These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
The present invention provides a light weight cover in the form of a bag assembly 10 for a gas cylinder 12 such as process gas cylinders employed in a clean room environment for the semiconductor industry. The invention provides protection for the clean room area from particulate contamination from the surface of the cylinder due to chipping or shedding of paint or other coating on the gas cylinder. The bag assembly includes a main body 20 constructed of non-particulating material that breaths to prevent condensation on the encapsulated cylinder. Fabric for the main body is a tight weave preventing egress of particulates through the fabric. Various embodiments of the invention employ Flouropolymer or polyester fabrics having porosities of approximately 4.0 CFM air transmission or less. Polytetraflouroethylene fabric such as Gore-Tex® has been demonstrated in exemplary embodiments of the invention. In certain embodiments, a B-FORE™ polyester material is employed. The main body is impregnated with carbon fibers. The natural conductivity of the fibers in the fabric is employed to enhance conductive properties of the bag for Electro-static Discharge (ESD) grounding. Exemplary surface resistivity of 107-108 ohms with a static decay of 0.01 sec is provided for the embodiments shown. A ESD contact button 26 secured to the bag assembly allows connection of a grounding lead.
Various color availability for certain embodiments of the invention allow for identification of the cylinder type enclosed in the bag. Conventional coloring consistent with standards for hazard identification may be employed.
A bottom boot 14 is provided as a portion of the bag assembly to increase abrasion resistance and provide increased durability when rolling an encapsulated cylinder as well as addition structural strength to support the cylinder. For the exemplary embodiments shown in the drawings, the boot is fabricated from durable rubber or polystyrene materials. An exemplary boot for the embodiments shown in the drawings employs hypalon adhered to polyester fabric typically employed in booties used for clean room personnel footwear. In various embodiments, the boot is attached to a circumferential opening 21 in the bottom of the main body while in alternative embodiments, the boot receives and encapsulates a contiguous bottom portion of the main body that is contoured to fit the gas cylinder. The embodiment shown in the drawings employs a simple contour for the external circumferential rim 15 of the boot. In alternative embodiments, an embossed ring or pad on the exterior circumference is employed for additional stability for the upright cylinder or to provide a rolling pad for the cylinder to enhance cylinder movement.
A tight cuff 16 of ESD compatible elastic knit cuff material is provided at the upper circumference of the main body of the bag to seal the bag to the neck of the cylinder at the regulator attachment boss. For exemplary embodiments, polyester knit materials comparable to those employed in clean room garment cuffs are employed. The cuff provides flexibility in the neck of the bag assembly to accommodate various neck boss configurations and manipulability to accommodate regulator attachment and protective cover removal while maintaining a seal in its normal configuration to prevent release of contaminants from inside the bag during use with a cylinder.
The main body of the bag incorporates a zipper 18 to allow easy installation and removal of the bag on the gas cylinder. A clean room approved, non-shedding, non-metallic, non-sparking zipper is employed in the embodiment shown. Alternative separation closure devices are employed on alternative embodiments.
For use with gas cylinders containing hazardous or flammable materials, the bag assembly incorporates transparent pockets 22 and 24 for diamond hazard placards 28 such as that shown in
For transport or storage of cylinders, a safety cap is typically employed to prevent damage to the valve or regulator on the cylinder. To provide particulate contamination protection from the safety cap, a hood 32 is provided as shown in
Stitching of seams in bag body and hood components employs sewing techniques applicable to clean room garments for prevention of contaminant egress through the seams.
Having now described the invention in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present invention as defined in the following claims.