Apparatus and method for monitoring and recording fumigant concentrations in chamber fumigation

Claim 1

Apparatus for monitoring and recording the fumigant concentration within a closed chamber containing a gaseous airfumigant mixture and the product to be fumigated comprising the combination of: a. a substantially airtight chamber containing air and a predetermined amount of gaseous fumigant, a plurality of tubes within said chamber having open terminal intake ends at different levels within said chamber and discharge ends outside said chamber, b. a thermal conductivity device separate from and outside said chamber including an electrically actuated thermal conductivity detector in an electrical circuit variably responsive to and in accordance with differences in the fumigant concentration in said air-fumigant mixture when said mixture is brought into contact therewith for indicating the degree of such concentration, and an electrically actuated recorder in said circuit-actuatable in accordance with variations in said circuit for graphically recording said concentration and variations thereof, c. a single conduit outside said chamber having an intake end and a discharge end, and connecting means for connecting the discharge ends of said tubes with said intake end of said conduit, d. said connecting means including timer-controlled valve means for automatically opening each tube to flow of the air-fumigant mixture therethrough to the intake end of said single conduit for a uniform period of time in a predetermined order in successive cycles and for automatically closing each tube to said flow at the end of each such period of time and holding it closed until opened and closed in the next cycle, and a timer operatively connected with said valve means for actuating the latter, e. continuously actuated mixture-moving means in said single conduit for moving the air-fumigant mixture from its inlet end to its discharge end at a uniform rate, f. said thermal conductivity device being within said single conduit in a position for continuous contact with the air fumigant mixture moved through said single conduit whereby the degree of fumigant concentration withdrawn from each of said levels will be graphically recorded by said recorder.

Claim 8

The method of monitoring the fumigant concentration in an air-fumigant mixture within an enclosed essentially air-tight chamber containing air and the product to be fumigated, comprising the steps of: a. circulating a predetermined amount of a gaseous fumigant in air within said chamber to provide an air-fumigant mixture, and at the same time in a plurality of successive cycles; b. successively withdrawing from said chamber, in a predetermined order, and from each of a predetermined number of different levels within said chamber along separate, enclosed paths extending to points outside said chamber, a uniform amount of said air-fumigant mixture during a uniform period of time for each such withdrawal; c. moving each succession of the air-fumigant mixture so withdrawn along the same single enclosed path extending substantially from said points to a discharge location, and discharging it from said location; d. continuously measuring at a measuring station along said single path the degree of concentration of the fumigant in the air-fumigant mixture of each succession so moved along said single path to said location, and at the same time; e. continuously, permanently, graphically recording variations in the air-fumigant concentration by a force responsive for movement by and in accordance with said variations during said continuous movement of each succession of said air-fumigant mixture past said measuring station; f. closing each of said separate paths to withdrawal of said air-fumigant mixture outside said chamber at each of said points at the end of each withdrawal from each of said levels in each cycle, and purging only said single path between said measuring station and said points of said air-fumigant mixture to said points, and after each purging recommencing said cycle of withdrawals.

Claim 9

The method of monitoring the fumigant concentration in an air-fumigant mixture within an enclosed essentially air-tight chamber containing air and the product to be fumigated, comprising the steps of: a. circulating a predetermined amount of a gaseous fumigant in air within said chamber to provide an air-fumigant mixture, and at the same time in a plurality of successive cycles; b. successively withdrawing from said chamber, in a predetermined order, and from each of a predetermined number of different levels within said chamber along separate, enclosed paths extending to points outside said chamber, a uniform amount of said air-fumigant mixture during a uniform period of time for each such withdrawal; c. moving each succession of the air-fumigant mixture so withdrawn along the same single enclosed path extending substantially from said points to a discharge location, and discharging it from said location; d. continuously measuring at a measuring station along said single path the degree of concentration of the fumigant in the air-fumigant mixture of each succession so moved along said single path to said location, and at the same time; e. continuously, permanently, graphically recording variations in the air-fumigant concentration by a force responsive for movement by and in accordance with said variations during said continuous movement of each succession of said air-fumigant mixture past said measuring station; f. closing each of said separate paths to withdrawal of said air-fumigant mixture outside said chamber at each of said points at the end of each withdrawal from each of said levels in each cycle, and purging only said single path between said measuring station and said points of said air-fumigant mixture to said points, and after each purging recommencing said cycle of withdrawals.