Abstract:
A portable olfactometer for sensing and measuring odors by sniffing has a barrel which carries selectively different D/T ratios of odorous air to a nose mask and has a selective set of inserts for providing different D/T ratios at the input to the barrel.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to sensing or detecting and measuring odors and in particular is aimed at detecting and measuring odors in the field, i.e., not under laboratory conditions.  
         DESCRIPTION OF THE PRIOR ART  
         [0002]    U.S. Pat. No. 6,018,984 and an earlier U.S. Pat. No. 3,902,851, referenced in the &#39;984 patent, discuss and describe in considerable detail olfactometers for detecting and measuring air polluting odors. These devices are quite sophisticated and are used as laboratory instruments in which the sample odors are fed from a container into the olfactometer in various dilution ratios commonly known as D/T, (“Dilution to Threshold”). In the device described in the &#39;984 patent odorous air is fed to a venturi mixing nozzle through various branches containing solenoid operated valves and different sized orifices for mixing with odor-free air to provide various D/T levels. The prior art also includes a device for field use for detecting and measuring air pollution in the form of a Scentometer manufactured and sold by Barnebey and Sutcliffe Corporation (now Barnebey-Cheney Company). The Scentometer essentially is a rectangular clear plastic box containing two chambers of activated carbon, two nasal outlet ports for sniffing separately into each nostril, two air inlets (one for each activated carbon bed) and six odorous air inlets of different sizes, to provide the various D/T ratios, which are directly connected with a mixing chamber and the nasal outlets. Odorless or odor-free air is obtained by air being drawn through beds of carbon and filtered air is mixed with the odorous air. The Scentometer user follows the generally accepted or standard practice of detecting and measuring the odor by first sniffing with the smallest odorous air inlet opening (lowest D/T ratio) and then successively opening the next largest odorous air inlet until the user or tester finds that an odor is discernible. The size of the opening or orifice for the odor inlet at which the odor is discernible then indicates to the tester the approximate concentration of the odor or the odor level. In the past, conventionally D/T was calculated by dividing the volume of odor free air by the volume of odorous air but more recently, the more sophisticated laboratory instruments calculate D/T by dividing the total air flow volume by the volume of odorous air.  
         SUMMARY OF THE INVENTION  
         [0003]    The present invention utilizes a fairly small lightweight housing suitable to be hand carried so it is convenient to use in the field. The housing contains a hollow tube or barrel open at both ends. One end is the air input end, the other is the air output end. Odorous air, i.e., the ambient polluted air, enters the inlet end and travels down the tube to the outlet end to which is attached a nose mask for directing the air to the sensor or tester&#39;s nostrils when the user inhales. The nose mask also has an outlet opening and there are check valves for the nose mask inlet openings and outlet openings so that the former is open and the latter closed when the user inhales and vice versa. Odorless or odor-free air is obtained from ambient air passing through a multi-media filter and is fed into the housing where it is mixed with the polluted or odorous air at the inlet end of the barrel. In the preferred form a disk having a series of apertures is rotatably attached to the housing at the air inlet end of the barrel with the apertures containing inserts having respectively different sized orifices and thicknesses. The disk is rotated by the user to bring each aperture successively to a position opposite the inlet opening of the barrel and sniffs as necessary to draw the air mixture into the nose mask. The setting at which the odor is discernible gives the D/T ratio. Filtering the ambient air through a multi-media filter instead of through a carbon filter as in the Scentometer provides a more universal and more complete filtering of odors out of the ambient air that is used to mix with the odorous air. Preferably these filters are commercially available devices which can be releasably secured to the housing in some convenient fashion such as snapping or press-fitting or threading them into place. They are suitably sealed to prevent any leakage of any of the polluted air into the odor-free air passageway yet they are attached in some fashion so they can be easily and quickly removed and replaced as necessary. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    [0004]FIG. 1 is a plan view or a side view of a preferred embodiment of the invention;  
         [0005]    [0005]FIG. 2 is an end view;  
