lift design toshiba dgvadv

8/22/2019 lift design toshiba dgvadv

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DESIGN OF LIFT


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For design of lifts factors to be consideredare

1. Population or no. of people who require

lift service.

2. Handling capacity or maximum flowrate required by the people.

3. Interval or quality of service required.


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1. Population : Population is calculatedbased on occupancy type of the building

Type Occupancyarea/per person

Residential 12.5

Educational 4

Institutional 15


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Assembly hall with(a)Dance floor

(b)Dinning

0.6

1.5

Business 10

Mercantile

(a)With basement

(b)With shops onuppers

3

6


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Industrial 10

Storage 30

Hazardous 10

Above area per person is gross areaof the floor in square meters. In case of

office building 75% of the inherentoccupancy is expected to arrive in time(period of hr. before opening timewhich peak traffic period also).


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Floating population may also bethere to counterfeit the effect of latecoming persons. 100% population as

calculated from floor occupancy basis tobe adopted as total population to beserved, during peak hours.


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2. Quantity of Service :

The quantity of service is a measure ofthe passenger handling capacity of a

vertical transport system. It ismeasured in terms of the total numberof passengers handled during each five

minutes peak period of the day.


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3. Quality of Service :The quality of service on the other handis generally measured by the passenger

waiting time of the various floors.Quality of service or Acceptable interval:

20 to 25 seconds Excellent

30 to 35 seconds Good35 to 40 seconds Fair

40 to 45 seconds Poor

Over 45 seconds Unsatisfactory


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Handling Capacity & RTT :

The handling capacity is calculated by theformula:

H = (300 x Q x 100)/T x P

Where

H = Handling capacity as the percentage ofthe peak population handled during 5min.

Q = Average number of passengers carried ina car


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T = waiting interval, and

P = Total population to be handled duringpeak morning period. (It is related to

the area by a particular bank of lifts)The value ofQ depends on the dimensionsof the car. It may be noted that the capacityloaded always to its maximum capacityduring each trip and, therefore, for calculatethe value of Q is taken as 80% of themaximum carry capacity of the car.


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The waiting interval is calculated by theformula :

T = RTT/N

Where,

T = waiting interval

N = number of lifts, and


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RTT = round trip time, that is, theaverage time required by each lift in

taking one full load of passengers fromground floor, discharging them invarious upper floors and coming back toground floor for taking fresh passengers

for the next trip.


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RTT is the sum of the time required in thefollowing process :

a) Entry of the passengers on the ground

floor,b) Exit of the passengers on each floor of

discharge,

c) Door closing time before each floor ofdischarge,

d) Door opening time on each discharging

operation,


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e)Acceleration periods,

f) Stopping and leveling periods,

g) Period of full rated speeds between stops

going up, and

h) Period of full rated speeds between stopsgoing down.

It is observed that the handling capacity isinversely proportional to the waitingtime which in turn is proportional to RTT.


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The round trip time can be decreased notonly by increasing the speed of the liftbut also by improving the design of the

equipment related to opening and closingof the landing and car doors,acceleration, deceleration, levelling andpassenger movement.


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a) The most important factor in shorteningthe time consumed between the entryand the exit of the passengers to the liftcar is the correct design of the door and

the proper car width, for comfortableentry and exit for passengers, it has beenfound that most suitable door width is1000 mm and that of car width is 2000.

b) The utilization of centre opening doorsalso favors the door opening and closingtime periods.


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Capacity :

Minimum size of car recommended

for a single purpose building is onesuitable duty load of 884 Kg. For largebuilding car 2040 Kg. according torequirement.


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Layout :

The width of car is determined by

the width of entrance, and the depth ofcar is regulated by loading per sq.mtr.Permissible. Centre opening door are themost practicable and most efficiency

entrance with for passenger lifts.


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Speed :

It is dependent upon quality of service

required and the quality of service desired.

Therefore, no set formulae for indicatingthe speed can be given.

Recommended Speeds :

The following are general guidelines :


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Office Building Passenger Lifts

Sl.No.

