Patent Application
20060213508
The present invention relates generally to humidification systems and, more particularly, to a humidification system for use in an environmental chamber to control the relative humidity within the environmental chamber during testing of products within the chamber.
Environmental chambers are designed to provide accurate environmental control of temperature and relative humidity within the chamber for use in ICH pharmaceutical stability testing, genetic studies, chromatography tests, tissue culture studies and other research and development applications such as shelf life tests and packaging, paper products or electronic component breakdown, for example. Environmental chambers typically include a heating and refrigeration control system to control the temperature within the enclosed internal chamber and a humidification system to control the relative humidity within the chamber. The products placed within the enclosed chamber are subjected to a predetermined temperature and relative humidity over a period of time to determine the reaction of the product and/or its packaging to prolonged exposure to various temperature and relative humidity ranges.
In the past, environmental chambers have controlled the relative humidity within the chamber through humidification systems incorporating water spray nozzles or atomizers for example. The spray nozzles or atomizers are designed to inject water droplets into the air flow path of the chamber in which the water droplets are mixed with forced air generated from air outside of the enclosed chamber. The mixture of the water droplets and forced air produce a moist air that is introduced into the enclosed chamber to thereby control the relative humidity within the chamber.
Conventional spray nozzles and atomizers used in known environmental chambers typically form water droplets that are not uniform in size so that both smaller and larger water droplets are mixed with the forced air introduced into the enclosed chamber. The larger water droplets are not readily absorbed by the air within the chamber so that it is oftentimes difficult to precisely and reliably control the relative humidity within the chamber at a predetermined relative humidity set-point. Also, the larger droplets have a tendency to accumulate on the walls of the enclosed chamber and eventually the droplets form a puddle of water on the floor of the chamber which is undesirable.
Therefore, there is a need for an environmental chamber having a humidification system that provides for precise and reliable control of the relative humidity within the chamber.
There is also a need for an environmental chamber having a humidification system that provides for efficient humidification of the chamber air without causing undesirable accumulation of water droplets within the chamber.
The present invention overcomes the foregoing and other shortcomings and drawbacks of environmental chambers and humidification systems for humidifying the chamber air heretofore known. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention.
In accordance with the principles of the present invention, an environmental chamber having an enclosed internal chamber is provided with a humidification system in the form of an ultrasonic nebulizer assembly. In one embodiment, the ultrasonic nebulizer assembly is connected in closed-loop fluid communication with the enclosed chamber so that a closed-loop air flow path is provided between the ultrasonic nebulizer assembly and the enclosed chamber. The ultrasonic nebulizer assembly is configured to generate water vapor, preferably having water droplets in the micron range, and introduce the water vapor into the enclosed chamber for controlling the relative humidity within the chamber.
The ultrasonic nebulizer assembly of the present invention includes an enclosed water reservoir in which water is introduced and maintained under float control. The ultrasonic nebulizer assembly also includes a replaceable ultrasonic nebulizer module that is configured to be immersed in the water within the enclosed reservoir. The ultrasonic nebulizer module includes an ultrasonic nebulizer and its associated electrical circuitry that are encapsulated in an electrically insulative and water-proof potting compound. The ultrasonic nebulizer is selectively energized by a power supply to generate the water vapor that is introduced into the enclosed chamber.
In one embodiment, an environmentally protected fan is mounted within the enclosed reservoir of the ultrasonic nebulizer assembly and is selectively energized by the same power supply that energizes the ultrasonic nebulizer module. The fan draws air from the enclosed chamber and forces the drawn air into contact with the water vapor within the enclosed reservoir. The water vapor is carried by the forced air and introduced into the enclosed chamber. The fan allows for pressurization of the humidified area in the enclosed reservoir for recirculating and humidifying the atmosphere of the enclosed chamber when there is a demand for relative humidity.
According to another aspect of the present invention, a breakwall is provided in the enclosed reservoir that effectively separates the enclosed reservoir into a float section and a nebulizing section. A float control switch is positioned within the float section and the ultrasonic nebulizer module is positioned in the nebulizing section. The breakwall functions to isolate the float switch from the water turbulence generated by the ultrasonic nebulizing module to minimize undesirable bouncing of the float switch.