         [0006]    [0006]FIG. 3 is a lengthwise partial section view;  
         [0007]    [0007]FIG. 4 is an illustration of a nose mask; and  
         [0008]    [0008]FIG. 5 is a detail diagramatic illustration of various sized orifices used in to obtain the desired D/T ratios in operation of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0009]    Housing  10  is molded out of some suitable material that is fairly light in weight so it is easily carried. Of course it must be made out of material that has characteristics which are such that it is inert to any of the polluting odors that it is used to detect and measure and further, does not produce any odors which could interfere with the readings. The housing has a handle  11  and for reference purposes has an air input end designated generally by reference numeral  12  and an air output end designated generally by reference numeral  13 . The housing contains an elongated rigid hollow tube or barrel  14  which must be made of a material such as Teflon or stainless steel which is inert to any of the odors encountered and which does not produce any of its own odors. At the air output end  13  a nasal mask  15  is removably attached to make air communication with the outlet end of barrel  14 . Nasal mask  15  has an inlet opening  16  in air communication with the outlet end of barrel  14  and an outlet opening  17 . Each of these openings has a check valve  18  and  19 , respectively, (FIG. 4). In use, the operator or tester places the nose mask  15  over his or her nose fairly securely and inhales or sniffs to bring air through barrel  14  into the nasal mask through opening  16 . In conventional fashion check valve  18  opens to permit air to enter into the nose mask and check valve  19  remains closed. When the operator discharges the air from his or her lungs the exhaled air is discharged through opening  17  with check valve  19  opening and check valve  18  remaining closed.  
         [0010]    Rotatably mounted at the input air end  12  of housing  10  in some conventional fashion, such as by a pivot pin  22 , is a disk  23 . Disk  23  has a series of circularly or circumferentially spaced circular apertures  24  which are located so that disk  23  can be rotated about pivot pin  22  to bring each of the apertures  24  directly opposite the air input end of sleeve or barrel  14  so that the aperture is then in air communication with barrel  14 . Disk  23  has a latching feature, not shown, of a conventional nature which can be overridden by the user manually turning the disk. The latching mechanism ensures that each of the apertures  24  when brought into place is located exactly opposite the open input end of barrel  14 . Typically, with no limitation intended, the latching mechanism may constitute a spring-loaded ball which engages an indentation on disk  23 .  
         [0011]    Each of the apertures  24  contains an insert  25  which seals off the aperture against the flow of any air through the aperture except for an orifice or small opening  26  at about the general center of the insert  25 . FIG. 5 illustrates samples of the nature of the respective inserts in the respective apertures. Typically the disk has six different apertures which, along with the thickness of the insert, (as will be explained later) provides six different D/T ratios. This seems to be fairly conventional in order to obtain a fairly accurate reading of the odor. Except for practical limitations the number of apertures on the disk may be a matter of choice.  
         [0012]    [0012]FIG. 3 is a partial section view of the housing to illustrate how the odor-free air enters into the housing in order to be mixed with odorous air to produce the various D/T ratios which are used to obtain a fairly accurate reading of the degree of pollution caused by the odor. A pair of multimedia filter cartridges  30  which are conventionally in disk-like shape, similar to a hockey puck, are suitably mounted in respective recesses  31  in housing  10 . Filter cartridges are conventional and are commercially available. Examples of these are Cartridge S10, PN 7276 by 3M Company and Cartridge GME, PN 492772 by MSA Company. The cartridges  30  might be threaded into place within their respective recesses  31  or may be press-fitted into place or attached in some fashion that will allow them to be removed and replaced as necessary from time to time. In any event, the cartridges  30  are sealed in their recesses such as by “0” rings  32  to prevent any air or gas from entering into the recesses around the outside of the filter cartridges. A pair of radial air passageways  34  in housing  10  allow the filtered air from the filter cartridges  30  to flow radially inward toward the outside of barrel  14  and continue toward the inlet end  12  of barrel  14  along the outside of barrel  14  through an annular passageway  35  coaxial with barrel  14 .  
