Ventilation Hood

Product Model	PP Corrosion-Resistant Fume Hood Series
Category	Laboratory Products
Reference Price	Price on request

Hot Customizable for Working Conditions 10 Technical Parameters

Product Overview

Fume Hood, also known as fume hood or exhaust cabinet, is the most commonly used and critical local exhaust safety equipment in chemical laboratories. Experimental personnel perform chemical operations that generate harmful gases, vapors, dust, or odors inside the ventilation cabinet's working chamber. The ventilation system continuously extracts air from the cabinet, creating a stable face velocity at the sliding window opening that flows into the cabinet. This confines pollutants within the cabinet and treats them through exhaust pipes before discharge, effectively isolating experimental personnel from toxic and harmful gases.

The ventilation cabinet is not simply an exhaust fan with a cabinet. Its core performance lies in the stability of the face velocity at the window opening and the airflow organization within the cabinet. If the face velocity is too low, harmful gases may escape from the window and endanger personnel. If the face velocity is too high, it leads to energy waste and may interfere with experiments or cause turbulent airflow within the cabinet. A well-designed ventilation cabinet maintains stable face velocity at different window openings through baffle plates, make-up air structures, and airflow control valves. The cabinet body material is selected based on the experimental medium, commonly including PP, all-steel, and stainless steel. Among these, PP ventilation cabinets are resistant to acid and alkali corrosion, making them suitable for chemical, electroplating, and semiconductor laboratories.

The PP ventilation cabinets supplied by Xicheng Environmental Protection are made of PP board, offering corrosion resistance and easy cleaning. They are equipped with adjustable tempered glass windows, work surfaces, baffle plates, waterproof power supply, lighting, and water supply/drainage interfaces. The exhaust outlet can be paired with fixed or variable airflow Venturi valves. Multiple ventilation cabinets can be supported to form a centralized exhaust system, with dimensions and configurations customizable to laboratory requirements.

Working Principle

The ventilation cabinet operates based on the safety curtain created by exhaust airflow. The exhaust fan draws air from the cabinet through pipes, creating a relative negative pressure inside the cabinet compared to the laboratory. Air enters the cabinet from the window opening at a relatively uniform speed, forming an air barrier. Harmful gases generated during experiments are carried into the exhaust channel by the airflow and cannot diffuse toward the operator. The airflow speed at the window opening is called the face velocity, which is the core indicator for measuring the safety performance of the ventilation cabinet.

The cabinet is equipped with baffle plates and upper and lower exhaust channels to organize airflow rationally within the working chamber, preventing dead zones and eddies from forming. The fixed airflow system maintains a constant exhaust volume through Venturi fixed airflow valves. The variable airflow system measures the window displacement or face velocity in real time using sensors, controlling variable airflow valves to adjust the exhaust volume, ensuring stable face velocity even when the window opening changes, and reducing exhaust volume when the window is closed for energy savings. The PP cabinet body and baffle components are resistant to acid and alkali corrosion, remaining rust-free and free from pollutant adsorption even with long-term exposure to corrosive gases.

Structural Components

The ventilation cabinet consists of a cabinet body, working chamber, window, work surface, baffle system, exhaust interface, control and lighting, and water/electricity accessories. The cabinet body and working chamber lining are welded PP boards, offering corrosion resistance and a smooth, easily cleanable surface. The upper part is the exhaust box and exhaust pipe connection, the lower part is the working chamber, and the bottom is the work surface and cabinet base.

The window is made of tempered glass that can slide up and down, equipped with counterweights or mechanical balancing devices to stay at any position with upper and lower limiters. Baffle plates are installed on the rear wall and top of the working chamber to form rational airflow channels. The work surface is made of corrosion-resistant solid chemical-resistant board, PP board, or ceramic board, equipped with cup holes and drip structures. The exhaust outlet is located at the top of the cabinet, connected to exhaust pipes and airflow control valves. The front panel or side column is equipped with lighting switches, waterproof power sockets, airflow indicators, and audible/visual alarms. LED corrosion-resistant lighting is provided inside the cabinet, and water supply/drainage and gas valves are configured based on experimental needs.

