What is the reasonable placement of experimental equipment in a fume hood?

The layout is reasonable in accordance with the law of air flow

The fume hood creates a negative pressure inside the cabinet through the suction of a fan. The airflow enters through the operation window, passes through the experimental area, and is discharged from the exhaust port. The placement of experimental equipment should conform to this air flow law to avoid interfering with the air flow.

Large equipment should be placed at the back: Large and heavy experimental equipment, such as large reactors and centrifuges, should be placed at the rear of the fume hood, that is, near the exhaust outlet. This can enable the airflow to pass smoothly around the equipment and reduce the obstruction to the airflow. For instance, in a chemical synthesis experiment, placing the reactor at the rear of a fume hood enables the airflow to more effectively carry away the harmful gases produced during the reaction, preventing them from accumulating inside the fume hood.

Small equipment should be placed at the front: Small equipment such as pipettes and test tube racks can be placed at the front of the fume hood, that is, near the operation window. In this way, the experimenters can conveniently access it during operation, and at the same time, it will not cause too much impact on the airflow. For instance, when conducting solution preparation experiments, placing the test tube rack and pipette at the front of the fume hood enables the experimenter to complete the sampling and transfer operations quickly and accurately.

Maintain the distance between devices

Maintaining an appropriate distance between experimental equipment is conducive to the uniform distribution of air flow and the effective discharge of harmful gases.

Horizontal spacing: A certain horizontal distance should be maintained between adjacent devices, and it is generally recommended to be no less than 10 to 15 centimeters. This can prevent the devices from blocking each other, ensuring that the airflow can fully contact the surface of each device and carry away the harmful gases produced. For instance, when multiple heating devices are placed simultaneously in a fume hood, maintaining sufficient lateral spacing can prevent heat and harmful gases from accumulating between the equipment.

Vertical spacing: For devices that are stacked up and down, attention should be paid to the vertical spacing to prevent them from being too closely packed. If the equipment is stacked too high or too densely, it will affect the vertical flow of air, resulting in poor air circulation around the lower equipment. Generally speaking, there should be at least a gap of 5 to 10 centimeters between the upper and lower equipment. For example, when stacking multiple beakers in a fume hood, make sure there is enough space between them for the airflow to pass through.

Avoid blocking the airflow passage

Do not block the exhaust vent: It is strictly prohibited to place any equipment or items near the exhaust vent of the fume hood, otherwise it will seriously impede the discharge of air flow, causing the pressure inside the fume hood to rise and harmful gases to be unable to be discharged in time. For instance, large instruments or sundries should not be piled up in front of the exhaust outlet. It is necessary to ensure that the exhaust outlet is unobstructed.

Do not block the airflow from the operation window: Do not place overly tall equipment or obstacles near the operation window to avoid affecting the airflow from entering the fume hood through the operation window. If the airflow at the operation window is blocked, the negative pressure environment inside the fume hood will be disrupted, and harmful gases may leak into the laboratory environment. For instance, tall reagent bottle racks should not be placed at the edge of the operation window. Instead, a stand of appropriate height should be selected to ensure that the airflow can enter smoothly.

Consider the convenience of experimental operation

Place frequently used equipment nearby: Put the equipment frequently used during the experiment, such as electronic balances and pH meters, in a position that is easily accessible to the experimenter, usually about 30 to 50 centimeters away from the operator. This can reduce the number of times the experimenter walks and bends over during the operation process, improve the experimental efficiency, and at the same time lower the safety risks caused by inconvenient operation. For instance, when conducting quantitative analysis experiments, place the electronic balance on the side of the fume hood close to the operator to facilitate the weighing of samples at any time.

The operation surface of the equipment should face the operator: For equipment with an operation panel or control device, its operation surface should face the laboratory personnel to facilitate operation and observation. For instance, if the operation panel of the constant temperature incubator is placed outside the fume hood, the laboratory personnel can set the temperature, time and other operations without entering the fume hood, reducing their contact with harmful gases.

Special equipment is treated specially

Volatile equipment should be placed away from the edge of the fume hood: For some equipment that is prone to emitting harmful gases, such as distillation units and rotary evaporators, they should be placed as close to the center of the fume hood as possible, away from the edge of the fume hood. This can reduce the possibility of harmful gases leaking into the laboratory environment. For instance, when conducting an organic solvent distillation experiment, place the distillation apparatus in the middle of a fume hood, leaving sufficient space around it to allow the airflow to carry away the volatile organic solvents.

Pay attention to heat dissipation for high-temperature equipment: When placing high-temperature equipment such as muffle furnaces and ovens, the heat dissipation issue should be taken into consideration. It should be placed in a well-ventilated position within a fume hood, avoiding being too close to other equipment. At the same time, it is necessary to ensure that there is sufficient space around the equipment to dissipate heat. For instance, place the muffle furnace at the rear of the fume hood and keep it at a certain distance from the surrounding equipment to prevent heat accumulation from affecting the normal operation of other equipment.