To determine the number of fluorescent tubes required for the drawing hall, along with their spacing, mounting height, and total wattage, follow these steps:
### 1. **Calculate the Total Luminous Output Required**
**1.1. Area of the Hall**
The area of the drawing hall is:
\[ \text{Area} = \text{Length} \times \text{Width} \]
\[ \text{Area} = 30 \, \text{m} \times 15 \, \text{m} = 450 \, \text{m}^2 \]
**1.2. Total Luminous Output Needed**
The general illumination required is 120 lumens per square meter. Therefore:
\[ \text{Total Luminous Output Required} = \text{Area} \times \text{Illumination Level} \]
\[ \text{Total Luminous Output Required} = 450 \, \text{m}^2 \times 120 \, \text{lumens/m}^2 = 54{,}000 \, \text{lumens} \]
**1.3. Adjust for Coefficient of Utilization and Depreciation Factor**
The coefficient of utilization (CU) is 0.5, and the depreciation factor (DF) is 1.4. Therefore:
\[ \text{Adjusted Luminous Output} = \text{Total Luminous Output Required} \times \text{CU} \times \text{DF} \]
\[ \text{Adjusted Luminous Output} = 54{,}000 \, \text{lumens} \times 0.5 \times 1.4 = 37{,}800 \, \text{lumens} \]
### 2. **Determine the Number of Fluorescent Tubes Required**
**2.1. Luminous Output per Tube**
For an 80-watt fluorescent tube with a luminous efficiency of 40 lumens per watt:
\[ \text{Luminous Output per Tube} = \text{Wattage} \times \text{Luminous Efficiency} \]
\[ \text{Luminous Output per Tube} = 80 \, \text{watts} \times 40 \, \text{lumens/watt} = 3{,}200 \, \text{lumens} \]
**2.2. Number of Tubes Required**
The number of tubes needed is:
\[ \text{Number of Tubes} = \frac{\text{Adjusted Luminous Output}}{\text{Luminous Output per Tube}} \]
\[ \text{Number of Tubes} = \frac{37{,}800 \, \text{lumens}}{3{,}200 \, \text{lumens/tube}} = 11.8125 \]
Since we can’t have a fraction of a tube, round up to the nearest whole number:
\[ \text{Number of Tubes} = 12 \]
### 3. **Determine the Total Wattage**
**3.1. Total Wattage**
The total wattage required is:
\[ \text{Total Wattage} = \text{Number of Tubes} \times \text{Wattage per Tube} \]
\[ \text{Total Wattage} = 12 \times 80 \, \text{watts} = 960 \, \text{watts} \]
### 4. **Spacing and Mounting Height**
**4.1. Spacing of Tubes**
The spacing of the tubes will depend on the layout, but to ensure uniform distribution:
- **Lengthwise Spacing**: The hall is 30 meters long. If placing tubes along the length, you need to determine the spacing such that the total length covered is approximately 30 meters.
- **Widthwise Spacing**: The hall is 15 meters wide. Ensure the tubes are evenly distributed along this width.
If you use a standard layout with tubes mounted in rows, you might consider a grid spacing based on the length and width of the hall. For simplicity, let’s assume you’ll place the tubes in a grid pattern:
- Place 3 rows of 4 tubes each (3 rows x 4 tubes = 12 tubes).
- **Spacing Between Tubes in Each Row**: For 30 meters length, with 4 tubes, place them approximately every 7.5 meters apart.
- **Spacing Between Rows**: For 15 meters width, with 3 rows, place them approximately every 5 meters apart.
**4.2. Mounting Height**
Mount the tubes at the ceiling height, which is 5 meters from the floor.
### Summary
- **Number of Fluorescent Tubes Required**: 12
- **Total Wattage**: 960 watts
- **Spacing of Tubes**:
- Lengthwise (30 meters): Approximately every 7.5 meters apart.
- Widthwise (15 meters): Approximately every 5 meters apart.
- **Mounting Height**: 5 meters
This setup will ensure that the drawing hall achieves the desired level of illumination uniformly.