Understanding the Calculation of the Weight of People in Elevators
Calculating the weight of people in elevators ensures safety and operational efficiency. This process involves precise measurement and estimation techniques.
In this article, you will find detailed formulas, tables, and real-world examples for accurate weight calculation in elevators.
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- Calculate total weight for 8 people with average weight 75 kg each.
- Determine maximum elevator load for 12 passengers with varying weights.
- Estimate weight distribution for 5 adults and 3 children in an elevator.
- Calculate safety margin for elevator carrying 10 people with average weight 70 kg.
Comprehensive Tables of Common Weight Values in Elevator Calculations
| Number of People | Average Weight per Person (kg) | Total Weight (kg) | Total Weight (lbs) | Safety Factor (1.25x) | Safety Factor Applied Weight (kg) |
|---|---|---|---|---|---|
| 1 | 70 | 70 | 154.3 | 1.25 | 87.5 |
| 2 | 70 | 140 | 308.6 | 1.25 | 175 |
| 4 | 70 | 280 | 617.3 | 1.25 | 350 |
| 6 | 70 | 420 | 925.9 | 1.25 | 525 |
| 8 | 70 | 560 | 1234.6 | 1.25 | 700 |
| 10 | 70 | 700 | 1543.2 | 1.25 | 875 |
| 12 | 70 | 840 | 1851.8 | 1.25 | 1050 |
| 15 | 70 | 1050 | 2314.9 | 1.25 | 1312.5 |
| 20 | 70 | 1400 | 3086.5 | 1.25 | 1750 |
| 25 | 70 | 1750 | 3858.7 | 1.25 | 2187.5 |
| 30 | 70 | 2100 | 4629.9 | 1.25 | 2625 |
| 5 | 60 | 300 | 661.4 | 1.25 | 375 |
| 5 | 80 | 400 | 881.8 | 1.25 | 500 |
| 10 | 65 | 650 | 1433.0 | 1.25 | 812.5 |
| 10 | 75 | 750 | 1653.5 | 1.25 | 937.5 |
Fundamental Formulas for Calculating the Weight of People in Elevators
Accurate weight calculation in elevators relies on several key formulas. These formulas incorporate variables such as the number of passengers, average weight per person, and safety factors.
1. Total Weight Calculation
The total weight of people inside an elevator is calculated as:
- W: Total weight of all passengers (kg)
- N: Number of passengers (unitless)
- Wavg: Average weight per passenger (kg)
Typical values for Wavg range from 60 kg (children or lightweight adults) to 80 kg (average adult weight). For safety and design, 70 kg is commonly used as a standard average weight per person.
2. Weight with Safety Factor
Elevator design must consider a safety factor to accommodate unexpected overloads or weight variations. The safety factor (SF) is typically 1.25 according to international standards such as ASME A17.1 and EN 81.
- Wdesign: Design load including safety factor (kg)
- SF: Safety factor (commonly 1.25)
This ensures the elevator can safely carry 25% more than the calculated total weight.
3. Weight Distribution per Floor
In multi-stop elevators, weight distribution per floor can be estimated to optimize motor load and braking systems:
- Wfloor: Weight on the elevator at a specific floor (kg)
- Nfloor: Number of passengers boarding or alighting at the floor
- Wcar: Weight of the empty elevator car (kg)
Knowing this helps in dynamic load calculations and energy consumption estimations.
4. Conversion Between Kilograms and Pounds
For international applications, weight conversion is essential:
- Wlbs: Weight in pounds (lbs)
- Wkg: Weight in kilograms (kg)
Detailed Explanation of Variables and Their Common Values
- Number of Passengers (N): Typically ranges from 1 to 30 depending on elevator capacity.
- Average Weight per Person (Wavg): Varies by region and demographic; 70 kg is a widely accepted average.
- Safety Factor (SF): Usually 1.25, mandated by elevator safety codes to prevent overload.
- Weight of Elevator Car (Wcar): Can range from 500 kg to over 2000 kg depending on size and materials.
These variables are critical for engineers to design elevators that meet safety and performance standards.
Real-World Applications and Case Studies
Case Study 1: Designing an Elevator for a Commercial Building
A commercial building requires an elevator with a capacity of 15 passengers. The average weight per passenger is assumed to be 70 kg. The empty elevator car weighs 1200 kg. Calculate the total design load including the safety factor.
- Step 1: Calculate total passenger weight: W = 15 × 70 = 1050 kg
- Step 2: Add elevator car weight: Wtotal = 1050 + 1200 = 2250 kg
- Step 3: Apply safety factor: Wdesign = 2250 × 1.25 = 2812.5 kg
The elevator must be designed to safely carry at least 2812.5 kg to comply with safety regulations.
Case Study 2: Weight Distribution Analysis in a Hospital Elevator
A hospital elevator serves multiple floors. At the 3rd floor, 4 people board, and 2 people alight. The average weight per person is 65 kg. The elevator car weighs 1000 kg. Calculate the weight on the elevator after the 3rd floor stop if initially there were 6 passengers.
- Initial passenger weight: 6 × 65 = 390 kg
- Passengers after 3rd floor: 6 – 2 + 4 = 8 passengers
- New passenger weight: 8 × 65 = 520 kg
- Total weight: 520 + 1000 = 1520 kg
This weight is used to adjust motor torque and braking force dynamically for safe operation.
Additional Considerations for Accurate Weight Calculation
- Demographic Variability: Average weights differ by region, age, and gender. Adjust Wavg accordingly.
- Children and Special Cases: Children typically weigh less; elevators in schools or pediatric hospitals should consider this.
- Load Sensors: Modern elevators use load sensors to measure actual weight in real-time, improving safety and efficiency.
- Regulatory Compliance: Follow standards such as ASME A17.1, EN 81, and ISO 25745 for elevator design and safety.