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SUPPLEMENTAL INFORMATION

SECTION 14 2020 (14202) – FREIGHT ELEVATORS

SECTION 14 2100 (14210) – ELECTRIC TRACTION ELEVATORS

SECTION 14 2400 (14240) – HYDRAULIC ELEVATORS

  1. General Description
  2. Types of Elevators
  3. Common Equipment
  4. Operation Systems
  5. Maintenance
  6. Seismic Safety Requirements
  7. How to Specify
  8. Design Considerations

1) General Description

Elevators are vertical transport equipment that efficiently moves people or freight as well as provide services between floors of a facility. Elevators are generally powered by electric motors driving traction cables with counterweight systems similar to a hoist, or by pumping hydraulic fluid to raise a cylindrical piston like a jack. If unfamiliar with elevators and their operation systems, consult with manufacturers' representatives for assistance to revise the Section text. These Sections are based on the 2013 edition of ASME A17.1/CSA B44, Safety Code for Elevators and Escalators (Elevator Code).  

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2) Types of Elevators

Section 14 2020 – Freight Elevators, specifies the freight elevator system that may be based on geared or gearless electric power system or hydraulic with cylinder buried in casing type system. The freight loading classifications are based on the five loading and design classifications of the Elevator Code.

Section 14 2100 – Electric Traction Elevators, specifies the gearless type of electric traction elevator for use by passengers and for service applications that may be used for passengers, service as well as freight.  

Section 14 2400 – Hydraulic Elevators, specifies the hydraulic elevators with cylinder mounted within the hoistway or hydraulic cylinder buried in casing below the elevator pit. The elevator may be for passenger use and for service applications that may be used for passengers, service as well as freight.  Hydraulic elevators are usually limited to four or five story buildings. The section specifies standard hydraulic elevators and may also be used for specifying highly customized elevators and car finishes.  

Electric traction elevators have a higher initial cost for installation, but consume half the energy used by hydraulic elevators. This energy efficiency often justifies using an electric traction elevators over hydraulic units as the energy savings makes up for the initial cost difference in an acceptable time frame. The structural loads of hydraulic elevators are primarily on the foundations rather than on the building frame as in other elevator types. Hydraulic elevators are considered acceptable for freight use, although most elevator manufacturers have electric traction elevator designs that are also suitable for limited story buildings.

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3) Common Equipment

There are numerous types of equipment and devices required for the proper operation of an elevator. These include the car itself, doors and entrances, signaling, hoistway, pit, and machine room. The following is a brief description of each of these:

a) Elevator Car

Elevator cars must be enclosed, with a comfortable and durable interior. This enclosure shall isolate the passengers from both the sound and vibration that may be transmitted from the supporting structure, or otherwise called the car frame. This structure must withstand the lifting forces on the elevator, as well as the weight of door operating mechanisms, switches, cams, car top equipment, and interior finishes. This space measured from the side of the hoistway to the side of the car platform is about 8 inches for elevators traveling at speeds up to 500 fpm, and as much as 10 to 12 inches for higher speed elevators and those with 5,000 lb. load capacities or more.

Floor covering, underlayment, and adhesive are required by the Elevator Code to have a critical radiant flux of not less than 0.45 W/sq. cm. in accordance with ASTM E648. Elevator finishes must have a flame-spread index of 75 or less and a smoke-development index of 450 or less in accordance with ASTM E84. Napped, tufted, woven, looped, and other similar materials may also be used as wall coverings subject to passing a vertical burn engineering test in accordance with the Elevator Code. Textile wall coverings in compliance with NFPA 265 acceptance criteria may also be used.

