Some things you need to know about laboratory ventilation system

Laboratory safety is paramount

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, low noise, easy operation, energy saving, and even requires indoor pressure difference and temperature and humidity to maintain the comfort of the human body.

Design principles of fume hoods

1. According to the structural characteristics of the building, open air wells nearby, divide the exhaust and air supply systems, and make the piping system "short, flat, smooth, and straight" to reduce system resistance and system noise.

2. The exhaust and air supply system achieves the balance of air volume, maintains the 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. Cool air in summer and warm air in winter to ensure the comfort of indoor temperature and humidity. Adopt intelligent frequency conversion control system to achieve the purpose of convenient operation, energy saving and noise reduction

4. Comprehensive consideration of various factors, the use of mature technology with less investment, stable operation, low operating cost and good operating effect. Fully consider noise, odor, etc. in the design to prevent the generation of secondary pollution and not cause new pollution to the surrounding environment.                                                        

Design parameters of fume hoods

1. The wind speed in the branch pipeline is 6~8m/s, and the wind speed in the main pipeline is 8~14m/s.

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

3. Number of air changes: General chemical laboratory ventilation rate: 8 to 12 times/hour. The terminal noise of the ventilation system is less than or equal to 62db. The fan adopts corrosion-resistant FRP centrifugal fan, and the system adopts frequency conversion control to achieve the purpose of energy saving and noise reduction.  

Ventilation system control methods

1. Constant air volume system control

The system adopts static pressure sensing automatic frequency conversion control (or PLC programming control). The static pressure sensing automatic frequency conversion control can convert the sensed static pressure into a 0-10v electrical signal and input it to the frequency converter according to the number of open ventilation equipment. In this way, the fan frequency is automatically adjusted, so that the exhaust air volume of the fan matches the actual required exhaust air volume, so as to ensure the exhaust air effect and achieve the effect of energy saving and noise saving. Each fume hood is installed with an electronic air volume control 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. The system air valve and the fan are integrally interlocked to realize the orderly flow of the air flow, balance the air volume of the system, and prevent the reverse flow and reverse flow of the air flow.

2. Variable Air Volume (VAV) control

The system adopts static pressure sensing automatic frequency conversion control. The static pressure sensing automatic frequency conversion control can change the sensed static pressure into a 0-10v electrical signal and input it into the frequency converter according to the number of open ventilation equipment to automatically adjust the fan frequency. Match the exhaust air volume of the fan with the actual required exhaust air volume, so as to ensure the exhaust air effect and achieve the effect of energy saving and noise saving. The system air valve and the fan are integrally interlocked to realize the orderly flow of the air flow, balance the air volume of the system, and prevent the reverse flow and reverse flow of the air flow.

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