Fume hood controller
First Claim
1. A fumed hood controller for controlling the air flow through a fume hood to maintain a relatively constant face velocity through a fume hood opening as the fume hood sash is moved, comprising:
- transducer means responsive to the position of the fume hood sash for producing a sash opening signal the value of which is a substantially continuous and monotonic function of the sash opening;
air flow control means, responsive to an air flow signal, for varying the air flow through the fume hood in accordance with the air flow signal;
flow control means, responsive to the sash opening signal, for producing the air flow signal, including;
means for setting a first air flow at a first sash position;
means for setting a second air flow at a second sash position; and
means for providing, to the air flow means, an air flow control signal having a value so as to maintain the air flow through the hood substantially proportional to the sash opening area as the sash is moved between the first and second sash positions, said means for providing including means for maintaining a linear relationship between the air flow signal and the air flow through the hood.
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Reexamination
Accused Products
Abstract
A fume hood controller system in which the sash position is monitored by a transducer which provides a signal indicative of the area of the hood opening. A variable speed motor controller is responsive to the sash position signal to provide a fan speed which varies in a substantially continuous and linear manner as a function of the sash opening. In an alternate embodiment, the air flow through the hood is controlled by a damper or similar device. Several embodiments are shown in which the present invention may be used to control a fume hood system in which a blower exhausts a plurality of fume hoods while maintaining a substantially constant face velocity in each hood.
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Citations
26 Claims
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1. A fumed hood controller for controlling the air flow through a fume hood to maintain a relatively constant face velocity through a fume hood opening as the fume hood sash is moved, comprising:
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transducer means responsive to the position of the fume hood sash for producing a sash opening signal the value of which is a substantially continuous and monotonic function of the sash opening; air flow control means, responsive to an air flow signal, for varying the air flow through the fume hood in accordance with the air flow signal; flow control means, responsive to the sash opening signal, for producing the air flow signal, including; means for setting a first air flow at a first sash position; means for setting a second air flow at a second sash position; and means for providing, to the air flow means, an air flow control signal having a value so as to maintain the air flow through the hood substantially proportional to the sash opening area as the sash is moved between the first and second sash positions, said means for providing including means for maintaining a linear relationship between the air flow signal and the air flow through the hood. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. In a fume hood installation having a plurality of fume hoods each including a sash which moves to provide an opening for access to the fume hood interior;
- and exhaust blower driven by a blower motor; and
exhaust ducting connecting each of the fume hoods to the blower;
a fume hood controller, comprising;a plurality of transducer means, equal in number to the number of fume hoods and each transducer being associated with a respective one of the fume hoods, each for producing a respective sash opening signal the value of which is a substantially continuous and monotonic function of the associated sash opening; a plurality of flow control means, each associated with a respective one of the transducer means and responsive to the sash opening signal therefrom, for producing an air flow signal representative of a desired air flow through the associated hood, the air flow signal being a function of the sash opening signal; and a plurality of air flow control means, each associated with a respective one of the fume hoods and responsive to the air flow signal, for controlling the air flow through the associated fume hood so that it varies in accordance with the air flow signal; each flow control means further including; means for setting a first air flow at the first sash position; means for setting a second air flow at the second sash position; and means for providing, to the air flow control means, an air flow signal having a value so as to maintain the air flow through the hood substantially proportional to the sash opening area as the sash is moved between the first and second sash positions, said means for providing including means for maintaining a linear relationship between the air flow signal and the air flow through the hood. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
- and exhaust blower driven by a blower motor; and
Specification