Car size is impacted by local building codes and other regulatory requirements. The 2012 International Building Code (IBC) requires that four or more story buildings, above or below the grade plane, have at least one elevator for use by the fire department providing emergency access to all floors, and this car shall accommodate a 24 by 84 inch stretcher with not less than 5 inch radius corners. The car shall be identified with the Star of Life international symbol for emergency medical services, 3 inches high, and placed inside on both sides of the hoistway door frame. The 2010 ADA Standards for Accessible Design requires elevators for accessible routes and provides four alternative arrangements to comply with that requirement. These are based on car door location and car door width. Refer to ADA Standards for additional details.

b) Car Doors and Entrances

Clear opening width of the hoistway doors is directly related to the clear width of the hoistway. Single-slide center-opening door space requirements are established by multiplying the desired door width by 2 and adding 8 inches for structural requirements behind the open doors. For two-speed doors, the hoistway width required is established by multiplying the desired door width by 1-1/2 and adding 17 inches. Two-speed doors are available in applications that have limits on overall size of door openings and require quicker opening speed to keep passenger traffic moving.

Horizontal sliding type elevator doors consist of two sets of doors, the car door and the hoistway door, that are connected via a mechanical clutch. These two sets of doors create a single door system. The door system operator is located on the car as a safety feature to prevent a hoistway door from being opened without an elevator car at the landing. Center-opening doors open and close faster than side-sliding doors. The Elevator Code stipulates that a force of only 30 lbf will stop the door from closing and cause it to reopen. Another safety measure includes a reopening device in the event the door opening is obstructed by a passenger passing thru while closing.

Doors may be finished in a variety of ways. There is a limited choice of standard finishes from the manufacturer. The hoistway doors at the main entry Lobby may be finished with a more decorative material blending in with the door jamb and wall return finishes, while upper floors have a more standardized finish. Keep in mind that the fire resistance rating of the hoistway must be maintained at each of the door openings and the cost implications of one material compared to another.

c) Signal Operation

In the early development of elevators, it was the skill of the elevator operator that stopped the car precisely at the floor landing. As the need for speed increased with taller buildings, the development of a push-button operating system became the standard system used and human operators were no longer needed. Signal operation allowed for elevator speeds of 1000, 1200, and 1400 fpm and has been developed for passenger convenience and to be easily understood. The symbols used to represent the various functions, such as; Door Open, Rear/Side Door Open, Door Close, Rear/Side Door Close, Main, Alarm, Phone, and Emergency are standardized, sized, and provided in braille as indicated in the Elevator Code.

These signals also benefit those waiting for the next elevator on landings throughout the building. Hall buttons can be pushed to call an elevator or have an elevator stop to pick you up as it travels by in the direction you indicate with the hall button. With the lanterns mounted adjacent to the elevator car, those waiting know when a car is coming and from what direction.

d) Hoistway

An elevator travels up and down smoothly and safely within the hoistway. The structural support of the elevator uses guides or rails that maintain the vertical pathway and the support columns if, for any reason, the elevator operation becomes unsafe. This safety application consists of a device mounted below the elevator platform that is applied to stop and hold the elevator on the rails if it over speeds in down direction. During this safety application, the entire weight of the elevator is restrained and transferred to the building structure through the use of these rails. Stopping an elevator that may weigh 3 or 4 tons plus a passenger load of 1 to 2 tons traveling at 100’s of feet per minute by clamping onto guiderails requires sizable rails and significant support of these rails.

The rails are typically located on the two narrow sides of the car, with the car doors opening on the wider side of the car. These rails may require brackets for support from off the hoistway wall. The hoistway may be constructed of steel columns and beams, concrete masonry units (CMU), gypsum board over metal studs, or poured concrete, and the brackets or rails need to be securely fastened using long term methods. The vertical open space between the parallel rails is critical given the required stiffness of the rail that only allows about an 1/8 inch of deflection. Typically the elevator rails are fastened at floor levels of up to 14 feet apart. For longer spans or seismic design factors, additional structural support is required or a larger hoistway to fit the larger rails and/or support beams. Strict adherence to the required edition of the Elevator Code is required for proper design of the hoistway and elevator guiderails.

Construction of the hoistway and installation of guiderails is not part of the elevator work, but there is certainly coordination that needs to take place. Ensure that the necessary information for hoistway structure, elevator support rails, door openings and entrance sills, etc. is provided in the construction documents.

