The Correct Timing for Using The Emergency Stop Button of The Fume Hood

When the fire broke out

If the flame spreads into the fume hood due to operational errors or equipment malfunctions during the experiment, the emergency stop button should be pressed immediately. For instance, when conducting the distillation experiment of organic solvents, if the temperature of the heating device is too high, causing the solvent in the distillation flask to boil vigorously and splash out flames, once the flames enter the fume hood, they may quickly ignite other flammable items inside the fume hood, such as experimental record paper and reagent packaging, leading to a larger fire. Pressing the emergency stop button can quickly cut off the power supply of the fan in the fume hood, stop the exhaust function of the fume hood, prevent the fire from spreading faster due to air flow, and create favorable conditions for subsequent fire-fighting work.

When a fire breaks out in the area around a fume hood and the fire shows a tendency to spread towards the fume hood, the emergency stop button should also be pressed. For instance, fires broke out in other areas of the laboratory due to short circuits in the wires, and the flames and thick smoke gradually approached the fume hood. During operation, fume hoods will draw in the surrounding air. If ventilation is not stopped in time, fire sources and thick smoke may be drawn into the interior of the fume hood, damaging the equipment and experimental items inside, and even causing more serious consequences such as explosions.

When the leakage of harmful gases is out of control

A large amount of toxic gas leakage: During the experiment, if the valve of the toxic gas cylinder used is damaged, the pipeline is broken, or other reasons cause a large amount of toxic gas to leak, and the fume hood cannot promptly and effectively discharge the harmful gas, the emergency stop button should be pressed at this time. For instance, when conducting experiments with chlorine-containing gases, chlorine is a highly irritating and corrosive toxic gas. Once it leaks in large quantities, it can cause serious harm to the respiratory system, eyes and other parts of the experimenters. If the exhaust capacity of the fume hood is insufficient to quickly expel the leaked chlorine gas to the outside, continuing to operate the fume hood may cause the chlorine gas to accumulate inside the fume hood and even spread throughout the laboratory, endangering the lives of the laboratory personnel. Pressing the emergency stop button can halt the operation of the fume hood, preventing the further spread of harmful gases. At the same time, other emergency measures can be taken promptly, such as activating the emergency ventilation system in the laboratory and evacuating personnel.

When different types of harmful gases in the fume hood react violently, generating new hazardous substances or releasing a large amount of energy, the emergency stop button should be pressed immediately. For instance, if ammonia and hydrogen chloride gases are stored simultaneously in a fume hood, and these two gases accidentally mix and react, solid ammonium chloride particles will be formed, releasing a large amount of heat at the same time. If the fume hood continues to operate, it may intensify the intensity of the reaction, causing a sharp increase in temperature and pressure inside the fume hood and triggering dangerous situations such as explosions. Pressing the emergency stop button can promptly halt the operation of the fume hood, reduce interference with reactions, and lower the possibility of accidents.

When equipment failure endangers safety

Abnormal operation of the fan: The fan of the fume hood is a key device to ensure the ventilation effect. If the fan operates abnormally, such as at an excessively high speed, generating abnormal noise, or experiencing excessive vibration, it may cause equipment damage, electrical faults, and even endanger the safety of the laboratory personnel. For instance, if the bearings of a fan are damaged, it will cause the fan to operate unsmoothly, generating intense vibration and noise. If the fan is not stopped in time, it may be further damaged and even lead to accidents such as fires. At this point, the emergency stop button should be pressed immediately to halt the operation of the fan, and then the fan should be inspected and repaired.

Electrical system failure: If the electrical system of the fume hood malfunctions, such as short circuit or leakage, it may cause electric shock accidents or fires. For instance, if a short circuit occurs in the control panel of a fume hood, causing an abnormal increase in current, it may lead to the wires heating up, smoking, and even causing a fire. In this situation, the emergency stop button should be pressed immediately to cut off the power supply of the fume hood to prevent the fault from expanding further, and then a professional electrician should be notified promptly for maintenance.

When personnel are in danger

If the experimenter is accidentally drawn into the equipment inside the fume hood during the experiment, such as the blades of the stirrer or the rotor of the centrifuge, the emergency stop button should be pressed immediately. For instance, when an experimenter is operating a stirrer, the corner of their clothing gets caught in the blades of the stirrer. If the operation of the stirrer is not stopped in time, it may lead to more serious injuries to the experimenter. Pressing the emergency stop button can quickly halt the operation of the equipment, buying time for rescue workers and reducing the harm to laboratory personnel.

When laboratory personnel inhale harmful gases: When laboratory personnel are operating near a fume hood and suddenly inhale a large amount of harmful gases, experiencing symptoms such as dizziness, nausea, and breathing difficulties, they should immediately press the emergency stop button to halt the operation of the fume hood to prevent more harmful gases from being inhaled. Meanwhile, quickly transfer the experimenter to a well-ventilated area for first aid treatment.