Method of cleaning gas cylinders with supercritical fluids
US5440824A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 21, 1993 |
| Grant date | Aug 15, 1995 |
| Priority date | — |
| Expiry date | Sep 21, 2013 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB08B7/0021
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
The interior of a gas cylinder is cleaned using a supercritical fluid. A treating material, such as carbon dioxide, is injected into the cylinder, and the pressure in the cylinder is increased until the pressure of the treating material exceeds its critical pressure. Then, the cylinder is heated until the temperature of the treating material exceeds its critical temperature. The treating material therefore becomes a supercritical fluid. The treating material is maintained in its supercritical state while the cylinder is rolled for a period of time, while the supercritical fluid dissolves contaminants on the interior surface of the cylinder, and on objects within the cylinder. Then, the supercritical fluid is vented from the cylinder, preferably while the fluid in the cylinder is maintained in its supercritical state. This process provides exceptionally thorough cleaning of the interior of the cylinder, and makes it possible to provide a cylinder gas having a level of contaminants of the order of parts per billion or better.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.