Specification Model Table

The table below shows the main configuration forms of ventilation cabinets. Specific dimensions and control methods are designed according to laboratory requirements.

Item	Configuration	Description
Cabinet Material	PP / All-Steel / Stainless Steel	Selected by medium
Airflow Control	Fixed Airflow / Variable Airflow	Based on energy-saving requirements
Window	Sliding Tempered Glass	Any position locking
Work Surface	Chemical-Resistant Board / PP / Ceramic	Corrosion-resistant

Product Features

PP ventilation cabinets are corrosion-resistant, feature rational airflow, and come with comprehensive configurations, making them the core protective equipment for chemical laboratories. The main features are as follows.

PP cabinet body and lining are resistant to acid and alkali corrosion, suitable for chemical experiments
Stable face velocity at window opening effectively isolates harmful gases
Baffle plates rationally organize airflow, eliminating exhaust dead zones within the cabinet
Adjustable tempered glass window locks at any position for excellent protection
Optional fixed or variable airflow control for safety and energy efficiency
Work surface with cup holes and integrated water/electricity/lighting for convenience
Face velocity display and alarm for intuitive and controllable operation status

Cabinet material	PP Polypropylene Sheet
window	Adjustable tempered glass
Exhaust Method	Upper mechanical exhaust
Control Method	Variable Air Volume (VAV) / Constant Air Volume (CAV) Optional
Face Airflow Speed Control	Constant face wind speed
Internal material flow	Back Wall Diffuser
Material of the work surface	Corrosion-Resistant Chemical-Physical Board / PP
Lighting	Enclosure Anti-corrosion Lighting
Exhaust Port	Duct Top Air Volume Damper
`Corrosion resistance performance`	Acid and Alkali Corrosion Resistance

Application Industries

Acid and alkali volatile operation protection in chemical and petrochemical laboratory
Sample pre-treatment fume hoods for testing and inspection institutions
Fume hoods for R&D and quality inspection laboratories in pharmaceutical enterprises
Fume hoods for wet chemical processes in semiconductor and electronics factories
Corrosive operation exhaust ventilation in electroplating and surface treatment laboratories
Chemical teaching experiment fume hoods in schools and research institutions
Reagent operation protection in hospital pathology departments and disease control laboratories

Typical Process Locations

The fume hoods are installed along the laboratory wall or dedicated exhaust shafts. Multiple fume hood exhaust branches are connected to horizontal exhaust main pipes, which are centrally extracted by floor or roof exhaust fans. Harmful gases are discharged after being treated by devices such as spray nozzles or adsorption equipment through exhaust stacks. Each fume hood's exhaust branch is equipped with an airflow control valve (constant airflow or variable airflow Venturi valve), and the main pipe is fitted with a fan and muffler. The laboratory maintains a negative pressure relative to the corridor, with make-up air supplied through the room's fresh air system or unorganized openings via windows and doors.

During installation, the fume hoods are positioned and leveled. The exhaust interface on the hood top is connected to corrosion-resistant ducts, airflow control valves, and flexible connectors. When multiple hoods share a fan, the airflow control valves on each branch are balanced according to the required face velocity. For variable airflow systems, the window displacement or face velocity sensors, controllers, and electric valve wiring are properly connected. Before operation, each hood is tested for uniformity and stability of face velocity, with alarm functions verified. Operators are trained to maintain reasonable window openings and avoid blocking airflow by stacking items inside the hood.

Face velocity should be determined based on the type of pollutants generated during experiments and relevant standards. Common chemical operations are typically controlled within the recommended face velocity range by standards, with specific values defined by laboratory ventilation design specifications and product requirements. Insufficient face velocity may allow harmful substances to escape, while excessive face velocity wastes air conditioning fresh air energy consumption and causes turbulence within the cabinet. Variable air volume (VAV) fume hoods maintain the set face velocity at any sash opening through sensors and regulating valves. Constant air volume (CAV) fume hoods only require face velocity compliance at the designed sash opening, and the face velocity changes with sash opening variations. This is the fundamental difference between the two systems.