No. of Floors RecommendedSpeed

1. 4 to 5 floors 1 MPS

2. 6 to 12 floors 1.5 MPS

3. Above 12 floors Above 1.5 MPS


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Residential Building Passenger Lifts

Sl.No.


1. 4 to 8 floors 1 MPS


3. Above 12 floors Above 1.5 MPS


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Hospital Lifts (Bed cum Passenger Lifts)

Sl.

No.

No. of Floors Recommended

Speed

1. Upto 4 floors 0.5 MPS


3. Above 8 floors 1 MPS


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Goods Lifts

Sl.No.


1. Upto 6 floors 0.5 MPS

2. Above 6 floors 0.75 MPS

Note:

(1) For passenger cum gods lifts speed shall befollowed as that of passenger lifts.

(2) Actual speed shall be worked out on the basisof traffic analysis.


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Calculation of R.T.T.

The most probable number of floors on

which lift may have to be stopped is givenby statistical formula:

Sn = n [ 1-(n-1)/n)Np]


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Where

Np= Total number of passengers enteringthe car at ground floor (Entrance Lobby)

during peak period which is equal to carcapacity.

n = Total number of floors served above

ground floor.Sn = Most probable number of stops.


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No. of upperfloors served Number of Passenger/Trip(Car Capacity)

10 12 14 16 18 20

18 8 9 10 11 12 1316 8 9 10 10 11 12

14 7 8 9 9 10 11

12 7 8 9 9 10 10

10 6 7 8 8 9 9

8 6 6 7 7 8 8

6 5 5 6 6 7 7


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Now,R.T.T. = Entrance lobby time + Sn x floorserving time + Return trip time (D-2d)/Vc.

Where, Sn = Probable number of stops

D = Total Lift travel in one direction (m)

d = Distance travelled during acceleration or

deceleration (m)

Vc = Contract speed of elevator in m/s also.


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D = ft2

Where,

f = acceleration in m/sec2

t = Time for acceleration

= 2 seconds for lifts upto 2.5 m/s.


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(a)Entrance Lobby Time : This consists ofdoor opening, car loading, door closingtime and acceleration at entrance lobbygenerally ground floor plus retardation

time (while returning from top).

(b)Floor serving time: This consists of dooropening time, transfer (loading or

unloading time), door closing time,acceleration and de-acceleration(retardation) time.


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(c)Loading/ Unloading time: Practicallyobserved loading and unloading time forlifts of different capacity are givenbelow:

No. ofPassengers

Entrance lobbyLoading time in

second

Transfer time i.e.loading and

unloading time atupper floors

8 7 1

13 12 1.25

16 14 1.5

20 17 1.6


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Actually average time required forentrance of each passenger in car dependsupon total number of persons entering thecar and already available in car. It may be

one second per person when car ispartially loaded and 0.75 second when it iscompletely empty. Time for emptying caris less and equal to 0.75 second for singleperson but there is a tendency that allpersons vacate the car simultaneouslyafter opening if the doors.


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(d)Door Opening and closing time: Doorclosing time is more as compared to dooropening time. This is due to fact that

when all persons have entered in the car,it takes time for people to select andpress the push button for summoning thelift to various destinations.

Total time for door opening and closingoperation can be taken as given below:


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Type of Door operation Capacity

8 13 16 20

(a) Power operated single slide

(b) Power operated double slide(c) Power operated centre

Opening

(d) Collapsible with attendant

(e) Collapsible without attendant

3.8 3.8 - -

3.2 3.2 - -2.8 2.8 3.2 3.2

2.5 2.5 3 3

4 4 - -

Door closing and opening time, at entrancefloor shall be one second more than all above.


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(e)Distance travelled by lift duringacceleration or retardation is assumed tobe equal. This can be calculated by using

formula.d = ut + ft2

Where U is initial speed = 0, f is

acceleration or retardation rate and t isthe time elapsed. It is assumed thatduring each cycle, lifts acceleration andretardation time is about 2 second.


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Rate of acceleration will vary with type ofas given below:

Lifts speed m/s Rate of acceleration

m/sec2

1 0.50

1.5 0.75

2.5 1.00More than 2.4 to 8 2.50

More than 8 and

fl th 50

4.00

lift design toshiba dgvadv

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