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BC Chapter 4

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What is the primary function of counterweights in traction elevators?

To reduce the effort the motor must produce to raise the car.

What type of elevator is most commonly used in buildings over six stories?

Traction elevators.

Where is the drive equipment for traction elevators typically located?

In a machine room directly over the hoist way.

What safety device terminates power before an elevator reaches its limits?

Terminal device.

What are buffers in elevator systems?

Large springs or hydraulic cylinders located at the bottom of the pit that act as shock absorbers.

What is the function of a speed governor in an elevator system?

To slow the drive motor when an elevator exceeds a safe speed.

Define an elevator hoist way.

The vertical shaft in which the elevator car travels, including the elevator pit.

What materials are hoist way enclosures typically constructed from?

Fire-resistive materials such as gypsum or reinforced concrete.

What is a sky lobby in high-rise buildings?

A common discharge floor for two separate elevator systems located some distance up in a building.

What is the role of air-cooled transformers in building systems?

To cool electrical units using surrounding air through fins and ventilation openings.

What are the three distinct parts of means of egress in a building?

Exit access, exit, and exit discharge.

What are the basic components of stairs?

Tread and riser.

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Discover the critical role of stair design in building construction related to fire safety. Learn about various stair types, their components, and how they ensure safe egress during emergencies, including the importance of consistent measurements and protective features.

Questions

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1. Which type of elevator is most commonly used for cargo rather than passenger use?

A Machine Room-Less (MRL) Elevators B Drum elevators C Traction elevators D Dumbwaiters

2. What type of elevator is designed to use a hoisting cable wound on a drum located directly over the hoist way?

A Dumbwaiters B Machine Room-Less (MRL) Elevators C Drum elevators D Traction elevators

3. What is the primary purpose of a sky lobby in a high-rise building?

A To provide a scenic view for passengers B To serve as a recreational area for residents C To house the building's HVAC system D To serve as a common discharge floor for two separate elevator systems.

4. Why are rooftop smoke and heat vents typically required on the roofs of large-area buildings?

A To reduce noise pollution B To facilitate smoke and heat removal C To enhance structural stability D To improve energy efficiency

5. What is the primary purpose of counterweights in a traction elevator?

A To stabilize the elevator during operation. B To increase the speed of the elevator. C To reduce the effort the motor must produce to raise the car. D To provide additional safety features.

6. Which type of elevator is most commonly used in buildings over six stories?

A Traction elevators B Dumbwaiters C Drum-type elevators D Hydraulic elevators

7. What is the most common voltage delivered via transformers to medium and large buildings?

A 3 phase 208/120 volt B 480/277 volt C 120/240 volt D 600/347 volt

8. What is a unique feature of spiral stairs?

A They are often found as grand stairs serving only two levels. B They are naturally ventilated on one or more sides. C They have an intermediate landing between floors. D Each tread is tapered and connects to the column at the tread’s narrow end.

9. Which type of stairs is most commonly found in residential occupancies to provide attic access?

A Spiral stairs B Scissor stairs C Folding stairs D Circular stairs

10. What is a characteristic requirement for circular stairs?

A The small radius of the full circle is greater than or equal to twice the widest part of the stair tread. B They consist of a series of steps spiraling around a single column. C They are naturally ventilated on one or more sides. D They have an intermediate landing between floors.

11. What is the primary advantage of scissor stairs in assembly occupancies?

A They provide access to an attic space. B They are often found as grand stairs serving only two levels. C They are cheaper and more space efficient than two separate stair enclosures. D They have an intermediate landing between floors.

12. What is a key safety feature of exit stairs as part of the means of egress?

A They must resist the effects of the products of combustion. B They are naturally ventilated on one or more sides. C They consist of a series of steps spiraling around a single column. D They have an intermediate landing between floors.

13. What is the standardized speed for escalators?

A 90 feet per minute B 120 feet per minute C 100 feet per minute D 80 feet per minute

14. What is the function of buffers in an elevator system?

A To act as shock absorbers should the terminal switch fail. B To control the speed of the elevator. C To stop a free-falling car. D To slow down the elevator during normal operation.

15. What material is commonly used for constructing hoist ways in low-rise buildings?

A Reinforced concrete B Gypsum or cement block C Steel D Wood

16. What is the role of a speed-reducing switch in an elevator system?

A To stop a free-falling car. B To terminate power before reaching upper or lower limits. C To slow the drive motor when an elevator starts to exceed a safe speed. D To act as shock absorbers.