Local building codes may also have specific elevator hoistway requirements such as fire-resistive construction, control of smoke and hot gases, and provisions for use of windows and skylights in hoistway. Become aware of these local requirements and comply with them.

e) Pits

An elevator pit shall be provided for every elevator. The construction of the pit floor, walls, and any necessary pit access doors shall comply with the Elevator Code. A fixed access ladder shall be within reach of the access door; may be retractable. Ladder shall extend at least 48 inches above sill of access door, have at least 16 inch wide rungs (may be reduced to 9 inch wide due to obstructions), rungs are spaced 12 inches vertically, rung centerline is at least 4-1/2 inches from back of ladder wall, and have a 300 lbs. support capacity. Coordinate the ladder location with elevator equipment location.

Firefighter’s Emergency Operation elevator pit shall be provided with drain and sump pump with at least 3,000 gal/hr capacity. Sump pumps and their control equipment shall not be installed in pit under National Building Code Canada (NBCC). Sump pumps and drains, where provided, shall comply with local plumbing code and provide a positive means to prevent water, gases, and odors from entering the hoistway.

Provide light fixture with at least 10 foot candles of illumination at pit floor and a switch accessible from the access door. Install an enclosed elevator stop switch in pit of each elevator. Refer to Elevator Code for additional elevator pit details and requirements.

f) Machine Rooms

Machine rooms for hydraulic elevators contain the pump, valves, tank, elevator and motor controller’s. For an electric traction elevator the machine room contains the driving machine, power converters, and controller. Only machinery and equipment used directly in connection with the elevator is permitted in elevator hoistways, machine rooms, and control spaces. Equipment necessary to maintain the heating and cooling of these spaces within ranges indicated by the equipment manufacturer is otherwise allowed. Fire suppression lines may be installed and require a power shut off for elevator equipment prior to activation; heat detectors or flow switches may be used, but not a smoke detector. At least 84 inches of clear headroom is required in machine rooms. The level of lighting at the floor of the machine room shall be at least 19 foot candles, with a light switch located adjacent to access door. An elevator stop switch shall also be provided adjacent to access door, with convenience outlets also available.

Machine rooms for electric traction elevators are usually located at the top of the hoistway over the elevator, although they may also be located alongside the hoistway at a lower level or underslung at the pit level adjacent to the hoistway. Another option, available by a growing number of manufacturers is the machine-room-less (MRL) type elevator control and drive system. MRL systems are starting to replace the elevators in the hydraulic market. A small geared or gearless machine is mounted within the hoistway utilizing the rail system for support. High efficiency motors utilizing permanent magnet (PM) synchronous AC motors and drives, along with a counterweighted mechanical system, provide for highly efficient elevator designs. Another benefit is the absence of hydraulic fluids being used.

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4) Operation Systems

Single, slow, and low-rise elevator operation systems can easily be over specified. For single elevators, as defined in the Elevator Code, the selective-collective automatic operation is appropriate. For groups of elevators the appropriate system is dependent on speed and height of the building. Selection is a matter of anticipated traffic flow and elevator performance capabilities regarding car size, speed, and the number of cars in a group.

In accordance with the Elevator Code; operation control is that portion of a control system that initiates the starting, stopping, and direction of motion, in response to a signal from an operating device.

a) Automatic Operation

Used for single elevator in building where exclusive use of the elevator is desired. Also referred to as Single Automatic Push-Button Operation or Single Automatic Operation, and consists of single button at landing and buttons in car identified with the landings. Car may be called from any other floor landing provided the doors are closed and no one is operating the car. Once a passenger enters the car, he or she has exclusive use for the trip. This is a light-service operation; the elevator can serve only one call at a time, and the next passenger must wait until the car is free before using it. Availability is indicated by landing call light fixture; when light is out a passenger can call the car.

b) Selective-Collective Automatic Operation

Collective refers to the means to “collect” or remember and answer all the calls in one direction, change direction, and then collect the calls in the opposite direction. Both up and down landing call buttons are provided. In addition to car calls, the elevator only stops for up calls in the up direction and down calls in the down direction, with all calls being remembered until answered.

One variation of Selective-Collective is Down Collective, when only down landing buttons are provided at upper floor landings. This is acceptable in most apartment buildings where people desire service up to their apartment from the Lobby and down to the Lobby from their apartment floor landing. Another variation is Single-Button Collective, when the landing button will stop either an up or down traveling elevator; also referred to as Interceptive Collective.

