CA2353298A1

CA2353298A1 - Pressure vessel

Info

Publication number: CA2353298A1
Application number: CA 2353298
Authority: CA
Inventors: Nick Chornyj
Original assignee: Failsafe Air Vest Corp
Current assignee: Failsafe Air Vest Corp
Priority date: 2001-07-19
Filing date: 2001-07-19
Publication date: 2003-01-19

Abstract

A protective over-wrap for a pressure vessel comprising a carbon composite thread and a liquid rubber, wherein the carbon composite thread is immersed in the liquid rubber and subsequently wound about the pressure vessel, and wherein the pressure vessel the said carbon composite thread and liquid rubber winding are then cured.

Description

PRESSURE VESSEL
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an over-wrap for pressure vessels, and in particular to an over-wrap for a fibre wound pressure vessels.
BACKGROUND
Pressure vessels are well known in the art. They are commonly used to store a variety of gasses at high pressure, and applications for these vessels include air canisters for breathing apparatus, fuel canisters for storing combustible gasses such as propane, or for storing gasses in industrial or laboratory settings.
One problem with pressure vessels is the weight of material required to store the gasses. To allow the vessel to store higher volumes of gasses, these gasses must be stored at higher pressures. In order to prevent failure of these pressure vessels they must be made of sufficient material to contain this pressure without rupturing and endangering those using the gasses. This material requirement causes the vessels to have a weight that becomes problematic when the vessels are used in portable applications such as SCUBA tanks, firefighting equipment, or oxygen tanks for those with respiratory difficulties.
One solution to this has been to create tanks with a thin metal liner surrounded by a filament-epoxy winding. This gives a better strength to weight ratio than all-metal tanks: An example of this type of vessel is taught by U.S. patent no.
5,287,987 to Gaiser.

However, filament-epoxy wound containers have several deficiencies. These vessels do have a good impact resistence capability, and are susceptible to rupturing if damaged. Further, rupturing of these vessels generally causes fragments to be propelled at high speeds, endangering those near the vessel.
Another problem with fibre-epoxy windings is that they do not withstand adverse environmental conditions very well. Exposure to caustic environments is possible, for example, in firefighting applications or in breathing devices designed for evacuation from chemical or industrial plants. These devices therefore need protection from the adverse environment.
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings of the prior art by providing a high strength flexible over-wrap for use on pressure vessels. Specifically, the present invention provides for the use of a carbon composite filament saturated with a liquid rubber compound which is wound around an existing pressure vessel and cured. In a preferred embodiment the carbon composite is KevlarT"".
The over-wrap of the present invention is used to add strength, impact resistance, explosion containment, and exposure protection to any existing pressure vessel.
Therefore, according to one aspect of the present invention there is provided a protective over-wrap for a pressure vessel comprising a carbon composite thread and a liquid rubber; wherein said carbon composite thread is immersed in said liquid rubber and subsequently wound about said pressure vessel, and wherein said pressure vessel with said carbon composite thread and liquid rubber winding are then cured.
According to a further aspect of the present invention there is provided a method of creating a protective over-wrap for pressure vessels comprising the steps of: saturating a carbon-composite thread in a liquid rubber compound; winding said saturated thread about said pressure vessel; and curing said pressure vessel and saturated thread; whereby said rubber and carbon composite thread comprise said protective over-wrap BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross-sectional plan view of a preferred embodiment of the present invention.
DETAILED DESCRIPTION
Reference is now made to Figure 1. This figure shows a pressure vessel 1 that is comprised of a liner 10 and a structural layer 20. These layers are well known in the art, and in general liner 10 is a metal layer to better contain a gas within pressure vessel 1. Structural layer 20 can be a carbon fibre / epoxy mixture, as disclosed in the background section above. This structural layer 20 ensures that the vessel can be inflated its preset pressure without rupturing.
In an alternative embodiment, liner 10 may not be necessary if structural layer 20 is comprised of stainless steel or aluminium. These materials provide enough containment and corrosion resistance to be used without a liner.

The present invention consists of an over-wrap layer 30 over structural layer 20. Over-wrap layer 30 is comprised of a carbon composite thread that is immersed in a liquid rubber. In a preferred embodiment the carbon composite thread consists of KevIarT""
The thread and rubber are then filament wound around the vessel to a predetermined thickness. In a preferred embodiment the winding is done using a computerized lathe in order to achieve a uniform thickness about pressure vessel 1.
Once the winding is complete, pressure vessel 1 with its over-wrap layer 30 are then cured to solidify over-wrap layer 30. Pressure vessel 1 is then ready to use.
Over-wrap 30 overcomes many of the disadvantages that pressure vessels currently have. In particular, due to the high strength of KevIarT"", the present over-wrap layer 30 will provide complete containment in the case of a failure of the pressure vessel. This will therefore protect those around the pressure vessel who could previously have been harmed or killed by high velocity fragments created by the failure of the pressure vessel.
Also, the rubber within the windings will create a better impact resistence for the pressure vessel, further protecting it. As is well known in the art, rubber will cushion any impact to the pressure vessel.
Still further, due to the rubber in the winding, the pressure vessel will better be able to withstand caustic environments without being damaged, ensuring greater safety for those dependent on the pressure vessel.
Also, due to the presence of the over-wrap, pressure vessel 1 can be pressurized closer to its maximum capacity. This will allow more gas to be stored within the pressure vessel.

Although the present invention has been described in detail with regard to the preferred embodiment thereof, one skilled in the art will easily realize that other versions are possible, and that the invention is only intended to be limited in scope by the following claims.

Claims

1. ~A protective over-wrap for a pressure vessel comprising:
a carbon composite thread; and a liquid rubber;
wherein said carbon composite thread is immersed in said liquid rubber and subsequently wound about said pressure vessel, and wherein said pressure vessel with said carbon composite thread and liquid rubber winding are then cured.

2. ~The protective over-wrap of claim 1 wherein said carbon composite thread is comprised of Kevlar TM.

3. ~A method of creating a protective over-wrap for pressure vessels comprising the steps of:
saturating a carbon-composite thread in a liquid rubber compound;
winding said saturated thread about said pressure vessel; and curing said pressure vessel and saturated thread;
whereby said rubber and carbon composite thread comprise said protective over-wrap.

4. The method of providing said protective over-wrap of claim 3 wherein said carbon composite thread is comprised of Kevlar TM.