Total Luminous Flux Calculation for Illumination in a Hall

How many fluorescent lamps are required to provide a general illumination of 130 lux in a hall measuring 35m x 20m?

Given the depreciation factor is 1.4 and the coefficient of utilization is 0.50.

Number of Fluorescent Lamps Required:

Approximately 23 lamps of fluorescent lamps are required to provide a general illumination of 130 lux in a hall measuring 35m x 20m, with a depreciation factor of 1.4 and a coefficient of utilization of 0.50.

Calculation Steps:

To determine the number of fluorescent lamps required, we need to calculate the total luminous flux required for the hall and then divide it by the luminous flux of each fluorescent lamp.

Step 1: Calculate the Total Luminous Flux Required

The formula to calculate the total luminous flux is:

Luminous flux (lm) = Illumination (lux) x Area (m²)

Given that the illumination required is 130 lux and the area of the hall is 35m x 20m, we can calculate the total luminous flux required:

Luminous flux = 130 lux x (35m x 20m)

Luminous flux = 130 lux x 700m²

Luminous flux = 91,000 lumens

Step 2: Calculate the Luminous Flux per Lamp

The luminous flux per lamp can be calculated using the luminous efficiency of the fluorescent tube. Given that the luminous efficiency is 50 lumens per watt and the lamp wattage is 80W, we can calculate the luminous flux per lamp:

Luminous flux per lamp = Luminous efficiency x Lamp wattage

Luminous flux per lamp = 50 lumens/watt x 80W

Luminous flux per lamp = 4,000 lumens

Step 3: Calculate the Number of Lamps Required

To determine the number of lamps required, we divide the total luminous flux required by the luminous flux per lamp:

Number of lamps required = Total luminous flux required / Luminous flux per lamp

Number of lamps required = 91,000 lumens / 4,000 lumens

Number of lamps required ≈ 22.75

Since we cannot have a fractional number of lamps, we round up to the nearest whole number, giving us approximately 23 lamps required for the hall.