4. Avoid a sudden expansion immediately before an AFG Flow Grid (See Fig. 2a).
5. A local contraction at the plane of the AFG Flow Grid is a use- ful technique to increase pressure differential when velocities are low (See Fig. 2b).
6. Where persistent swirl is expected it is advisable to install an anti-swirl device at least 1D upstream from the AFG Flow Grid.
Note: For rectangular duct D = Width + Height of Duct/ 2
INSTALLATION The AFG Flow Grids are supplied in kit form, and tube lengths are cut to suit the required duct size by the customer.
The AFG Flow Grid is available in two tube diameters and lengths (See Table 1).
Table 1: Dimensions
Tube Diameter “A” 5/16˝ (8 mm) 5/8˝ (16 mm)
Tube & Adapters Supplied Length Size “B” 27˝ (688 mm) 59-4/5˝ (1518 mm)
They may be used in square, rectangular or round ducts.
Unpack your AFG Flow Grid. The kit should contain the following parts:
Adapter & Pressure Tube Adapter Plate Duct Cap Cap Plate Adapter Drilling Template Duct Cap Drilling Template Diaphragm Elbow Tube Cap Grommet Cap Seal Adapter Seal
2 2 2 2 2 2 2 2 2 2 2 2
Screws, Self Tapping No. 6 x 5/8˝
Decide on the best location for your AFG Flow Grid.
The AFG Flow Grid is designed to fit into the shortest duct sides of a rectangular duct or across a duct diameter. Mark out the duct to the dimensions shown in Fig. 4 and 5. Attach the self-adhesive templates supplied, and produce the holes to the sizes indicated on the templates. DEBURR the 1.26˝ (32 mm) diameter holes.
Table 2: Included Parts
Introduce tubes into the duct and secure at the adapter end using the clamping plate and No. 6 self-tapping screws supplied (See Fig. 6 and 7). Note position of tubes relative to the direction of flow (See Fig. 7).