Triangulatuon ? Flashcards
What 2 ways can triangulation be described ?
1- finding the length of a hypotenuse useing ther vertical and horizontal legs of a right angle
2- developing the surfaces of fittings with surfaces that slant at diffrent angles
What type of fittings can be developed with triangulation ?
Square to round /offsets
Top takeoffs
Right angle and end boots
Hoppers
Breaches
Ship ventilators
Twist
Rectangular duct transitions
Transitional duct elbow
dropCheck elbow
Y branches
transitonal offsets
Lines perpendicular to the viewer line of vision are ? Can also be defined as dimension or line that is not distorted by the view ?
True length lines
An object, construction or element line that is shorter than it Accutalky is because it is slanting towards or away from the viewer?
Foreshortened lines
The horizontal leg is equal to the length of the foreshortened lines taken from the plan view. The vertical leg is equal to height of the fitting from elevation view. The length taken from the vertical leg to horizontal leg is known as the triangulated length. What is this describing ?
True length triangle
A perpendicular line repressing the branch opening for an elbow or Y branch?
Face line
What is vertical height ?
It’s a measurable length. The vertical height of the fitting may or may not include seams and allowances. When using the vertical height for triangulation all seams and allowances must be subtracted
Define triangulation
Method used to develop patterns for irregular shapes and forms in which parallel or radial line cannot be used
What is Pythagorean theorem?
An equation that recognizes the relationship between the sides of a right angle triangle
Formula for Pythagorean theorem?
A2+B2=C2
The hypotenuse is a side of what kind of triangle ?
Right angle triangle
A foreshortened line is a line that appears shorter than it is ?
True or false
True
What are true length triangles horizontal leg ?
A foreshortened dimension
What is used to retro fit a new furnace to the existing plenum ?
Rectangular transitions
Does the face line run 90 to a secondary y branch opening ?
No
When determine the vertical height of a pattern what must be subtracted ?
Seams and allowances
What are transitions and twists used for ?
Change duct sizes and positions in hvac system
What must be used to develop center transitions ?
A plan view
How would u label a transition plan view ?
Label top opening of transition 1-4 in clockwise direction label bottom abcd in clockwise direction as well
Off center transition development steps ?
Plan view
Label all 4 sides
If labeled ba it’s outside if labeled ab its inside
Would line 2b be a true length or foreshortened line ?
Foreshortened anytime a letter goes to a number
How many sides of an off center transition can be developed without triangulation ?
2
How many triangulated lines are in an off center transition?
2
Does vertical height include collars ?
No
What is the advantage of transitional elbows ?
Change direction dimensions and elevation all in one fitting .
Try to keep both the throat and heel radius to a maximum
What is a transitional y branches used for ?
Split airflow in 2 directions while changing size of duct as well
Cheek patterns for transitional y branches are developed from what view ?
Elevation
What line do u use to swing the heel arc on transitonal cheek for y branches ?
Face line
When is an ogee offset used?
When the offset would be to great for a straight side offset
Where can rectangular to round fittings be found ?
Dust collection fittings
Roof jacks
Rectangular to round offset fittings
Rectangular to round 90s
Garbage chutes
When is the method of triangulation used?
When they cannot be developed from the plan view
What is the work line equal to ?
1/2 the depth of fitting
What are the diffrent types of boots ?
Right angle boots
End boots
Top takeoffs
U boots
What kind of hvac systems are boots normally found in ?
Residential
Where are boots commonly found ?
By windows
How many work lines are needed for on center boots ?
1
How many work lines are needed for off center boots ?
2
Top take offs allow branch lines to run where ?
Within the joists
When triangulating boots what kind of view is used ?
Elevation
A 1/2 pattern is needed when developing a pattern for off center right angle boots ?
True or false
False
It is acceptable to use boot configuration when installing a wall stack ?
True or false ?
True
What portion of a square to round on center do u need to develop it ?
1/4
Do the distances around the opening of a square to round need to be triangulated ?
No
When labeling a square to round where is the best place to start ?
Seam
Are both plan and elevation views needed to develop a square to round ?
No
Are the steps for laying out an off center square to round the same as an on center one ?
Yes
What does vh on the right angle triangle refuse to ?
The length of fitting
The horizontal leg on the right angle triangle is used for what?
Triangulating letters to numbers
Are 12 equal spaces always used to divide the round opening ?
No
What are commercial side take offs made out of compared to residential stos?
A heavier gauge
What are round reducing y branches used for ?
Dust collection
Commercial or industrial air handling
When swinging from the middle crotch point for round y branches what is it called ?
Major axis
What is the divided portion of the major axis called ?
Minor axis
What work line does 2 and 3 go on for round y Branches ?
The small branch opening
What is chord offset ?
Subtracting the small opening divided section from the large opening dived sections
Where is point 10,12 and 14 located on round y branches?
The center seam line
A round y branche consists of a primary opening and 2 what ?
Secondary openings
Do we use a chord offset on round reducing y branches ?
True or false ?
True
The crotch mitre plan view is developed from what ?
Major and minor axis
What is developed with the major and minor axis ?
Ellipse
What two types of pattern development are used for a bull head tee?
Line to line and triangulation
Where are bull head tees coming found ?
Blow pipe installations
How many sides of the base triangle for a bull head tee needs to be triangulated ?
2
When is it necessary to have a plan view for a bull head tee ?
Never
What can the design of a bull head tee affect ?
Static pressure and friction loss
What is a chord offset ?
A distance between a point on collar opening and a point on the plan view perpendicular to the collar openings
When developing a round reducing elbow what type of pattern development is used ?
Parallel line and triangulation
How many diffrent types of fittings are used to develop one round reducing elbow ?
2
When subtracting one chord offset from another you must ?
Outside in
Do collar patterns need to be developed first before u can develop body of a round reducing elbow ?
Yes
