Safety notes for high purity gas equipment Rathenaustraße 55 63263 Neu Isenburg Phone 49 6102 7883 70 Fax 49 6102 7883 40 www hornung org info hornung org Contamination by air humidity when initially using the equipment or after changing a cylinder will be removed by multiple purging with changing pressures up to 10 bar increase relief using dry Nitrogen or other inert gases Contamination caused by inappropriate piping material or inappropriate valves and regulators can be avoided by the consequent use of control equipment with metal diaphragms gases with high purity the appropriate use of pipe work electropolished minimising of dead space usage of orbital welding techniques with Argon inert gas regular purging and conservation of the pipe work avoiding leaks by Helium leakage tests and the use of VCR fittings Automatic change over is recommended when a higher gas flow with frequently cylinder changes will be required an interruption of gas supply should be avoided or when over weekends the gas supply has to be guaranteed without any staff activities Dual stage regulators should be used if the operating pressure has to be absolutely stable even if the inlet pressure drops during discharging of cylinder or if the pressure has to be reduced from a high pressure level e g 200 300 bar to a very low pressure e g 1 bar When using liquefied gases it is sufficient in nearly all applications e g SF6 NH3 HCL CO2 and others to use the single stage pressure regulator because the vapour pressure of liquefied gases remains constant until the cylinder is nearly empty High purity pressure regulator will reach their limits because of the metallic elements flexibility of the metal diaphragm inside For operating pressure below 100 mbar in most of the cases a compromise has to be made between the quality of the gas and the control capabilities of the pressure regulator For analytical processes metal diaphragm or metal bellows components have to be used For toxic and corrosive gases or for calibration gases with contents of corrosive ingredients even in ppm or ppb areas a purging device is recommended A decentralized gas supply from single gas cylinders is useful if gas is needed temporarly or for a few hours If gases are needed continously it is recommended to use a centralized gas supply system A centralized gas supply system offers economical advantages if the same gas will be used at different points of use less cylinders less handling less renting costs less indoor transport more safety CONTAMINATION AND PREVENTION USE OF AUTOMATIC OR MANUAL CHANGE OVER SELECTION OF SINGLE OR DUAL STAGE CONTROL IN MBAR RANGES GAS PURGING EQUIPMENT CENTRALISED OR DECENTRALISED GAS SUPPLY

Vorschau Catalogue for high purity gas control equipment - Hornung GmbH (05-2021) Seite 201
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