Fume Hood with Windable Sash
In various example embodiments, a fume hood apparatus is disclosed. The fume hood apparatus comprises an enclosure defining a workspace with a windable transparent sash at the face of the hood that is wound around a roller shaft when in a storage state. The apparatus further comprises an air filter assembly, sash position sensors, exhaust and supply air ducting with fans and dampers controlled by a microprocessor, along with a user interface that allows monitoring and control of the various functions of the apparatus.
1 . A fume hood apparatus comprising:
an enclosure defining a workspace and an access opening;
a windable transparent sash;
a roller shaft which rotates about a main axis connected to the sash; and
wherein the sash is wound around the roller shaft in a storage state and is at least partially
unwound from the roller shaft in an operating state of the fume hood.
2 . The apparatus of claim 1 further comprising:
an air filter assembly located above the workspace;
an auxiliary air supply duct;
an exhaust duct with a regulating mechanism disposed above the workspace for regulating exhaust air flowing from the fume hood through the exhaust duct;
an auxiliary air supply regulating mechanism disposed above the workspace for regulating air ambient supply input;
sash position sensors measuring the position of the sash, capable of outputting a signal corresponding to sash position;
a face velocity measuring device capable of outputting a signal corresponding to a measured value of face velocity;
a microprocessor in communication with the face velocity measuring device, the sash position sensors, the auxiliary air supply regulating mechanism, and the exhaust regulating mechanism, the microprocessor containing data representing an air flow response characteristic of the exhaust regulating mechanism; and
a controller for controlling the exhaust regulating mechanism and auxiliary air supply regulating mechanism in response to the signal outputted from the face velocity measuring device, the sash position sensors, a face velocity setpoint, and an air flow response characteristic of the exhaust regulating mechanism.
3 . The apparatus of claim 2 , wherein the exhaust regulating mechanism comprises:
an exhaust damper, the damper position controlled by the controller; and
an exhaust fan, the fan speed controlled by the controller.
4 . The apparatus of claim 2 , wherein the auxiliary air supply regulating mechanism comprises:
a supply fan, the fan speed controlled by the controller; and
a supply damper, the damper position controlled by the controller.
5 . The apparatus of claim 3 , wherein the exhaust damper has a nonlinear response of flow rate to damper position.
6 . The apparatus of claim 4 , wherein the supply damper has a nonlinear response of flow rate to damper position.
7 . The apparatus of claim 2 , wherein the face velocity measuring device is positioned at approximately the face of the fume hood.
8 . The apparatus of claim 5 , wherein the face velocity measuring device comprises a pitot.
9 . The apparatus of claim 6 , wherein the pitot measures air pressure at the face of the fume hood and the microprocessor further includes means for converting pressure measurement of the pitot into face velocity.
10 . The apparatus of claim 2 , further comprising sidewall sensors measuring air velocity along sidewalls of the enclosure and reporting this data to the microprocessor;
the microprocessor in communication with the sidewall sensors, the face velocity measuring device, the sash position sensors, the exhaust regulating mechanism and auxiliary air supply regulating mechanism, the microprocessor containing data representing an air flow response characteristic of the exhaust regulating mechanism; and
a controller in communication with the microprocessor for controlling the exhaust regulating mechanism and auxiliary air supply regulating mechanism in response to the signal outputted from the face velocity measuring device, the sidewall sensors, the sash position sensors, a face velocity setpoint, and an air flow response characteristic of the exhaust regulating mechanism.
11 . The apparatus of claim 2 , further comprising gas detectors sensing the presence and concentrations of gas fumes, wherein this data is communicated to the microprocessor.
12 . The apparatus of claim 11 , wherein the controller adjusts the air flow based on fume type and concentration and preset minimum levels, increasing the air flow to maintain a level of air flow as required to meet these minimum levels.
13 . The apparatus of claim 11 , further comprising visual and audible alerts communicating gas types and concentration levels to a user or users.
14 . The apparatus of claim 11 , wherein the gas detectors are of one or more type comprising: semiconductors; oxidation; catalytic; photoionization; infrared point; infrared imaging; electrochemical; catalytic bead; ultrasonic; metal oxide, acid array and holographic.
15 . The apparatus of claim 1 , further comprising two or more sashes covering two or more openings.
16 . The apparatus of claim 15 , wherein one or more of the two or more sashes cover an area within the enclosure, separating the area from the remainder of the space within the enclosure.
17 . The apparatus of claim 15 , wherein one or more of the two or more sashes are flexible and windable, transparent or opaque, wound or unwound onto the roller shaft by an electric motor; the motor controlled by a user operated switch or the controller.
18 . The apparatus of claim 2 , further comprising a touchscreen display monitor for facilitating communication and control between microprocessor and a user.
19 . The apparatus of claim 2 , wherein the exhaust duct and auxiliary supply air duct are connected and extended to external devices or air handling systems;
Wherein the microprocessor interfaces with the control system of the external devices or air handling systems;
the devices comprising venturi valves; VAV boxes; blade and frame dampers; pressure based flow stations; and thermal based flow stations.
the apparatus further comprising additional sensors and control equipment as required to enable the apparatus to be compatible with the connected devices and systems while maintaining the required functionality of the fume hood apparatus.
20 . The apparatus of claim 15 , further comprising: monitoring the extent to which the sashes cover the openings periodically over a period of time; and adjusting the rate of air flow to maintain a preselected average face velocity.