Installation

26
SECTION G - GREASE DUCT APPLICATION (DIS ONLY)
ACCESS
Grease Duct installations require provisions for cleaning the interior of
the duct. NFPA 96 clean-out requirements are as follows:
1. A clean-out must be provided at each change of direction except
where the entire length of the duct can be inspected and cleaned
from either the hood or the discharge end.
2. On horizontal duct runs, at least one (1) 20” (508) diameter opening
must be provided. Where the duct is smaller than 20” (610) diam-
eter, openings large enough to permit cleaning must be provided at
intervals of not more than 12’ (3.66m).
3. Openings may be at the side or the top of the duct whichever is more
accessible. When the opening is on the side of the duct, the lower
edge of the opening must be at least 1-1⁄2” (38) above the bottom
of the duct. For Model DIS Grease Duct, this is accomplished by the
use of the Grease Tee (GT90) with a Tee Cap (TC).
4. On vertical duct 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 AC-
CORDANCE WITH LOCAL CODE. LOCAL AUTHORITIES SHOULD BE
CONSULTED FOR EXACT REQUIREMENTS.
USE AND INSTALLATION OF INDIVIDUAL PARTS
1. Duravent Model DIS parts numbering and parts usage are discussed
under chimney applications beginning on page 4 of these installation
instructions.
2. Those parts specific to grease duct, which are not normally used in
chimney applications, are discussed in the following sections.
3. Installation is the same as described for standard application on page
5, but a additional bead of sealant must be applied. See figure 2.
HORIZONTAL DRAIN LENGTH (HDL)
1. Horizontal Drain length is equipped with a 1” (25) NPT nipple, which
is attached to the inner flue and extends through the outer casing to
provide a path to drain grease, condensate or wash water from the
duct. See Figure 67.
2. A dam is attached to the inside of the inner flue adjacent to the nipple
to channel the effluent to the drain.
3. The duct drain is intended for use at the end of a horizontal run where
access and drainage is needed (See Figure 68).
4. The drain coupling must be connected to a grease trap or approved
container (supplied by others).
Figure 70 - Square to round adaptor
SQUARE TO ROUND ADAPTOR
1. When the hood is equipped with a square or rectangular collar, a
square to round adaptor is needed to connect the round DIS chimney
to the hood (See Figure 70).
2. The outside dimensions of the square end are slightly smaller than the
hood collar. It will fit inside the collar and be connected by welding
the two parts.
Figure 67 - Horizontal Drain length
NOZZLE SECTION
1. The nozzle section is used when the duct is required to be equipped
with a fire suppression system or washdown is desired.
2. The nozzle section allows a spray head or nipple to be attached to
the duct through a 1” (25) NPT coupling attached to the inner flue
and when the chimney section is in a vertical orientation, the nozzle
may be located at the most convenient place. See Figure 69.
3. Local authorities should always be consulted regarding the need for
fire protection or washdown systems be installed so that the coupling
is at or above the horizontal centerline of the chimney.
Figure 69 - Nozzle Section
Grease dam
Drain
Grease dam
Drain
Nozzle
Nozzle
Not UL listed
Figure 68 - Horizontal drain length typical location
Hood (by others)
Drop to hood
Up to fan
Standard 90° tee
Clean-out cap
Horizontal
drain length
Plan view
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.