Dry purge desiccator and method

Abstract

My desiccator comprises a plurality of chambers in series communication with each other so a desiccating gas flows from one chamber into an adjacent chamber. A desiccating purge gas is introduced through an inlet into the desiccator's chambers at a predetermined flow rate, and a one-way bleed valve allows gas within the chambers to constantly flow from the desiccator while maintaining a positive pressure within the desiccator. A fan that constantly mixes and circulates the gas between the chambers as the desiccating purge gas is introduced into the desiccator, constantly diluting the gas within the chambers with a fresh supply of the desiccating gas. My method employs my desiccator to store items, wherein a dry, pressurized desiccating gas is introduced into the desiccator's chambers in a manner that constantly circulates the gas between the chambers as gas is slowly bled from the chambers, constantly diluting the gas within the chambers with a fresh supply of the desiccating gas. In my method the dew point of the desiccating gas is from 20 to 90 F, the pressure of the desiccating gas is from 30 to 120 psi, and the average flow rate of the desiccating gas into the desiccator is from 0.25 to 4.0 cubic feet per minute.

Claims

1. A desiccator comprising: a humidity sensor within the desiccator, a plurality of chambers in series communication with each other so a desiccating gas flows from one chamber into an adjacent chamber, an inlet through which the desiccating gas is introduced into said chambers at a predetermined flow rate, a door for each chamber that is manually opened and closed, and a position sensor that detects when said door is opened and closed, a purge controller that regulates the flow rate of the desiccating gas through the inlet and into the chambers, introducing the desiccating gas into the chambers to maintain the chambers at a predetermined humidity, a one-way bleed valve that allows gas within the chambers to constantly flow from the desiccator at a rate that is less than said predetermined flow rate, and a fan that, with the chamber doors closed, constantly circulates the gas between the chambers as the desiccating gas is introduced into the desiccator, constantly diluting the gas within the chambers with a fresh supply of the desiccating gas.

2. The desiccator of claim 1 where the purge controller operates to provide a low positive pressure within the chambers when the doors of the chambers are closed and a high flow rate that inhibits moisture or contaminants from entering the chambers upon opening a door of a chamber or upon detection of the relative humidity exceeding the set point.

3. The desiccator of claim 1 where the fan includes a variable speed control mechanism enabling a user to change the speed of the fan.

Description

DESCRIPTION OF THE DRAWING

(1) Some embodiments of my desiccator and method are discussed in detail in connection with the accompanying drawing, which is for illustrative purposes only. This drawing includes the following figures (Figs.), with like numerals and letters indicating like parts:

(2) FIG. 1A is a schematic illustration of one version of a prior art desiccator.

(3) FIG. 1B is a schematic illustration of a second version of a prior art desiccator.

(4) FIG. 1C is a schematic illustration of my desiccator.

(5) FIG. 1 is a perspective view of one embodiment of my desiccator with top and side panels removed to show the interior of the desiccator.

(6) FIG. 2 is an exploded perspective view of the embodiment of my desiccator shown in FIG. 1.

(7) FIG. 3 is a left side view of the embodiment of my desiccator shown in FIG. 1.

(8) FIG. 4 is a front view, with chamber doors, removed of my desiccator shown in FIG. 1.

(9) FIG. 5 is a right side view of the embodiment of my desiccator shown in FIG. 1.

(10) FIG. 6 is a perspective view of a magnetic door sensor.

(11) FIG. 7 is an end view of a door for the storage chambers of my desiccator shown in FIG. 1.

(12) FIG. 8 is a perspective view of a door for the storage chambers of my desiccator shown in FIG. 1.

(13) FIG. 9 is a top edge view of the door shown in FIG. 8.

(14) FIG. 10 is a front view of the door shown in FIG. 8.

(15) FIG. 11 is a front frame side of my desiccator depicted in FIG. 1 showing its exterior surface.

(16) FIG. 12 is the front frame side depicted in FIG. 11 showing its interior surface.

(17) FIG. 13 is a perspective view of a storage rack used in my desiccator shown in FIG. 1.

(18) FIG. 14 is a perspective view of a fan assembly used in my desiccator shown in FIG. 1.

(19) FIG. 15 is a plan view of the inside of the top panel of my desiccator.

(20) FIG. 16 is a cross-sectional view taken along line 16-16 of FIG. 4.

(21) FIG. 17 is a plan view of the bottom panel of my desiccator.

(22) FIG. 18 is a perspective view of a rear panel of my desiccator, showing its exterior surface.