17. What is the purpose of venting at the top of most hoistways?

A To allow fresh air circulation B To reduce noise levels C To prevent mushrooming D To improve elevator speed

18. How many elevators can be contained in a single hoistway in a building with three or fewer elevators?

A One B Three C Four D Two

19. What is the function of fire-rated vestibules in buildings?

A To improve air quality B To provide additional elevator access C To enhance structural stability D To prevent smoke and hot gases from moving throughout the building

20. In very tall buildings, how are express elevators typically divided?

A By elevator speed B By passenger capacity C By floor number D Into zones, with each set serving a separate zone

21. What is the primary function of smokeproof stair enclosures?

A To support the structural integrity of the building B To provide ventilation to the building C To reduce noise in the stairwell D To prevent smoke from entering the stairwell during a fire.

22. What is the maximum number of adjacent floors that open stairs can connect above the basement level?

A Two B Three C One D Four

23. What is a common protection feature for vertical openings of escalators serving more than two floors?

A Water spray systems B Closely spaced sprinklers and draft stops C Fire doors D Shutters

24. How do hydraulic elevators control the movement of the car?

A Through mechanical gears B With electric motors C Using counterweights D Through the flow of hydraulic fluid

25. What is the function of duct detectors in HVAC systems?

A To stop these systems under fire conditions and minimize unwanted smoke movement. B To monitor air quality continuously C To increase air circulation efficiency D To regulate temperature more effectively

26. What is a double-deck elevator?

A An elevator with two separate cabins side by side B Two cars that are permanently connected to each other vertically and travel in the same hoist way. C An elevator that can switch between passenger and cargo modes D An elevator with an additional emergency exit

27. What is the primary advantage of an automatic smoke control system?

A Relatively fast activation B Ease of maintenance C Manual operation D Lower installation cost

28. What is the purpose of draft curtains in large open areas?

A To minimize the mushrooming effect of heat and smoke B To increase air circulation C To provide aesthetic appeal D To support the ceiling structure

29. What is a smoke tower also known as?

A Smokeproof Enclosure B Heatproof Stairway C Fireproof Corridor D Emergency Exit

30. What is a limitation of smoke and heat vents when used with sprinkler systems?

A Less effective B More expensive C Require more maintenance D Harder to install

Study Notes

Overview of Elevator Systems and Building Safety

This document synthesizes key concepts related to elevator systems, safety features, and building design principles. It highlights the functionality of various elevator types, safety mechanisms in place for passenger protection, and essential construction elements that ensure compliance with fire safety regulations.

Elevator Types and Functionality

  • Traction Elevators: Commonly used in buildings over six stories, these elevators utilize counterweights for efficiency and speed.
  • Dumbwaiters: Designed for transporting lightweight items between floors, enhancing convenience without requiring large elevators.
  • Machine Room-Less (MRL) Elevators: These save space by integrating controls within the hoist way.

Safety Features in Elevators

  • Braking Systems: Essential for normal operations and emergencies; they include devices like brake drums on motor shafts.
  • Speed Monitoring Devices: Mechanisms such as speed governors and overspeed switches prevent excessive speeds, while car safeties engage to stop free-falling cars.
  • Regulatory Compliance: Strict regulations ensure regular inspections and maintenance to uphold safety standards.

Hoist Way Construction and Fire Safety

  • Hoist Way Definition: The vertical shaft where the elevator operates must be constructed from fire-resistant materials.
  • Fire-Rated Assemblies: Required to withstand fire for 1 or 2 hours based on building height; this includes venting at the top of hoistways to manage smoke.
  • Utility Restrictions: Installation of non-essential wiring or piping is prohibited within hoist ways to maintain safety.

Stair Design Principles

  • Means of Egress: Clear paths are crucial for safe evacuation during emergencies; stairs play a vital role in this system.
  • Types of Stairs:
    • Straight-run Stairs: Extend continuously without turns.
    • Return Stairs: Change direction at landings, facilitating access between floors.
    • Scissor Stairs: Space-efficient designs ideal for large public areas like airports.

Key Takeaways

  1. Traction elevators are preferred in high-rise buildings due to their speed and efficiency compared to other types.
  2. A robust set of safety features ensures passenger protection across all elevator systems.
  3. Proper construction practices regarding hoist ways are critical for maintaining fire safety standards in buildings.