Selective-Collective is the accepted operation for single elevators in any type of building and for service elevators in major office buildings. Its utility is enhanced by the following; a home landing feature where the elevator returns to a given floor upon completion of any trip; a load-sensing device that prevent the car from stopping for additional landing calls if the weight exceeds predetermined capacity; independent service operation when the car can be used to handle special loads and not respond to landing calls; and attendant operation when operation is manually controlled for security and freight-handling requirements. Two-car Selective Collective Operation is commonly known as Duplex Collective, and can be either Full Selective or Down Collective.

c) Group Automatic Operation

Automatic operation of two or more elevators equipped with power-operated car and hoistway doors. Car operation is coordinated by a supervisory control system that includes automatic dispatching. Each car includes one button for each floor served, and “UP” and “DOWN” buttons on each floor landing with single buttons on terminal landings. Car stops are established by the momentary actuation of the car buttons and are made automatically in succession as the car reaches the landing without consideration of the cars travel direction or the sequence that buttons are actuated. Stops set up by the momentary actuation of the landing buttons may be made by any elevator in the group, and are made automatically by the first available car approaching the landing in the corresponding direction.

d) Computer Control-Group Dispatching

This type of system consists of a computer that uses multitasking/multiprocessing design to connect to the individual computer controller of each elevator through high-speed data communication links. This creates a network that can constantly analyze changing building traffic conditions, such as; the number of elevators in service; each elevators status, loading, position, direction of travel, door-opening and closing times; the number of assigned Lobby calls; Lobby call demand; and estimated time of arrival, as a start. The system can then select and dispatch the most suitable elevator to answer a given Lobby call request. The group supervisory system constantly reassesses its allocation by scanning the status of each elevator many times a second. Using this real time data, it can reassign Lobby calls to the elevator that can provide the best service.

Each manufacturer designs these types of systems differently from each other and also describes each of them differently, so it is best to specify using each manufacturers proprietary term for their system. If that is not permitted, use a generic term that indicates a more sophisticated system than Group Automatic Operation as defined in the Elevator Code.

e) Destination Based-Group Supervisory Operation

For use in large, high-rise buildings, a passenger enters a desired final floor destination in the Lobby prior to entering the elevator, rather than pressing an up or down Lobby call button. Using an illuminated sign over the designated elevator, the supervisory system responds to the passenger by indicating which elevator is assigned for that trip. The assignment is instantaneous and fixed. The passenger then walks over to the assigned elevator and waits for its arrival, eliminating the need for gongs and lanterns. Upon arrival of the elevator, the passenger boards the car and needs only to wait for arrival of the elevator at the selected destination. The passenger cannot press any car buttons, because there are no call buttons in the car. Only position indicators and destination confirmation indicators are included in the car for passenger information.

It is a major paradigm shift for passengers not having call buttons in the car. After boarding an elevator, the passenger may not change their destination, similar to the options upon boarding a plane, train, or bus. A passenger desiring another floor destination must exit the car at a landing stop, re-book the new destination with the system, and take the newly assigned elevator.

This type of system has difficulty adjusting with false calls and can be thrown into disarray by pranksters; its use is impractical in an unsecure building unless the elevator Lobby is supervised.

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5) Maintenance

Although elevator equipment is well designed and manufactured with high quality, once in service, like any electromechanical device, an elevator required periodic maintenance. A systematic maintenance program is essential to the continued performance at peak efficiency. Over time there is wear on the parts and they will require replacement. The Elevator Code requires a written Maintenance Control Program with a list of minimum requirements. This maintenance program must be designed to meet the specific needs of the facility and its elevator equipment.

Where heavy continuous traffic is encountered, the program should call for weekly, and in some cases daily, maintenance. For moderate use, semimonthly examinations are usually sufficient. In lightly loaded buildings, a monthly program may be applicable. In many buildings, manufacturers are now using a system called “use-based maintenance.” They track the number of starts that the elevator makes, and establish their maintenance frequency and tasks in accordance with usage. This program varies by manufacturer and needs to be compared against building use, equipment use, and age to ensure that a proper maintenance program is in place.

