Service 
Selection of the proper type of fume hood to use in a lab should be based on the actual requirements. Penway Science fume hood is made of ceramic fiber aluminum, steel.

Safety
Plays as a pioneer in lab industry
Fume hood VAV valve
Air differential pressure control system for air output and compensation
Third-party on-site inspection
Those four points can make the laboratory to be safe

Health
European and US design, integrated frames.
The sash slideway, balance weight, communication system all of those are embedded in fume hood`s front aluminum frames.

Category
Modular frames design.
The front frame is made of aluminum environmental protection material.
The back frame is made of high-quality steel plate - Baosteel





Constant air volume principle (CAV)
Conventional hood: This term is used to describe a constant air volume (CAV) hood, an older, traditinally less elaborate hood design used for general protection of the laboratory worker. Because the amount elaborate hood design used for general protection of the laboratory worker. Because the amount of exhausted air is constant, the face velocity of a CAV hood is inversely proportional to the sash height. That is, the lower the sash, the higher the face velocity. CAV hoods can be installed with or without a bypass provision which is an additional opening for air supply into the hood.

Variable air volume vs. constant air volume?
• Constant volume is good for small applications, for dedicated exhaust, or for two to four units sharing an exhaust.
• Most hoods have "setup" time and "run" time, or are only used on a limited basis. While slightly more expensive to buy, that makes a two-speed exhaust more cost effective in use. Typically, low speed is 50% of high speed. Set the blower on high for setup, low for runtime, or for limited-use purposes.
• Hoods should be in close proximity to one another to save money on installing and maintaining the exhaust system.
• You can also plan for future hoods to be added to the system. But make sure future expansion is identified in the building plan, so that the whole building exhaust and supply can accommodate future needs. For example, you can buy a blower for a 4-hood system when you're only planning to install two hoods at first. Then just block off your "future" duct until you buy the additional hoods.