A baffle member is mounted in the enclosed reservoir so that it faces the ultrasonic nebulizing module. When the ultrasonic nebulizer module is operating, a water spout is created directly above the ultrasonic nebulizer. The baffle member is configured to contain the water spout so that larger droplets are redirected back into the reservoir while allowing the forced air to carry only the atomized water vapor into the enclosed chamber. The baffle member also prevents water droplets formed in the water spout above the ultrasonic nebulizer from splashing onto the environmentally protected fan.
According to another aspect of the prevent invention, the environmental chamber includes a relative humidity controller to control the relative humidity within the enclosed chamber. The relative humidity controller is electrically coupled to the power supply that energizes both the ultrasonic nebulizer and the fan. When the relative humidity controller determines there is a demand for relative humidity, the power supply is turned “ON” to simultaneously energize both the ultrasonic nebulizer and the fan. The fan is turned “ON” and “OFF” at the same time the ultrasonic nebulizer is turned “ON” and “OFF” so that water vapor is not introduced into the enclosed chamber when there is no demand for relative humidity.
The environmental chamber of the present invention includes a nebulizer hour timer to monitor the length of time that the ultrasonic nebulizer is operating. The timer increments in hours and tenths of an hour when the ultrasonic nebulizer is operating so that the timer is independent of the run time of the environmental chamber. The timer includes an hour-accumulator display to provide the user with a precise indication of how much life is left in the ultrasonic nebulizer module before it needs to be replaced. A timer reset micro-switch is provided to reset the nebulizer hour timer following replacement of the ultrasonic nebulizer module.
According to yet another aspect of the present invention, the ultrasonic nebulizer assembly is connected to a source of water and a common drain through flexible tubing. The free ends of the flexible tubing are provided with quick disconnect fittings that are accessible by the user at the rear of the environmental chamber. The quick disconnect fittings are actuatable by one hand of the user and automatically close to prevent leakage from the ultrasonic nebulizer assembly when the flexible tubing is disconnected from the enclosed water reservoir.
The environmental chamber and ultrasonic nebulizer assembly of present invention provide for precise and reliable control of the relative humidity within the chamber. The environmental chamber and ultrasonic nebulizer assembly of present invention also provide for efficient humidification of the chamber air without causing undesirable accumulation of water droplets within the chamber.
The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
Referring to the figures, and to
According to one aspect of the present invention, the environmental chamber 10 includes a lower chamber section 16 having an enclosed internal chamber 18 (
As shown diagrammatically in
As will be readily understood by those of ordinary skill in the art, the heating and refrigeration control systems include heating elements (not shown), a condenser (not shown) and an evaporator coil (not shown) that are operable to control the temperature within the enclosed chamber 18, such as temperatures ranging from about 0° C. to about 50° C. by way of example. The dehumidification control system includes a dehumidification coil (not shown) that condenses moist air within the enclosed chamber 18 so as to maintain the humidity within the chamber 18 at or below ambient conditions. The condensate is drained out of the chamber 18 through a drain pan (not shown) that is connected by flexible tubing 36 to a common drain 38 (
In accordance with the principles of the present invention, the relative humidity (RH) within the enclosed chamber 18 is controlled by a humidification system in the form of an ultrasonic nebulizer assembly 40 that is connected in fluid communication with the enclosed chamber 18 as will be described in greater detail below. As shown in
Referring now to
In one embodiment of the present invention, the ultrasonic nebulizer assembly 40 is connected in closed-loop fluid communication with the enclosed chamber 18 so that a closed-loop air flow path is provided between the ultrasonic nebulizer assembly 40 and the enclosed chamber 18. As shown in
Further referring to
The tubular extensions 72a, 72b are connected to the respective upper sections 68a, 68b of the tubes 64a, 64b through a pair of generally J-shaped hoses 80. In one embodiment, the pair of hoses 80 are made of vinyl although other materials are possible as well. The hoses 80 are fitted over the respective tubular sections 72a, 72b and tubes 64a, 64b and are secured thereto by hose clamps 82. The tube 64a functions as an air intake from the enclosed chamber 18 through which air is drawn from the enclosed chamber 18 and introduced into the ultrasonic nebulizer assembly 40 through the inlet 74. The tube 64b functions as an air exhaust through which water vapor 42 from the ultrasonic nebulizer assembly 40 is introduced into the enclosed chamber 18 from the outlet 76. Of course, other configurations, locations and connections of the ultrasonic nebulizer assembly 40 are possible as well without departing from the spirit and scope of the present invention.
