1. A hand tool, comprising:
conductive tool head that is at least one of a wire cutter, a wire stripper, a screw driver, a wrench, and a pliers;
a non-contact voltage sensing circuit electrically connected to the conductive tool head, the non-contact voltage sensing circuit including a comparator for comparing a voltage sensed at the conductive tool head to a threshold voltage level and an alarm circuit for generating a human perceptible alarm signal when the threshold voltage level is exceeded, the alarm circuit including at least one of a visual and an audio indicator device electrically connected to receive the alarm signal and to provide an output that is perceptible by a human; and
a handle operatively connected to the tool head and housing the non-contact voltage sensing circuit including the at least one indicator, the indicator providing a human perceptible signal to a user indicating that the tool head is in proximity to a live electrical wire.
2. The hand tool as defined in claim 1, further comprising an actuator for selectively activating the non-contact voltage sensing circuit.
3. The hand tool as defined in claim 1, wherein the handle comprises an insulated material.
4. The hand tool as defined in claim 3, wherein the handle further comprises a metal foil coupled to a circuit common in the non-contact voltage sensing circuit.
5. The hand tool as defined in claim 1, further comprising a momentary actuator switch coupled to the handle, the momentary actuator switch being coupled between a power supply and the non-contact voltage sensing circuit to activate the non-contact voltage sensing circuit.
6. A hand tool comprising:
a) a conductive tool head that is at least one of a wire cutter, a wire stripper, a screw driver, a wrench and a pliers to work a work piece;
b) a handle, connected to the tool head so as to operate the tool head to work the work piece;
c) a non-contact voltage sensing circuit electrically coupled to the conductive tool head; and
d) an alarm device, the alarm device being activated by the non-contact voltage sensing circuit to provide a signal to indicate that the tool head is in an electrical field at an elevated voltage.
7. A hand tool as defined in claim 6, wherein the alarm device comprises at least one of a visible alert indicator and an audible alert indicator.
8. A hand tool as defined in claim 7, wherein the alarm device comprises a light emitting diode.
9. A hand tool as defined in claim 7, wherein the non-contact voltage alert circuit comprises an oscillator for driving the audible alert indicator in an audio frequency range.
10. A hand tool as defined in claim 6, further comprising a switch for activating the non-contact voltage sensing circuit.
11. A hand tool as defined in claim 6, further comprising a conductive foil, the conductive foil being coupled to a circuit common of the non-contact voltage sensing circuit and capacitively coupled to the user’s hand to provide a connection through the user to provide a ground for the circuit.
12. A hand tool as defined in claim 6, wherein the non-contact voltage detection circuit is housed in the handle.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for detecting a fume containment breach from an exhaust hood, comprising:
a detector configured to indicate changes in the speed of light through a sample path based on an interferometric effect;
said detector being positioned near an exhaust hood;
a controller configured receive an indication signal from said detector and to control an exhaust flow rate responsively to said indication signal.
2. A system as in claim 1, wherein said detector includes a sample gap through which laser light is transmitted and through which gases may pass.
3. A system as in claim 1, wherein said controller is configured to continuously adjust said exhaust flow rate to minimize said exhaust flow rate consistent with a specified average interval between signals from said detector indicating a threshold amount of gas contact with said detector.
4. A system for selectively increasing capture and containment of an exhaust hood, comprising:
a movable side skirt attachable to an exhaust hood such that said skirt may be placed in retracted and extended positions;
the extended position being effective to reduce the exposure of an area between a fume-generating process and a hood;
the retracted position being effective to increase the open area between a fume-generating process and a hood.
5. A system as in claim 4, further comprising:
an actuator connected to move said side skirt between said retracted and extended positions;
a controller with a fume load detector connected to control said actuator and configured to control said position of said side skirt responsively to a fume load.
6. A system as in claim 4, further comprising:
an actuator connected to move said side skirt between said retracted and extended positions;
a controller with a fume escape (breach) detector connected to control said actuator and configured to control said position of said side skirt responsively to a fume escape.
7. A fume hood, comprising:
a hood portion connectable to an exhaust system and having a recess and a lower edge therearound, the hood portion being configured to cover a fume source;
a jet generator located at said lower edge and configured to generate first and second jets, said first being relatively horizontal in direction and said second being relatively vertical in direction;
said first being directed toward said hood portion recess.
8. A fume hood as in claim 7, wherein said at least one of said first and second jets are defined by a series of circular jets arranged along a line along said lower edge.
9. A fume hood as in claim 7, wherein said first and second jets are defined by respective series of circular jets arranged along respective lines following said lower edge.
10. A fume hood as in claim 7, wherein:
said hood portion has corners;
said first jet is directed perpendicular to said lower edge between said corners and in a direction that is diagonal with respect to said lower edge between said corners, and thereby toward a middle of said hood portion, at said corners.
11. A fume hood, comprising:
a hood portion connectable to an exhaust system and having a recess and a lower edge therearound, the hood portion being configured to cover a fume source;
a jet generator located at said lower edge and configured to generate a horizontal jet directed toward said hood portion recess;
said hood portion having corners;
said jet being directed perpendicular to said lower edge between said corners and in a direction that is diagonal with respect to said lower edge between said corners, and thereby toward a middle of said hood portion, at said corners.
12. An exhaust hood, comprising:
a hood with a make-up air plenum having a short-circuit discharge and a room-mixing discharge;
said hood further having an apportioning damper for selectively directing a first selected fraction of make-up air stream to said room-mixing discharge and a second directed fraction of a make-up air stream to said short-circuit discharge;
a controller configured to control the damper to increase the ratio of said first and second selected fractions according to an outside air enthalpy such that energy consumption is minimized.