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CTS-D > Structural and Mechanical Considerations > Flashcards

Structural and Mechanical Considerations Flashcards

1
Q

Local Authority Circular 59/5: Advice on the Enforcement of the Noise at Work Regulations 1989
in Leisure Premises (Where Recorded or Amplified Music is Played) states that employees should not be subjected to more than an average of _____ A-weighted decibels (dBA) over an eight-hour period without some protective action taken.

A

85

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2
Q

In the case of AV systems, guidelines dictate that every presenter or end-user must have access to the same control functions. This typically means that operator controls should be between __ and __ in above the floor, depending on whether someone in a wheelchair is directly in front of the equipment or approaching from the side.

A

15 and 54

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3
Q

If the equipment must be approached from the front because a wheelchair cannot come beside it, then the access points should be between __ and __ in high.

A

15 and 48

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4
Q

The ADA recommends certain design guidelines related to head and aisle clearance. For example, equipment, such as a display, should protrude no farther than__ in from a wall.

A

4

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5
Q

When hanging screens, projectors, or other devices from a ceiling, it’s important to note that ADA guidance states that __ in is the minimum height for any passageway.

A

80

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6
Q

____ is the support system or construction material that is added to the wall, typically before the wall finish is applied.

A

Blocking

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7
Q

Load limit is an important part of AV equipment’s specifications. One element of the load limit is the_____, or a similar rating called the _____, which is the weight that must not be exceeded.

A

safe working load (SWL) / working load limit (WLL)

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8
Q

Load Limits

The separation between the wall and the mounting. It’s measured by how much weight is necessary to break the mounting from the wall.

A. Shear
B. Tensile Strength
C. Pullout

A

A. Shear

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9
Q

Load Limits

The maximum amount of tension—pulling apart—that the hardware can withstand before it fails.

A. Shear
B. Tensile Strength
C. Pullout

A

B. Tensile Strength

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10
Q

Load Limits

_____ takes into account the pounds of force needed to pull a fastener from the wall.

A. Shear
B. Tensile Strength
C. Pullout

A

C. Pullout

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11
Q

In general, bolts placed at the ____ of a mounting carry more stress than bolts placed at the ____. Placement should match manufacturers’ instructions.

A

top / bottom

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12
Q

When your goal is to mount equipment safely (which is always), multiply published design weights by no less than __. This is the safety factor, also known as the design factor, load factor, or safety ratio.

A

5

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13
Q

The ASTM International (American Society of Testing Materials International) and SAE (Society of Automotive Engineers) use a unique marking technique for bolt heads. The raised bumps on the head of the bolt indicate the bolt’s ____.

A

grade

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14
Q

When designing for mounted equipment, specify ASTM and SAE bolts that are at least Grade __.

A. 2
B. 3
C. 5
D. 8

A

C. 5

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15
Q

When designing for mounted equipment, specify ISO-rated hardware that is at least Grade __.

A. 4.6
B. 5.8
C. 8.8
D. 9.8

A

C. 8.8

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16
Q

The term _____ associated with pipe utilization refers to the material thickness, similar to wire gauge.

A

schedule

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17
Q

A standard AV equipment rack is __ in wide.

A

19

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18
Q

AV equipment rack height is specified in terms of _____.

A

rack units (RUs)

19
Q

1 RU (basically, a single slot in a rack) is an Electronic Industries Alliance (EIA) standard of ___ in.

A

1.75

20
Q

Rack heights vary considerably depending on whether the rack is a standard or custom configuration. The total number of rack units available will usually range up to __ RUs, or __ in (1955.8 mm) tall.

A

44 / 77

21
Q

Rack depth typically varies from __ to __+ inches.

A

12 to 32

22
Q

Equipment that is manufactured for a rack has ____—extensions on both sides of the faceplate that align with the holes in the mounting rail.

A

ears

23
Q

In the United States, it is important to follow the Americans with Disabilities Act guidelines for equal experience, which dictate “_____” for people in wheelchairs who need to insert media or operate controls from the front or side of a rack.

A

reach ranges

24
Q

In rack layout design, it is common to group equipment according to function. For instance, you may want to specify that all video components be installed together in one area of the rack. This practice is called _____.

A

signal separation

25
Q

_____ protects against the effects of electromagnetic interference (EMI)— noise or crosstalk.

A

Signal separation

26
Q

A ____ gives you a visual representation of the signal flow between the various components of a system.

A

Block Diagram

27
Q

Any piece of electronic equipment that is powered on generates heat, whether it is idle or doing work. The resulting _____ is measured in British thermal units (BTU).

A

heat load

28
Q

___ BTU equals about ___ joules.

A

1 / 1,055

29
Q

___ watt per hour equals ___ BTU.

A

1 / 3.41

30
Q

The formula for calculating heat load is as follows:

A

Total BTU = We × 3.41

where:

  • We is the total watts of all equipment used in the room.
  • 3.41 is the conversion factor, where 1 watt of power generates 3.41 BTU of heat per hour.

This formula does not account for the heat load generated by amplifiers.

31
Q

_____ refers to how much of the time an amplifier is powered on and how much it is at rest.

A

duty cycle

32
Q

What are some factors that need to be considered what calculating heat load from power amplifiers?

A
  • The efficiency of the amplifier. Of the power that is consumed, how much of it is used up within the mounted case compared with the amount transferred to the loudspeakers?
  • Voice paging, music, rock music, and pink noise have drastically different demands on the amplifier. This is referred to as the duty cycle—how much of the time it is powered on and how much it is at rest. What kind of program material is being amplified?
  • How much power will be demanded of the amplifier? Just because it is capable of producing 200W per channel, are you designing it to do so?
  • How often is the power amplifier turned on? Is it always on and operational or only one hour per week?
33
Q

There are two main methods of cooling a rack:

A
  • Pressurization

* Evacuation

34
Q

The ____ cooling method uses fans to blow cooler air into the rack. The fans may have a filter to prevent dust and dirt from entering the rack. Vents on the sides and top of the rack provide an escape for the hot air.

A. pressurization
B. inhalation
C. evacuation
D. excavation

A

A. pressurization

35
Q

The ____ cooling method uses fans to draw air out of the rack, usually through the top vents. Cool air is drawn into the rack from the side and bottom vents.

A. pressurization
B. inhalation
C. evacuation
D. excavation

A

C. evacuation

36
Q

_____ within a room can affect speech intelligibility, which creates additional challenges for AV designers. One common source is the building HVAC system.

A

Background noise

37
Q

Sound systems typically need to perform __ dB above the noise level.

A

25

38
Q

You should use a(n) ____ sound pressure level (SPL) meter and measure the noise level of the HVAC system.

A. A-weighted
B. B-weighted
C. C-weighted
D. Z-weighted

A

A. A-weighted

39
Q

The open cavity above the visible ceiling is called a ____.

A

return air plenum

40
Q

Always use ____ when pulling cable through a firewall. It comes in many forms, such as foam, blocks, or plugs, but it all has the same basic function. It acts as an impenetrable insulator against flames.

A

firestop

41
Q

The Energy Management Standard centers on three big ideas:

A
  • Data collection
  • Automation
  • Education and training
42
Q

Data collection is all about the _____ of devices and how they’re measured.

A

power factor

43
Q

A critical design concept is not what should be on—it’s what should be off. This is known as _____.

A

off thinking

CTS-D (17 decks)

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