(23) FIG. 19 is a plan view of the rear panel depicted in FIG. 18, showing its exterior surface.

(24) FIG. 20 is a plan view of the rear panel depicted in FIG. 18, showing its interior surface.

(25) FIG. 20A is an enlarged fragmentary view taken along the line 20A of FIG. 20.

(26) FIG. 21 is a perspective view of a rear panel of my desiccator, showing its interior surface.

(27) FIG. 22 is a plan view of the left side panel of my desiccator, showing its interior surface.

(28) FIG. 22A is an enlarged fragmentary view taken along the line 22A of FIG. 22.

(29) FIG. 23 is a perspective view of a left side panel of my desiccator, showing its interior surface.

(30) FIG. 24 is a plan view of the right side panel of my desiccator, showing its interior surface.

(31) FIG. 24A is an enlarged fragmentary view taken along the line 24A of FIG. 22.

(32) FIG. 25 is a perspective view of a right side panel of my desiccator, showing its interior surface.

(33) FIG. 26 is a graph showing results of performance test of prior art case I.

(34) FIG. 27 is a graph showing results of performance test of prior art case II.

(35) FIG. 28 is a graph showing results of performance test of prior art case III.

(36) FIG. 29 is a graph showing results of performance test of my desiccator case I.

(37) FIG. 30 is a graph showing results of performance test of my desiccator case I.

(38) FIG. 31 is a graph showing results of performance test of my desiccator case II.

(39) FIG. 32 is a graph showing results of a theoretical model of relative humidity dilution.

(40) FIG. 33 is a graph showing results of air circulation performance comparison.

(41) FIG. 34 is a table showing efficiency comparisons of air circulation speeds.

(42) FIG. 35 is a diagram illustrating the control circuit for one embodiment of my desiccator using a 120 volt AC power supply.

(43) FIG. 36 is a diagram illustrating the control circuit for another embodiment of my desiccator using a 12 volt DC power supply.

(44) FIG. 37 shows perspective views of different embodiments of my desiccator, from one embodiment using only one single chamber desiccator, and desiccators using different stacking configurations of desiccators employing multiple chambers.

(45) FIG. 38 is a perspective view of individual component parts used in my desiccator.

DETAILED DESCRIPTION OF SOME ILLUSTRATIVE EMBODIMENTS

(46) General

(47) Figure C illustrates one embodiment of my desiccator 100 comprising a plurality of chambers 1-5 in series communication with each other so gas flows from one chamber into an adjacent chamber. There is an inlet 13 near the top of the chamber 1 through which a desiccating purge gas PG is introduced into the desiccator 100 at a predetermined flow rate. A one-way bleed valve BV allows gas within the chambers to constantly flow from the desiccator 100 at a rate that is less than the predetermined flow rate of purge gas entering the desiccator 100. A fan F constantly mixes and circulates gas between the chambers 1-5 as fresh desiccating purge gas PG is introduced through the inlet 13 into the desiccator 100, constantly diluting the gas within the chambers with a fresh supply of the desiccating purge gas PG.

(48) Each chamber 1-5 has a front door D along the same one side S1 of the desiccator 100. Associated with each front door D is a magnetic door sensor DS that detects when a door D is open and closed. These door sensors DS provide a signal to a purge gas controller 50 (FIG. 35 & FIG. 36) to shut off the fan F to discontinue mixing and circulating the gas upon detecting a door D being opened. A suitable purge gas controller 50 is sold by Terra Universal, Inc. of Fullerton, Calif., under the name DUALPURGE. This purge gas controller 50 also regulates the flow rate of the desiccating gas through the inlet 13 and into the chambers 1-5, introduces enough desiccating gas into the chambers so the chambers are at a predetermined humidity set point, and optionally may provide a low positive pressure within the chambers when the doors D of the chambers are closed and a high positive pressure that inhibits moisture or contaminants from entering the chambers upon opening a door D of a chamber. The fan F is stopped whenever a door D is opened to avoid drawing moist air and contaminants into the desiccator 100.

