Abstract:
A portable apparatus is provided for detecting the presence in a local atmosphere of gases that are hazardous to the health of humans and animals, the detector providing a warning to the operator of the apparatus of the presence of such gases.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 U.S.C. 119(e) and 37 C.F.R. 1.78(a)(4) based upon copending U.S. Provisional Application Ser. No. 60/838,535 for a Portable Gas Detector filed Aug. 11, 2006 the specification of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The apparatus relates to the detection of low molecular weight gases such as natural gas or LP gas etc. which typically are found in common use in the consumer environment such as a dwelling or in the area of a gas appliance. The present device provides a low cost, portable gas detection unit which may be used by unskilled home owners for the detection of improper gas levels in their environment. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present-day consumer is frequently confronted with instances of use of LP gas and natural gas in the home and recreational settings, and frequently the LP gas container may be transported from one location to another wherein the LP gas container is subjected to movement or rolling about or other impacts which may affect the integrity of the gas valve stem and other connections related to the LP gas cylinder. 
         [0004]    While the most frequent instance of natural gas connections in the home is adjacent the gas water heater or gas furnace, LP gas cylinders are increasingly used to provide a gas source for other combustion devices such as grills or gas heaters or gas powered mosquito killing devices. In summary, the present-day consumer is confronted with a greater variety of uses of natural gas which frequently depend on the portable LP gas cylinder in addition to the historically standard uses of the gas water heater and the gas furnace within the home. Therefore, it is increasingly important that a consumer be able to test natural gas and LP gas cylinders for their integrity and to determine whether or not leakage might be occurring. This issue is particularly important with LP gas cylinders which are refillable and transportable. LP gas cylinders, as mentioned above, are subject to conditions in which impacts against the gas regulator or gas valve stem can occur resulting in the potential for leakage of the gas cylinder. Also, as LP gas cylinders may be used over a long period of time and frequently refilled, the quality or integrity of the seal of the stem and/or shut off valve on the LP gas cylinder should be checked to determine whether the cylinder continues to be leak free over time. 
         [0005]    With respect to gas heaters and furnaces and other natural gas fittings within the home, such as those leading to a gas stove, the consumer may believe that they detect the smell of the odorant used in natural gas or LP gas thus becoming concerned about the safety of their in-home natural gas circumstances. 
         [0006]    In each of these situations, it would be of benefit if the consumer were able to personally and immediately check the integrity of the seal on these gas fittings and devices without incurring the delay or expense of contacting a plumber or a gas service person to examine the fittings and devices within the home. 
         [0007]    It also would be a benefit if a consumer were able to check the seal and the stem and valve condition of an LP gas tank prior to transporting the tank within a closed vehicle. Frequently, a portable LP gas tank must be transported, either for use of the gas tank or for refilling of the gas tank, within a closed vehicle, and the consumer may become subject to olfactory fatigue and be unable to detect the presence of leaking gas within such a confined space. Therefore, the availability of an easily used and portable gas detector would benefit the consumer in these situations. 
       SUMMARY OF THE INVENTION 
       [0008]    A portable noxious gas detector is provided for detecting noxious gasses and gas mixtures including natural gas (predominately methane and ethane), butane, propane, acetylene and methane gasses. The detector shows a safe condition when the concentration of any noxious gas detected is less than 2000 ppm. A low level gas warning is shown when any noxious gas is detected that is less than 5000 ppm. When a noxious gas concentration is over 5000 ppm, or exceeds 10% of the Lower Explosive Limit (LEL) for the gas, a red alarm condition is shown by the detector. The total range of gas detection for portable gas detector  10  is 0 to 10,000 ppm. The device is operable in a temperature range of minus 14 degrees Fahrenheit to 122 degrees Fahrenheit (minus 10 degrees C.-50 degrees C.). 