Referring to
The level of the water 46 within the main water reservoir 48 is controlled by a pivotal float switch 98 that extends into the main water reservoir 48 and is electrically coupled to the water inlet valve 86. When the water level within the main water reservoir 48 falls below a predetermined level, the falling float switch 98 causes the water inlet valve 86 to open so that water is introduced into the main water reservoir 48 through the flexible tubing 96. When the predetermined water level is reached, the rising float switch 98 causes the water inlet valve 86 to close. In this way, the level of water within the main water reservoir 48 is accurately maintained at or near a predetermined level.
Further referring to
In one embodiment, the water fill/drain port 94 and the water overflow port 100 are accessible by the user at the rear of the environmental chamber 10. The free ends of the flexible tubing 96 and 102 are each provided with a 90° elbow fitting 104 and the water fill/drain port 94 and the water overflow port 100 are each provided with a quick disconnect fitting 106 and 108, respectively. The quick disconnect fittings 106 and 108 are actuatable by one hand of the user and automatically close to prevent water leakage from the main water reservoir 48 when the flexible tubing 96 and 102 are disconnected from the water inlet/drain port 94 and water overflow port 100. One suitable quick disconnect fitting for use in the present invention is commercially available from Industrial Specialties of Englewood, Colo. and designated Part No. CPC-C1-S-A31-PP. One suitable elbow fitting for use in the present invention is commercially available from Colder Products of St. Paul, Minn. and designated Part No. PMC2104. Of course, other commercially available quick disconnect and elbow fittings, as well as other types and configurations of fittings, are possible as well.
In accordance with the principles of the present invention, the ultrasonic nebulizer assembly 40 includes a replaceable ultrasonic nebulizer module 110 that is configured to be immersed in the water 46 within the main water reservoir 48. As will be described in greater detail below, the ultrasonic nebulizer module 110 is operable to generate the water vapor 42 (
In one embodiment, as shown in
During assembly of the ultrasonic nebulizer module 110, the ultrasonic nebulizer 114 and its associated printed circuit board 120 are mounted within the tray 112 through fasteners 124 (
The oscillating disk 116 is temporarily covered with foil (not shown) or other barrier material while an electrically insulative and water-proof potting compound 134 is poured into the tray 112 to encapsulate the ultrasonic nebulizer housing 118 and the associated printed circuit board 120. The potting compound 134 may be a urethane, silicone, epoxy or other suitable material that does not expand, contract or heat up excessively during its setting or curing stage. Following the potting process to encapsulate the housing 118 and printed circuit board 120, the foil (not shown) is removed so that the disk 116 and a top 136 of the ultrasonic nebulizer housing 118 are exposed as shown in
As shown in
Referring to
In one embodiment as shown in
The float control switch 98 is positioned within the float section 148 and the ultrasonic nebulizer module 110 is positioned within the nebulizer section 150. The gaps 152 permit a constant water level to be maintained within the float and nebulizer sections 148, 150 while the breakwall 146 functions to isolate the float switch 98 from the water turbulence generated by the ultrasonic nebulizer 114 when it is operating. Without the breakwall 146, the water turbulence generated by the ultrasonic nebulizer 114 could cause the float switch 98 to “bounce” while near the fill level, and this could cause rapid activation-deactivation or “chatter” of the water inlet valve or solenoid 86 which is undesirable. The breakwall 146 minimizes this bouncing effect by effectively separating the turbulent nebulizer section 150 from the non-turbulent float section 148. This allows the float switch 98 to be mounted in close proximity to the ultrasonic nebulizer module 110 without undesirable bouncing of the float switch 98 during operation of the ultrasonic nebulizer 114.
