Ratio and Selection Scheme for High-Voltage Switchgear
Publish Time : 2021-11-16 Author : Longde R&D
1. Calculated according to the length of the "hood"
take 2000m ³/h for each meter of smoke hood. For Sichuan and Hunan cuisine with a lot of lampblack, it can be 2500 m/h.
2. How to determine wind speed
air pipe is usually 8~15 m/s, and the best wind speed of the high-pressure air cabinet is 10~14 m/s; if the wind speed exceeds 12 m/s, the air pipe will vibrate, if it exceeds 14 m/s, the air pipe will make the highest space become insufficient, so the footstep can be stabilized, so there is no doubt that the footstep can be raised. When selecting, the operating cost and noise caused by the use of excessive wind speed should also be considered.
| Duct speed (m/s) | 2 | 4 | 6 | 8 | 10 | 12 |
| Airflow Noise (DB) | 22 | 37 | 46 | 52 | 57 | 61 |
| Category | Area | Daytime | Night |
| 0 | Need quiet areas, such as in the suburbs and rural areas of the nursing home, high-end villas and hotels, should be strictly enforced 5DB, which is more stringent than 0 level. | 50 | 40 |
| I | Can be used as reference for the implementation of residential areas, cultural and educational institutions residential areas and rural residential environments | 55 | 45 |
| ii | Mixed residential, commercial and industrial areas | 60 | 50 |
| Ⅲ | Industrial area | 65 | 55 |
| iv | Both sides of thecity's main roads, both sides of the city's inland waterways, and both sides of the railway passing through the city (no train noise level) | 70 | 55 |
there are pipes through the site hall, double silencer pipes can be used. The wind speed is controlled at a speed of 8 to 10 m/s. The double silencer tube requires more installation space. In actual production, the expansion of the four sides is 5~10cm instead of the inner diameter, and the noise can be reduced by 10 ~ 15dB.
3. Determination of the cross-sectional area of the pipe
The cross-sectional area of the main air pipe = air volume selected by the wind cabinet/wind speed × 3600 = air volume selected by the wind cabinet/(15 m/s × 3600)= air volume/54000 The high-pressure air cabinet has the characteristics of high pressure and sufficient air volume. When calculating the cross-sectional area, the wind speed is selected to be 15 m/s to determine the minimum cross-sectional area and retain a certain safety value of flue gas exhaust.
4. Determination of wind pressure
The selection offlue gas exhaust fan and pipe calculation are only the first step, and the flue gas exhaust pressure on the way is equally important. The pressure loss of each item needs to be calculated separately, and cannot be calculated in a fixed way. According to the actual construction experience, listed as follows:
| Category | Pressure loss (PA/piece) | Category | Pressure loss (PA/piece) |
| High voltage electrostatic purifier | 150-200 | gradually expanding diameter | 50 |
| Fin low altitude purifier | 300-360 | gradually reduce | 45 |
| 90 ° elbow | 45 | Suction Tee | 50 |
| 45 ° elbow | 25 | Umbrella-shaped rain hat, smoke exhaust decorative shutters | 60 |
| Elbow 60 ° | 30 | U-shaped elbow | 80 |
| S-Elbow | 50 | Ventilation hood 30PA/m | Pipe 5PA/m |