFPA 96, 2004 EDITION, Chapter 3, Definition of Combustible, Limited Combustible and Non-
Combustible.
CLEARANCE TO
NON
COMBUSTIBLES
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Zero Clearances to Combustibles
This duct is to be used in non-combustible surroundings. Where the duct does not require an enclosure, it
must have a minimum clearance to adjacent combustible walls as shown above in Table 5 – CLEARANCES.
In cases where the ducting extends through any story of a building above the location at the connected
appliances, it must be enclosed in the upper stories with walls having a fire resistance rating of not less than
one hour for buildings of two or three stories in height. If the building is four stories or more in height, the
enclosure wall shall have a fire resistance rating of not less than two hours.
METHODS USED TO TEST DUCT AFTER ASSEMBLY
Prior to the concealment of any portion of a grease duct system, a leakage test shall be performed in the
presence of the code official. Duct shall be considered to be concealed where installed in shafts or covered
by coatings or wraps that prevent the ductwork from being visually inspected on all sides. A light test or
approved equivalent test method (smoke test) shall be performed to determine that all joints are liquid tight.
The smoke test is used for longer duct runs while the light test is used for short duct runs, both methods are
approved for use.
Method 1 – Light Test per IMC 506.3.3.1
A light test shall be performed by passing a lamp having a power rating of not less than 100 watts through
the entire section of ductwork to be tested. The lamp shall be open so as to emit light equally in all directions
perpendicular to the duct walls. The test shall be performed for entire duct system, including the hood-toduct connection. The ductwork shall be permitted to be tested in sections, provided that every joint is tested.
Method 2 – Smoke Test
After the ductwork has been installed allow the listed sealant to cure for a minimum of 24 hours. Smoke
bombs are lit and placed at the bottom of the duct system, natural upwards drafts will pull the smoke to the
top of the duct system. Various length duct runs may require multiple smoke bombs. Once the smoke has
reached the top of the duct run, cap the duct, making sure it’s secure. Inspect all joints for leakage.
GENERAL DUCT WEIGHT
Two different material gauges are available, 20 gauge is the minimum / 18 gauge is the maximum allowable
material per this listed duct. Both gauges have been tested by ETL and comply with standard UL-1978. 20
gauge is the standard material used in application with 18 inches or more to combustible surfaces. 20 gauge
duct may also be wrapped using a listed duct wrap for zero clearance to combustibles, 18 gauge is required
in some JHA when duct needs to be wrapped using a listed duct wrap for zero clearance to combustibles.
Weight – 20 Gauge Duct
The following formula can be used to approximate the weight of total lengths of duct for 20 GA duct (.0327 x
“L” x “D”). “L” and “D” should be calculated in inches, where L is the length and D is the diameter. Example:
A total length of duct is 25 ft long, 14” diameter (.0327 x (25’ x 12”) x 14” = 137 LBS).
Weight – 18 Gauge Duct
The following formula can be used to approximate the weight of total lengths of duct for 18 GA duct (.0417 x
“L” x “D”). “L” and “D” should be calculated in inches, where L is the length and D is the diameter. Example:
A total length of duct is 25 ft long, 14” diameter (.0417 x (25’ x 12”) x 14” = 175 LBS).
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NOTES
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Factory Service Department
CLEANING & MAINTENANCE RECORD
Date Service Performed
Phone: 1-866-784-6900
Fax: 1-919-554-2415
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