Constant volume bypass hood no larger than 6 foot in length (unless VAV is specified), equipped with an Alnor model 405 fume hood flow alarm.

The work surface of the bench is recessed 1/2-inch or more below the front edge of the bench, and the sides and back of the bench are provided with a seamless vertical lip 1/2-inch high.

An airfoil with a 90-degree arc with a minimum radius of 1-1/2 inches (1-inch air gap between the foil and the corner of the bench), shall be provided at the front edge of the bench external to the sash.

The side posts of the front face are provided with an airfoil, except that side posts wider than 3-1/2 inches are substituted for a 45-degree taper at least 4 inches long at the forward inside edge of the face.

Utilities serving the hood shall have valves and switches at readily accessible locations outside the hood. Additional valves and switches also may be located inside the hood. All valves shall meet ASME or JIC codes, and all switches should meet NEC codes.

The rear and top interior of the hood should be furnished with baffles to provide at least two (preferably three) slots, adjustable in width, to attain reasonably uniform face velocity under different conditions of hood use as related to heat sources, size, and configuration of equipment within the hood, and other factors. There must be screen at the bottom baffle to prevent small papers from entering the ductwork. Screens will have a one-inch grid size.

Connection(s) for exhaust duct(s) should be provided in the walls or roof of the hood behind the adjustable baffles. The connection(s) should have a flow cross-section sized for a velocity of 2000 fpm maximum at the rated volume flow of the hood with the front sash wide open, and should be located so the adjustable baffles are effective in attaining uniform face velocity.

The open face of the hood should be provided with one vertically movable sash capable of closing the entire front face, constructed of shatterproof flame-resistant material. A sash lock (swivel lock) that can be disengaged is required at the maximum operating height of 18 inches.

The vertically moving sash should be movable throughout its travel by application of no more than 5 pounds of force and should remain stationary when force is removed.

The fume hood shall be tested prior to leaving the factory and meet the ASHRAE 110-most current Tracer gas test protocol with a rating of 4 AM 0.05. Documentation shall be provided.

The hood shall be equipped with an airflow monitor that measures flow and has both visual and auditory alarm. The alarm should be provided and installed by the fume hood manufacturer.