Fume hood with improved counterbalance system
AssigneeFisher Hamilton Scientific Inc.
InventorJames J. Schlies
Life of this patent
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Abstract
A fume hood includes a housing with a work chamber, an access opening to the work chamber, and a sash that one may move between raised and lowered positions to open or close the access opening. It also includes a counterbalance system that maintains the sash at a desired position between two predetermined limits. An adjusting weight system reduces the weight provided by the counterbalance system or increases the weight of the sash to allow the sash to drop to a predetermined position after it has moved above that predetermined position.
Claims16
In a fume hood apparatus having a housing with a work chamber, an access opening to the work chamber, and a sash member moveable between raised and lowered positions for opening or closing the access opening, counterbalance means for normally maintaining the sash member at a desired position and adjusting weight means for adjusting the weight provided by the counterbalance means or increasing the weight of the sash member at a predetermined point during the movement of the sash between the raised and lowered positions to allow the sash member to drop to a predetermined position after being raised above that predetermined position.
A fume hood apparatus comprising:
- a housing with a work chamber, an access opening to the work chamber and a sash member moveable between raised and lowered positions for opening or closing the access opening;
- first weight means supported by the housing for maintaining the sash member at a desired position;
- connecting means for connecting the first weight means with the sash member;
- second weight means for adjusting the magnitude of the first weight means or increasing the weight of the sash member at a predetermined point during the movement of the sash between the raised and lowered positions to allow the sash member to drop to a predetermined position after being raised above that predetermined position.
A fume hood apparatus comprising:
- a housing with a work chamber, an access opening to the work chamber and a sash member moveable between raised and lowered positions for opening or closing the access opening;
- a counterweight supported by the housing;
- a cable for connecting the counterweight to the sash member;
- at least one adjusting weight member disposed in the housing with a connecting portion for connecting the adjusting weight member to the sash member;
- the adjusting weight member increasing the weight of the sash member at a predetermined point during the movement of the sash between the raised and lowered positions to allow the sash member to drop to a predetermined position after being raised above that predetermined position;
- the housing including portions for containing the adjusting weight member and guiding the adjusting weight member along a predetermined path.
A fume hood apparatus comprising:
- a housing with a work chamber, an access opening to the work chamber and a sash member moveable between raised and lowered positions for opening or closing the access opening;
- a counterweight supported by the housing;
- a cable for connecting the counterweight to the sash member;
- an adjusting weight member disposed in the housing with a connecting portion for connecting the adjusting weight member to the counterweight;
- the adjusting weight member adjusting the magnitude of the counterweight to allow the sash member to drop to a predetermined position after being raised above that predetermined position;
- the housing including portions for containing the adjusting weight member.
An improved fume hood apparatus including a housing with a work chamber, an access opening to the work chamber, and a sash member moveable between raised and lowered positions for opening and closing the access opening and further including counterbalance means for maintaining the sash member at a desired position, wherein the improvement comprises at least one adjusting weight that adjusts the weight provided by the counterbalance means or increases the weight of the sash member when the sash reaches a predetermined position.
An improved fume hood apparatus including a housing with a work chamber, an access opening to the work chamber, and a sash member moveable between raised and lowered positions for opening and closing the access opening and further including counterbalance means for maintaining the sash member at a desired position, wherein the improvement comprises at least one adjusting weight that connects automatically with either the weight provided by the counterbalance or the sash and that adjusts the weight provided by the counterbalance means or increases the weight of the sash member when the sash reaches a predetermined position.
Dependencies are inferred from the claim text.