Filter for humidity control, typically for control of humidity in a bulk liquid tank

Abstract

A filter is includes a housing and at least first and second adsorbent materials within the housing. The second adsorbent material has different characteristic from the first adsorbent material and is in series with the first adsorbent material. When assembled, a labyrinth arrangement is located between a first port in the housing and the first adsorbent material such that gas travels between the first port and the first adsorbent material by passing through the labyrinth arrangement. A filtration system and methods for humidity control of a liquid tank head space uses a filter, including first and second adsorbent and a diffusion channel or labyrinth arrangement

1 . A filter for use with a moisture sensitive container; the filter comprising:
 (a) a housing assembly having a first port and a second port;   (b) at least a first adsorbent material within the housing;   (c) at least a second adsorbent material within the housing assembly and layered in series with the first adsorbent material; the second adsorbent material having a characteristic different from the first adsorbent material;
 (i) the first adsorbent material and the second adsorbent material arranged within the housing assembly so that gas travels between the first port and second port by passing through each of the first adsorbent material and the second adsorbent material; and 
   (d) a labyrinth arrangement in fluid communication with the first port and being between the first port and the first adsorbent material; the labyrinth arrangement being located such that gas travels between the first port and the first adsorbent material by flowing through the labyrinth arrangement.   
     
     
         2 . A filter according to  claim 1  wherein:
 (a) the first adsorbent material is between the labyrinth arrangement and the second adsorbent material; 
 (b) the second adsorbent material is between the first adsorbent material and the second port; and 
 (c) the first adsorbent material adsorbs a greater amount of moisture at a first relative humidity than the second adsorbent material adsorbs at the first relative humidity. 
 
     
     
         3 . A filter according to  claim 2  wherein:
 (a) the second adsorbent material adsorbs a greater amount of moisture at a second relative humidity than the first adsorbent material adsorbs at the second relative humidity. 
 
     
     
         4 . A filter according to  claim 3  wherein:
 (a) the second adsorbent material changes in color in response to a predetermined level of adsorption. 
 
     
     
         5 .- 9 . (canceled) 
     
     
         10 . A filter according to  claim 1  wherein:
 (a) the labyrinth arrangement forms a channel between the first port and an aperture; and 
 (b) an L/D ratio is at least 50, wherein L is a length of the channel and D is an equivalent channel diameter, in which:
 A=channel width X channel height; and 
 D=square root of (4/pi X A). 
 
 
     
     
         11 .- 12 . (canceled) 
     
     
         13 . A filtration system for humidity control of a fluid tank headspace comprising:
 (a) a fluid tank configured to hold a liquid therein and a headspace between the liquid and a surface of the tank; and   (b) a filter in fluid communication with the headspace of the tank; the filter including
 (i) a housing assembly having a first port in communication with atmosphere; and a second port in communication with the headspace of the fluid tank; 
 (ii) at least a first adsorbent material within the housing assembly; 
 (iii) at least a second adsorbent material within the housing assembly and layered in series with the first adsorbent material; the second adsorbent material having a characteristic different from the first adsorbent material;
 (A) the first adsorbent material and the second adsorbent material arranged within the housing assembly so that gas travels between the first port and second port by passing through each of the first adsorbent material and the second adsorbent material; and 
 
 (iv) a labyrinth arrangement in fluid communication with the first port and being between the first port and the first adsorbent material; the labyrinth arrangement being located such that gas travels between the first port and the first adsorbent material by passing through the labyrinth arrangement; 
   
       wherein, when liquid in the fluid tank drops, gas is drawn in through the first port, the labyrinth arrangement, the first adsorbent material, the second adsorbent material, and then through the second port to flow into the headspace of the fluid tank; and, when liquid in the tank rises, air is forced from the headspace, through the second port, the second adsorbent material, the first adsorbent material, the labyrinth arrangement, and then exits through the first port to the atmosphere. 
     
     
         14 .- 20 . (canceled) 
     
     
         21 . A filter cartridge for use in a filter assembly; the filter cartridge comprising:
 (a) a cartridge shell including a surrounding wall and a top cover; the shell defining a cartridge interior;
 (i) the top cover having a gas opening covered with a penetrable boundary; 
   (b) at least a first adsorbent material within the cartridge interior;   (c) at least a second adsorbent material within the cartridge interior and layered in series with the first adsorbent material; the second adsorbent material having a characteristic different from the first adsorbent material; and
 (i) the first adsorbent material and the second adsorbent material arranged within the cartridge interior so that gas travels through the cartridge by passing through each of the first adsorbent material and the second adsorbent material. 
   
     
     
         22 . A filter cartridge according to  claim 21  wherein the penetrable boundary includes a penetrable film covering the gas opening. 
     
     
         23 . A filter cartridge according to  claim 21  wherein:
 (a) the top cover, in cross-section viewed in a direction perpendicular to a direction in which the first and second adsorbent materials are arranged, includes a plurality of alternating recesses and segments along the gas opening boundary. 
 
     
     
         24 . A filter cartridge according to  claim 23  wherein:
 (a) the alternating segments are configured to mate with a detachable end piece. 
 
     
     
         25 . A filter cartridge according to  claim 23  wherein:
 (a) the second adsorbent material characteristic includes at least one of particle size, adsorbent capacity, and/or specific surface area. 
 
     
     
         26 . A filter cartridge according to  claim 21  wherein:
 (a) the first adsorbent material adsorbs a greater amount of moisture at a higher relative humidity than the second adsorbent material. 
 
     
     
         27 . A filter cartridge according to  claim 21  wherein:
 (a) the second adsorbent material changes in color in response to a predetermined level of adsorption. 
 
     
     
         28 . A filter cartridge according to  claim 21  further comprising:
 (a) a labyrinth arrangement secured to the top cover; the labyrinth arrangement forming a channel in communication with and ending at the gas opening. 
 
     
     
         29 . A filter cartridge according to  claim 28  wherein:
 (a) the labyrinth arrangement comprises a wall forming a spiral channel ending at the gas opening. 
 
     
     
         30 . An end cap for use with a filter assembly; the end cap comprising:
 (a) an outer wall defining a first port;   (b) a labyrinth arrangement within the outer wall; the labyrinth arrangement forming a channel between the first port and an aperture;
 (i) the aperture having a border defined by a labyrinth wall; the aperture border having a height greater than a height of the labyrinth arrangement; the aperture border including a plurality of spaced projections; 
   (c) a closed top end; and   (d) an open bottom end in communication with the channel formed by the labyrinth arrangement.   
     
     
         31 . An end cap according to  claim 30  wherein:
 (a) the labyrinth arrangement comprises a wall in the end cap forming a tortuous path between the first port to the aperture; and 
 (b) the wall in the first end cap forms a spiral channel between the first port and the aperture. 
 
     
     
         32 . An end cap according to  claim 30  wherein:
 (a) an L/D ratio is at least 50, wherein L is a length of the channel and D is an equivalent channel diameter, in which:
 A=channel width X channel height; and 
 D=square root of (4/pi X A). 
 
 
     
     
         33 . An end cap according to  claim 32  wherein:
 (a) the L/D ratio is no greater than 380. 
 
     
     
         34 . An end cap according to  claim 32  wherein:
 (a) the L/D ratio is about 150. 
 
     
     
         35 . (canceled)