The industry offers a variety of maintenance programs to provide for the care and replacement of equipment. These services range from full maintenance that is the most desirable and costly, through several lesser forms of service.

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6) Seismic Safety Requirements

When an earthquake occurs, it releases energy in the form of waves that radiate out from the earthquake source in all directions. These energy waves shake the ground in different ways and travel at different speeds. The fastest wave, and the first to arrive, is part of the Body Waves and called the “P” wave or Primary. The P, or compression wave, alternately compresses and expands material in the direction it is traveling. The other Body Wave, called the “S” wave or Secondary/Shear wave arrives next, shaking the ground up and down, and back and forth, perpendicular to the direction it is traveling. Surface waves come along after the Body Waves.

The magnitude of an earthquake is measured on different scales; the Richter scale is the most common. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. An increase in one unit of magnitude on the Richter scale corresponds to 10 time’s greater ground motion. An increase of two is 100 time’s greater ground motion, and so on, in a logarithmic series.

Seismic induced ground motion can have adverse effect on elevator operation and integrity of building supports and elevator equipment. One potential hazard is the disengagement of counterweights in the hoistway and having them swing into the hoistway and collide into a running elevator. Preventive measures include placement of counterweights within box-type brackets to restrain it and prevent it from swinging. Another is a taught wire deployed from the top to bottom of hoistway that will electrically intercept the counterweight if it is displaced and shut-off electrical circuit and stop the elevator. Other measures include the secure fastening down of the elevator driving machine and other machine room equipment sufficient to withstand the expected seismic shock. Rope guards are provided to prevent them from jumping out of the sheave grooves, and a car-to-counterweight compensating rope system is tied down with an arrangement to prevent the car and counterweight from bouncing upward during the shock of an earthquake. Retainer plates are provided on the car to keep it within the rails. Anti-swag guards are required in the hoistway to prevent swinging ropes and traveling cables from catching on rail brackets, interlocks, switches and cars, and so on. Provisions are also available for detecting equipment to sense the Body Waves of the earthquake and provide an early warning. This information is used to stop all the elevators in the building at the next available floor and remain there with the doors opened. Upon the end of an earthquake shock wave, emergency personnel have the option of opening the top of the car from inside by key to make visual observations before the car is activated.

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7) How to Specify

Editing of Elevator Sections 14 2020, 14 2100, and 14 2400 is designed to start in PART 2 - PRODUCTS, progress to PART 3 - EXECUTION, and finish up with PART 1 - GENERAL. The various types of elevators specified comprise the main articles in PART 2. When a particular type of elevator is activated for use in the project, the appropriate elevator type listed under SECTION INCLUDES article in PART 1 will be activated. Related articles and optional text in PART 1 and PART 3 will be activated as well.

When a particular article or paragraph is chosen that contains a reference standard in PART 2 and PART 3 the corresponding standard cited under REFERENCE STANDARDS article in PART 1 is activated. If the Consolidated List of Citations option is active, cross sectional links (not visible in the links window) will activate the reference standard in Section 01 4219 – Reference Standards as well.
When a particular article or paragraph is chosen that cites another section in PART 2 and PART 3, the corresponding Section cited under RELATED REQUIREMENTS article in PART 1 is activated.

Certain Sections cited under RELATED REQUIREMENTS article in PART 1 are not cited in either PART 2 or PART 3 but are listed under RELATED REQUIREMENTS because they include items that might be expected to be found within this Section or include action items important for the completion of the work that are not specified in an obvious location (e.g. isn't obvious from the section title).
Optional text and choices under PART 2 include a fill-in option to accommodate any updates that listed manufacturers may offer but are not shown in the listed choice of options. Default options for choices are based upon what would be reasonable for the application. The content of PART 2, including the choices, has been structured to accommodate the listed manufacturers.

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8) Design Considerations

The following is general information regarding the installation of elevators within a building to assist in the proper layout of the elevator system. There are numerous factors involved in this process, as follows:

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