The cabinet body and lining of the PP fume hood are made of polypropylene, which is resistant to acid, alkali, and salt corrosion, does not rust, and is suitable for laboratories that frequently use hydrochloric acid, nitric acid, sulfuric acid, alkaline solutions, and corrosive gases in chemical, electroplating, and semiconductor fields. The all-steel fume hood has high strength and good performance in high-temperature and organic solvent resistance, making it suitable for laboratories primarily using organic reagents and high-temperature heating. The surface is treated with anti-corrosion coating, but its resistance to strong corrosion is inferior to PP. For highly corrosive environments, choose PP; for organic solvents and open flames at high temperatures, select all-steel or stainless steel. When the medium is complex, specify the commonly used reagents to the manufacturer for material selection.

Constant airflow fume hoods maintain a constant exhaust volume with a simple structure and low investment. However, when the viewing window is partially closed, the wind speed increases and energy consumption does not decrease, making them suitable for laboratories with a small number of fume hoods and low usage frequency. Variable airflow fume hoods adjust the exhaust volume by the displacement of the viewing window or through the linkage with venturi variable airflow valves, increasing the exhaust volume when the window is opened and decreasing it when closed, while maintaining a constant face velocity. This ensures safety and significantly reduces the energy consumption of air conditioning fresh air, making them suitable for modern laboratories with a large number of fume hoods, long operating hours, and energy-saving requirements. However, they require a higher initial investment and more stringent control and maintenance requirements.

It is not recommended to use fume hoods as storage cabinets for long-term storage. Prolonged accumulation of reagent bottles and equipment inside the operational chamber will block the baffle plates and rear air intake channels, disrupt internal airflow organization, result in insufficient local velocity, create pollutant accumulation and eddies, and increase the risk of chemical mixing and leakage reactions. Fume hoods are operational protection equipment, designed to hold only a small amount of items currently in use during experiments. After experiments, chemicals should be stored in dedicated medicine cabinets, reagent cabinets, or explosion-proof cabinets to maintain the operational chamber, baffle plates, and exhaust channels clear. Waste liquids and debris should not be accumulated in the cabinet's cups/troughs, work surfaces, or behind the baffle plates for extended periods. For chemical storage, configure specialized cabinets that meet storage requirements, and store chemicals by compatibility classification to fundamentally eliminate safety and ventilation hazards caused by accumulation inside the fume hood.

Depends on the pollutants emitted and local environmental protection requirements. When emitting general waste heat and small amounts of harmless gases, dilution and high-altitude discharge through the exhaust stack are typically used. For experiments producing acidic or alkaline mists, organic volatile compounds, toxic or harmful, or odoriferous gases, corresponding treatment equipment such as spray scrubbers or activated carbon adsorption should be connected, and emissions should be discharged after meeting standards. It is common practice to centrally collect exhaust air from multiple fume hoods and then treat it. Whether treatment is required and what process to adopt should be determined based on pollutant types, emission volumes, and environmental impact assessment approval. It cannot be judged solely based on the number of fume hoods.

Follow the system sequence for troubleshooting: First, check the window opening degree and whether there are obstructions blocking airflow inside the cabinet, and whether the flow guide plates are properly installed; then, verify the correct opening of the exhaust branch duct airflow valve, check if the filters or exhaust treatment equipment are clogged, and whether the ductwork is leaking air or accumulating dust; next, inspect the fan operating status, belts and impellers, and frequency converter settings; for multi-cabinet systems, also check whether the airflow balance of each branch is compromised. For variable airflow systems, also check if the sensors, controllers, and damper actuators are functioning properly. After troubleshooting, use an anemometer to re-measure the air velocity, and readjust the airflow balance if necessary.

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