Classification of common fume hoods
1. Exhaust fume hood
It is called full exhaust type, which is widely used.
2. Air supply type fume hood
When the fume hood is set in the room with heating or temperature and humidity control requirements, in order to save energy consumption of heating and air conditioning, the method of taking make-up air from the outside and discharging it outside after circulating in the cabinet is called make-up air fume hood.
3. Variable air volume fume hood
Ordinary constant air volume system needs to manually adjust the air valve of fixed blade to adjust the exhaust air volume of fume hood. When the valve is adjusted to a certain angle, it can achieve the desired surface wind speed. VAV control is to change the air volume to reach the given surface wind speed by adjusting the sensor of the valve. Of course, the standard type has low cost and high VAV cost. It is suitable for occasions requiring high precision.
The fume hood is classified according to the exhaust mode
It is divided into three types: upper exhaust type, lower exhaust type and upper and lower simultaneous exhaust type.
In order to ensure uniform wind speed in the working area, the lower exhaust type shall be adopted for the fume hood in the cold process, and the upper exhaust type shall be adopted for the fume hood in the hot process. For the process with unstable calorific value, exhaust outlets can be set up at the top and bottom to adjust the ratio of the upper and lower exhaust air volume with the change of calorific value in the cabinet, so as to obtain uniform wind speed.