         [0009]    The foregoing and other objects are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. Various features and subcombinations of invention may be employed without reference to other features and subcombinations. Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    Preferred embodiments of the invention, illustrative of the best modes in which the applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
           [0011]      FIG. 1  is a top and front and right side perspective view of the gas detector; 
           [0012]      FIG. 2  is a right side view of the embodiment of  FIG. 1 ; 
           [0013]      FIG. 3  is a front view of the embodiment of  FIG. 1 ; 
           [0014]      FIG. 4  is a top view of the embodiment of  FIG. 1 ; 
           [0015]      FIG. 5  is a rear elevation view of the embodiment of  FIG. 1 ; 
           [0016]      FIG. 6  is a left side view of the embodiment of  FIG. 1 ; 
           [0017]      FIG. 7  is a bottom view of the embodiment of  FIG. 1 ; 
           [0018]      FIG. 8  is an exploded view of the embodiment of  FIG. 1 ; 
           [0019]      FIG. 9  is a top and front and right side perspective view of the embodiment of  FIG. 1  having a protective cap placed over the end of the detector; 
           [0020]      FIG. 10  is a right side view of the embodiment of  FIG. 1  having a protective cap placed over the end of the detector; and 
           [0021]      FIG. 11  is a front view of the embodiment of  FIG. 1  having a protective cap placed over the end of the detector. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0023]    Referring now to  FIG. 8 , the detector  10  is shown in exploded view and is comprised of the following components. Detector  10  is provided with off/on switch  12  which is seated within top housing portion  14 . The user, by depressing off/on switch  12 , allows the detection circuits  26  within detector  10  to be powered by batteries  16 , which in the preferred embodiment of the present invention, comprise two AAA batteries. Detector  10  is provided with grip  18   a  connected to top housing portion  14 , and grip  18   b  connected to bottom housing portion  20 . Housing portions  14  and  20  are press fitted together and secured together by a screw passing through screw mount  22 . Batteries  16  are held within space provided between top housing  14  and bottom housing  20  by battery cover  24 . Also secured between top housing  14  and bottom housing  20  is circuit board  26  having detector unit  28  thereon. Intake nozzle  30  is seated within a top portion of top housing  14  and bottom housing  20 . It will be appreciated by examination of  FIG. 5  that top housing  14  and bottom housing  20  are comprised of a handle portion  32  and a wand portion  34 , the handle portion  32  being grasped by the user while manipulating the device and wand portion  34  being directed by the user toward the area of interest for detecting a noxious gas emission in a local atmosphere. 
       Preparation of Device for Use 
       [0024]    The portable gas detector  10  is available for immediate use once power is provided to the device and short warm-up period is provided for the sensor. To install batteries or to change out batteries, the user removes battery cover  24  by unscrewing a screw fastener  26  ( FIG. 7 ) that holds battery cover  24  in place between top housing  14  and bottom housing  20 . The user then removes battery cover  24  to expose the battery chamber  17  which is a void created by the coupling together of top housing portion  14  and bottom housing portion  20 . The user then inserts two AAA batteries (1.5 volts each) and secures battery cover  24  in place by use of a screw  26  or by a press fit or frictional fit of cover  24  with top housing portion  14  and bottom housing portion  20  to hold the inserted batteries within handle portion  32  of portable gas detector  10 . 
       Operation 
       [0025]    To operate detector  10  a user removes cap  45  ( FIG. 9 ) turns on detector  10  by depressing off/on switch  12  and holding detector  10  in the vicinity of the local atmosphere to be tested for the presence of noxious gasses. A portion of the local atmosphere enters detector  10  through slits  37  ( FIG. 8 ) in wand portion  34  of detector  10 . 
         [0026]    Portable gas detector  10  is provided with LED signal display  36  ( FIG. 8 ) which is comprised of green LED signal  38  and yellow LED signal  40  and red LED signal  42  ( FIG. 3 ). Green LED  38  serves the purpose of showing that power is being provided to the detector and that the device is on and operational. Green LED  38  also shows a safe condition and is lit when a concentration of any noxious gas detected is at a range of less than 2000 ppm. Portable gas detector  10  also is provided with a yellow LED which is the low level gas warning detection alarm. Yellow LED  40  is activated and glows yellow when any noxious gas is detected that is less than 5000 ppm. When the yellow detector is activated, the consumer should be aware that extraneous noxious gas is present in the local atmosphere and further investigation is necessary. Portable gas detector  10  further is provided with red LED  42  which represents the noxious gas high alarm condition. Red LED  42  glows when the gas concentration detected is over 5000 ppm or exceeds 10% of the Lower Explosive Limit (LEL) for any detectable noxious gas. The user, upon observing a red LED glowing or a high alarm condition, should become immediately concerned and contact an appropriate repair or service person to examine the problem. The user should ventilate the area, if possible, and/or evacuate the area where the noxious gas is detected. 
         [0027]    The total range of gas detection of portable gas detector  10  is 0 to 10,000 ppm. The device is operable in a temperature range of minus 14 degrees Fahrenheit to 122 degrees Fahrenheit (minus 10 degrees C.-50 degrees C.). The detector of the present device is sensitive to the noxious gases comprising: natural gas (predominately methane and ethane), butane, propane, acetylene and methane gasses. At the conclusion of use of the device, the off/on switch  12  should be released to terminate powering of the circuit board and detector. The device is then placed in storage at a convenient location for its next use. 
         [0028]    The detector uses a semiconductor gas sensor that is designed for detection of flammable gas. As the concentration of gas increases the resistance of the sensor changes. The change in resistance is then electronically detected. A detected change in the resistance of the sensor indicates the presence of a flammable gas in the local atmosphere. The amount of detected change in the resistance of the sensor indicates the concentration of flammable gas that is present. 
         [0029]    In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the inventions is by way of example, and the scope of the inventions is not limited to the exact details shown or described. 
         [0030]    Certain changes may be made in embodying the above invention, and in the construction thereof, without departing from the spirit and scope of the invention. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not meant in a limiting sense. 
         [0031]    Having now described the features, discoveries and principles of the invention, the manner in which the inventive Portable Gas Detector is constructed and used, the characteristics of the construction, and advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims. 
         [0032]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.