In accordance with another aspect of the present invention, an environmentally protected fan 156 is mounted within the enclosed reservoir 44 to draw air from the enclosed chamber 18 through the air intake tube 64a. The fan 156 forces this drawn air into contact with the water vapor 42 within the enclosed reservoir 44 so that the water vapor 42 is carried by the forced air and introduced into the enclosed chamber 18 through the air exhaust tube 64b. The fan 156 allows for pressurization of the humidified area in the enclosed reservoir 44 for recirculating and humidifying the atmosphere of the enclosed chamber 18 when there is an RH demand (i.e., the ultrasonic nebulizer 114 is “ON”). The air intake and air exhaust tubes 64a and 64b are positioned within the enclosed chamber 18 to prevent pressurization and subsequent air flow into the enclosed chamber 18 when RH is not required (i.e., the ultrasonic nebulizer 114 is “OFF”). When the ultrasonic nebulizer 114 is in its “OFF” state, the air flow across the ultrasonic nebulizer assembly 40 is negligible thereby preventing further humidification of the enclosed chamber 18 when RH is not required.
In one embodiment, the fan 156 is mounted within the enclosed reservoir 44 below the inlet 74 and above the level of water 46 so that its axis of rotation is generally aligned with the axis of the inlet 74. Of course, other orientations and locations of the fan 156, and other types of forced air devices, are possible as well. One suitable environmentally protected fan 156 for use in the present invention is commercially available from Comair Rotron of San Diego, Calif. and designated Model No. SU2B-E1, although other commercially available fans are possible as well. The fan 156 is turned “ON” only when the ultrasonic nebulizer module 114 is turned “ON” by the power supply 144 as will be described in greater detail below.
In accordance with another aspect of the present invention as shown in
Referring now to
Further referring to
As shown in
According to another aspect of the present invention, a nebulizer hour timer 178 is provided to monitor the length of time that the ultrasonic nebulizer 114 is operating. The timer 178 is energized by the power supply 144 only when the power supply 144 is turned “ON” by the RH PID controller 168 to simultaneously energize the fan 156 and the ultrasonic nebulizer 114. The timer 178 increments in seconds and fractions of a second only when the ultrasonic nebulizer 114 is operating so that the timer 178 is independent of the run time of the environmental chamber 10. The timer 178 includes a battery-operated hour-accumulator display to provide the user with a precise indication of how much life is left in the ultrasonic nebulizer module 110 before it needs to be replaced as described in detail below. Without a true indicator of the operational running time of the ultrasonic nebulizer 114, a user could conceivably miss the recommended replacement time of the ultrasonic nebulizer, such as 5,000 hours for example, and the environmental chamber 10 could stop humidifying without any forewarning. For drug stability testing for example, the unexpected stoppage of humidification could be very costly.
When the recommended life of the ultrasonic nebulizer 114 has been reached, the ultrasonic nebulizer module 110 is designed to be easily replaced by the user. To this end, the user removes the top cover 22 of the environmental chamber 10 to expose the ultrasonic nebulizer assembly 40 located in the upper control section 20. The user loosens the pair of hose clamps 82 holding the vinyl hoses 80 to the top cover 50 of the enclosed reservoir 44 and slides the hose clamps 82 toward the other ends of the vinyl hoses 80. The vinyl hoses 80 are removed from the top cover 50 which is then removed from the ultrasonic nebulizer assembly 40 by removing the cover screws (not shown). The annular grommet 130 on the power cord 128 is unseated from the notch 138 and the spent ultrasonic nebulizer module 110 is disconnected from the power supply 144 by disconnecting the mating electrical connectors 132 and 140. The ultrasonic nebulizer module 110 is then removed from the main water reservoir 48 and discarded.
A new ultrasonic nebulizer module 110 is immersed in the water 46 within the main water reservoir 48 and the annular grommet 130 on the power cord 128 is seated in the notch 138. The top cover 50 is replaced and secured to the main water reservoir 48 through the cover screws (not shown) and the new ultrasonic nebulizer module 110 is then connected to the power supply 144 by connecting the mating electrical connectors 132 and 140. The vinyl hoses 80 are then reconnected to the top cover 50 through the pair of hose clamps 82.
In accordance with another aspect of the present invention, a timer reset micro-switch 180 (
Due to the immersible construction of the ultrasonic nebulizer module 110 as described in detail above, the user is not required to drain the main water reservoir 48 during replacement of the ultrasonic nebulizer module 110. If draining of the main water reservoir 48 is desired by the user for maintenance or other purposes, the user first disconnects the flexible tubing 96 from the water inlet/drain port 94 by manually actuating the quick disconnect fitting 106 as shown in
While the present invention has been illustrated by the description of an exemplary embodiment thereof, and while the embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicants' general inventive concept.
