Understanding the types of duct features - Intergraph Smart 3D - Help

Intergraph Smart 3D HVAC

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Smart 3D Version
11 (2016)

You use the following features to create a duct run:

Straight Feature

Straight features are defined by two linear data points that form a straight line. Basic geometric principles dictate that two points define a line, thus the straight section of a duct run is a straight feature.

End Feature

End features act as a place holder for future connections to the run. It is located at the end of a run, where a port exists on a part that is managed by the run. When an end feature is connected to a run, it is removed and replaced with another feature, based on the nature of the addition to the run. An end feature represents either end of a physical duct run. When you change a cross section, the software automatically inserts a transition feature. Also, when you change routing direction, the software automatically inserts or changes the turn feature. You can type a value in the Angle box only if the specification is set for continuous angle type.

Transition Feature

A transition feature represents a change in the cross section or size of the duct run. The path of this feature is defined by a transition between cross sections or sizes or other defining constraints that result in the first port of the part being fundamentally different from the second port. Transition features close the gap between these ports. The default transition feature has cross sections that either you specify manually or that the software defines by default. Transition features can be concentric or centerline-aligned.

The following illustration depicts the rule that defines the length of the default transition feature:

(A) - W2 or the value of the second width in the default transition feature

(B) - L or length in the default transition feature; to determine the length, subtract the second length from the first length; then divide the difference by the tangent of the transition wall angle; in algebraic form, the equation is L = (W1 -W2) / tan x (where x is equal to the transition wall angle)

(C) - W1 or the value of the first width in the default transition feature

Turn Feature

Turn features represent a deviation in a path resulting in a turn. Turn features, such as elbows, miter elbows, and gooseneck elbows, change direction of the duct. If the centerline of the active duct is not collinear with the existing duct, the software automatically inserts the turn feature at both duct ends. If the two ducts are collinear, the software merges the two sections into one section. The default turn feature has the same cross sections on both ends. An administrator can edit the reference data to add values to display as options in lists on the ribbon.

Properties for turning vanes and branch vanes in turn features and branch features appear on orthographic drawings but are not needed for the model. The property names are Number of Vanes and Vane Length, and you need to type the values for these properties. The vane material, vane thickness, and vane width are the same as the parent feature. If you modify a feature with vanes, the software automatically recalculates the vane length, part weight, and part center of gravity.

An example would be three data points provided by a user. The first two data points generate a straight feature. The third data point, if not in-line with the first set, constitutes a deviation in path from the existing straight projection, as shown in the following illustration.

(A) - Uses a width ratio (depth divided by width) to calculate the turn radius for a rectangle

(B) - Uses a width ratio (depth divided by width) to calculate the turn radius for a flat oval

Split Feature

A split feature represents a break and a joint in the duct. It divides a duct along a straight section into two straight features to connect the ends of the two ducts at the cut location. Examples are a joint sleeve, butt weld, coupling, and a flange set, either sloped or flat. These examples also are called split parts, which the software reads from the reference data.

Branch Feature

Branch features represent junctions whose path is defined by branching components, such as tees, wyes and crosses. The location that you select can be on the duct surface for a square cross section or the centerline of the duct for a round cross section. When you locate the point on a duct surface, by default the software aligns it with the centerline of the duct. The third port of a branch feature will always, by rule, constitute a new run that is independent of the header connections. When you change routing direction, the software automatically changes the branch surface.

If you modify a feature with vanes, the software automatically recalculates the vane length, part weight, and part center of gravity. Properties for turning vanes and branch vanes in turn features and branch features appear on orthographic drawings but are not needed for the model. The property names are Number of Vanes and Vane Length, and you need to type the values for these properties. The vane material, vane thickness, and vane width are the same as the parent feature.

Along Leg Feature

Along leg features represent in-line components such as dampers or filters where port 1, the origin, and port 2 are collinear.

Free Leg

A leg is a set of continuously connected features routed in the same direction. A free leg has an open end and does not have a straight feature. An offline leg such as a branch is a free leg if it has an open end.

You can move an entire leg and maintain connectivity by moving any straight feature on that leg. Use the common Move command to move the straight feature. If the leg does not have a straight feature, use the Get Features > On Same Leg command on the right-click menu to select the leg.

With the route selection commands, you can select any section of route network by selecting any associated straight feature, along-leg feature, or end feature. See Route Selection Commands.

Inline Free Leg

1

Leg 1

Leg 2 does not have a straight feature and has open end. When you move leg 1, the software also moves leg 2.

2

Leg 2 - Free leg

Inline free leg with a straight feature:

1

Leg 1

Leg 2 has a straight feature and an open end. When you move leg 1, the software shrinks or stretches leg 2 depending on the move direction.

2

Leg 2

Offline Free Leg

1

Leg 1

Leg 2 has a straight feature and an open end. When you move leg 1, the software also moves leg 2.

2

Leg 2 - Free leg

Rules for Copying and Pasting Features

Rules for Moving Features