Drying and gas or vapor contact with solids – Apparatus – Houses – kilns – and containers
Reexamination Certificate
2003-04-15
2004-06-01
Wilson, Pamela A. (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
Houses, kilns, and containers
C034S105000, C034S106000, C034S233000
Reexamination Certificate
active
06742276
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to drying devices, and, more particularly, to devices for drying plastic suits and similar items.
BACKGROUND
Many industries utilize plastic (i.e., synthetic material) environmental body suits, which are worn by workers for protection from hostile environments and/or substances, or for reducing contamination from the workers themselves in “clean rooms.” Because such suits are largely self-contained and closed to the outside environment when worn, and because the synthetic materials used to make the suits do not “breathe” or absorb liquids to much of an extent, the suits tend to become interiorly soiled from human sweat and grime. Accordingly, the suits have to be both washed and dried on the inside and outside after use.
For drying plastic environmental suits, it is possible to let the suits air dry at room temperature. However, a simple study performed by the applicants of the present application indicated that at 52% relative humidity (a typical value), a plastic suit took around 90 minutes to air dry. Accordingly, air drying is impractical for institutions that clean a significant number of plastic suits.
To decrease drying time, it is known to direct heated air into the plastic suits. However, the devices that have been heretofore used for such purposes (e.g., drying cabinets), have not decreased drying turnaround time to the extent desired by the industry. More specifically, plastic suits are rather convoluted, and existing driers are not optimized for delivering air into the plastic suits' “nooks and crannies.” This sometimes results in the suits not being completely dried. Moreover, existing driers do not apply heated air to the suits' cooling air channels (the air conditioning ducts in the walls of some environmental suits), and require a significant amount of time for suit changeover, i.e., to take one batch of suits out of the drying cabinet and insert the next batch of suits.
Accordingly, it is a primary object of the present invention to provide a drier for plastic environmental suits that significantly decreases the amount of time needed to completely dry the suits.
Another object of the present invention is to provide a plastic suit dryer that has quick changeover between one batch of suits and the next.
SUMMARY
A plastic suit drying system comprises: a fixed drying chamber; a mobile suit dryer cart or rack; and a compressed air warmer. The drying chamber is a cabinet with an interior accessible by front doors. For circulating air, a fan is located on top of the drying chamber. Air is guided to the fan by a fan intake plenum, which includes openings to the chamber interior, and to the outside via an intake filter. Additionally, a transition duct extends down the back of the drying chamber, and directs air from the fan output over a thermostatically-controlled heater positioned inside the transition duct and to a connection flange inside the cabinet that mates with a similar flange on the mobile rack. The mobile rack comprises: an air plenum (i.e., an enclosure with one air inlet and a plurality of air outlets for distributing heated air) mounted on four casters; thirty vertically-oriented, perforated air ducts or pipes that protrude from the top of the plenum (three for each suit); and a flanged air inlet or opening in the back of the plenum that mates with the connection flange on the fixed drying chamber. Through this flanged connection hot air is forced into the plenum and then into the perforated air ducts.
The compressed air warmer is fixed to a facility's existing compressed air distribution piping network. The compressed air warmer connects to individual plastic suits through a flexible hose manifold system (i.e., an array of ten hoses) having quick-release fittings that mate with similar, existing fittings on the plastic suits.
The plastic suit drying system works in a batch mode to dry wet plastic suits. Operation can be broken down into three cycles: a loading cycle, a drying cycle, and a cool-down cycle. In the loading cycle, the operator places each wet plastic suit upside down on one of the ten drying positions present on the mobile rack (each drying position includes three perforated air ducts: two that extend into the suit's legs, and a center duct that extends into the suit's torso). When all ten positions are filled, the mobile rack is rolled into the drying chamber so that the rack's flange mates with the drying cabinet's connection flange. Then, the operator connects the ten quick-release hoses from the compressed air warmer's manifold to the corresponding fitting on each plastic suit. The operator then closes the drying chamber doors, starts the drying cycle (via an electronic control), which turns on the fan and the low-pressure heater, and opens a valve that admits warmed compressed air into the hose manifold.
During the drying cycle, the fan draws outside air in through the filter until pressure builds up in the drying chamber, at which time the air is simply recirculated in the chamber. The fan blows air at low pressure down the transition duct, across the low-pressure heater, through the flanged opening, into the plenum of the mobile rack, and up into the air ducts extending up into the suits. High-pressure air from the facility's compressed air system is heated by the compressed air warmer, and is directed, via the hose manifold and hoses, into the suits' existing internal air distribution systems. The low-pressure air and the high-pressure air remove free water by a combination of sheer velocity and evaporation. Both air streams exhaust through the suit's “necks,” which are located near the bottom of the drying chamber because the suits are upside-down on the drying positions. This air, still warm, is then drawn by the fan back past the external surfaces of the garments, where additional drying occurs, and up into the fan intake plenum and into the fan.
For decreasing drying time, a moisture exhaust damper may be opened on the back of the transition duct. This causes moist air to exit the drying chamber and drier outside air to enter through the intake filter.
When the drying cycle is over, a cool-down cycle begins, during which the fan continues to run, but the heating elements are turned off. The cool-down cycle renders subsequent handling of the suits by the operators less stressful for both the operator and garments.
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Copy of Certified English Translation dated Mar. 10, 2003 of German EPO Patent No. EP 0 468 212 A1.
Anderson Kent D.
Case Les
Fuller Michael R.
Tardy Richard F.
Welcher, II David K.
Holland & Bonzagni, P.C.
Kramer, Esq. John A.
UniFirst Corporation
Wilson Pamela A.
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