Description:The present invention relates to the field of high-pressure gas storage systems, particularly to Type IV Composite Overwrapped Pressure Vessels (COPVs) incorporating polymeric liners. Specifically, it concerns a dome-shaped polymeric liner design that facilitates easy cleaning and ensures minimal residual contamination during manufacturing and boss assembly.

BACKGROUND OF THE INVENTION:
Type IV cylinders are commonly used for storage of compressed natural gas (CNG), hydrogen, and other gases. These cylinders comprise a polymeric liner overwrapped with carbon or glass fibers and fitted with metallic end bosses to secure valves.
During the production process, polymer liners are often contaminated with particles such as polymer chips, dust, or residuals from the molding and trimming processes. These contaminants can remain lodged inside the liner body, especially near the dome or neck region, and may lead to quality issues or internal damage during boss insertion, leakage, or long-term degradation.
Conventional , Claims:1. A polymeric liner for use in a Type IV composite overwrapped pressure vessel, the liner comprising:
 (a) a cylindrical body having a longitudinal axis;
 (b) a first dome-shaped end and a second dome-shaped end positioned on opposite ends of the cylindrical body;
 (c) a first open neck region at the apex of the first dome-shaped end and a second open neck region at the apex of the second dome-shaped end;
 wherein each dome-shaped end has a smooth, continuous internal curvature configured to enable unrestricted flow of a cleaning fluid from one neck to the other, thereby facilitating complete flushing and internal cleaning of the liner.
2. The polymeric liner according to claim 1, wherein the internal curvature of the dome-shaped ends is free from shoulders, abrupt transitions, or concave recesses, thereby reducing the risk of fluid stagnation and particle accumulation.
3. The polymeric liner according to claim 1, wherein the open neck regions are dimensioned to receive metallic end bosses for subsequent va