(49) An elongated plenum chamber PC2 extends vertically lengthwise along a side S2 of the desiccator 100 opposite the side S1 along which the doors D are positioned. The plenum chamber PC2 is in communication with the inlet 13 and has one end in communication with the top storage chamber 1 and another end in communication with the bottom storage chamber 5. A solid wall W of the plenum chamber PC2 forms the rear wall of the chambers 2, 3, and 4, preventing gas in the plenum chamber PC2 from directly entering these chambers from the plenum chamber PC2. The fan F is located in the upper portion of the plenum chamber PC2 and pulls gas from chambers 1-5 through a rear opening O1 in the chamber 1 into the upper end of the plenum chamber PC2 that is in direct communication with the inlet 13 at the top of the plenum chamber PC2. The fan F pushes gas downward along the plenum chamber PC2 and through a rear opening O2 in chamber 5 into this chamber. The chambers 1-4 have perforated floors PF that enable the gas in my desiccator 100 to be pushed upward by the fan F through these perforated floors PF, continually circulating the gas in series through the chambers 1-5 and the plenum chamber PC2.

(50) FIGS. 1 through 25 and FIG. 35

(51) The embodiment depicted in FIGS. 1 through 25 is generally designated by the numeral 200 and, as best shown in FIGS. 1 and 2, the components of the desiccator 200 are assembled together to form the vertically aligned chambers 1-5 and the vertical plenum chamber PC2. These components include a top panel TP, a plenum panel PP, a right panel 19, a left panel 20, a door panel 21, plenum rear access panel 22, and a bottom floor panel FL, all of which are made from stainless steel. A series of spaced apart, perforated shelves 3a positioned between the right panel 19 and left panel 20 form the perforated floors PF of the chambers 1-5. The shelves 3a have fingers 30b (FIG. 16) that fit into slots 30 on the inside surfaces of the right panel 19 and left panel 20 and the plenum panel PP to position these shelves horizontally in a spaced apart relationship. The door panel 21 has rectangular opening O2 therein in which the doors D individually fit into snugly, and these doors D are held in position between a rack R and a door latch strip DLS. Catch lift latches are aligned with door handles DH.

(52) A vertical plenum supports 23 and a horizontal plenum supports 24 retain the side panels 19 and 20, plenum panel PP and plenum rear access panel 22 in position. A fan assembly FA (FIG. 14) is attached to the plenum panel PP, which has a pair of circular openings O3 near its upper end. The fan assembly FA comprises a pair of fans F1 and F2 aligned with openings O3, a housing 10, a cover plate 9, and fan guard 11. Opposed wire racks 15 are respectively attached to the inside surface of the right panel 19 and left panel 20. A pair of tube fittings 14 are inserted in small orifices in the top panel TP. These fittings 14 are connected to the purge gas controller 50 (FIG. 35 & FIG. 36) that controls the flow rate and monitors the pressure within the overall chambers 1-5. The automatic bleed valve BV is inserted into the upper end of the left panel 20, and the door sensors DS are adjacent each closed door D, contacting a door upon closing the door. A humidity sensor HS is in the chamber 1 attached to the inside surface of the right panel 19.

(53) FIG. 35

(54) As FIG. 35 illustrates, 120 volt AC power is provided to the purge gas controller 50 operably connected to the desiccator 200 through a relay. An output from the purge gas controller 50 provides 120 volt AC power to the fan assembly FA. A pressure sensing tube PST connected between the interior of the desiccator 200 and the desiccator 200 signals the purge gas controller 50 when to increase or decrease the rate of flow of purge gas into the desiccator 200 through the fan assembly FA. The relative humidity set-point controller 51 has a line connected to the humidity sensor HS and another line connected to the door sensor DS. A power and communication connecter PCC places the relative humidity set-point controller 51 in communication in communication with the purge gas controller 50. An audio or visual alarm 53 may be used to indicate any malfunction.

(55) FIG. 36

(56) FIG. 36 illustrates, a desiccator 300 where the fan assembly FA is powered by 12 volt DC current and includes a variable speed control that enables a user to change the speed of the individual fans F1 and F2.

(57) FIG. 37

(58) FIG. 37 illustrates various types of multi-chambered desiccators. One embodiment uses only one single chamber desiccator. Other embodiments employ multiple chambers in different stacking configurations.

(59) FIG. 38

(60) FIG. 38 illustrates various component parts used in the above embodiments illustrated.

SCOPE OF THE INVENTION

(61) The above presents a description of the best mode I contemplate of carrying out my desiccator and method and of the manner and process of making and using them, in such full, clear, concise, and exact terms as to enable a person skilled in the art to make and use. My desiccator and method are, however, susceptible to modifications and alternate constructions from the illustrative embodiments discussed above which are fully equivalent. Consequently, it is not the intention to limit my desiccator and method to the particular embodiments disclosed. On the contrary, my intention is to cover all modifications and alternate constructions coming within the spirit and scope of my desiccator and method as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of my invention: