Control system of laboratory variable air volume (VAV) fume hood

Abstract

The invention provides a control system of a laboratory variable air volume (VAV) fume hood. The control system is characterized by comprising a fume hood, a Venturi valve arranged on an air exhaust branch pipe of the fume hood, a displacement sensor, a door height warning switch, a face velocity monitoring and control system, a fan variable frequency system, a valve controller and a valve actuator, wherein, the face velocity monitoring and control system comprises a face velocity sensor and a VAV controller; the VAV controller measures the open degree of the fume hood in real time, and meanwhile the face velocity sensor measures the face velocity in real time, converts the face velocity into a voltage signal and then transfers the voltage signal to the VAV controller; the VAV controller compares the actual value with the set value of the face velocity; and if the face velocity is not within the range of the set value, the VAV controller outputs a signal to the valve controller, the valve controller outputs a signal to the valve actuator, and the valve actuator drives a piston of the Venturi valve to move up and down so as to change the ventilation sectional area and adjust the ventilation volume.

Description

technical field [0001] The invention relates to the field of laboratory equipment, in particular to a ventilation system. Background technique [0002] Most of the ventilation systems in existing laboratories use ordinary frequency conversion systems, and the signal source of ordinary frequency conversion systems starts to turn on the control switch of the fume hood, which means that every time a fume hood is turned on / off, the system will increase / decrease a certain exhaust Air volume, the air volume of the entire system is adjusted in gears; ordinary valves are manually adjusted without automatic functions, which affects system safety; pressure is not independent, and will affect each other in the same system; the control accuracy is low, and the smaller the air volume, the worse the accuracy; Due to the quick opening characteristics, the measurable ratio is often only 3:1; on-site debugging and regular maintenance are required during installation. The surface wind speed ...

AI Technical Summary

Problems solved by technology

[0002] Most of the ventilation systems in existing laboratories use ordinary frequency conversion systems, and the signal source of ordinary frequency conversion systems starts to turn on the control switch of the fume hood, which means that every time a fume hood is turned on / off, the system will increase / decrease a certain exhaust Air volume, the air volume of the entire system is adjusted in gears; ordinary valves are manually adjusted without automatic functions, which affects system safety; pressure is not independent, and will affect each other in the same system; the control accuracy is low, and the smaller the air volume, the worse the accuracy; Due to the quick opening characteristics, the measurable ratio is often only 3:1; on-site debugging and regular maintenance are required during installation

The surface wind speed of the fume hood of the ordinary frequency conversion system changes, and the change of the wind speed will affect the experimental results

Images