         [0013]    [0013]FIG. 5 is a functional illustration or diagram to illustrate the manner in which the odor free air is mixed with the odorous air and inputted to the input end of a barrel  14  to produce the respective D/T ratios to arrive at a fairly accurate reading of the degree of odor air pollution. Typically, but with no intent to be limitive, six different D/T ratios generally are used in order to arrive at a fairly accurate reading. Only four examples are shown in FIG. 5 for illustrative purposes. Leftmost illustrates one extreme, i.e., the situation where only odorous air is allowed to enter the input end of barrel  14  and the odor-free air is blocked out which results in a D/T ratio of 0. Orifice  26 A of insert  25 A provides the largest opening for the odorous air and the thickness of insert  25 A is such that it closes off the end of passageway  35  so that no odor-free air is mixed with the odorous air which flows down barrel  14  to nasal mask  15 . The other extreme, not shown, has an insert which has no orifice and is quite thin so only odor-free air and no odor is allowed to enter the nasal mask. In practice, the operator may and usually will use the “no odor” position between each odor presentation in order to refresh the nostrils between each odor test. Rightmost illustrates a high D/T ratio in which orifice  26 D is quite small so that only a small amount of odorous air is allowed to enter the input end of barrel  14 . The insert  25 D is quite thin so that the end of annular passageway  35  is substantially open so that a large amount of odorless air mixes with the odorous air to produce a high D/T ratio. In between are illustrations of intermediate settings for intermediate D/T ratios. The size of orifice  26  and the thickness of insert  25  are directly related; i.e., the larger the orifice opening (to allow more odorous air), the thicker the insert (to reduce the amount of odorless air). Examples of dimensions for the orifice and the insert thickness for each of the desired D/T ratios, no limitation intended, are shown in Table 1 for use with a barrel  14  having an inner diameter of about 0.364 inch and an outer diameter of about 0.540 inch and an annular passageway  35  having an outer diameter of about 0.750 inch with the outside of insert  25  about 0.283 inch from the end of barrel  14 . Naturally, other dimensions can be used to produce the same or different D/T ratios, as desired.  
                               TABLE 1                                   Orifice Size   Insert Thickness   Ratio                           .364   .283   (All Odor)           .300   .180   D/T = 1           .120   .140   D/T = 7           .050   .110   D/T = 100                      
 
         [0014]    Typically, in operation, after doing whatever is necessary to make sure that there are no lingering odors within cartridge or mask  15 , the user with nose mask  15  placed snugly over his or her nose moves or rotates disk  23  so that the aperture containing the smallest orifice  26 , and, correspondingly the thinnest insert  25 , is in position opposite the inlet opening of barrel  14  and sniffs to draw air into the nostrils. The operator normally takes a number of sniffs and exhales each one to make sure that a suitable sample of a mixture of odor-free and odorous air is being inhaled into the nostrils. As explained earlier, the respective checkvalves  18  and  19  respond in the proper manner so that only the mixture is inhaled and the exhaled air goes out the outlet opening and not back into the barrel  14 . In order to assure that the user is inhaling a sufficient volume of mixture of odor-free and odorous air a meter  37  may be attached to the housing and coupled in some fashion to barrel  14  in order to give a visual reading of air flow rate being inhaled. If initially there is no discernible odor, then the operator rotates disk  23  to place the opening or aperture  24  with the next larger orifice and thicker insert opposite the end of barrel  14  and repeats the procedure. This continues on until an odor is discernible to the operator. The setting at which the odor is discernible gives the D/T ratio. Ordinarily the operator repeats the tests over a period of time and then records the results. By providing a correlation between the size of the orifice and the thickness of the insert for each setting the air flow rate down barrel  14  can be kept the same for all settings with differing ratios of odor-free and odorous air. The multimedia filters  30  are much more effective than the carbon filter of the earlier Scentometer because they are able to remove various odor contaminants that were not filtered out by the carbon filters.  
         [0015]    Meter  37  preferably has a dial face, not shown, to give a visual indication to the operator of the air flow rate in barrel  14  to the nasal mask. Suitable tubing  38  attached at one end to meter  37  is connected at the other end to a pressure tap or port  39  on barrel  14 . Preferably the operator inhales and views meter  37  to make sure a prescribed air flow rate is drawn down barrel  14 .