The laboratory ventilation system is one of the largest and most influential systems in the entire laboratory design and construction process. A scientific and reasonable ventilation system requires good ventilation effect, low noise, easy operation, energy saving, and even requires indoor pressure difference and temperature and humidity to maintain the comfort of the human body.

The safety of the laboratory is the most important

What are the design principles of fume hoods?

1. According to the structural characteristics of the building, set up air shafts nearby to divide the exhaust and supplementary air systems. The pipe system should be "short, flat, smooth and straight" to reduce system resistance and system noise;

2. The exhaust and supplementary air system achieves a balance of air volume, maintains a negative pressure of -5Pa—-10Pa in the room, prevents the escape of harmful gases, and ensures the physical and mental health of the experimenters;

3. Add cold air in summer and warm air in winter to ensure the comfort of indoor temperature and humidity;

4. The intelligent frequency conversion control system is adopted to achieve the purpose of convenient operation, energy saving and noise reduction;

5. Comprehensive consideration of various factors, adopting mature technology with low investment, stable operation, low operating cost and good operating effect;

6. The selected process must meet the on-site conditions, the layout is simple, compact, occupy a small area, and is convenient for production, operation, maintenance and repair;

7. Non-standard equipment should comply with relevant national or industry regulations, and ensure stable performance and beautiful appearance;

8. Fully consider noise, odor, etc. in the design to prevent secondary pollution and not cause new pollution to the surrounding environment;

9. The treatment facilities have shock load capacity to ensure that the exhaust gas meets the emission standards.

Design parameters of fume hood

1. The wind speed in the branch pipeline is 6-8m/s, and the wind speed in the dry pipeline is 8-14m/s;

2. Design air volume of ventilation equipment: surface wind speed of fume hood: 0.3～0.8 m/s, design air volume of single 1200*800*2350 fume hood is 1500m3/h, design air volume of single 1500*800*2350 fume hood is 1800m3/h, single The designed air volume of the 1800*800*2350 fume hood is 2200m3/h, the wind speed of the universal exhaust hood: ≥0.35 m/s, the exhaust volume of the universal exhaust hood is 150～350 m3/h, the wind speed of the atomic absorption cover: ≥ 0.35 m/s, exhaust air volume 350～600 m3/h.

3. The number of air changes: the number of air changes in a general chemical laboratory: 8-12 times/min

4. The terminal noise of the ventilation system is ≤62db.

5. The fan adopts corrosion-resistant glass fiber reinforced plastic centrifugal fan, and the system adopts frequency conversion control to achieve the purpose of energy saving and noise reduction.

What are the control methods of the ventilation system?

Constant air volume system control:

1. The system adopts static pressure sensor automatic frequency conversion control (or PLC programming control), static pressure sensor automatic frequency conversion control can change according to the number of open ventilation equipment, and convert the static pressure sensed into 0-10v electrical signal input The frequency converter automatically adjusts the frequency of the fan, so that the fan's exhaust volume matches the actual required exhaust volume, so as to ensure the exhaust effect and achieve the energy-saving and noise-saving effect;

2. Each fume hood is equipped with an electronic air volume regulating valve, and its control switch is linked with the frequency conversion control system and the fan, which can realize the control of single or multiple ventilation equipment under different working conditions. The air volume control valve adopts an electronic air volume control valve with digital display and adjustable angle, and has a memory function (that is, it can remember the adjusted angle this time, and it will still be adjusted to the designed angle when it is opened next time).

3. The system air valve and the fan are integrally interlocked to realize the orderly flow of air flow, balance the air volume of the system, and prevent the air flow from backflow and backflow.

Variable air volume system (VAV) control:

1. The system adopts static pressure sensor automatic frequency conversion control. The static pressure sensor automatic frequency conversion control can change according to the number of open ventilation equipment, and convert the static pressure it senses into 0-10v electrical signals and input the frequency converter to automatically adjust the fan Frequency, so that the fan's exhaust volume matches the actual required exhaust volume, so as to ensure the exhaust effect and achieve the energy-saving and noise-saving effect;

2. Each fume hood is equipped with a Venturi variable air volume air valve, and its control switch is linked with the frequency conversion control system and the fan, which can realize the control of single or multiple ventilating equipment under different working conditions. The variable air volume control valve adopts a digital display adjustable angle venturi valve, and has a memory function (that is, you can remember the adjusted angle this time, and it will still be adjusted to the designed angle when you open it next time).

3. The system air valve and the fan are integrally interlocked to realize the orderly flow of air flow, balance the air volume of the system, and prevent the air flow from backflow and backflow.

The laboratory ventilation system is one of the large-scale and extensively influential systems in the entire laboratory design and construction process. Whether the ventilation system is perfect or not has a direct impact on the laboratory environment, the health of the experimenters, and the operation and maintenance of the experimental equipment.

Excessive negative pressure in the laboratory, gas leakage in the fume hood, and laboratory noise have always been problems that plague laboratory staff. These problems have caused serious physical and psychological damage to the personnel who have been working in the laboratory for a long time, and even the management and logistics personnel working around the laboratory.

A scientific and reasonable ventilation system requires good ventilation effect, low noise, easy operation, energy saving, and even requires indoor pressure difference and temperature and humidity to maintain the comfort of the human body.