Table of Contents
Classification of Lifts
The lifts are classifies based on usage, speed and motor drive as below:
- Goods Lift.
- Passenger Lift.
- Service Lift.
- Hospital Lift.
- Slow speed, v < 1.0 m/s.
- High speed, v > 1.0 m/s.
Selection of Lifts
For selection of a Passenger lift, following factors are considered:
Quantity of service: It is a measure of passenger carrying capacity during 5 minutes peak period of day and is also known as passenger handling capacity (H). Following is the criterion followed:
- 10 - 15 % for diversified tenancy buildings.
- 15 - 20 % for single purpose occupancy.
- 7.5 % for residential building.
Quality of service: Generally measured by passenger waiting time during peak period, and is classified as follows:
|Waiting Time||Quality||No of floor||Speed|
|20 - 25 s||Excellent|
|30 - 35 s||Good||4 - 5||0.5 to 0.75 m/s|
|35 - 40 s||Fair||6 - 12||0.75 to 1.5 m/s|
|45 s||Poor||13 - 20||More than 1.5 m/s|
|More than 45 s||Unsatisfactory|
For residential buildings, longer intervals upto 90 seconds are permissible.
Determination of no. & capacity: The capacity calculation is done as in the procedure and example outlined below. The various terms associated with the Lift operation are:
- Total travel of lift: Total travel of lift from ground to last floor.
Round trip time: Total time taken by the lift to pick up the passenger to the capacity from ground floor, unloading them at various floors and come back to ground floor. It includes:
- Time required for passengers to enter at ground floor (i) - 3 seconds.
- Exit of passengers at each discharge (ii) - (F-1) × 2 sec.
- Door closing time (iii) - F × 2 seconds.
- Door opening time (iv) - F × 2 seconds.
- Stopping and leveling time (v) - F × 2 seconds.
- Acceleration period (vi) - 10% of (i + ii + iii + iv).
- Total travel time (vii) - (2 × maximum distance traveled in one direction) / speed of lift.
Then Round Trip Time : (i) + (ii) + (iii) + (iv) + (v) + (vi) + (vii).
F is the number of floors including ground.
Handling Capacity (H): It is a measure of how many number of passenger in percentage can be handled within 5 minutes of the peak hours.
H = (300 × Pc × 100) / (T × Q).
Pc = Average no. of passengers carried in a car = 80 % of P.
P = Capacity of lift e.g. 10, 13 etc.
T = Waiting interval = RTT / n.
n = number of lifts.
Q = Total number of passengers to whom service of lift is provided.
Residential Building : 5/6 persons per flat.
Office Building : 100 ft²/person.
Technical Building : 400 ft²/person.
Note: Weight of a person is considered to be 68 kg.
G + 3 technical building, floor height 5 m.
4th to 8th floor for administrative purpose, floor height 4 m.
Area of each floor = 1500 m² ≈ 15,000 ft².
Let lift capacity is 10 persons (P = 10) and speed is 1.5 m/s (v).
Total travel of lift = 4 × 5 + 5 × 4 = 40 m.
Number of persons (Q) = 4 × 15 000 / 400 + 5 × 15 000 / 100 = 900.
RTT = 3 + 8 × 2 + (9 × 2) × 3 + 0.1 (3 + 16 + 36) + 2 × 40 / 1.5 = 145 seconds.
So far n = 4, T = 36 seconds and H = 7.40 %.
Comparison of lifts: Comparison of lifts is given in the table below:
|Single Speed Lift||Two Speed Lift||Variable Voltage Lift||Gearless Lift|
|Residential Buildings||Office and Telephone Exchanges||Office and Telephone Exchanges||High Rise Buildings|
|Up to 5 floors||5 to 12 floors||5 to 15 floors||Above 15 floors|
|0.3 to 0.65 m/s||0.75 to 1.0 m/s||1.0 to 1.5 m/s||1.5 to 2.5 m/s|
|Power door not advisable||Power door recommended||Power door recommended||Power door recommended|
|Single call control or semi-dual push button control||Selective and collective||Selective and collective||Selective and collective|
|Automatic rescue device is not possible||Automatic rescue device is possible||Automatic rescue device is possible||Automatic rescue device is possible|
|Fireman switch can be provided||Fireman switch can be provided||Fireman switch can be provided||Fireman switch can be provided|
Typical Dimensions of Lift: Dimension of lift in mm for speed upto 1.5 m/s. (All dimensions are with reference to plan of machine room given below)
|Goods (Telephone Exchange)||3000||1500||4000||2500||4500||1500 vertical bi-parting door|
Trap Door : 1500 × 750 / 1500 × 1000 with a hook of 1500 kg capacity in center for passenger lift and 1950 × 1150mm with a hook of 3000 kg for goods lift.
Clearance between machine room and last floor served:
= 4800 mm for speed upto 1.5 m/s.
= 5600 mm for speed more than 1.5 m/s.
Lift pit height:
= 1600 mm for speeds upto 1.5 m/s.
= 2600 mm for speeds more than 1.5 m/s.
Width and depth same as lift well.
IS 3534 : 1976 - Dimensions of Lift.
IS 4666 : 1968 - Specifications for passenger and goods Lift.
IS 1860 : 1968 - Operation, Installation and Maintenance.