What Are The Causes And Solutions for The Unpleasant Smell in Fume Hoods?

Cause of malfunction

Ventilation system problems

Insufficient exhaust volume: If the exhaust duct of the fume hood is blocked, such as due to long-term accumulation of dust and debris, or if there are too many elbows or the pipe diameter is too small, it will increase the ventilation resistance, resulting in a decrease in exhaust volume. When the exhaust air volume is insufficient, the odorous gas produced by the experiment cannot be discharged in time and will accumulate in the fume hood and be released.

Fan failure: The fan is the core component of the ventilation system. If the fan blades deform, the motor is damaged or the bearings wear out, it will affect the normal operation of the fan and make the ventilation effect worse. For instance, deformation of fan blades can lead to airflow disorder, reduce exhaust efficiency, and thus make it difficult for unpleasant odors to be discharged.

Poor sealing of ventilation ducts: If the connection points, flanges and other parts of ventilation ducts are not well sealed, air leakage will occur. External air will enter the ventilation duct through the air leakage, diluting the discharged odorous gas. At the same time, it will also bring the outside odors into the fume hood, causing an unpleasant smell in the fume hood.

Problems with experimental operation

Evaporation of experimental reagents: During chemical experiments, some reagents have strong volatility, such as organic solvents (ethanol, acetone, etc.) and acids (hydrochloric acid, sulfuric acid, etc.). If the reagents are left open for too long during the experimental operation or the heating temperature is too high, it will accelerate the evaporation of the reagents and produce a large amount of odorous gas.

Non-standard experimental operation: Laboratory personnel did not conduct experiments in accordance with the correct operating procedures. For instance, when conducting experiments that produced a large amount of odor in a fume hood, the window was not adjusted to an appropriate height, causing the odor gas to spread outside the fume hood. In addition, if the residues on the laboratory countertop and in the fume hood were not cleaned up in time after the experiment, these residues will continue to emit unpleasant odors.

Problems with the fume hood itself

Internal contamination: If the interior of a fume hood is not cleaned for a long time, dust, experimental residues, etc. will accumulate. These pollutants are prone to breed bacteria and mold in a humid environment, generating unpleasant odors. For instance, the corners and drainage channels of fume hoods are prone to accumulate dirt and become the sources of unpleasant odors.

Filter device failure: Some fume hoods are equipped with filter devices to filter out harmful gases and odors produced during experiments. If the filter device is not replaced for a long time, the filter material will reach a saturated state and lose its filtering effect, resulting in the odor gas being unable to be effectively filtered and being released.

Processing method

Ventilation system treatment

Clean the exhaust ducts: Regularly inspect and clean the exhaust ducts. Professional duct cleaning equipment such as vacuum cleaners and duct brushes can be used to remove the dust and debris inside the ducts. For pipes with too many elbows or too small diameters, it is advisable to consider making renovations to optimize the layout of ventilation ducts and reduce ventilation resistance.

Repair or replacement of the fan: If the fan malfunctions, it needs to be inspected and repaired by professionals. For the case of blade deformation, you can try to repair or replace the blade. If the motor is damaged, a new one needs to be replaced. Worn bearings can be lubricated or replaced. If the fan is severely aged and cannot be repaired, a new one needs to be replaced.

Sealed ventilation ducts: Inspect the connection points, flanges and other parts of the ventilation ducts. If any air leakage is found, seal it in time. Sealing materials such as sealant and gaskets can be used for sealing to ensure good sealing performance of the ventilation duct.

Experimental operation processing

Standardize experimental operations: Laboratory personnel should strictly follow the operating procedures to conduct experiments, control the amount of reagents used and the heating temperature, and minimize the evaporation of reagents as much as possible. When conducting experiments that produce odors, adjust the window of the fume hood to an appropriate height to ensure that the odorous gases can be effectively discharged. After the experiment, it is necessary to clean up the residues on the laboratory bench and inside the fume hood in a timely manner to keep the fume hood clean.

Strengthen the management of fume hood usage: Establish a management system for fume hood usage, clearly defining the responsibilities of laboratory personnel and operational norms. Train the laboratory personnel to enhance their safety awareness and operational skills to ensure the normal use of fume hoods.

Fume hood self-handling

Clean the interior of the fume hood: Regularly conduct a thorough cleaning of the interior of the fume hood, including the countertop, inner walls, drainage trough and other parts. It can be wiped with a cleaner and clean water to remove dust, experimental residues and other contaminants. For stubborn stains, specialized cleaning tools can be used for treatment.

Replace the filter device: According to the user manual of the fume hood, replace the filter device regularly. When replacing the filter device, select the filter material that matches the model of the fume hood to ensure the filtration effect. At the same time, attention should be paid to the installation direction and sealing performance of the filter device to avoid air leakage