Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-12-23
2001-10-23
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S627000, C340S693500, C340S641000
Reexamination Certificate
active
06307478
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas detection system. More particularly, the present invention relates to a multi-zone gas detection system.
2. Description of the Prior Art
Numerous innovations for gas detectors have been provided in the prior art that will be described. Even though the~se. innovations may be suitable for the specific individual purposes to which they address, however, they differ from the present invention in that they do not teach a multi-zone gas detection system.
FOR EXAMPLE, U.S. Pat. No. 5,280,273 to Goldstein teaches a detector system for sensing the presence of a toxic gas, such as carbon monoxide, and sounding an alarm. The presence of the gas is detected by passing light through a bimetallic sensing material that darkens in the presence of the gas. The system includes a housing containing a light emitter, a light detector and a mechanism for sounding an alarm. The sensing material is contained in a cell, which, together with a battery to power the system, are mounted in a drawer insertable into the housing, which has openings permitting ambient air to reach the sensing material. When fully inserted, the drawer positions the cell between the emitter and detector and brings battery contacts into connection with contacts for the light emitter and alarm. Both the battery and sensing material must be replaced periodically, typically about once every three years. The drawer is configured so that it cannot be inserted without a battery in place. Both the battery and cell are easily replaced in the drawer. A micro porous filter is preferably placed between the cell and ambient air to prevent contamination by large airborne particles.
ANOTHER EXAMPLE, U.S. Pat. No. 5,184,500 to Krema et al. teaches a battery-powered detector that comprises a gas sensor coupled to a current source and a power supply. The power supply generates a relatively high voltage when the gas sensor is warming up and a relatively low voltage after the sensor has warmed up.
The gas sensor, which is responsive to the presence of a gas, is coupled to an amplifier having a variable sensitivity circuit. The amplifier is connected to a microprocessor that determines the concentration of the sensed gas and provides a visual indication of the concentration on a display. The gas detector can sense the presence of a variety of different gases. The gas concentration of the sensed gas is determined based upon the magnitudes of a gas sensing signal generated by the amplifier, a calibration signal generated during a calibration routine, when the detector is in a controlled environment, and an error signal generated when the detector is in a no-gas environment.
STILL ANOTHER EXAMPLE, U.S. Pat. No. 4,219,806 to Enemark teaches a detector of a significant gas condition in the atmosphere that comprises one or more elements for sensing the condition, the elements being connected to an alarm channel which sounds a warning alarm or controls a corrective device such as a gas valve in the event of an excessive atmospheric condition. The detector includes a threshold sensing and alarm amplifying channel, and a trouble sensing electronic valve or stage responsive to failure of one of the sensing elements both to enable operation of a trouble channel to cause the alarm to indicate the failure and also to inhibit operation of the warm channel. The trouble channel may also relay power supply failures such as a decrease in battery voltage.
YET ANOTHER EXAMPLE, U.S. Pat. No. 4,083,226 to Eckstein et al. teaches a portable explosion-proof gas detection device that comprises a housing which defines an interior flameproof motor chamber with an electric motor in the chamber having a power drive shaft which extends outwardly into a pump chamber having a rotor connected to the electric motor shaft. The rotor engages a hose connection which is arranged in an openable chamber and which is engaged by a rotor over a pump squeezing surface defined by the housing surrounding wall. The hose is connected through a twin fitting to a holder for a testing tube which has an opening at each end and is positionable in a tube holder so that its open end is oriented in an opening in the housing for the inflow of air through the tube and through the pump for discharge out of the housing. The apparatus includes a control knob which actuates an electrical control circuit which is magnetically actuable by rotation of the knob to energize the electric motor from a battery source which is also within the housing. The housing includes a cover which includes an end and a top wall portion which, when fitted upwardly, provides an access to the contact tube holder and also to the pump fitting to permit the replacement thereof, if necessary.
FINALLY, STILL YET ANOTHER EXAMPLE, U.S. Pat. No. 4,045,729 to Loh teaches a gas detector for sensing the presence of a gaseous medium consisting of a helical coil for connection to a dc power source for generating both an electromagnetic field and radiant heat. The coil is wrapped around a tubular sleeve constructed of a sensing material, such as a semiconductor, and disposed in the magnetic and heating fields of the coil. An electrode is disposed in the sleeve so that when a current sensing medium is connected between the electrode and one end of the rod, a current will be produced proportionally to the concentration of the gas being detected. In several embodiments, the sleeve is constructed of an n-type semiconductor material, such as zinc oxide, stannic oxide, or gallium oxide and is for detecting hydrocarbons. If the sleeve is constructed of tungsten trioxide or molybdenum mixed with silicon dioxide, the sleeve can be used for detecting hydrogen. The sleeve is generally operated at temperatures between 100 deg. and 450 deg. C. An additional battery can be coupled between the current sensing element and one end of the coil for increasing the sensitivity of the sleeve.
It is apparent that numerous innovations for gas detectors have been provided in the prior art that are adapted to be used. Furthermore, even though these innovations may be suitable for the specific individual purposes to which they address, however, they would not be suitable for the purposes of the present invention as heretofore described.
SUMMARY OF THE INVENTION
ACCORDINGLY, AN OBJECT of the present invention is to provide a multi-zone gas detection system that avoids the disadvantages of the prior art.
ANOTHER OBJECT of the present invention is to provide a multi-zone gas detection system that is simple and inexpensive to manufacture.
STILL ANOTHER OBJECT of the present invention is to provide a multi-zone gas detection system that is simple to use.
BRIEFLY STATED, YET ANOTHER OBJECT of the present invention is to provide a gas detection system for use in multiple zones. The system includes a plurality of gas sensor assemblies, a central control, and an alarm. The alarm includes a plurality of indicator lights that are disposed at the central control, with a respective indicator light being in electrical communication with an associated gas sensor so as to allow the respective indicator light to illuminate when the associated gas sensor detects the gas and provide a visible alarm that is detected from a central location remote from the plurality of gas sensor assemblies, and a sound generator that is disposed at each sensor assembly, with a respective sound generator being in electrical communication with an associated gas sensor so as to allow the respective sound generator to activate when the associated gas sensor detects the gas and provide an audible alarm that is detected at the associated gas sensor. The central control includes an internal test circuit that periodically tests operation of the gas sensors, and if the test fails, activates the alarm, and an internal ventilator circuit that is operatively connected to and turns on a ventilation system in a zone when an associated gas sensor detects the gas.
The novel features which are considered characteristic of the present
Hofsass Jeffery
Previ Daniel
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